Abstract:
An energy information management method for use with a circuit breaker coupled between a power source and a load, the method comprising the steps of: (a) sensing at least one of a voltage and a current flowing between the power source and the load through the circuit breaker; (b) counting a number of times the circuit breaker trips and interrupts the current flow between the power source and the load; (c) measuring the current flow through the circuit breaker when the circuit breaker trips and interrupts the current flow between the power source and the load; (d) determining a plurality of conditions of the circuit breaker; (e) accepting a user input, the user input for at least one of controlling the circuit breaker and displaying the plurality of conditions of the circuit breaker; (f) displaying at least one of the plurality of conditions of the circuit breaker responsive to the user input; and (g) communicating at least one of the plurality of conditions to a remote terminal.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention is directed to apparatus for monitoring and obtaining energy information in an electric power distribution system and in particular to a multiprocessor unit that provides circuit protection and extended monitoring and energy information features having a graphical display to display power related parameters in graphical form, and which may be controlled from a local control panel and/or a remote location using its communication features.  
         BACKGROUND OF THE INVENTION  
         [0002]    In certain factory power distribution systems, relatively high-voltage power (i.e. greater than 1,000 volts) provided by the power company generation station may be stepped down to lower voltage power using a transformer. The lower voltage power may then be distributed around the factory to various power equipment such as, motors, welding machinery and large computers. Such power a distribution systems of this type may be divided into branches, where each branch may supply power to a portion of the factory. The power distribution system is protected by installing low voltage fuses or circuit breakers in each branch so that a fault, such as a short circuit in a piece of equipment, supplied by one branch should not affect the power distributed to equipment coupled to the other branches. In addition to detecting large overcurrent conditions relating to short circuit faults, industrial circuit breakers may also detect long-time overcurrent conditions and excessive ground current. Relatively simple circuit breakers may be thermally tripped as a result of heating caused by an overcurrent condition, and is considered to be better for detecting relatively low level overcurrent conditions since it measures the cumulative heating effect of the low-level overcurrent condition over some time period. Such breakers may, however, respond too slowly to provide effective protection against high-current short circuit conditions.  
           [0003]    Another type of circuit breaker monitors the current level being passed through the branch circuit and trips the breaker when the current exceeds a predefined maximum value. Such circuit breakers may include a microcontroller coupled to one or more current sensors. The microcontroller continually monitors the digitized current values using a curve which defines permissible time frames in which both low-level and high-level overcurrent conditions may exist. If an overcurrent condition is maintained for longer than its permissible time frame, the breaker is tripped. Although this breaker type is believed to provide protection against both long-time and short time overcurrent conditions, if it does not calculate Root-Mean Square (RMS) current values, it may erroneously trip the circuit when a nonlinear load, such as a welding machine, is coupled to the branch that it is protecting. Nonlinear loads may produce harmonics in the current waveform. These harmonics may distort the current waveform, causing it to exhibit peak values which are augmented at the harmonic frequencies. When the microcontroller, which assumes a sinusoidal current waveform, detects these peaks, it may trip the circuit breaker even though the heating effect of the distorted waveform may not require that the circuit be broken or otherwise interrupted.  
           [0004]    Since the above described circuit breakers monitor overcurrent conditions, other types of faults such as over or under voltage conditions and phase imbalances may be missed unless or until they result in an overcurrent fault. Circuit protection for such faults may require special purpose line monitoring and relaying equipment, separate from the overcurrent breakers.  
           [0005]    Another issue with certain existing circuit breakers involves the time required to restore the branch to operation once the breaker has tripped. For transient faults, such as a power surge during an electrical storm, a technician must go onto the factory floor, locate the tripped breakers and reset them. Depending on the technician&#39;s experience and knowledge, this may take a few minutes or a few hours. In this instance, however, the delay may be reduced by using a circuit breaker with an automatic recloser.  
           [0006]    Faults caused by the equipment that is powered by the branch may be more difficult to locate. Certain circuit breakers may provide little if any information on the type of fault that caused the breaker to trip. Thus, the technician may need to install power monitors on each piece of equipment to determine if the fault was a long-time low-level overcurrent condition caused, for example, by a defective motor winding, or an intermittent short circuit fault. Such faults may take several days to locate and correct.  
           [0007]    Another issue with existing low-voltage circuit breaker systems concerns the lack of effective backup protection if the circuit breaker fails to trip. This is more of a concern with microcontroller based trip units than with the older thermal trip units. In general, effective backup protection may include a fuse, in series with the branch line, which blows at a short-circuit current slightly higher than the short-circuit current of the breaker. If the microcontroller or any of its associated circuitry fails, a lower-level overcurrent condition may damage the distribution system and/or the equipment being protected before the backup fuse is blown.  
           [0008]    Increasingly, the consumption of electrical power by a load is also monitored. Such power monitoring has been known at least since about the mid-1980s. As such, equipment manufacturers are increasingly using electronic circuit protection devices with circuit breaker units. These electronic circuit protection units may sample signals to provide various information, such as current, voltage, power factor, harmonics, kilowatt hours, var-hours, va-hours, instantaneous power, phase balance/imbalance, phase loading in relation to historical numbers and a percentage of maximum level. Moreover, these values may be stored to form a database.  
           [0009]    Such information was only available in alpha-numeric displays at the power meter or electronic trip unit. An example of a graphical display interface for displaying power information of an electronic circuit device is U.S. Pat. No. 5,675,745 issued to King et al. and assigned to Siemens Energy &amp; Automation, Inc., which is the assignee of the present application. Other forms of display were accomplished by down loading the relevant data to another computer either directly or in a network configuration.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention relates to an Energy Information Device (EID) for an Energy Information System and more specifically for the graphical interface generally for a circuit breaker which senses and measures voltage, current and frequency and determines a variety of conditions of the circuit breaker based on these measurements. The EID counts and stores the number of times the circuit breaker trips for any reason. The EID has a display to provide a combination of waveform and histogram displays to the user and a keyboard to allow the user to set a trip parameters and to control display modes. The EID also has a communications port for access of the measured parameters and conditions of the circuit breaker as well as control of the energy management unit through a remote terminal.  
           [0011]    According to yet another aspect of the invention, an energy information system for use with a circuit breaker coupled between a power source and a load, the energy information system comprising: sensing means for sensing at least one of i) a voltage, and ii) a current flowing between the power source and the load through the circuit breaker; detecting means for detecting transitions of a sensed voltage; counting means for counting a number of times the circuit breaker trips and interrupts the current flow between the power source and the load; measuring means for i) measuring the current flow through the circuit breaker when the circuit breaker trips and interrupts the current flow between the power source and the load and ii) determining a plurality of energy related parameters including a measure of at least one of the voltage, the current and the frequency based on an output from the detecting means, between the power source and the load; input means for accepting a user input, the user input controlling at least one of the circuit breaker and a display means; the display means for displaying at least one of the plurality of conditions of the circuit breaker responsive to the input means; and communication means coupled to the input means for selectively communicating at least one of the plurality of energy related parameters to a remote terminal.  
           [0012]    According to yet another aspect of the invention, the energy information system described above, wherein the counting means includes: a mechanical counter means for determining a first count value based on a total number of times the circuit breaker trips; an interruption level counter means for determining a second count value, the second count value indicating a current range flowing between the power source and the load when the circuit breaker trips; and a fault counter means for determining a third count value, the third count values indicating a count of a fault condition that trips the circuit breaker.  
           [0013]    According to yet another aspect of the invention, the energy information system described above, further comprising security means for selectively allowing access to control the energy information system.  
           [0014]    Still another aspect of the invention, the energy information system described above, wherein said security means is a password entered using said input means.  
           [0015]    Yet another aspect of the invention, the energy information system described above, wherein the sensing means further comprises: converting means for converting the voltage of the power source to a lower voltage; biasing means for biasing the lower voltage above a ground potential by a predetermined bias value to produce a full-wave biased voltage, wherein the measuring means processes the full-wave biased voltage to determine the plurality of conditions of the circuit breaker.  
           [0016]    According to yet another aspect of the invention, the energy information system described above, wherein the biasing means further comprises: a generating means for generating a stable reference voltage; and a buffer means coupled to the generator for buffering the stable reference voltage and generating the predetermined biased value.  
           [0017]    According to yet another aspect of the invention, the energy information system described above, wherein the sensing means has a voltage input range from about 50% to 125% of the voltage of the power source.  
           [0018]    According to yet another aspect of the invention, the energy information system described above, wherein the display means displays the plurality of conditions in one of a plurality of languages based on a user selection.  
           [0019]    According to yet another aspect of the invention, the energy information system described above, further comprising memory means for storing a date of manufacture of the circuit breaker.  
           [0020]    According to yet another aspect of the invention, the energy information system described above, wherein the date of manufacture is at least one of i) displayed on the display means and ii) sent to the remote terminal by the communication means.  
           [0021]    According to yet another aspect of the invention, the energy information system described above, wherein the plurality of energy related parameters includes at least one of i) an energy demand based on at least one of the current and the voltage sensed by the sensing means over a predetermined period of time and ii) a plurality of RMS parameters measured over a range of harmonics of a fundamental frequency of the power source.  
           [0022]    Still another aspect of the invention, the energy information system described above, wherein the predetermined period of time is between about 1 and 90 minutes, the period of time selectable by the user through at least one of the input means and the communications means.  
           [0023]    According to yet another aspect of the invention, the energy information system described above, wherein the demand is determined by calculating according to the following equation:  
             ∑     n   =   1       T   PRG            (         I   A     +     I   B     +     I   C       3     )         T   PRG       =   AmpDemand                         
 
           [0024]    where T PRG  is a programmable demand period, and I A , I B  and I C  are phase currents for phases A, B and C, respectively.  
           [0025]    According to yet another aspect of the invention, the energy information system described above, wherein the energy information system is adaptable for mounting within the circuit breaker.  
           [0026]    According to still another aspect of the invention, the energy information system described above, wherein the energy information system is field installable within the circuit breaker. According to yet another aspect of the invention, an energy information system for use with a circuit breaker coupled between a power source and a load, the energy information system comprising: a sensor to sense at least one of i) a voltage and ii) a current flowing between the power source and the load through the circuit breaker; a transition detector to detect transitions of a sensed voltage from the sensor; a counter coupled to the sensor to count a number of times the circuit breaker trips and interrupts the current flow between the power source and the load; a energy information controller coupled to the sensor and counter to measure the current flow through the circuit breaker when the circuit breaker trips and interrupts the current flow between the power source and the load and for measuring a plurality of related parameters, including a measure of at least one of the voltage, the current and the frequency based on an output from the transition detector; an input device coupled to the energy information controller to enter a user input for controlling at least one of the circuit breaker and a display; the display coupled to the energy information controller to display at least one of the plurality of power related parameters responsive to the user input; and a communication port coupled to the energy information controller to selectively communicate at least one of the plurality of power related parameters to a remote terminal.  
           [0027]    According to yet another aspect of the invention, the energy information system described above, wherein the counter further includes: a mechanical counter to determine a first count value based on a total number of times the circuit breaker trips; an interruption level counter to determine a second count value, the second count value indicating a current range flowing between the power source and the load when the circuit breaker trips; and a fault counter to determine a third count value, the third count value indicating a count of a fault condition indicative of a circuit breaker trip.  
           [0028]    According to yet another aspect of the invention, the energy information system described above, wherein the second count value is a plurality of count values of respective ranges of current flows, the ranges of current flows selected from the group consisting of i) the current flow being less about than 100% of a trip rating of the circuit breaker; ii) the current flow being between about 100% and 300% of the trip rating of the circuit breaker; iii) the current flow being between about 300% and 600% of the trip rating of the circuit breaker; iv) the current flow being between about 600% and 900% of the trip rating of the circuit breaker; and v) the current flow being greater than about 900% of the trip rating of the circuit breaker.  
           [0029]    Still another aspect of the invention, the energy information system described above, wherein the third count value includes at least one of the group consisting of: i) an overload fault count value; ii) a short time fault count value; iii) an instantaneous fault count value; and iv) a ground fault count value.  
           [0030]    According to yet another aspect of the invention, the energy information system described above, further comprising a security controller to selectively allow access to the energy information system by the input device.  
           [0031]    According to yet another aspect of the invention, the energy information system described above, wherein the sensor comprises: a voltage transformer to convert a line voltage of the power source to a voltage lower than the line voltage; and a voltage shifter to bias the lower voltage above a ground potential by a predetermined voltage to produce a full-wave biased voltage signal, wherein the energy information controller measures the full-wave biased voltage signal to determine the plurality of energy related parameters.  
           [0032]    Still another aspect of the invention, the energy information system described above, wherein the transition detector has a voltage input range from about 50% to 125% of the voltage of the power source.  
           [0033]    According to yet another aspect of the invention, the energy information system described above, wherein the communication port comprises at least one of an RS-232 communication port and an RS-485 communication port, each of the communication ports providing for upload and download of data between the remote terminal and the energy information controller.  
           [0034]    Yet another aspect of the invention, the energy information system described above, wherein the display displays the plurality of energy related parameters in one of a plurality of languages based on a user selection, the selection made through at least one of the input device and the communication port.  
           [0035]    According to still another aspect of the invention, the energy information system described above, further comprising a memory for storing a date of manufacture of the circuit breaker.  
           [0036]    According to yet another aspect of the invention, the energy information system described above, wherein the date of manufacture is at least one of displayed on the display and sent to the remote terminal through the communication port.  
           [0037]    According to yet another aspect of the invention, the energy information system described above, wherein the plurality of energy related parameters includes at least one of i) an energy demand based on at least one of the current and the voltage sensed by the sensor over a predetermined period of time and, ii) a plurality of RMS parameters measured over a range of harmonics of a fundamental frequency of the power source.  
           [0038]    According to still another aspect of the invention, the energy information system described above, wherein the range of harmonics includes up to at least about a 19th harmonic of the fundamental frequency.  
           [0039]    Yet another aspect of the invention, the energy information system described above, wherein the predetermined period of time is between about 1 and 90 minutes, the period of time selectable by the user through at least one of the input device and the communication port.  
           [0040]    According to yet another aspect of the invention, the energy information system described above, wherein the demand is determined by calculating according to the following equation:  
             ∑     n   =   1       T   PRG            (         I   A     +     I   B     +     I   C       3     )         T   PRG       =   AmpDemand                         
 
           [0041]    where T PRG  is a programmable demand period, and I A , I B  and I C  are phase currents for phases A, B and C, respectively.  
           [0042]    According to still another aspect of the invention, the energy information system described above, wherein the demand calculation is performed automatically about once a second.  
           [0043]    Still another aspect of the invention, the energy information system described above, wherein the energy information system is adaptable for mounting within the circuit breaker.  
           [0044]    Yet another aspect of the invention, the energy information system described above, wherein the energy information system is field installable within the circuit breaker.  
           [0045]    Yet another aspect of the invention, the energy information system for use with a circuit breaker coupled between a power source and a load, the energy information system comprising: a sensor to sense at least one of i) a voltage and ii) a current flowing between the power source and the load through the circuit breaker; a transition detector to detect transitions of a sensed voltage from the sensor; a voltage shifter coupled to the sensor to bias the voltage above a ground potential by a predetermined voltage to produce a full-wave biased voltage waveform; a counter to determine i) a first count value based on a total number of times the circuit breaker trips; ii) a second count value indicating a current range flowing between the power source and the load when the circuit breaker trips, the current range based on percentage of a trip rating of the circuit breaker; and iii) a third count value indicating a count based on a predetermined fault condition of the circuit breaker; an energy information controller coupled to the sensor, the counter, the transition detector and the voltage shifter, the energy information controller measuring i) the current flow through the circuit breaker when the circuit breaker trips and ii) the full-wave biased voltage waveform to determine the plurality of energy related parameters of the circuit breaker; an input device coupled to the energy information controller to enter a user input for controlling at least one of the circuit breaker and a display; a memory to store a date of manufacture of the circuit breaker; the display coupled to the energy information controller to display at least one of i) the plurality of conditions and ii) the date of manufacture of the circuit breaker responsive to the user input, the plurality of energy related parameters including a) an energy demand; and b) a plurality of RMS parameters measured over a range of harmonics of a fundamental frequency of the power source based on at least one of the voltage, the current and the frequency over a predetermined period of time, a security controller to selectively allow access of the energy information system by the input device; and a communications port including at least one serial communications port, the communications port coupled to the energy information controller to selectively communicate with a remote terminal; wherein the communication port provides for upload and download of data between the remote terminal and the energy information controller.  
           [0046]    Still another aspect of the invention, an energy information system mounted within a circuit breaker coupled between a power source and a load, the energy information system comprising: a sensor to sense at least one of i) a voltage and ii) a current flowing between the power source and the load through the circuit breaker, the sensor having a voltage input range from about 50% to 125% of the voltage of the power source; a voltage transformer to convert a line voltage of the power source to a voltage lower than the line voltage; a transition detector to detect transitions of a sensed voltage from said sensor and to generate a transition signal, said transition detector comprising: i) a filter having an input coupled to an output of the voltage transformer to filter an AC signal from the transformer; ii) a comparator coupled to the filter to compare a filtered output of the filter to a voltage; iii) an amplifier for amplifying an output of the comparator; and iv) an inverter for inverting an output of the amplifier and producing a signal representative of a frequency of the AC signal; a voltage shifter to bias the lower voltage above a ground potential by a predetermined voltage to produce a full-wave biased voltage waveform; a mechanical counter to determine a first count value based on a total number of times the circuit breaker trips; an interruption level counter to determine a second count value, the second count value indicating a current range flowing between the power source and the load when the circuit breaker trips, the interruption level counter includes a plurality of count values of respective ranges of current flows, the ranges of current flows selected from the group consisting of i) the current flow being less than about 100% of a trip rating of the circuit breaker; ii) the current flow being between about 100% and 300% of the trip rating of the circuit breaker; iii) the current flow being between about 300% and 600% of the trip rating of the circuit breaker; iv) the current flow being between about 600% and 900% of the trip rating of the circuit breaker; and v) the current flow being greater than about 900% of the trip rating of the circuit breaker; a fault counter to determine a third count value, the third count value indicating a count of a fault condition that trips the circuit breaker, the fault condition being at least one of: i) an overload fault;ii) a short time fault; iii) an instantaneous fault; and iv) a ground fault; an energy information controller coupled to the sensor, the transition detector, the interruption level counter, and the voltage shifter, the energy information controller measures i) the current flow through the circuit breaker when the circuit breaker trips and interrupts the current flow between the power source and the load, and ii) the full-wave biased voltage to determine a plurality of energy related parameters using an AC signal frequency based on the transition signal; a keypad coupled to the energy information controller to enter a user input, the user input for controlling at least one of the circuit breaker and a display; a memory to store a date of manufacture of the circuit breaker; the display coupled to the energy information controller to display at least one of i) the plurality of energy related parameters and ii) the date of manufacture, of the circuit breaker responsive to the user input, the plurality of energy related parameters including: a) an energy demand calculated according to the following equation:  
             ∑     n   =   1       T   PRG            (         I   A     +     I   B     +     I   C       3     )         T   PRG       =   AmpDemand                         
 
           [0047]    where T PRG  is a programmable demand period, and I A , I B  and I C  are phase currents for phases A, B and C, respectively and b) a plurality of RMS parameters measured over a range of harmonics of a fundamental frequency of the power source based on at least one of the voltage, the current and the frequency, over a predetermined period of time, the range of harmonics including up to at least about a 19th harmonic of the fundamental frequency; a security controller for selectively allowing access of the energy information system by the keypad; and a communication port including at least one of an RS-232 communication port and an RS-485 communication port, the communication ports coupled to the energy information controller to selectively communicate at least one of the plurality of energy related parameters and the date of manufacture to a remote terminal; wherein the communication ports provide for upload and download of data between the remote terminal and the energy information controller; the display displays the plurality of energy related parameters in one of a plurality of languages based on a user selection through at least one of the keypad and the communication port; and the energy information system is field installable within the circuit breaker.  
           [0048]    According to yet another aspect of the invention, an energy information device for use with a circuit breaker having a trip unit, the energy information device coupled between a power source and a load, the device comprising: a plurality of current sensors having an input coupled to respective ones of a plurality of power lines between the power source and the load; a plurality of transformers coupled between the respective ones of the plurality of power lines and an analog to digital converter (ADC); a transition detector having an input coupled to an output of one of the plurality of transformers; an override circuit coupled to an output of the plurality of current sensors, an input of a power supply and a first microprocessor; a trip circuit having a first input coupled to an output of the override circuit; the first microprocessor further coupled to a first programmable read only memory (PROM), a second input of the trip circuit, and a second microprocessor; and the second microprocessor further coupled to an output of the transition detector, an output of the ADC, a clock circuit, a second PROM and a random access memory (RAM).  
           [0049]    According to still another aspect of the invention, the energy information device described above, further comprising: a first digital input/output (I/O) interface coupled to the first microprocessor; and a second digital I/O interface coupled to the second microprocessor.  
           [0050]    Yet another aspect of the invention, the energy information device described above, further comprising a liquid crystal display (LCD) coupled to the second microprocessor.  
           [0051]    Still another aspect of the invention, the energy information device described above, further comprising a test connector coupled to the second microprocessor.  
           [0052]    According to yet another aspect of the invention, the energy information device described above, further comprising a rating plug coupled to the first microprocessor.  
           [0053]    According to yet another aspect of the invention, the energy information device described above, further comprising: a first signal conditioner coupled between the plurality of current sensors and the first microprocessor, and a second signal conditioner coupled between 1) the plurality of current sensors and the plurality of transformers and ii) the ADC.  
           [0054]    Yet another aspect of the invention, the energy information device described above, wherein the transition detector comprises: a filter having an input coupled to the output of one transformer to filter an AC signal from the transformer; a comparator coupled to the filter to compare a filtered output of the filter to a voltage; an amplifier for amplifying an output of the comparator; and an inverter for inverting an output of the amplifier and producing a signal representative of an AC signal frequency, wherein transition information is supplied to the second microprocessor based on the AC signal frequency.  
           [0055]    According to still another aspect of the invention, an energy information device described above for use with a circuit breaker having a trip unit, the energy information device coupled between a power source and a load, the device comprising: a signal conditioner coupled to a plurality of power lines between the power source and the load providing conditioned signals based on an input signal representative of a current flowing between the power source and the load; an override circuit coupled to an output of the signal conditioner; a filter coupled to a first output of the override circuit to filter the first output of the override circuit; a microprocessor coupled to an output of the filter; a memory coupled to the microprocessor; and a trip circuit coupled to an output of the microprocessor and a further output of the override circuit, and generating a trip signal for the trip unit based on at least one of i) the further output of the override circuit and ii) the output of the microprocessor.  
           [0056]    According to yet another aspect of the invention, the energy information device described above, further comprising a rating plug coupled to the microprocessor.  
           [0057]    According to still another aspect of the energy information device described above, wherein the input signal is a differential input signal and the override circuit converts the differential input signal into a single ended output signal.  
           [0058]    Still another aspect of the invention, an energy information device for use with a circuit breaker having a trip unit, the energy information device coupled between a power source and a load, the device comprising: a first amplifier coupled to a plurality of power lines between the power source and the load, providing first amplified signals based on a first input signal representative of a plurality of currents flowing between the power source and the load; a second amplifier coupled to the plurality of power lines between the power source and the load, providing second amplified signals based on a second input signal representative of a respective plurality of voltages provided by the power source to the load; a transition detector coupled to an output of the second amplifier to detect a transition of a voltage signal based on one of the plurality of voltages, and generating a transition signal used in determining a frequency of the voltage signal; a first analog-to-digital converter (ADC) coupled to an output of the first amplifier to generate a first digital output signal representative of the plurality of currents based on an offset value; a second ADC coupled to an output of the second amplifier to generate a second digital output signal representative of the plurality of voltages based on the offset value; an offset generator coupled to the first amplifier, the second amplifier, the first ADC and the second ADC, and generating the offset value; a first clock generator for generating a clock signal to control a sample timing of the first ADC and the second ADC; a microprocessor coupled to the first ADC and the second ADC, said microprocessor processing the first and second digital output signals of the first and second ADC, respectively; a second clock generator coupled to the microprocessor for generating a system time base; a first memory coupled to the microprocessor, the memory containing an executable program for the microprocessor; a second memory coupled to the microprocessor for storing data from and providing data to the microprocessor; and a communications port coupled to the microprocessor for remote access of the microprocessor.  
           [0059]    According to yet another aspect of the invention, the energy information device described above, wherein the transition detector comprises: a filter having an input coupled to one output of the second amplifier to filter the voltage signal based on one of the plurality of voltages from the second amplifier; a comparator coupled to the filter to compare a filtered output of the filter to a voltage; an amplifier for amplifying an output if the comparator; and an inverter for inverting an output of the amplifier and producing transition information relating to a voltage signal frequency, wherein the transition information is supplied to the microprocessor, which determines the voltage signal frequency.  
           [0060]    According to yet another aspect of the invention, the energy information device described above, wherein the communication port is at least one of an RS-232 port and an RS-485 port.  
           [0061]    According to yet another aspect of the invention, the energy information device described above, wherein the communication port is coupled to a remote computer.  
           [0062]    According to yet another aspect of the invention, an energy information management method for use with a circuit breaker coupled between a power source and a load, the method comprising the steps of: (a) sensing at least one of a voltage and a current flowing between the power source and the load through the circuit breaker; (b) counting a number of times the circuit breaker trips and interrupts the current flow between the power source and the load; (c) measuring the current flow through the circuit breaker when the circuit breaker trips and interrupts the current flow between the power source and the load; (d) determining a plurality of conditions of the circuit breaker; (e) accepting a user input, the user input for at least one of controlling the circuit breaker and displaying the plurality of conditions of the circuit breaker; (f) displaying at least one of the plurality of conditions of the circuit breaker responsive to the user input; and (g) communicating at least one of the plurality of conditions to a remote terminal.  
           [0063]    According to yet another aspect of the invention, the method described above, further comprising the steps of: (h) converting a line voltage of the power source to a voltage lower than the line voltage; and (i) biasing the lower voltage above a ground potential by a predetermined voltage to produce a full-wave biased voltage, wherein the plurality of conditions of the circuit breaker are determined from the full-wave biased voltage.  
           [0064]    According to still another aspect of the invention, an energy information management method for use with a circuit breaker coupled between a power source and a load, the method comprising the steps of: (a) sensing at least one of a voltage, and a current flowing between the power source and the load through the circuit breaker; (b) detecting at least two transitions of a sensed voltage and determining a corresponding frequency; (c) converting the voltage of the power source to a lower voltage, (d) biasing the lower voltage above a ground potential by a predetermined voltage to produce a full-wave biased voltage; (e) counting a number of times the circuit breaker trips and interrupts the current flow between the power source and the load; (f) measuring the current flow through the circuit breaker when the circuit breaker trips and interrupts the current flow between the power source and the load; (g) determining a plurality of conditions of the circuit breaker based on at least one of the voltage and the current sensed in Step (a), and for the frequency determined in step (b);(h) accepting a user input for controlling the circuit breaker; (i) displaying at least one of the plurality of conditions of the circuit breaker device responsive to the input accepted in Step (h); and (j) communicating at least one of the plurality of conditions to a remote terminal.  
           [0065]    According to yet another aspect of the invention, a method for graphically displaying a menu for selection and viewing of the load related parameters of a load connected to an AC load control device, comprising the steps of: (a) monitoring the load related parameters of the load connected to the AC load control device; (b) displaying on a graphical display device a menu of a plurality of indicia representing the monitored load related parameters; (c) scrolling through each indicia on said menu; and (d) selecting an item from said menu thereby causing the load related parameters relating to the said indicia to appear on said graphical display device as a signal representation.  
           [0066]    According to still another aspect of the invention, a method for graphically displaying a menu for selection and viewing of the load related parameters of a load connected to an AC load control device, comprising the steps of: (a) monitoring the load related parameters of the load connected to the AC load control device; (b) displaying on a graphical display device a menu of a plurality of indicia representing the monitored load related parameters; (c) scrolling through each indicia on said menu; and (d) selecting an item from said menu thereby causing the load related parameters relating to the said indicia to appear on said graphical display device in signal representation and histogram forms simultaneously.  
           [0067]    According to still another aspect of the invention, a graphical energy information display system having a menu for user selection of energy related information for an AC load control device, comprising: a device for monitoring AC electrical load usage of a load; a graphical display device connected to said device for monitoring AC electrical load usage, said graphical display device adapted so as to graphically display indicia and at least one parameter of the AC electrical load usage of the load said parameters being displayed as a signal representation; menu means for displaying a plurality of selections on said graphical display device, each of said plurality of selections representing at least one parameter of the AC electrical load usage; and menu selection means for selecting at least one of said plurality of selections so as to cause said graphical display device to graphically present the signal representing said at least one parameter of the AC electrical load usage associated with said selections.  
           [0068]    According to yet another aspect of the invention, a graphical energy information display system described above, wherein said menu means displays said indicia on said graphical display device in a hierarchical format.  
           [0069]    According to still another aspect of the invention, a graphical energy information display system described above, wherein said menu selection means comprises a user selectable keypad input for scrolling through said indicia displayed by said menu means onto said graphical display device, thereby enabling a user to select and view the said at least one parameter of the AC electrical load usage of a load.  
           [0070]    According to yet another aspect of the invention, a graphical energy information display system described above, wherein said user selectable keypad input comprises a touch input keypad.  
           [0071]    According to still another aspect of the invention, a graphical energy information display system described above, wherein said user selectable keypad input comprises a touch input device overlaid onto said graphical display device.  
           [0072]    According to yet another aspect of the invention, a graphical energy information display system described above, wherein said graphical display device comprises an LCD display.  
           [0073]    According to still another aspect of the invention, a graphical energy information display system described above, wherein said LCD display is at least 128 pixels square.  
           [0074]    According to yet another aspect of the invention, a graphical energy information display system described above, wherein said graphical display device comprises an Electrofluorescent display.  
           [0075]    According to yet another aspect of the invention, a graphical energy information display system described above, wherein the graphical display device simultaneously produces multiple corresponding power related signals representing the same parameter for a plurality of different indicia of the AC electrical load usage.  
           [0076]    According to still another aspect of the invention, a graphical energy information display system having a menu for user selection of energy related information for an AC load control device, comprising: a device to monitor AC electrical load usage of a load; a graphical display device connected to said device to monitor AC electrical load usage, said graphical display device adapted so as to graphically display indicia and at least one parameter of the AC electrical load usage of the load said parameters being displayed as a waveform; menu structure to display a plurality of selections on said graphical display device, each of said plurality of selections representing at least one parameter of the AC electrical load usage; menu selection structure to select at least one of said plurality of selections so as to cause said graphical display device to graphically present the power related signal representing said at least one parameter of the AC electrical load usage associated with said selections; and a circuit protective device to interrupt electrical power to the load responsive to said at least one parameter of the AC electrical load usage.  
           [0077]    According to yet another aspect of the invention, a graphical energy information display system described above, wherein said circuit protective device is a circuit breaker.  
           [0078]    According to still another aspect of the invention, a graphical energy information display system described above, wherein the graphical display device essentially simultaneously produces graphic images of the processed signals representing voltage and current by signal representations, and harmonics and phase balance in a histogram format.  
           [0079]    According to yet another aspect of the invention, a graphical energy information display system having a menu for user selection of energy related information for an AC load control device, comprising: a circuit protective device for interrupting electrical power to a load; means for monitoring AC electrical load usage of a load comprising a first means for controlling said circuit protective device and a second means for producing a plurality of signals representative of at least one of a current, a voltage and a power related characteristic of the load; menu means for displaying a plurality of indicia on a graphical display device, each of said plurality of indicia representing at least one parameter of the AC electrical load usage; menu selection means for selecting at least one of said plurality of indicia so as to cause the graphical display device to graphically present said at least one parameter of the AC electrical load usage associated with said indicia; and a graphical display device connected to said means for monitoring AC electrical load usage and adapted so as to graphically display at least one parameter of the AC electrical load usage of the load as a signal representation, said graphical display device comprising an energy information means connected to said second means for receiving and processing and storing said plurality of signals and for producing graphics related output image signals, and a display means connected to said energy information means and adapted to receive said graphics related output image signal for producing graphic images which are viewable by the user.  
           [0080]    According to still another aspect of the invention, a graphical energy information display system described above, wherein said graphical display device comprises an LCD display.  
           [0081]    According to yet another aspect of the invention, a graphical energy information display system described above, wherein said LCD display is at least 128 pixels square.  
           [0082]    According to yet another aspect of the invention, a graphical energy information display system described above, wherein said graphical display device comprises an Electrofluorescent display.  
           [0083]    According to yet another aspect of the invention, a graphical energy information display system described above, wherein the graphical display device simultaneously produces multiple corresponding signal representations representing the same parameter for a plurality of different indicia of the AC electrical load usage.  
           [0084]    According to yet another aspect of the invention, a graphical energy device simultaneously produces graphic images of the processed signals representing voltage and current by signal representations, and harmonics and phase balance in a histogram format.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0085]    [0085]FIG. 1A is a schematic diagram, partly in block diagram form of a power distribution system which includes a circuit breaker containing an embodiment of the present invention.  
         [0086]    [0086]FIG. 1B is a block diagram which illustrates the data communications interconnections of selected ones of the circuit breakers shown in FIG. 1A.  
         [0087]    [0087]FIG. 2A is a block diagram, partly in schematic diagram form of a portion of the circuit breaker suitable for use in the system shown in FIGS. 1A and 1B.  
         [0088]    [0088]FIGS. 2B and 2C are block diagrams of circuit boards, partly in schematic diagram form detailing the bus structure and interconnection of the components of FIG. 2A.  
         [0089]    [0089]FIG. 2D is a diagram showing the interconnection of the circuit boards detailed in FIGS. 2B and 2C.  
         [0090]    [0090]FIG. 3 is a drawing showing the interconnection of the EID of FIG. 2A and a trip unit.  
         [0091]    [0091]FIG. 4 is an exemplary front panel of one of the EID shown in FIGS. 2A.  
         [0092]    [0092]FIGS. 5A through 5D are representative graphs and histograms of the present invention.  
         [0093]    [0093]FIGS. 6A through 6F are various displays showing exemplary menu displays and an exemplary waveform display of the EID shown in FIG. 2A.  
         [0094]    [0094]FIGS. 7A through 7J are various displays of settings and conditions of the EID shown in FIG. 2A.  
         [0095]    [0095]FIGS. 8A and 8B are graphs of current versus time which are useful in describing the operation of the EID of FIG. 2A.  
         [0096]    [0096]FIG. 9A through 9C are perspective drawings which show the installation of the EID of FIG. 2A in a circuit breaker.  
         [0097]    [0097]FIG. 10 is a schematic of an exemplary transition detector of the EID of FIG. 2A.  
         [0098]    [0098]FIGS. 11A and 11B are flow charts outlining an exemplary Sampling Task of the present invention.  
         [0099]    [0099]FIG. 12 is a flow chart outlining an exemplary Initiate Sampling Task of the present invention.  
         [0100]    FIGS.  13 A- 13 C are flow charts outlining an exemplary Meter Task of the present invention.  
         [0101]    [0101]FIGS. 14A and 14B are flow charts outlining an exemplary LCD Scroll Task of the present invention.  
         [0102]    [0102]FIG. 15 is a flow chart outlining an exemplary Events Task of the present invention.  
         [0103]    [0103]FIG. 16 is a flow chart outlining an exemplary Keypad Task of the present invention.  
         [0104]    [0104]FIG. 17 is a flow chart outlining an exemplary Display Task of the present invention.  
         [0105]    [0105]FIG. 18 is a flow chart outlining an exemplary RS232 Task of the present invention.  
         [0106]    [0106]FIG. 19 is a flow chart outlining an exemplary RS485 Task of the present invention.  
         [0107]    [0107]FIG. 20 is a flow chart outlining an exemplary Transmit Message Task of the present invention.  
         [0108]    [0108]FIG. 21 is a flow chart outlining an exemplary SPI Message Task of the present invention.  
         [0109]    [0109]FIG. 22 is a flow chart outlining an exemplary Error Task of the present invention.  
         [0110]    FIGS.  23 A- 23 I are schematic diagrams of the Energy Information circuit board of the present invention.  
         [0111]    [0111]FIGS. 24A and 24B are schematic diagrams of the Protective circuit board of the present invention. 
     
    
     DETAILED DESCRIPTION  
     Overview  
       [0112]    [0112]FIG. 2A shows a dual processor circuit breaker and an energy information system, in which two processors are implemented using respective microprocessor circuits  214  and  222 . The Protective microprocessor  214  monitors the current flowing through the three-phase power lines  202   a ,  202   b  and  202   c  of an exemplary three-line system to detect overcurrent conditions and to trip the circuit breaker  116  (shown in FIG. 1A) immediately if a large overcurrent is detected or if a relatively small but sustained overcurrent is detected using a programmable delay time. In a four-line system a neutral power line is also available. In the following explanation, a four-line system will be assumed although a single phase system or a three-line multiphase system is equally applicable.  
         [0113]    The EID Protective microprocessor  214  monitors the potential developed across the power lines  202   a ,  202   b ,  202   c  and  202   n  and the current flowing through the power lines  202   a ,  202   b ,  202   c  and  202   n . From these values, the Protective microprocessor  214  calculates the power flowing through the lines and the frequency of the power signal. Based on these parameters, the Protective microprocessor  222  can trip the breaker, update a variety of stored parameters or change the state of an alarm output signal. An alarm signal may be used to actuate an alarm device, such as a light and/or a buzzer, or it may be used, through a trip unit  302  (shown in FIG. 3), to open the circuit breaker  116  (shown in FIG. 1A).  
         [0114]    The Energy Information/Communications microprocessor  222  is capable of logging minima and maxima for various monitored parameters, including the overcurrent conditions, also known as pickup events and trip events. Referring to FIG. 1B, a remote host computer  140  and/or personal computers (PC)  115 ,  117  and  119  may obtain the logged information. The computer  140  may be coupled to multiple trip units to obtain the continuing status of the electric power distribution system. As is shown in FIG. 4, much of the logged information may be monitored using a local front panel display unit. The host computer  140  and PCs  115 ,  117 ,  119  may also be used to control respectively the operation of the circuit breakers  114 ,  116 ,  118 .  
         [0115]    Referring to FIG. 2A, all input and output signals to and from the Energy Information/Communications microprocessor  222  and Protective microprocessor  214 , including the operational power signals, are electrically isolated from the outside circuitry to prevent damage to the trip unit circuitry.  
       Detailed Description of the Exemplary Embodiment of the Invention  
       [0116]    [0116]FIG. 1A is a simplified diagram of an electrical power distribution system. In FIG. 1, all of the power lines include three-phase lines and a neutral line, even though only one line is shown. FIG. 1A high voltage source  110 , which may be a power company substation, provides a relatively high voltage electrical signal to the primary winding of a transformer  112 . The secondary winding of the transformer provides, for example, three-phase low voltage to a factory power distribution system. The lower stepped-down voltage is distributed around the factory through respective step-down transformers  124 ,  126 ,  128  and  130  to provide power to equipment represented as respective loads  125 ,  127 ,  129  and  131 .  
         [0117]    The power distribution system is protected by multiple circuit breakers  114 ,  116 ,  118 ,  120  and  122 . In this configuration, the circuit breakers  116 ,  118 ,  120  and  122  each protect the system from faults occurring on a respective branch of the power distribution system. The circuit breaker  114  protects the transformer  112  from faults not handled by any of the other circuit breakers and from faults on the main distribution bus  113 .  
         [0118]    [0118]FIG. 1B schematically illustrates how the circuit breakers may be connected to the host computer  140  for monitoring the power distribution system. While only three of circuit breakers  114 ,  116  and  118  are shown in FIG. 1B, other circuit breakers may be connected to the host computer  140 . The host computer  140  may comprise an ACCESS™ electrical distribution communication system, available from Siemens Energy and Automation, Inc., connected to an RS-485 port of the circuit breaker. A standard PC  115 ,  117 ,  119  connected to another communications port of the circuit breaker may also be used.  
         [0119]    As shown, the host computer  140  is coupled to a display device  142  and a keyboard  144 . As set forth below, the host computer  140  may periodically poll each of the trip units, using a multi-drop line  141  such as an EIA-RS-485 line, to monitor the status of the power distribution system at the main bus and at each branch bus. In addition, the host computer  140  may issue commands to the various circuit breakers causing them to open or to change the levels at which pickup and trip events occur for certain parameters. As is further shown in FIG. 1B, each of the trip units  114 ,  116  and  118  may be coupled to respective PCs  115 ,  117  and  119  by a separate data communications port, such as an EIA-RS-232 communications port. The PC may be used to monitor the status and history of the circuit breaker it is connected to as well as issue commands to the circuit breaker causing it to open or to change the levels at which pickup and trip events occur for certain ones of the monitored parameters. These monitoring and control features are generally independent of those of the host computer  140 .  
         [0120]    [0120]FIG. 2A is a block/schematic diagram of the trip unit portion of an exemplary circuit breaker  116 . The circuit breaker is assumed to be the unit  116  which isolates its branch line from the main bus  113  as shown in FIG. 1A. The circuit breaker includes the Protective microprocessor  214  for implementing the overcurrent protection functions of the circuit breaker and the Energy Information/Communications microprocessor  222  for implementing data communications features and monitors certain parameters and conditions and for providing display and input control functions. The Protective microprocessor  214  includes an 68HC11 microcontroller (available from Motorola), that is connected to a Programmable Read Only Memory (PROM)  216 . The PROM  216  stores program and fixed-value data.  
         [0121]    Electrical current flowing through the three-phase lines  202   a ,  202   b , and  202   c  and the neutral line  202   n  is sensed by four current transformers  204   a ,  204   b ,  204   c  and  204   n . In the present embodiment, the current transformers  204   a ,  204   b ,  204   c  and  204   n  provide power for the circuit protection features. Current induced in the secondary winding of each current transformer is coupled to the  
         [0122]    Energy Information Device(EID)  200  of circuit breaker  116  through current inputs  254 . These currents are then conditioned by signal conditioner  210  and provided to Protective microprocessor  214 .  
         [0123]    The current transformers  204  supply operational power when the external power supply is not on. When the external power supply  226  is on, it supplies power to both the Protective microprocessor  214  and Energy Information/Communications microprocessor  222 . As shown in FIGS. 2A and 2B, the secondary windings of the transformers  204   a ,  204   b ,  204   c  and  204   n  are coupled to power supply  208  of the Protective microprocessor  214 . External control power required for Energy Information, communication and protective relaying functions is provided by external power supply  226 . Fail-safe protection is provided by overcurrent circuit  256  which is connected to trip circuit  212 . Trip circuit  212  is used to trip the contactor portion (not shown) of circuit breaker  116  under control of either override circuit  256  or Protective microprocessor  214 .  
         [0124]    If during current monitoring, the Protective microprocessor  214  detects a large overcurrent condition indicative of a short circuit condition, or a smaller overcurrent condition persisting for longer than a predefined time interval, the Protective microprocessor  214  activates the trip circuit  212 , which activates trip solenoid  302  of FIG. 3 to break the connection between the branch lines  202   a ,  202   b  and  202   c  and the main bus  113 .  
         [0125]    Referring to FIG. 4, a front panel  400  of EID  200  has a keypad  244  for setting the pickup and trip levels used for primary overcurrent protection through a menu system (shown in Table V below). As set forth above, a pickup level is an overcurrent condition which may cause the trip unit to trip the circuit breaker, either after a delay (depending on the level) or instantaneously for relatively large overcurrent conditions. The configuration of the keypad  244  is described below with reference to FIG. 4.  
         [0126]    As shown in FIG. 2C, a Real-Time-Clock (RTC)  234  is used as a time stamp for Energy Information/Communications microprocessor  222  and for keeping time within the energy information system. In the present embodiment, RTC  234  is a DS1283S available from Dallas Semiconductor Corp.  
         [0127]    Referring to FIG. 4, the Energy Information/Communications microprocessor  222  is coupled to the front panel  400  of the EID  200 . The Energy Information/Communications microprocessor  222  indicates on the front panel  400  the event type, which caused the trip, by illuminating the appropriate LED display.  
         [0128]    In the present embodiment, the Energy Information/Communications microprocessor  222  can activate three light emitting diodes  402 ,  404 ,  422  (LEDs) on front panel  400 . LED  402  is activated when a trip event occurs and LED  404  is activated when an alarm condition occurs. Trip events and alarm conditions are outlined below. The status of the current, voltage and frequency is monitored by the EID. As described below, various results of this monitoring are available for display within the display area  406  on the front panel  400 .  
         [0129]    The Computer Operating Properly (COP) watchdog timer (not shown) continually monitors the status of the Protective microprocessor  214 . The exemplary watchdog timer must be written to by the Protective microprocessor  214  at regular intervals. If it fails to be written to within the expected time interval, code is invoked that:1) turns off the Protective System Check LED; (2) turns on the Protective microprocessor&#39;s Alarm line to indicate a system failure has occurred; (3) continues to provide a simplified type of over current protection such that if the instantaneous peak value of any phase current exceeds 130% of nominal, the breaker is tripped.  
         [0130]    The Protective System Check LED  240 , activated by the Protective microprocessor  214 , and the Metering System Check LED  422 , activated by the Energy Information/Communications microprocessor  222 , provide “heartbeat” signals which provide a visual indication of the health of the respective microprocessors. In the exemplary embodiment, these LEDs flash when the respective microprocessors are operating normally.  
         [0131]    In the present embodiment, the display area  406  is a liquid crystal display (LCD) which may display power related signals, histograms and alphanumerics representing user selected information on the status of the circuit breaker  116 . The display area  406  is a 128 by 128 monochrome pixel display. Of course, other sizes may be used as well as the use of color and the like. Further, the display area  406  may also be electrofluorescent or any other suitable display type. As shown in FIGS. 5A to  5 D, the types of signals  502 ,  504  may be voltage and/or current for any or all phases of the power system. Histograms  506 ,  508  may also be displayed to present information such as frequency harmonics, phase balance, pickups and delays, and other information. The alphanumerics display may provide an indication of current draw, phase voltage, phase angle, power factor, power consumption and other information.  
         [0132]    The signals and histograms may be separately or commonly displayed in any combination as selected by the user. Information to be displayed is selected using a menu system available to the user by the display area  406 . Selections are made using the keypad  244 . The menu system may also provide for housekeeping items such as contrast adjustment for the LCD display. This is accomplished by having the appropriate menu appear on the screen and using the Up or Down keys to adjust the contrast. It has been found that adjustable contrast in an electronic trip unit is a desirable feature due to the variety of lighting environments in which circuit breakers are installed. The details of the menu system are described below with reference to Table V.  
         [0133]    Referring to FIG. 2A, The Energy Information/Communications microprocessor  222  and Protective microprocessor  214  are interconnected by data path  258  in a master-slave relationship with Protective microprocessor  214  acting as the master. Communications between microprocessors  214  and  222  are based on a fixed length messages of 32 bytes each using an interrupt scheme initiated by Energy Information/Communications microprocessor  222 . Information, such as an indication that a long-time pickup event has occurred or that a trip event has occurred, are sent from Protective microprocessor  214  to Energy Information/Communications microprocessor  222  for display on the display  240  and/or communication to an external system, such as host computer  140  (FIG. 1B).  
         [0134]    Referring again to FIG. 4, keypad  244  includes switches  408 ,  410 ,  412  and  414  for setting the various set points such as for instantaneous trip and display modes of the breaker  116  through the menu system displayed in display area  406 . For example, current is specified as a multiple of the rated current of the current sensors  204  (FIG. 2A). In the present embodiment, the current may be set to between twice and fifteen times the rated current of the sensor. When a Menu screen is displayed. The Up switch  408  moves the display cursor (not shown) upward in the menu list. The Down switch  410  moves the display cursor downward in the menu list. The Enter switch  412  selects the highlighted menu item and takes the user to that next lower level in the menu hierarchy. The Escape switch  414  moves the user up to the next higher level in the menu hierarchy.  
         [0135]    When a Setting screen is displayed, the UP switch  408  increases the setting level. The Down switch  410  decreases the setting level. The Enter switch  412  moves to the next setting displayed on the screen (if more than one setting is displayed). The action of the Escape switch  414  depends on whether the user has changed a setting while a Setting screen is displayed. If no setting is changed, pressing Escape moves the user up to the next higher level in the menu hierarchy. If a setting is changed, pressing Escape causes a screen to be displayed that instructs the user to press Enter to accept and implement the change or press Escape to the reject change. When one or the other of these switches is pressed, the user is then moved up to the next higher level in the menu hierarchy. The ground fault trip parameters are also selected using the menu system. In the present embodiment, the ground-fault pickup may be set to no less than 20% and no more than 100% of the rated current of the breaker. The actual setting range allowed varies with the current rating of the specific breaker. The time delay before trip can be set to between 0.1 seconds and 0.5 seconds.  
         [0136]    In addition to the display area  406 , switches  408 ,  410 ,  412 ,  414 , the front panel  400  includes a connector  416  which may be used by the Energy Information/Communications microprocessor  222  to implement data communications with the PC using a EIA-RS232 communications protocol, and a connector  418  as a maintenance and test point to diagnose internal conditions of the EID  200 . Referring to FIG. 9B, a rear connector  702  couples the EID  200  to the circuit breaker  116  using connector  704  which in turn uses a connector (not shown) to connect the Energy Information/Communications microprocessor  222  to the host computer  140  to implement data communications using a EIA-RS485 communications protocol.  
         [0137]    Referring again to FIG. 2A, the Energy Information/ Communications microprocessor  222  includes a 68HC16Z1 microcontroller available from Motorola, Inc. and a memory. This memory includes an external programmable read-only memory (PROM)  238 , which is used to store the program instructions and a random access memory (RAM)  236  which are external to the microcontroller. In the present embodiment, the PROM  238  is a pair of 27C010 integrated circuits and the RAM  236  is a pair of 62256 integrated circuits.  
         [0138]    The Energy Information/Communications microprocessor  222  possesses both communications and monitoring capability and features. In addition to monitoring the current flowing through the lines, the Energy Information/Communications microprocessor  222  obtains the current and voltage of the three phase lines to monitor demand, power, energy and imbalances among the three phases. Voltage on one phase is used to obtain frequency information.  
         [0139]    Data on the current and voltage flowing through the lines  202   a ,  202   b ,  202   c  and  202   n  is collected by an analog-to-digital converter (ADC)  232  which is coupled to the current sensors  204 . In addition, the ADC  232  is coupled through signal conditioner  230  to a potential transformer  206  which provides a measure of the voltage at each of the three phases. Signal conditioner  230  biases the voltage from transformers  206  and the current from transformers  204  above ground by an amount sufficient to result in a full-wave biased voltage. ADC  232  comprises a pair of ADC12048 12-bit ADCs manufactured by National Semiconductor and are coupled in parallel to Energy Information/Communications microprocessor  222  using bi-directional octal buffers (not shown). ADC  232  provides instantaneous samples of the current signals and voltage signals. The microcomputer  222  controls the ADC  232  to determine which sample to provide at any given time. Of course, it is believed that sigma-delta converters may also be used, as has been known since at least about the mid-1980&#39;s.  
         [0140]    As set forth above, the Energy Information/Communications microprocessor  222  has two substantially independent communication ports. One port is a dedicated EIA-RS-485 communications port  246  that is coupled to the host computer  140 , and the other is an EIA RS-232 port  248  through which the Energy Information/Communications microprocessor  222  may be coupled to PC  117 . Both ports  246  and  248  include conventional opto-isolators to prevent any electrical connection between the Energy Information/Communications microprocessor  222  and the host computer  140  or the PC  117 . The Protective microprocessor  214  is also configured with an output line to the trip circuit  212 . This allows Protective microprocessor  214  to trip the circuit breaker  116 .  
         [0141]    [0141]FIGS. 2B, 2C and  2 D provide a more detailed view of the interconnection of elements described above with respect to FIG. 2A. FIG. 2B shows the details of the protective board  298 . FIG. 2C shows the details of the metering board  299 . FIG. 2D shows the details of the interconnection between protective board  298 , metering board  299  and certain other components of circuit breaker  116 .  
         [0142]    Referring to FIG. 2B, Protective microprocessor  214  uses an eight-bit data bus and sixteen-bit address bus  272 . The eight-bit data bus  270  and sixteen-bit address bus  272  are connected to PROM  216  Protective microprocessor  214  accesses PROM  216  using select line  274 . In the present embodiment, rating plug  218  uses four bits of the eight-bit data bus. The data from the rating plug  218  is accessed by Protective microprocessor  214  using select line  276 . The select lines  274  and  276  are controlled by Protective microprocessor  214 .  
         [0143]    The current signals I A , I B , I C , and I N  from transformers  204  are provided through connector  702 A (part of connector  702  mentioned above) to signal conditioner  210 , Protective microprocessor power supply  208 , and Energy Information/Communications board  299 . The conditioned current signals (I A ′, I B ′, I C ′, and I N ′), are provided to override circuit  256 . The power supply generates voltage from the current signals I A , I B , I C , and I N  and supplies this voltage to trip circuit  212 . Trip circuit  212  is also provided with override trip signal  284  from override circuit  256  and microprocessor trip signal  286  from Protective microprocessor  212 . These signals are used to activate the trip solenoid (not shown). Override circuit  256  converts the current signals (I A ′, I B ′, I C ′, and I N ′) from differential signals to single ended signals and produces a differential current sum signal I S ′. These signals are provided to filter  282  which low pass filters the current signals to remove high frequency noise. The filtered current signals I A ″, I B ″, I C ″, I N ″, and I S ″ are then provided to Protective microprocessor  212 .  
         [0144]    Referring now to FIGS. 24A and 24B the details of the interconnection of elements of the protective board  298  are explained. Referring to FIG. 24A, the IA+ signal is provided to one end of capacitor  2602 , the anode of diode  2606 , and the cathode of diode  2604 . The IA− signal is provided to the other end of capacitor  2602  and one end of resistor  2608 . The other end of resistor  2608  is connected to the cathode of diode  2610  and the anode of diode  2612 . The cathode of diode  2606  is connected to the cathode of diode  2612  the REF input of circuits  2624 ,  2626 , and  2628 , and the anode of diode  2618  and the source of transistor  2620 . The anode of diode  2604  is connected to one end of the resistor  2614  and the IA+ input of circuit  2622 . The anode of diode  2610  is connected to one end of resistor  2616  and the IA− input of circuit  2622 . The other end of resistors  2614  and  2616  are connected to ground.  
         [0145]    Circuits  2624 ,  2626  and  2628  are identical to the circuits described above. Therefore, a detailed explanation of these circuits is not provided for simplicity. Circuit  2624  interfaces to the phase B current source, circuit  2626  interfaces to the phase C current source and circuit  2628  interfaces to the neutral current source respectively. Inputs IA+ and IA−, IB+ and IB−, IC+ and IC−, and IN+ and IN− are provided from connector  702  and are also connected to respective pins of connector  295 B. Similar to the inputs IA+ and IA− to circuit  2622  described above, the-outputs of circuits of  2624 ,  2626 , and  2628  are connected to the IB+, IB−, IC+, IC−, IN+ and IN− inputs of circuit  2622 , respectively.  
         [0146]    The VOR input of circuit  2622  is connected to one end of resistor  2694  and one end of resistor  2696 . The other end of resistor  2694  is connected to the +5 volts supply (not shown) and the second end of resistor  2696  is connected to ground. The gate of transistor  2620  is connected to one end of resistor  2630 , one end of capacitor  2632 , the cathode of zener diode  2634 , the anode of zener diode  2636 , and the FG input of circuit  2622 . The drain of transistor  2620  is tied to the other end of resistor  2630 , the other end of capacitor  2632 , the anode of diode  2634  and ground. The cathode of diode  2618  is connected to the cathode of zener diode  2636 , the positive input of capacitor  2638 , one end of resistor  2644 , the collector of transistor  2640 , the cathode of diode  2668 , and pins  9  and  5  of connector  702  (shown in FIG. 9B). The emitter of transistor  2640  is connected to the BJT input of circuit  2622 . The base of transistor  2640  is connected to the cathode of diode  2642 . The anode of diode  2642  is connected to the second end of resistor  2644  and the anode of diode pair  2648 . One cathode of diode pair  2648  is connected to the anode of diode  2672 , the cathode of diode  2674 , the anode of SCR  2662 , one end of capacitor  2603 , and one end of switch S 1   2664 . The second cathode of diode pair  2648  is connected to the anode of diode  2668 , the cathode of diode  2672 , one end of MOV  2676 , the anode of SCR  2656 , one end of capacitor  2601 , and pin  13  of connector  702 . The UT output of circuit  2622  is connected to one end of resistor  2650 . The second end of resistor  2650  is connected to one end of resistor  2652 , one end of capacitor  2654 , and the gate of SCR  2656 . The SG output of circuit  2622  is connected to the cathode of zener diode  2625 , one input of OR gate  2686 , and one end of resistor  2678 . The RST output of circuit  2622  is connected to the cathode of diode  2627  and the reset input of microprocessor  214 . The anode of diode  2627  is connected to the second input of OR gate  2686 , one end of resistor  2680 , one end of resistor  2670 , and the PA 7  input of microprocessor  214 . The second end of resistor  2670  is connected to one end of resistor  2658 , one end of capacitor  2660 , and the gate of SCR  2662 . The cathode of SCR  2656  is connected to the cathode of SCR  2662 , the second end of resistor  2652 , the second end of capacitor  2654 , the second end of resistor  2658 , the second end of capacitor  2601 , the second end of capacitor  2660 , the second end capacitor  2603 , the second end and case of switch  2664 , and ground. The second end of zener diode  2625  is connected to ground. The second end of resistor  2678  is connected to one anode of diode pair  2682 . The second end of resistor  2680  is connected to the second anode input of diode pair  2682 . The cathode of diode pair  2682  is connected to one end of resistor  2684 , and pin  1  of connector  296 . The other end of resistor  2684  is connected to ground. The anode of diode  2674  is connected to the second end of MOV  2676  and pin  17  of connector  702 . The output of OR gate  2686  is connected to one end of resistor  2688 . The second end of resistor  2688  is connected to one end of capacitor  2690  and pin  1  of connector  702 . The second end of capacitor  2690  is connected to ground. The second end of capacitor  2638  is connected to ground. The GS output of circuit  2622  is connected to one end of resistor  2692  and the PG 0  output of microprocessor  214 . The second end of resistor  2692  is connected to ground.  
         [0147]    The IA output of circuit  2622  is connected to one end of filter  2629 . The second end of filter  2629  is connected to the AN 0  input of microprocessor  214 . The IB output of circuit  2622  is connected to one end of filter  2631 . The second end of filter  2631  is connected to the AN 1  input of microprocessor  214 . The IC output of circuit  2622  is connected to one end of filter  2633 . The second end of filter  2633  is connected to the AN 2  input of microprocessor  214 . The IN output of circuit  2622  is connected to one end of filter  2635 . The second end of filter  2635  is connected to the AN 3  input of microprocessor  214 . The ISUM+ output of circuit  2622  is connected to one end of filter  2639 . The second end of filter  2639  is connected to the AN 6  input of microprocessor  214 . The ISUM− output of circuit  2622  is connected to one end of filter  2637 . The other end of filter  2637  is connected to the AN 7  input of microprocessor  214 . The AN 4  input of microprocessor  214  is connected to pin  21  of connector  296 . The AN 5  input of microprocessor  214  is connected to pin  19  of connector  296 . Pin  19  of connector  702  is connected to one end of resistor  2702  and one end of resistor  2704 . A second end of resistor  2702  is connected to a 10 volt power source (not shown). Pin  14  of connector  702  is connected to the anode of zener diode  2706 , and to ground. The cathode of zener diode  2706  is connected to the second end of resistor  2704  and the PA 0  input of microprocessor  214 . The VRH input of microprocessor  214  is connected to the first end of resistor  2710 , the first end of resistor  2708 , and the first end of capacitor  2712 . The second end of resistor  2708  is connected to the digital voltage supply. The second end of capacitor  2712  is connected to second end of resistor  2710  and to ground. Pin  28  of connector  702  is connected to one end of resistor  2714  and pin  10  of connector  295 . The second end of resistor  2714  is connected to the YA input of buffer  2720 . Pin  35  of connector  702  is connected to one end of resistor  2716  and pin  20  of connector  295 . The second end of resistor  2716  is connected to the YB input of buffer  2720 . Pin  36  of connector  702  is connected to one end of resistor  2717  and pin  18  of connector  295 . The second end of resistor  2717  is connected to the YC input of buffer  2720 . Pin  4  of connector  702  is connected to one end of resistor  2718 . The second end of resistor  2718  is connected to the YD input of buffer  2720 . Pin  32  of connector  702  is connected to one end of resistor  2722  and pin  12  of connector  295 . The second end of resistor  2722  is connector A input of buffer  2730 . Pin  30  of connector  702  is connected to one end of resistor  2724  and pin  14  of connector  295 . The second end of resistor  2724  is connected to the B input of Buffer  2730 . Pin  31  of connector  702  is connected to one end of resistor  2726  and pin  18  of connector  295 . The second end of resistor  2726  is connected to the C input of buffer  2730 . The OE input of buffers  2720  and  2730  are connected to ground. The A, B, C, D outputs of buffer  2720  are connected to the TXD, PA 6 , PA 5  and PA 4  inputs of microprocessor  214 , respectively. The YA, YB, YC, and YD outputs of buffer  2720  are connected to the RXD, PA 3 , PA 2  and PA 1  inputs of microprocessor  214  respectively.  
         [0148]    The A 0 -A 15  outputs of microprocessor  214  are connected to PROM  216 . The A 0  address line is further connected to the A input of selector  2768  and pin  11  of connector  2766 , the A 11  address line is further connected to the B input of selector  2768  and pin  9  of connector  2766 . The A 2  address line is further connected to pin  7  of connector  2766 . The A 8 , A 9 , A 10  and A 11  address lines are further connected to the A, B, C and G 2 B inputs of selector  2732  respectively. The A 13  address line is connected to an input of NAND gate  2734 . The A 12 , A 14  and A 15  address lines are further connected to respective inputs of OR gate  2738 . The output of NAND gate  2734  is connected to the G 2 A input of selector  2732 . The output of OR gate  2738  is connected to both inputs of NAND gate  2736 . The output of NAND gate  2736  is connected to the G 1  input of selector  2732  and the CE input of PROM  216 . The ECLK output of microprocessor  214  is connected to the OE input of PROM  216  and a second input of NAND gate  2734 . The D 0 -D 7  databus is output from microprocessor  214  and connected to the D 0 -D 7  input of PROM  216 , the B 1 -B 8  input of buffer  2764 , and pins  10 ,  8 ,  6 ,  4 ,  3 ,  5 ,  7  and  9  of connector  296  respectively. Data lines D 0 , D 1 , D 2  and D 3  are further connected to inputs YA, YB, YC and YD of buffer  2746  respectively. The Y 1  output of selector  2732  is connected to OE input of buffer  2746  and pin  16  of connector  296 . The Y 2 , Y 3  and Y 4  outputs of selector  2732  are connected to pins  18 ,  20 , and  22  of connector  296 , respectively. The Y 5  output of selector  2732  is connected to both inputs of NAND gate  2740 , the G input of selector  2768  and pin  3  of connector  2766 . The output of NAND gate  2740  is connected to an input of OR gate  2742 . The second input of OR gate  2742  is connected to the PG 5  output of microprocessor  214  and pin  18  of connector  2766 . The output of OR gate  2742  is connected to both inputs of NAND gate  2744 . The output of NAND gate  2744  is connected to the OE input of buffer  2764 . The RAN output of microprocessor  214  is connected to the DIR input of buffer  2764  and to the D input of buffer  2770 .  
         [0149]    The A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , A 7  and A 8  outputs of buffer  2764  are connected to pins  19 ,  17 ,  15 ,  13 ,  2 ,  4 ,  6  and  8 , respectively of connector  2766 . The MODB output of microprocessor  214  is connected to pin  5  of connector  2766 . The SS output of microprocessor  214  is connected to pin  20  of connector  295 . The SCK output (SCLK signal) from microprocessor  214  is connected to pin  24  of connector  295 A. The MOSI output of microprocessor  214  is connected to one end of resistor  2781 . The second end of resistor  2481  is connected to pin  16  of connector  295 A. The MISO output of microprocessor  214  is connected to one end of resistor  2783 . The second end of resistor  2783  is connected to pin  18  of connector  295 A. The PG 1  signal is connected between microprocessor  214  and the COOL input of circuit  2622 . The PG 2  output of microprocessor  214  is connected to pin  11  of connector  296 . The PG 3  output of microprocessor  214  is connected to pin  13  of connector  296 . The PG 4  signal is connected between microprocessor  214  and pin  15  of connector  296 . The IRQ signal is connected between the microprocessor  214  and pin  14  of connector  295 A. The XTAL input of microprocessor  214  is connected to a first end of resistor  2774 , a first end of crystal  2772 , and a first end of capacitor  2778 . The EXTAL input of microprocessor  214  is connected to the second end of resistor  2774 , the second end of crystal  2772 , and the first end of capacitor  2776 . The second end of capacitor  2776  is connected to the second end of the capacitor  2778  and to ground. The VRH input of microprocessor  214  is connected to the first end of capacitor  2780 , a first end of resistor  2782  and a first end of resistor  2784 . The second end of the resistor  2784  is connected to the logic voltage supply. The second end of capacitor  2780  and the second end of the resistor  2782  are connected to ground.  
         [0150]    The PG 7  input of microprocessor  214  is connected to the first end of resistor  2786  and a normally open contact of switch  2788 . The second end of resistor  2786  is connected to ground. The common pole of switch  2788  is connected to the logic supply. The Y 0 , Y 1  and Y 2  outputs of selector  2768  are connected to the C, B and A inputs, respectively, of buffer  2770 . The OE input of buffer  2770  is connected to ground. The YA, YB, YC and YD outputs of buffer  2770  are connected to pins  16 ,  14 ,  12  and  10 , respectively, of connector  2776 . The A output of buffer  2746  is connected to a first end of resistor  2754  and a first end of resistor  2762 . The second end of resistor  2762  is connected to pin  3  of connector  218 . The B output of buffer  2746  is connected to a first input of resistor  2752  and a first end of resistor  2760 . The second end of resistor  2760  is connected to pin  4  of connector  218 . The C output of buffer  2746  is connected to a first end of resistor  2750  and a first end of resistor  2758 . The second end of resistor  2758  is connected to pin  5  of connector  218 . The D output of buffer  2746  is connected to a first end of resistor  2748  and a first end of resistor  2756 . The second end of resistor  2756  is connected to pin  6  of connector  218 . The second end of resistors  2748 ,  2750 ,  2752  and  2754  are connected to ground.  
         [0151]    As mentioned above, the Protective microprocessor  212  communicates with Energy Information/Communications microprocessor  222 . The communication interface is shown in FIGS. 2B and 2C. Protective microprocessor  212  is connected with Energy Information/Communications microprocessor  222  using SPI data line  258  and SPI interrupt line  259 . The transfer of data between Protective microprocessor  212  and Energy Information/Communications microprocessor  222  is further described below.  
         [0152]    [0152]FIG. 2D shows the interconnection of protective board  298  and Energy Information board  299 . FIG. 2D Protective board  298  and metering board  299  are interconnected with wire bundles  295 A,  295 B and  296  through connectors  295 C/ 295 D,  295 E/ 295 F, and  296 A/ 296 B, respectively. In the present embodiment, wire bundles  295  and  296  may be ribbon cable or discrete wires, for example. The protective board  298  is also connected to the rating plug  218  and the circuit breaker  116  using connectors  291 ,  292  and  293 , respectively. The metering board  299  is connected to test connector  220 , LCD  240 , keypad  244 , and serial port  248  using connectors  291 ,  292 ,  293  and  294 , respectively.  
         [0153]    Referring now to FIGS.  23 A- 23 I, a detailed schematic diagram of the Energy Information board  299  is shown. Elements identical to those in FIG. 2C use identical reference numbers. Information Energy/Communications microprocessor  222  is connected to PROM  238 A,  238 B and to RAM  236 A  236 B by the address bus  223  and address bits A 1 -A 17  and A 1 -A 15 , respectively. Information Energy/Communications microprocessor  222  is connected to RTC  234  through address bits A 0 -A 5  via address bus  223 . Address bus  223  is also connected to UART  248 A by address bits A 0 -A 2 , to OR gate  2302  with address bit A 1 , and OR gate  2304  with address bit A 2 . R/W signal  229  is connected between Information Energy/Communication microprocessor  222 , RTC  234 , RAM  236 A,  236 B, the input of inverter  2306 , one input of NOR gate  2308 , one input of OR gate  2312 , one input of UART  248 A, one input (DIR) of buffer  2316 , and one input (DIR) of buffer  2318 . Chip select  2324  (CS 9 ) is connected from Energy Information/Communication microprocessor  222  to the inputs of NAND gate  2320 . The output of NAND gate  2320  is connected to one input of NAND gate  2322 . The other input of NAND gate  2322  is connected to the reset input of Energy Information/Communication microprocessor  222 , a pin output of diagnostic connector  2326 , the output of reset circuit  2328 , one end of resistor  2330 , and the inputs of NAND gate  2332 . The output of NAND gate  2322  is connected to the chip enable of RTC  234 . The CS 10  output of Energy Information/Communication microprocessor  222  is connected to the output enable input of RTC  234 . One end of crystal  2334  is connected to an input (X 1 ) of RTC  234  and the other end of crystal  2334  is connected to another input (X 2 ) of RTC  234 . In the present embodiment, crystal  2334  is a 32.768 KHz crystal. Databus  225  is connected between Energy Information/Communication microprocessor  222  PROM  238 A,  238 B, RAM  236 A,  236 B, RTC  234 , UART  248 A, Buffer  2316 , Buffer  2318 , and LCD interface  240  A. In the present embodiment, databus  225  is a 16-byte bus with bits D 0 -D 7  connected to PROM  238 A, RAM  236 A, and Buffer  2318 , and bits D 8 -D 15  connected to PROM  238 B, RAM  236 B, RTC  234 , UART  248 A, LCD interface  240 A, and Buffer  2316 . In the present embodiment, LCD interface  240 A is an 8-bit latch such as a 74HC373.  
         [0154]    The input of reset circuit  2328  is connected to the other end of resistor  2330  and the logic voltage source (not shown). It is understood that logic and analog voltages are supplied to various circuits of Energy Information board  299  but are not shown for simplicity. CS boot signal  2391  is output from Energy Information/Communication microprocessor  222  and connected to an input (CE) of PROM  238 A,  238 B. CS 2  signal  2336  is connected from an output of Energy Information/Communication microprocessor  222  to an input (CE) of RAM  236 B.  
         [0155]    CS 3  signal  2338  is connected between Energy Information/Communication microprocessor  222  and an input (CE) of RAM  236 A. The LCD enable signal (LCD_ENABLE) is output (CS 5 ) from Energy Information/Communication microprocessor  222  to the input of inverter  2340 . The output of inverter  2340  is connected to pin of LCD connector  292 . The CLKOUT signal is output (CLKOUT) from Energy Information/Communication microprocessor  222  to an input (CLK) of Counter  2342 . The output of NAND gate  2332  is connected to an input (CLK) of Counter  2342  and an input (MR) of UART  248 A. An output (Q 2 ) of counter  2342  is connected to an input (XIN) of UART  248 A. Another output (Q 1 ) of counter  2342  is connected to an input (CLK) of ADC  232 A and to an input (CLK) of ADC  232 B. LCD_CS signal  2344  is connected between an output (CS 4 ) of Energy Information/Communication microprocessor  222  and the LCD connector  292 .  
         [0156]    One end of crystal  2346  is connected to one end of capacitor  2348 , a first end of resistor  2354  and an input (EXTAL) of Energy Information/Communication microprocessor  222 . The other end of crystal  2346  is connected to one end of capacitor  2350  and one end of resistor  2352 . The other end of resistor  2352  is connected to the second end of resistor  2354  and to an input (XTAL) of Energy Information/Communication microprocessor  222 . The second end of capacitor  2348  is connected to the second end of capacitor  2350  and to ground. One end of capacitor  2356  is connected to an input (XFC) of Energy Information/Communication microprocessor  222 . The other end of capacitor  2356  is connected to one end of capacitor  2358 , one end of capacitor  2360 , and to the digital voltage supply. The other end of capacitor  2358  and the other end of capacitor  2360  are connected to ground. One end of resistor  2362  is connected to an input (MODCLK) of Energy Information/Communication microprocessor  222 , and the other end of resistor  2362  is connected to the digital voltage supply. UART select (UART_CS)  227 A is output (CS 8 ) from Energy Information/Communication microprocessor  222  and connected to an input (CS 2 ) of UART  248 A.  
         [0157]    An interrupt (INTRPT) of UART  248 A is connected to an input of inverter  2390  and the output of inverter  2390  is connected to an interrupt input (IRQ 4 ) of Energy Information/Communication microprocessor  222 . Contrast control signal  227 D is output (CS 7 ) from Energy Information/Communication microprocessor  222  to both inputs of NAND gate  2392 . The output of NAND gate  2392  is connected to a latch enable input of LCD interface  240 A. Each of the 8 latched outputs (Q 0 :Q 7 ) from LCD interface  240 A are respectively connected to one end of resistors  2394 A- 23941 . The second ends of resistors  2394 A- 23941  are connected to one another and to one end of resistor  2396  and to an inverting input of OPAMP  2398 . The non-inverting input of OPAMP  2398  is connected to ground and the output of OPAMP  2398  is connected to the other end of resistor  2396  and to pins of the LCD connector  292 . A first pin of diagnostic connector  2326  is connected to one end of resistor  2368  and an input (BERR) of Energy Information/Communication microprocessor  222 . The other end of resistor  2368  is connected to the digital voltage supply. A second pin of connector  2326  is connected to an input (DS) of Energy Information/Communication microprocessor  222 . A third pin of connector  2326  is connected to one end of resistor  2366  and an input (BK/DSCLK) of Energy Information/Communication microprocessor  222 . The other end of resistor  2366  is connected to the digital voltage supply. Two additional pins of connector  2326  are connected to digital ground. One additional pin of connector  2326  is connected to the digital voltage supply. Three additional pins of connector  2326  are connected to respective inputs (IP 0 /DS 0 , IP 1 /DS 1 , FRZ/QUOT) of Energy Information/Communication microprocessor  222 . The LCD—RST signal is connected between the LCD connector  292  and an output (OC2) of Energy Information/Communication microprocessor  222 . The alarm output (OC3) of Energy Information/Communication microprocessor  222  is connected an input of NAND gate  2402 . The other input of NAND gate  2402  is connected to one end of capacitor  2404  and one end of resistor  2406 . The other end of capacitor  2404  is connected to ground. The other end of resistor  2406  is connected to the output of NAND gate  2402  and one end of resistor  2408 . The other end of resistor  2408  is connected to alarm LED  404  and the other end of alarm LED  404  is connected to the logic voltage supply.  
         [0158]    The TRPMB signal (PWMB) from Energy Information/Communication microprocessor  222  is connected to one end of resistor  2410 . The second end of resistor  2410  is connected to the base of transistor  2412 . The emitter of transmitter  2412  is connected to ground, and the collector is connected to one end of resistor  2414 . The second end of resistor  2414  is connected to trip LED  402  and the other end of trip LED  402  is connected to the logic voltage supply. One end of resistor  2416  is connected to watchdog signal from the microprocessor  214  (PG 6 ) on the protective circuit board via pin  12  of connector  296 . The other end of resistor  2416  is connected to the base of transistor  2418 .  
         [0159]    The emitter of transistor  2418  is connected to ground and the collector is connected to one end of resistor  2420 . The other end of resistor  2420  is connected to protective LED  420  on front panel  400 . METR_CHK signal is output (OC4) from Energy Information/Communication microprocessor  222  to one end of resistor  2364 . The other end of resistor  2364  is connected to one end of meter LED  422  and the other end of meter LED  422  is connected to the logic voltage supply. One end of switch  408  is connected to one end of resistor  2374 , one end of capacitor  2376 , and the UP signal input (ADA 0 ) to Energy Information/Communication microprocessor  222 . One end of switch  410  is connected to one end of resistor  2380 , one end of capacitor  2378 , and the DOWN signal input (ADA 1 ) of Energy Information/Communication microprocessor  222 . One end of switch  412  is connected to one end of resistor  2382 , one end of capacitor  2386 , and the RETURN input (ADA 2 ) of Energy  
         [0160]    Information/Communication microprocessor  222 . One end of switch  414  is connected to resistor  2384 , one end of capacitor  2388 , and the ESC input (ADA 3 ) of Energy Information/Communication microprocessor  222 . The other end of switches  408 ,  410 ,  412 ,  414 , and the second end of capacitors  2376 ,  2378 ,  2386  and  2388  are connected to ground. The second end of resistors  2374 ,  2380 ,  2382 ,  2384  are connected to the digital voltage supply.  
         [0161]    The ADC_CS signal is connected between Energy Information/Communication microprocessor  222  (CS 6 ) and an input of OR gate  2302 , an input of OR gate  2304 , enable input (OE) of buffer  2316 , and enable input (OE) of buffer  2318 . The output of OR gate  2304  is connected to an input of OR gate  2308 , an input of OR gate  2310 , and a chip select input (CS) of ADC  232 A. The output of OR gate  2302  is connected to an input of OR gate  2312 , an input of OR gate  2314 , and a chip select input (CS) of ADC  232 B. An output of inverter  2306  is connected to the other input of OR gate  2310 , the other input of OR gate  2314 , and the RD input of UART  248 A. The output of OR GATE  2308  is connected to the WR input of ADC  234 A. The output of OR GATE  2310  is connected to the RD input of ADC  232 A. The output of OR GATE  2312  is connected to the WR input of ADC  232 B. The output of OR GATE  2314  is connected to the RD input of ADC  232 B. Bi-directional data inputs D 0 -D 7  of ADC  232  A are connected to the D 0 -D 7  bi-directional data inputs of ADC  232 B and the bidirectional data inputs (A 1 :A 8 ) of buffer  2318 . The D 8 -D 12  bidirectional data inputs of ADC  232 A are connected to the D 8 -D 12  bidirectional data inputs of ADC  232 B and to the A 1 -A 5  inputs of buffer  2316 . The SYNC output of ADC  232 A is connected to an input of OR gate  2309 . The SYNC output of ADC  232 B is connected to the other output of OR gate  2309 . The RDY output of ADC  232 A is connected to an input of OR gate  2311 . The RDY output of ADC  232 B is connected to the other input of OR gate  2311 . The output of OR gate  2309  is connected to the ADCDONE input (IC1) of Energy Information/Communication microprocessor  222 . The output of OR gate  2311  is connected to the ADCREADY input (IC2) of Energy Information/Communication microprocessor  222 .  
         [0162]    The SOUT signal is connected between UART  248  A and one end of resistor  2333 . The other end of resistor  2333  is connected to the base of transistor  2331 . The emitter of transistor  2331  is connected to ground. The collector of transistor  2331  is connected to one end of resistor  2329 , and the other end of resistor  2329  is connected to the cathode of optoisolator  2335 . The anode of optoisolator  2335  is connected to the digital voltage supply. The base of optoisolator  2335  is connected to one end of resistor  2337 . The other end of resistor  2337  is connected to the emitter of optoisolator  2335 , the collector of transistor  2341  and an output pin of connector  2353 . The base of transistor  2341  is connected to the anode of diode  2343  and one end of resistor  2339 . The other end of resistor  2339  is connected to the collector of optoisolator  2335 , one end of resistor  2327 , and one end of resistor  2345 . The other end of resistor  2327  is connected to the collector of transistor  2349  and a pin of connector  2353 . The other end of resistor  2345  is connected to the base of transistor  2349  and the cathode of diode  2347 . The anode of diode  2347  is connected to the emitter of transistor  2349 , the emitter of transistor  2341 , the cathode of diode  2343 , and one end of the resistor  2351 . The other end of resistor  2351  is connected to a pin of connector  2353 . The SIN input of UART  24 A is connected to one end of resistor  2313  and a collector of optoisolator  2315 . The emitter of optoisolator  2315  is connected to ground. A second collector of optoisolator  2315  is connected to the other end of resistor  2313  and to the digital voltage supply. The cathode of optoisolator  2315  is connected to one end of resistor  2321  and a pin of connector  2353 . The other end of resistor  2321  is connected to the base of transistor  2317 , the collector of transistor  2319  and the anode of diode  2325 . The cathode of diode  2325  is connected to the emitter of transistor  2319 , one end of resistor  2323 , and a pin of connector  2353 . The base of transistor  2319  is connected to the other end of resistor  2323  and to the emitter of transistor  2317 . The RI input of UART  248 A is connected to the digital voltage supply and the CTS and DCD inputs of UART  248 A to connected ground.  
         [0163]    The PF 3  signal of Energy Information/Communication microprocessor  222  is connected to one end of the resistor  2359 . The other end of resistor  2359  is connected to the DE input of UART  246 A. The TXD output of Energy Information/Communication microprocessor  222  is connected to one end of resistor  2357 , and the other end of resistor of  2357  is connected to the DI input of UART  246 A The RO output of UART  246 A is connected to one end of resistor of  2361  and the input of inverter  2363 . The other end of resistor  2361  is connected to the digital voltage supply. The output of inverter  2363  is connected to the RX input (RCD) of Energy Information/Communication microprocessor  222 . One end of resistor  2365  is connected to the IRO LED input of UART  246 A and the other end of resistor  2365  is connected to the IRODRV input of UART  246 A. One end of resistor  2367  is connected to the IDEDRV and IDEIN inputs of UART  246 A. The other end of resistor  2367  is connected to one end of resistor  2369  and to the IVCCB and IBCCA inputs of UART  246 A. The other end of resistor  2369  is connected to the IDIIN and IDIDRV inputs of UART  246 A. The A input of UART  246 A is connected to one end of temperature compensating resistor  2373  and one end of diode  2375 . The other end of diode  2375  is connected to ground and the other end of temperature compensating resistor  2373  is connected to a pin of connector  295 A. The B input of UART  246 A is connected to one end of temperature compensating resistor  2371  and one end of diode  2377 . The other end of  2377  is connected to ground and the other end of temperature compensating resistor  2371  is connected to a pin of connector  295 A.  
         [0164]    The signals SCLK, MISO, MOSI, SS, and PUPIRQ (SCK, MISO, MOSI, PCS 0 /SS, PCS 1 ) of Energy Information/Communication microprocessor  222  are connected to the protective board via respective pins of connector  295 A. One end of resistor  2381  is connected to the SS input of Energy Information/Communication microprocessor  222  and the other end of resistor  2381  is connected to the digital voltage supply. The PF 1  input of Energy Information/Communication microprocessor  222  is connected to one end of resistor  2372  and a pin of LCD connector  292 . The PF 2  input of Energy Information/Communication microprocessor  222  is connected to one end of resistor  2370  and a pin of LCD connector  292 . The other end of resistor  2370  is connected to the other end of resistor  2372  and to the digital voltage supply. The IC3 (signal TRIP_CLK) input of Energy Information/Communication microprocessor  222  is connected to a pin of connector  296 . The IC4/OC5 input (signal VFREQ) of Energy Information/ Communication microprocessor  222  is connected to the output of inverter  1032  shown in FIG. 10.  
       Voltage and Current Sensing  
       [0165]    The VIN input of temperature compensating circuit  2355  is connected to the analog voltage supply. The TEMP output of temperature compensating circuit  2355  is connected to the non-inverting input of comparator  2457 . The GND input of temperature compensating circuit  2355  is connected to ground. The COMP output of temperature compensating circuit  2355  is connected to one end of capacitor  2465 . The other end of capacitor  2465  is connected to the VOUT output of temperature compensating circuit  2355 , one end of capacitor  2463 , and the inverting input of comparator  2467 . The output of comparator  2457  is connected to one end of resistor  2459 . The other end of resistor  2459  is connected to the inverting input of comparator  2457 , one end of resistor  2461  and the CH 3  input of ADC  232 B. The other end of resistor  2461  is connected to ground. The output of comparator  2467  is connected to the base of transistor  2469 , the base of transistor  2473 , and one end of capacitor  2471 . The other end of capacitor  2471  is connected to the emitter of transistor  2469 , the emitter of transistor  2473 , the non inverting input of comparator  2467 , one end of resistor  2401 , one end of resistor  2441 , and the VREF inputs of circuits  2429 ,  2431 ,  2433 ,  2435 ,  2437 , and  2439 . The collector of transistor  2469  is connected to the positive analog voltage supply, and the collector of transistor  2473  is connected to the negative analog voltage supply. The other end of capacitor  2463  is connected to ground.  
         [0166]    The circuitry of voltage offset circuits for phase A  2455 , phase B  2439 , and phase C  2437  is identical and for brevity will only be described with reference to the voltage offset circuit for phase A  2455 . In the phase A voltage offset circuit  2455 , the VREF signal is connected to one end of resistor  2401 . The second end of resistor  2401  is connected to one end of resistor  2403  and to an output VAO to the CH 0  input of ADC  232 B as the phase A voltage. Circuits  2439  and  2437  have corresponding outputs VB 0  and VC 0  which are connected to the CH 1  and CH 2  inputs of the ADC  232 B respectively. The VA input to circuit  2455  is received from a pin of connector  295  and is connected to one end of resistor  2415  and one end of capacitor  2419 . Circuits  2439  and  2437  have corresponding inputs VB and VC from connector  295 . The other end of capacitor  2419  is connected to ground. The other end of resistor  2415  is connected to one end of capacitor of  2417 , one end of resistor  2413 , and the non-inverting input of comparator  2409 . The inverting input of comparator  2409  is connected to one end of resistor  2411 , one end of capacitor  2405 , and one end of the resistor  2407 . The other ends of capacitor  2417 , resistor  2413 , and resistor  2411  are connected to ground. The output of comparator  2409  is connected to one end of resistor  2421 , the other end of resistor  2407 , the other end of capacitor  2405 , and the other end of resistor  2403 . The other end of resistor  2421  is connected to one end of resistor  2425 , one end of capacitor  2423 , and the inverting input of comparator  2427 . The non-inverting input of comparator  2427  is connected to ground. The other end of capacitor  2423  is connected to the other end of resistor  2425  and the output of comparator  2427  and one end of resistor  1038  shown in FIG. 10 (input  1002  of amplifier  1004  ).  
         [0167]    The circuitry of current offset circuits for phase A  2429 , phase B  2431 , phase C  2433 , and neutral  2435  are identical and will be described below with reference to the current offset circuit for phase A as shown in FIG. 231, the M.IC+ signal is connected from pin on connector  295  to one end of resistor  2500 . Phase A, B, and neutral current offset circuits have corresponding signals M.IA+, M.IB+, and M.IN+ respectively. The other end of resistor  2500  is connected to one end of capacitor  2504  and one end of resistor  2506 . The P&amp;M.IC− signal is connected from a pin on connector  295  to one end of resistor  2502 . Phase A, B, and neutral current offset circuits have corresponding signals P&amp;M.IA−, P&amp;M.IB−, and P&amp;M.IN−, respectively, connected to pins on connector  295 . The other end of resistor  2502  is connected to the second end of capacitor  2504  and one end of resistor  2508 . The other end of resistor  2508  is connected to one end of resistor  2516 , and one end of resistor  2510 . The second end of resistor  2506  is connected to one end of resistor  2512  and one end of resistor  2518 . The other end of resistor  2516  is connected to one end of resistor  2520  and the inverting input of comparator  2522 . The other end of resistor  2518  is connected to one end of resistor  2514  and the non-inverting input of comparator  2522 . The second end of resistors  2510 ,  2512 , and  2514  are connected to ground. The output of comparator  2522  is connected to the other end of resistor  2520  and one end of  2524 . The other end of resistor  2524  is connected to one end of resistor  2526  and to the CH 2  input of ADC  232 A as signal IC. Phase A, B, and neutral current offset circuits have corresponding signals IA, IB, and IN connected to inputs CH 0 , CH 1 , and CH 3  of ADC  232 A respectively. The second end of resistor  2526  is connected to the VREF source. Phase A, B, and neutral current offset circuits have corresponding connections to the VREF source.  
         [0168]    The second end of resistor  2441  is connected to the VREF+ input of ADC  232 A and the VREF+ input of ADC  232 B, one end of capacitor  2443  and one end of capacitor  2445 . The other end of capacitors  2443  and  2445  are connected to ground.  
         [0169]    Referring to FIG. 2C, current signals I A , I B , I C , and I N  are provided from protective board  298  by wire bundle  295  to current offset amp  230 A. Voltage signals V A , V B , and V C  are provided from circuit breaker  116  through connector  704 C to voltage offset amp  230 B. Offset generator  230 C generates a fixed offset voltage and provides this offset voltage to current offset amp  230 A and voltage offset amp  230 B to offset the current and voltage, respectively, such that the resulting signals are full wave signals offset above ground potential. This allows EID  200  to process full wave voltage and current signals rather than full wave rectified signals. The exemplary offset reference generator  230 C supplies a stable 4.096 V reference voltage. The offset amplified current signals are supplied to current ADC  232 A and the offset amplified voltage signals are supplied to voltage ADC  232 B. Phase A of the offset amplified voltage signal is also provided to zero-crossing frequency sensor  228 , which is shown in greater detail in FIG. 10.  
         [0170]    [0170]FIG. 10 shows the circuit of the transition detector  228 . The offset amplified phase A voltage signal is provided at input  1002  of amplifier  1004 . The output of amplifier  1004  is coupled to resistor  1006  to provide current limiting. The other end of resistor  1006  is connected to the base of transistor  1008  and the cathode of diode  1010 . In the present embodiment, diode  1010  is a zener diode. The anode of diode  1010  is connected to analog signal ground reference  1012 . Diode  1010  clips the output signal of amplified  1004  to approximately the avalanche voltage of diode  1010 . The collector of transistor  1008  is connected to one end of resistor  1014  and the emitter of transistor  1020 . The other end of resistor  1014  is connected to +5 V analog supply  1036 . The emitter of transistor  1008  is connected to the collector of transistor  1016  and the emitter of transistor  1018 . The emitter of transistor  1016  is connected to the emitter of transistor  1024  and the −12 V supply  1034 . The base of transistor  1018  is connected to analog signal ground reference  1012 . The collector of transistor  1018  is connected to the base of transistor  1020 , the emitter of transistor  1026  and one end of resistor  1028 . The other end of resistor  1028  is connect to the +5 V analog supply  1036 . The base of transistor  1016  is connected to the base of transistor  1024  and the emitter of transistor  1022 . The base of transistor  1022  is connected to the collector of transistor  1024  and one end of resistor  1038 . The other end of resistor  1038  as well as the collector of transistor  1022  are connected to analog signal ground reference  1012 . The collector of transistor  1020  is connected to the collector of transistor  1026 , one end of resistor  1030 , and the input of inverter  1032 . The output of inverter  1032  provides signal VFREQ as an interrupt to the Energy Information/communication microprocessor  222 .  
         [0171]    The voltage signal from voltage offset amp  230 B is further amplified by amplifier  1004 . The resultant signal is coupled to resistor  1006  to provide current limiting. Diode  1010  limits the output signal to less than or equal to the avalanche voltage, which in the exemplary embodiment is 4.7 V. The transistors  1008 ,  1016 ,  1018 ,  1020 ,  1022 ,  1024  and  1026  and their associated biasing resistors  1014 ,  1028 ,  1030  and  1038  are arranged such that the voltage signal presented at the cathode of diode  1010  will be converted to a “1” to “0” transition when the voltage signal from voltage offset amp  230 B has a zero crossing. This “1” to “0” transition is inverted by inverter  1032  to a “0” to “1” transition which results in an interrupt to Energy Information/Communications microprocessor  222  for an input voltage transition or zero crossing.  
         [0172]    Energy Information/Communications microprocessor  222  uses a 16-bit data bus  225  and a 19-bit address bus  223  to communicate with current ADC  232 A, voltage ADC  232 B, PROM  238 , RAM  236 , UART  248 A, RTC  234  and LCD interface  240 A. Energy Information/Communications microprocessor  222  also uses a combination of unique select lines  227 A,  227 B,  227 C as well as read/write (R/W) signal  229  to control data flow to and from these devices. Not all devices use the entire 16 bits of data bus  225  and all 19 bits of address bus  223 . For example, 17 bits of address bus  223  are connected to PROM  238 , and address bits A 1 -A 17  are connected to PROM  238  and 15 bits of address bus  223  are connected to RAM  236 .  
         [0173]    To access the data stored in PROM  238 , Energy Information/Communications microprocessor  222  selects PROM  238  by invoking ROMSEL  227 C. When ROMSEL  227 C is set to a logic level of “0” (active low) the 16 bit data stored in PROM  238  corresponding to the address represented by A 1 -A 17  will be placed on data bus  225  by PROM  238 . RAM  236  is accessed in a similar manner with the following exceptions. Two select lines  227 B are used to select either or both a low byte of data or a high byte of data from RAM  236 . In addition, R/W signal  229  is appropriately set if data is to be written (R/W set to a logic “0”) or read (R/W set to a logic “1”) from RAM  236 . As above, as long as the appropriate select lines are active, data corresponding to address lines A 1 -A 15  will be read from or written to RAM  236 .  
         [0174]    In the present embodiment, two National ADC  12048  twelve-bit AND converters (ADC)  232 A,  232 B are used. ADC  232 A samples current and ADC  232 B samples voltage. The ADC  232 A,  232 B provide 12-bits of resolution plus a sign bit and a 13-bit parallel output port. When used in the 13-bit mode, only a single read is required to retrieve the data from a conversion. As mentioned above, since data bus  225  is 10 bits wide, a single read returns all 13 bits of the voltage data and another read returns all 13 bits of the current data. ADC  232 A, and ADC  232 B each use 3 control lines, a chip select, an active low read enable and an active low write enable to read and write. A configuration register inside the AID (not shown) is written to set up which channel ( 0 - 7 ) will be converted. The addressing logic (not shown) is set up such that a single write is received by ADC  232 A,  232 B essentially simultaneously. On the other hand, each ADC  232 A,  232 B is read using individual commands and addressing to prevent bus contention problems which might corrupt the data.  
         [0175]    In the present embodiment, chip select 6 of the Energy Information/Communications microprocessor maps ADC  232 A,  232 B into a 2K memory block starting at address 7E800 hex (see Table IX below). Chip Select 6 enables ADC  232 A,  232 B for reads and writes. Bits A 1  and A 2  of address bus  223 , in conjunction with R/W line  229  enable writes to both ADC  232 A and  232 B for address 7E800, reads of ADC  232 A for current samples at address 7E802, and reads of ADC  232 B for voltage samples at address 7E804. An and conversion is started by writing into the configuration register of ADC  232 A,  232 B a command indicating the start mode with the channel of interest selected. The next read of ADC  232 A,  232 B will start a conversion in the respective ADC. The RDY  237  and DONE  233  outputs from ADC  232 A,  232 B will be driven high while the conversion is in progress, then they will go low when the conversion is complete. The falling edge of the DONE  233  line will cause an interrupt to Energy Information/Communications microprocessor  222 . At this time the results of the conversion may be read from ADC  232 A,  232 B.  
         [0176]    A reference voltage for ADC  232 A,  232 B is provided by offset reference generator  230 C and is set to 4.096 V in the present embodiment. This configures ADC  232 A,  232 B to accept signals ranging from 0 V to +4.096 V. This corresponds to approximately 1 mV per bit. The center point of the range which corresponds to a 0 output is 2.048 V so that ADC  232 A,  232 B operates in the positive domain. Therefore, the 13th bit (sign bit) is not used and the 12th bit represents the sign bit. In addition, ADC  232 A,  232 B are isolated from possible noise on data bus  225  by two bi-directional octal buffers  2316  and  2318  (shown in FIG. 23G). ADC  232 A,  232 B is also supplied with an ADC CLK signal  239  of approximately 8 Mhz from ADC CLK generator  232 C. This clock is derived from a 15.991 Mhz clock generated by Energy Information/Communications microprocessor  222 . As a result, a maximum conversion time of about 5.5 μs is obtained.  
         [0177]    The Energy Information/Communications microprocessor  222  monitors line current and voltage for each of the branch lines  202  through the ADC  232  and, from these values calculates other values which indicate the status of the lines  202 . It also controls communication between the host computer  140 , PC  117 , keypad  244  and LCD  240 . The monitoring feature involves obtaining voltage and current samples from the branch lines  202 , calculating and storing various parameters derived from these samples which indicate certain events and, logging certain of these events as they occur. Table I lists the parameters which may be determined by the Energy Information/Communications microprocessor  222 .  
                   TABLE I                       Parameter   Parameter                   Phase A current   Phase A voltage (to neutral)       Phase B current   Phase B voltage (to neutral)       Phase C current   Phase C voltage (to neutral)       Average current (A, B &amp; C)   Average phase voltage       Neutral current 1     Crest Factor (peak/RMS for       Ground Fault current   each phase)       Present Current Demand   Real power       Maximum Current Demand   Reactive power       Line voltage A-B   Apparent power       Line voltage B-C   Frequency       Line voltage C-A   Kilowatt hours forward       Power factor (each phase and Avg.)   Kilowatt hours reverse       Avg. line-line voltage   kVAR       Avg. L-N voltage (each phase)   Kilowatt demand       Demand period time       Harmonic analysis       (THD, each phase &amp; neutral)                          
 
         [0178]    For each parameter, the Energy Information/Communications microprocessor  222  records in a log the present value, as well as the maximum and minimum values, that have occurred since the last time the log was cleared. The monitored voltage and current values are RMS values generated from sample values taken, for example, over a one-second interval. The frequency is determined by measuring the time interval between zero-crossing points of the measured voltage signal for only one of the three phases, doubling the measured interval and inverting it to convert it into a frequency. Sixty-four (64) samples are taken each cycle with each phase being sampled over 6 cycles once per second resulting in 384 samples per second. The EID has a nominal frequency input range of about 40 Hz to 70 Hz. Frequency is not believed to be essential to measuring the various parameters. Without using the frequency of one phase, the accuracy of various measurements, such as power factor, may be slightly degraded. If a measured frequency is not available, then a user selected pre-programmed frequency of either 60 Hz (U.S.) or 50 Hz (European) is used.  
         [0179]    Power measurements are determined using the measured voltage, current and determined frequency. As is well known to those of ordinary skill, the power calculations include active (real) power, apparent power, reactive power and power factor, which may be determined using the following equations:  
         [0180]    Active Power (Watts)  
             P   =         V     rm                 s       ×     I     r                 m                 s       ×   cos                 φ     =       1   N            ∑   N          (       V     i                 nst       ×     I     i                 nst         )                   Equation  1                               
 
         [0181]    Apparent Power (VA) 
           S=V   rms   ×I   rms   Equation (2) 
         [0182]    Reactive Power (VARs)  
             Q   =         V     r                 m                 s       ×     I     r                 m                 s       ×              sin                 φ     =       1   N            ∑   N          (       V   inst     ×     I     -   2         )                   Equation  3                               
 
         [0183]    Power Factor  
             PF   =       cos                 φ     =       Active                 Power                   (   Watts   )         Apparent                 Power                   (   VA   )                   Equation  4                               
 
         [0184]    Where:  
         [0185]    V inst=Instantaneous Voltage Sample  
         [0186]    I inst=Instantaneous Current Sample  
         [0187]    φ=Phase Angle between V &amp; I  
         [0188]    I-2=I inst shifted 90 electrical degrees  
         V     rm                 s       =         1   N            ∑     n   =   1     N          V   n   2                       I     rm                 s       =         1   N            ∑     n   =   1     N          I   n   2                  
        N   =     number                 of                 samples                 taken                           
 
         [0189]    Note that the VAR calculation requires that each current sample be shifted by 90 degrees, which is referred to in the equations as I −2 . The VAR calculation produces a signed quantity. A negative VAR quantity indicates a leading power factor and a positive VAR quantity indicates a lagging power factor. The number of samples per cycle is 64 (64 is divisible by 4, which allows a more accurate 90 degree phase shift and thus is believed to significantly reduce the VAR calculation error.)  
         [0190]    The demand period for kW Demand and Amp Demand is the same and consists of a “programmable demand period (T PRG )” from 1 to 90 minutes in step such as 1, 2, 5, 10, 16, 20, 30, 60, and 90. During this demand period, the demand is calculated by first averaging the three phase currents and then summing the currents each time a new value is calculated. At the end of the period the sum is divided by the number of samples taken during the period (see Equation 5, below). The maximum demand is calculated based on the user selected “number of demand periods (N T )” (1 to 15). If N T  is 1, then the maximum demand is the largest demand value that has been calculated since demand was last cleared. Setting the number of demand periods N T  equal to a number greater than one allows for a sliding window calculation method. The maximum demand is the largest average demand over N T  periods. Each time a new demand value is calculated, the oldest calculation is discarded and the new one is used to generate a new average.  
                   ∑     n   =   1     □          (         I   A     +     I   B     +     I   C       3     )         T   PRG       =   AmpDemand           Equation  5                               
 
         [0191]    Where: T PRG  is a programmable demand period, and I A , I B  and I C  are phase currents for phases A, B and C, respectively. The kW, kW Demand, kVAR and kW Hour calculations account for reverse power flow, and indicate this with forward (line to load) and reverse (load to line) power displays on LCD  240 . Alarm and trip set-point limits may also be set for forward and reverse power levels. The Power Factor calculation indicates leading and lagging conditions.  
         [0192]    Voltage and current are sampled such that the data of one phase is calculated while the data of another phase is sampled. For example, phase A data is calculated while phase B data is sampled, phase B data is calculated while phase C data is sampled, and phase C data is calculated while neutral data is sampled. Either the host computer  140 , PC  117  or EID  200  may retrieve monitored parameter values and clear the monitored parameter log.  
         [0193]    The protective features implemented in the Protective microprocessor  214  and the Protective Relay functions implemented in the Energy Information/Communications microprocessor  222  allow it to trip the contactor portion of circuit breaker  116  when certain events occur or to activate the alarm signal to either sound an alarm or open the circuit breaker  116 , depending on the system configuration selected by the user. Table II lists the events for which the Protective microprocessor  214  may trip the circuit breaker  116  and the parameters that may be stored in the trip log when the circuit breaker is tripped. In particular, I X  indicates the present current in phase X. V X-Y  indicates the present voltage measured from phase X to phase Y, V AVE  indicates the average phase-to-phase voltage, KW, KVAR and KVA indicate the present value of real power, reactive power and apparent power, respectively.  
                           TABLE II                                   Cause of Trip   Parameters logged                           Long Time   I A , I B , I C , I N , &amp; I G             Short Time   I A , I B , I C , I N , &amp; I G             Instantaneous   I A , I B , I C , I N , &amp; I G             Ground Fault   I A , I B , I C , I N , &amp; I G             Over Neutral Current   I A , I B , I C , I N , &amp; I G             Current Unbalance   I A , I B , I C , I N , &amp; I G             Over Voltage   V A-B , V B-C , V C-A  &amp; V AVE             Under Voltage   V A-B , V B-C , V C-A  &amp; V AVE             Voltage Unbalance   V A-B , V B-C , V C-A  &amp; V AVE             Over Frequency   Freq., V A-B , V B-C , V C-A  &amp; V AVE             Under Frequency   Freq., V A-B , V B-C , V C-A  &amp; V AVE             Reverse Power   KW, KVAR, and KVA                      
 
         [0194]    Table III lists the events and associated parameters that are logged in the event log.  
                           TABLE III                                       Over Neutral Current   I A , I B , I C , I N , &amp; I G             Current Unbalance   I A , I B , I C , I N , &amp; I G             Under Voltage   V A-B , V B-C , V C-A  &amp; V AVE             Voltage Unbalance   V A-B , V B-C , V C-A  &amp; V AVE             Over Voltage   V A-B , V B-C , V C-A  &amp; V AVE             Reverse Power   KW, KVAR, and KVA           Over Frequency   Freq., V A-B , V B-C , V C-A  &amp; V AVE             Under Frequency   Freq., V A-B , V B-C , V C-A  &amp; V AVE             Over Current   I A , I B , I C , I N , &amp; I G             Ground Over Current   I A , I B , I C , I N , &amp; I G             Over Amp Demand   Amp Demand, I A , I B , I C             Over KW   KW, KVARs, KVA           Over KW Demand   Watt Demand, Instantaneous Watts           Over KVA   KW, KVARs, KVA           Over KVAR   KW, KVARs, KVA           Over Leading PF   Total Power Factor, I A , I B , I C             Under Lagging PF   Total Power Factor, I A , I B , I C             Over THD   Total Harmonic Distortion, I A , I B , I C , I N                        
 
         [0195]    The Protective Relay features include: Neutral Over Current, Current Unbalance, Under Voltage, Voltage Unbalance, Over Voltage, Reverse Power, Over Frequency, and Under Frequency appear in both the Trip Log and the Event Log. The Protective Relay features can be configured by the user to alarm or to alarm and trip (alarm is automatically enabled when trip is enabled). When a Protective Relay feature&#39;s alarm is enabled and the alarm pickup and delay are exceeded, the event is logged in the Event Log and the Protective microprocessor  214  is instructed to signal the alarm. When the trip&#39;s pickup and delay settings are exceeded, the event is logged in the Trip Log and the Protective microprocessor  214  is instructed to trip.  
         [0196]    The Alarm features include: Over Current, Ground Over Current, Over Amp Demand, Over KW, Over KW Demand, Over KVA, Over KVAR, Over Leading Power Factor, Under Lagging Power Factor, and Over Total Harmonic Distortion only appear when an Alarm function is enabled. When its pickup and delay are exceeded, the event is logged in the Event Log and the Protective microprocessor  214  is instructed to signal the alarm. The alarm features which the EID may recognize are listed in Table III. All of these events are recognized by the Protective microprocessor  214  or Energy Information/Communications microprocessor  222 .  
         [0197]    Table IV lists exemplary alarm ranges of various parameters measured by EID  200 .  
                       TABLE IV                       Alarm event   Measured Parameter   Alarm Range                   Over current (phase)   I A , I B  &amp; I C     115%-250% of Ir       Over current (ground)   I G      20%-100% of In       Over current (demand)   I A , I B  &amp; I C      60%-100% of Ir       Total Harmonic Distortion   Frequency    5%-50%       Over KW   KW       20-5300 kW       Over KW Demand   KW       20-5300 kW       Over KVA   KVA       20-5300 kVA       Over KVAR   KVAR       20-5300 kW       Over Power factor (leading)   PF      .50-.95       Under Power Factor (lagging)   PF      .50-.95                  
 
         [0198]    The protective features which the EID may recognize are listed in Table V. These events are recognized by the Protective microprocessor  214  or Energy Information/Communications microprocessor  222 .  
                       TABLE V                       Protective Function   Measured Parameter   Pick-up Range                   Over current   I N     115%-250% of Ir       (neutral)       Current Unbalance   I A , I B  &amp; I C      5%-50%       Under Voltage   V A-B , V B-C  &amp; V C-A      50%-95% of Vr       Voltage Imbalance   V A-B , V B-C  &amp; V C-A      5%-50%       Over Voltage   V A-B , V B-C  &amp; V C-A     105%-125% of Vr       Over Reverse Power   Reverse KW       20-5300 kW       Over Frequency   Frequency       1-12 Hz above nominal       Under Frequency   Frequency       1-12 Hz below nominal                  
 
         [0199]    The Energy Information/Communications microcomputer  222  maintains three logs for reporting significant events: the trip log, the event log and the min/max log. The trip log is a nonvolatile memory which holds the last five trip events that have occurred. The trip log stores the data and time of the event, as well as the data associated with the event. The event log is a volatile memory which holds the ten most recent alarm events, including the start time and date of each event, the end time and date of each event and the data associated with each event. The min/max log holds the minimum and/or maximum energy information values in a volatile memory. The min/max values are time stamped to the nearest second. Examples of the data stored in the min/max log are: current, voltage, VA, watt demand, frequency, crest factor, watts, VARS, power factor, and THD. The data contained in each log is available at the LCD  240 . These logs may also be read by the host computer  140  and PC  117 . EID  200  also has operation counters to record the number and types of events that occur in the circuit breaker  116 . In the present embodiment, three count values are maintained in non-volatile memory by the EID  200 : 1) a mechanical count value; 2) an interruption level count value; and 3) a fault count value. The information held by each count value is further described below.  
         [0200]    The mechanical count value records the total number of circuit breaker openings, but does not determine the reason the circuit breaker opened. For example, the mechanical count may reflect the number of circuit breaker openings due to electrical overload, the number of fault openings and the number of operator induced openings. The mechanical count may be displayed on LCD  240  through a menu selection. In the present embodiment, the mechanical count and the circuit breaker serial number may be displayed. This count may also be read using the communication ports by the host computer  140  or PC  117 . The interruption level count records the number of times the circuit breaker tripped and a respective current range representing the circuit breaker current when the trip occurred.  
         [0201]    The number and span of the current ranges may be user selectable or predetermined in the EID software. In the present embodiment, the ranges are preset to: 1) less than 100% of contact rating (CT); 2) 100% to 300% CT; 3) 300% to 600% CT; 4) 600% to 900% CT: and 5) greater than 900% CT. These ranges are exemplary and any suitably appropriate number ranges and range spans may be used. The interruption level count may be displayed on LCD  240  through a menu selection. This count may also be read using the communication ports by the host computer  140  or PC  117 . Finally, the fault count value reflects the faults and the number of trips. In the present embodiment the faults are listed by type of protection, such as: 1) overload; 2) short time; 3) instantaneous; and 4) ground fault. The display lists the fault type in one column and the respective fault count in a second column. In addition, the total number of trips due to these faults may also be displayed.  
         [0202]    As discussed above, a menu system is used to select and control a variety of display modes, pick-up points, delays, etc. of the EID  200 . On startup, the highest level menu selections are displayed. The exemplary selections are: “SYSTEM CONFIG”; “PROTECTIVE”; “METERING”; “COMMUNICATIONS”; “LOGS”; “OPERATIONS”; “SECURITY”; and “VIEW DATA”. The main menu of the present invention is shown in FIG. 6A. When the EID  200  has been inactive for approximately five minutes, it enters an idle display mode. The idle display mode may be a blank screen or a cyclic display of informational screens, such as date, time, etc. Pressing any key, such as the ESC  414  key terminates the idle display mode and activates the highest level menu.  
         [0203]    The System Configuration menu has selections for Viewing Configuration Information and Frequency, Wiring, PT Rating, Short Circuit Protection, External Neutral Sensor, Time &amp; Date, LCD Contrast, and Breaker Serial Number settings. The Protective menu has selections for the Viewing Protective Settings, and establishing the Long Time, Short Time, Instantaneous, Ground Fault, Alarms and Relay settings. The energy information or metering menu has selections for Metered Data, Demand Configuration and Resetting the  
         [0204]    Metered Data. Additionally, the Communication menu has selections for Viewing the Communication Configuration, setting ACCESS/EIA-485 baud rate, setting the EMU&#39;s ACCESS device address, setting EIA-232 baud rate and Remote Trip/Open enable/disable. The Logs menu has selections for the Event Log, the Trip Log, and the Min-Max Log as well as clearing each of the logs. The Operations menu has selections for Breaker Test and the various counters; mechanical operations, fault by level and faults by type. The Security menu has selections for entering and changing passwords and enabling security. Table VI provides an outline of the menu system hierarchy of the present embodiment as follows.  
                                                                                                                                                                                                                                                                                                                                                                                                   TABLE VI                           System Config                View Config           Frequency           Wiring           PT Rating           Short Circuit Prot           Ext. Neutral Sensor           Time and Date           LCD Contrast           Breaker S/N            Protective                View Settings           Long Time           Short Time           Instantaneous           Ground Fault           Alarms                Over Current           Ground Over Current           Over Amp Demand           Total Harmonics           Over KW           Over KW Demand           Over KVAR           Over KVA           Under Power Factor Lagging           Over Power Factor Leading                Protective Relays                Neutral Over Current           Current Unbalance           Under Voltage           Voltage Unbalance           Over Voltage           Over Reverse Power           Over Frequency           Under Frequency            Metering                Metered Data                Volts, Amps, Power Factor, and Frequency           Watts, Volt-Amps Reactive, Volt-Amps, and Crest Factor           Demand           Harmonics                Current Data           A Current Graphs           B Current Graphs           C Current Graphs           N Current Graphs                Waveforms                Phase A Graphs           Phase B Graphs           Phase C Graphs           Phase N Graphs                Phase Balance                Voltage Balance           Current Balance                Demand Config           Reset Meter Data                Energy Registers           Demand            Communication                View Communications Configuration           ACCESS BAUD Rate           Slave Address           RS232 BAUD Rate           Remote Trip/Close            Logs                View Event Log                ↑ (Scroll up through Log)           ↓ (Scroll down through Log)                Reset Event Log           View Trip Log                ↑ (Scroll up through Log)           ↓ (Scroll down through Log)                Reset Trip Log           View Min/Max Log                Amps and Crest Factor                Phase A Amps           Phase B Amps           Phase C Amps           Average Phase Amps           Phase N Amps           Ground Amps           Amps Demand           Phase A Crest Factor           Phase B Crest Factor           Phase C Crest Factor                Volts                Phase A Volts           Phase B Volts           Phase C Volts           AB Line Volts           BC Line Volts           CA Line Volts           Average Line Volts                Power                Instantaneous Watts           Instantaneous VARs           Instantaneous VA           Watt Demand                Power Factor and Frequency                Phase A Power Factor           Phase B Power Factor           Phase C Power Factor           Total Power Factor           Frequency                Total Harmonic Distortion                Phase A THD           Phase B THD           Phase C THD           Neutral THD                Reset Min/Max Log            Operations                Breaker Test           Mechanical Counter           Interruption Level           Fault Counter            Security                Enable Security           Change Password           Enter Password            View Data                  
 
         [0205]    By using the menu system, the user may select and display any number of conditions of the EID  200  in various combinations. For example, the user may select a histogram display of phase frequency harmonics in combination with a voltage signal display. The number and combination of displays is generally limited by the display resolution and the capacity of the display memory.  
         [0206]    Referring to FIGS.  6 A- 6 F, a procedure for using the menu system is now described. Once the main menu (FIG. 6A) is displayed (at power on or exit of idle display mode) the operator may press keys  408  and  410  to scroll up and down, respectively, through the available selections to highlight one of the displayed selections. To activate a highlighted selection, the operator presses key  412 . For example, from the main menu, if the operator wishes to enter the energy information or metering feature, key  410  may be pressed twice or key  408  may be pressed five times (to scroll from the last displayed selection). Alternatively, keys  410  or  412  may be pressed and held by the operator to allow the highlighted selection to automatically scroll through the selections. The operator releases the depressed key when the desired selection is highlighted by highlight bar  602 . Highlight bar  602  may be accomplished, for example, by inverting the selected item, flashing the selected item, or changing the color of the selected item.  
         [0207]    [0207]FIG. 6B shows the metering menu selected as described above. As is shown in FIG. 6B and in Table V, this menu shows another layer of selections. In this example, “METERED DATA”, “DEMAND CONFIG” and “RESET METER DATA” are available. Again, by moving the highlight bar  602  with keys  408  and  410 , and selecting with key  412  yet another menu layer may be displayed. Assuming that the operator selected “METERED DATA” then the FIG. 6C menu is displayed. Referring to FIG. 6C, the data display provides “V, A, PF, and Freq”, “W, VAR, VA, and CF, Demand, Harmonics, “WAVEFORMS”, and “PHASE BALANCE” selections. Once again, by moving the highlight bar  602  with keys  408  and  410  and selecting with key  412 , another menu layer or data may be displayed. If the operator selected “DEMAND”, the FIG. 6D demand data screen is displayed providing the operator with an alphanumeric display of current and power demand. As mentioned above, waveform data may also be displayed on display  240 . In this example, if the operator highlights and selects “WAVEFORMS”, the FIG. 6E WAVEFORM GRAPHS menu is displayed. Selecting the “PHASE A GRAPHS” option results in the display of the FIG. 6F waveforms.  
         [0208]    As mentioned above, the present embodiment is not limited to displaying singular menu selection data. Multiple waveforms, waveforms and histograms, waveforms and alphanumeric data, histograms and alphanumeric data, etc. may be displayed on display  240  using the appropriate menu selections. Furthermore, the menu selections shown in Table 5 are exemplary and any other appropriate menu hierarchy and selection options may be used depending on system requirements. The menu system may further include a language selection allowing the operator to set the system language to a language other than English, such as, for example: French, German and Italian.  
         [0209]    FIGS.  7 A- 7 J further show various display types available to the user for setting a variety of pick-up points and delays, as well as alphanumeric readouts of the circuit breaker conditions. It is understood that FIGS.  7 A- 7 J are exemplary and do not reflect the entire extent to which the present system may be used to set and display parameters of circuit breaker  116 . As set forth above, multiple displays such as those shown in FIGS.  7 A- 7 J may be simultaneously displayed on display  240 . As shown in FIG. 7A, over current pick-up  700  and delay  702  may be set in a bar graph mode. In addition, an alarm condition may be activated by selecting over current alarm  704 . FIGS.  7 B- 7 F show other exemplary settings available in EID  200  through front panel  400 . These settings may also be made using the communications ports  246 ,  248 . FIGS. 7G through 7J show alphanumeric displays of the protective configuration, voltage, current and phase conditions, and demand of the EID  200 . The information shown in FIGS. 7A to  7 J are merely exemplary of the data available to the user.  
         [0210]    Security is a concern in any industrial environment. Inadvertent and purposeful interruptions of power to a section of a factory may have severe financial, safety, and other impacts. Furthermore, tampering with the set-points of a programmable circuit breaker may ultimately damage the protected equipment. The present embodiment is believed to address such concerns by incorporating security features accessible through the menu system. The exemplary security system may be accessed by selecting the SECURITY entry point of the main menu. This allows a user with a valid password to enable or disable the security features, as well as to change the security password. To prevent lockout if the password is lost or forgotten, the security system has a backdoor password which may for example be based on the current date. A password protection system sets a flag when security is active and checks the flag before executing any routine interpreting data from the front panel, except when the front panel data contains the proper password. In addition, the menu based security system will not affect host computer  140  or PC  117  accessibility of the circuit breaker  116 . It is contemplated that the resident software in each of the host computer  140  or and PC  117  includes another security system.  
         [0211]    [0211]FIG. 8A is a graph of the trip curve  810 , and FIG. 8B is a curve illustrating how the ground-fault trip function is implemented on a system that provides a ground sensor input signal to the trip unit. In FIG. 8A, the point A coordinates on the solid-line curve  810  represent the pickup current and delay parameters of the long-time trip setting. The point C coordinates represent pickup current and delay parameters for the short-time trip setting and the point D current coordinate represents the instantaneous trip current. Point B on the curve  810  is determined as the intersection of a fixed slope line, originating at the long-time trip coordinates, and a line drawn vertically from the short-line trip coordinate. This line is referred to as an I 2 T curve. The sloped line between points C and D is a fixed-slope line originating at the short-time trip coordinates and intersecting a line drawn vertically from the instantaneous trip coordinate. The broken line  811  illustrates the trip function without this short-time I 2 T curve. The solid line  810  defines the pickup and trip functions performed by the Protective microprocessor  214 . A pickup occurs whenever the current sensed on one of the phases can be mapped onto the curve  810 . The circuit breaker  116  is not tripped, however, until after the time delay indicated by the time coordinate of the trip curve at the pickup current value. Finally, the ground fault curve shown in FIG. 8B consists of two points, a variable trip coordinate E, which may be specified by the operator using the front-panel switches  410 ,  412 ,  414 , and a short-time trip coordinate F which is automatically set to a current that is 1.5 times the specified ground-fault pickup value and a delay of one-half second. The slope between the points E and F is a fixed-slope I 2 T curve drawn between the variable trip coordinate and the resulting short-time trip coordinate.  
         [0212]    Referring to FIG. 9A, circuit breaker  116  is shown in a relatively simple configuration as installed in the field. As shown in FIG. 9B, circuit breaker  116  may be upgraded in the field by the user by installing EID  200  into circuit breaker  116 . A connector  702  in the rear portion of EID  200  mates with a connector  704  of circuit breaker  116 . Referring to FIG. 9C, EID  200  is shown installed in circuit breaker  200 .  
         [0213]    Energy Information/Communications microprocessor  222  uses an interrupt scheme to direct control to components that requiring attention. This interrupt structure and operation are as follows:  
         [0214]    For Energy Information/Communications microprocessor  222 , each interrupt source, whether internal or external, has an associated Interrupt Level, Interrupt Arbitration Value and Interrupt Vector Value. The Interrupt Level establishes the interrupt priority. The Interrupt Arbitration Value is used by the Energy Information/Communications microprocessor  222  to settle contention between two equal priority interrupts. The Interrupt Vector Number determines which interrupt handler will service the interrupt. It is believed to be preferable to assign Interrupt Levels and Interrupt Arbitration Values for each software module used by Energy Information /Communications microprocessor  222  that will generate interrupts. It is also believed to be preferable to provide a Vector Value for each user defined interrupt. Certain interrupts, such as Reset for example, have predefined Interrupt Vector Values.  
         [0215]    In the present embodiment, there are seven interrupt levels. In the present embodiment, interrupt level  1  has the lowest priority and interrupt level  7  has the highest priority. Interrupt recognition is based on the states of the interrupt request signals  1  through  7  and the 3-bit interrupt priority (IP) field in the Energy Information/Communications microprocessor  222  Condition Code Register (CCR). Binary values of 000 to 111 provide eight priority masks. All interrupts having priorities less than 7 may be masked (disabled). When the IP field equals 000, no interrupts are masked. Only interrupts with a priority greater than the IP field mask are recognized and processed. During interrupt processing the IP field is set to the priority of the interrupt being serviced. Exception processing for multiple exceptions is done by priority, from highest to lowest. If an interrupt request of equal or lower priority than the current IP mask value is generated, Energy Information/Communications microprocessor  222  does not recognize the interrupt. Therefore, for an interrupt to be serviced it must remain active until acknowledged by Energy Information/Communications microprocessor  222 .  
         [0216]    Each software module that generates an interrupt has a 4-bit Interrupt Arbitration (IARB) field in its configuration register. These bits may be assigned a value from 0001 (lowest priority) to 1111 (highest priority). A value of 0000 in an IARB field causes Energy Information/Communications microprocessor  222  to process a spurious interrupt exception when an interrupt from that module is recognized. When two or more modules, which have been assigned the same priority level, request interrupt service essentially simultaneously, the IARB fields of the requesting modules are used to determine which interrupt request is recognized. Therefore, each module must have a unique IARB field. If two contending modules have their IARB fields set to the same value, Energy Information/Communications microprocessor  222  may interpret multiple vector values simultaneously with unpredictable consequences. When arbitration is complete, the dominant module supplies an Interrupt Vector Value.  
         [0217]    As mentioned above, each interrupt has an associated vector value. The vector value is used to calculate a vector address in a data structure called the Exception Vector Table. An exception is an event, such as an interrupt, that can preempt the normal instruction process. In the present embodiment, the Exception Vector Table is located in the first 512 bytes of Energy Information/Communications microprocessor  222  address space. The Exception Vector Table contains the addresses of the exception (interrupt) handler routines. All vectors except the Reset vector consist of one word (2 bytes). The Reset vector consists of 4 words (8 bytes). There are 52 pre-defined or reserved vector values and approximately 200 user assignable vector values. There is a direct mapping of vector number to vector table address. Energy Information/Communications microprocessor  222  multiplies the vector value by two to convert it to a vector table address. Table VII is an exemplary Exception Vector Table.  
                       TABLE VII                       VECTOR   VECTOR TABLE           VALUE   ADDRESS   TYPE OF EXCEPTION                   00   0000-0006   Reset       04   0008   Breakpoint       05   000A   Bus Error       06   000C   Software Interrupt       07   000E   Illegal Instruction       08   0010   Division by Zero       09-0E   0012-001C   Unassigned, Reserved       0F   001E   Uninitialized Interrupt       10   0020   Unassigned, Reserved       11   0022   Level 1 Interrupt Autovector       12   0024   Level 2 Interrupt Autovector       13   0026   Level 3 Interrupt Autovector       14   0028   Level 4 Interrupt Autovector       15   002A   Level 5 Interrupt Autovector       16   002C   Level 6 Interrupt Autovector       17   002E   Level 7 Interrupt Autovector       18   0030   Spurious Interrupt       19-37   0032-006E   Unassigned, Reserved       38-FF   0070-01FE   User Defined Interrupts                  
 
         [0218]    Exception processing may be performed in four distinct phases.  
         [0219]    1. The priority of all pending exceptions is evaluated and the highest priority exception is processed first.  
         [0220]    2. The processor state is stacked, then the CCR PK extension field cleared.  
         [0221]    3. An Interrupt Vector Value is acquired and converted to a vector table address that is used to select the address of an exception handler routine from the vector table.  
         [0222]    4. The address of the selected exception handler routine is loaded into the program counter and the processor jumps to the exception handler routine. All addresses for exception handler routines, except for Reset, are 16-bit addresses. Therefore, it is preferable that the routines be located either within the first 512 bytes of memory or that the vectors point to a jump table.  
         [0223]    The present embodiment also uses up to nine external interrupts sources. The external interrupts may be divided into external system interrupts and external device interrupts. The external system interrupts are Reset and Breakpoint. Their Interrupt Vector Values and respective priorities are pre-defined. The external device interrupts are IRQ1 through IRQ7 and are associated with interrupt levels 1 through 7, respectively. As mentioned above, level 1 has the lowest priority and level 7 has the highest priority. In the present embodiment, IRQ1 through IRQ6 are active-low level sensitive inputs, while IRQ7 is an active-low edge sensitive input. Interrupts IRQ1 through IRQ6 are maskable, while IRQ7 is non-maskable. Energy Information/Communications microprocessor  222  treats external interrupt sources as though they are part of the System Integration Module (SIM). Therefore the IARB field in the SIM&#39;s configuration register is used to arbitrate between external interrupts and interrupts generated by other internal modules.  
         [0224]    When an external device interrupt wins arbitration, a vector value is supplied to invoke the appropriate interrupt handler. The external device that generated the interrupt signal can supply a vector value or Energy Information/Communications microprocessor  222  can supply an autovector number. In the present embodiment, there are 7 autovectors. Each one is associated with an external interrupt. There are five ways the response can be implemented when an external device interrupt wins arbitration, and they are as follows:  
         [0225]    1. The external device that generated the interrupt signal can provide Energy Information/Communications microprocessor  222  with the Interrupt Vector Value of an interrupt handler and generate a Data Size Acknowledge (DSACK) response for Energy Information/Communications microprocessor  222 . The external device that requested interrupt service decodes the priority value on address lines A 1 -A 3 . If the priority value equals that device&#39;s priority level, the external device places a vector value on data lines D 8  through D 15  (if the device is an 8-bit port) or data lines D 0  through D 7  (if the device is a 16-bit port) and generates the appropriate 8-bit or 16-bit DSACK signal. If the SIM module wins arbitration, the Interrupt Vector Value supplied by the external device is used to select the interrupt handler.  
         [0226]    2. The external device that generated the interrupt signal can pull the Autovector (AVEC) input to Energy Information/Communications microprocessor  222  low to request that Energy Information/Communications microprocessor  222  supply the appropriate Autovector value. The external device that requested interrupt service decodes the priority value on address lines A 1  through A 3 . If the priority value equals that device&#39;s priority level, the external device asserts the AVEC signal. If the SIM module wins arbitration, the appropriate Autovector value is generated.  
         [0227]    3. A chip select pin of Energy Information/Communications microprocessor  222  can be programmed to decode the interrupt acknowledge bus cycle, generate an interrupt acknowledge signal to the external device, and generate a Data Size Acknowledge (DSACK) response for Energy Information/Communications microprocessor  222 . Program the appropriate chip select pin assignment register (CSPAR 0  or CSPAR 1 ) to configure the chip select to select an 8-bit port ( 10 ) or a 16-bit port ( 11 ). Program the base address register (CSBAR) of the chip select with a base address field (bit A 3  through A 15 ) of all ones. The block size is programmed to no more than about 64 K bytes so that the address comparator checks address lines A 16  through A 19  against the corresponding bits in the base address register. The appropriate chip select options register (CSOR) are programmed as follows:  
         [0228]    a. Set the MODE bit to asynchronous mode (0).  
         [0229]    b. Set the BYTE field to lower byte (01) when using a 16 bit port, since the external vector for a 16 bit port is fetched from the lower byte. Set the BYTE field to upper byte ( 10 ) when using a 8 bit port.  
         [0230]    c. Set the RIW field to read only (01).  
         [0231]    d. Set the STRB bit to synchronize with AS (0).  
         [0232]    e. Set the DSACK field to the desired number of wait states.  
         [0233]    Select External (1111) if the external device will generate DSACK signals.  
         [0234]    f. Set the SPACE field to CPU space (00).  
         [0235]    g. Set the IPL field to respond to the desired interrupt request level, or to 000 to respond to all request levels.  
         [0236]    h. Set the AVEC bit to 0 to disable autovector generation.  
         [0237]    4. A chip select can be programmed to generate an AVEC response instructing Energy Information/Communications microprocessor  222  to supply the appropriate autovector value.  
         [0238]    a. Program the appropriate chip select pin assignment register (CSPAR 0  or CSPAR 1 ) to configure the chip select pin you have chosen for either discrete output (00) or its alternate function (01). This prevents the pin from being asserted during interrupt acknowledge cycles.  
         [0239]    b. In the base address register (CSBAR) of the chip select pin you have chosen, program the base address field (bit  3  through  15  ) to all ones. Program the block size to no more than 64 K so that the address comparator checks address lines  16  through  19  against the corresponding bits in the base address register. (The CPU places the CPU space type on address lines  16  through  19 .)  
         [0240]    c. Program the appropriate chip select options register (CSOR) as follows:  
         [0241]    i. Set the MODE bit to asynchronous mode (0).  
         [0242]    ii. Set the BYTE field to both bytes (11).  
         [0243]    iii. Set the RAN field to read/write (11).  
         [0244]    IV. Set the STRB bit to synchronize with AS (0).  
         [0245]    v. Set the DSACK field to 0 wait (0000).  
         [0246]    vi. Set the space field to Supervisor space (10).  
         [0247]    vii. Set IPL to respond to the desired interrupt request level, or to 000 to respond to all request levels.  
         [0248]    viii. Set the AVEC bit to 1 to enable autovector generation.  
         [0249]    5. The Energy Information/Communications microprocessor  222  AVEC pin may be permanently wired low (asserted) to generate the appropriate Autovector value for any external interrupt request that wins arbitration. When the Autovector pin is wired low (asserted) and any external device interrupt wins arbitration, the SIM supplies the Interrupt Vector Value of the Autovector associated with that external interrupt. This is the approach used in the present embodiment.  
         [0250]    The System Integration Module (SIM), Queued Serial Module (QSM), and General Purpose Timer module (GPT) may be sources of internal interrupts. The sources of internal SIM interrupts are the Software Interrupt, the Periodic Timer, bus errors, illegal instructions, division by zero, un-initialized interrupts, and spurious interrupts. The QSM can generate interrupts to signal SPI Finished, SCI Transmitting, SCI Transmit Complete, SCI Receive, and SCI Line Idle. The interrupt sources from the GPT are Input Captures 1 through 3, Output Compares 1 through 4, the programmable Input Capture-4 or Output Compare 5, Timer Overflow, Pulse Accumulator Overflow, and Pulse Accumulator Input. To use these internal interrupt sources their respective modules must be configured for interrupts and the individual interrupts must be enabled.  
         [0251]    In addition to handling the exemplary nine external interrupts, the SIM has seven interrupt sources and seven interrupt vectors. The Interrupt Vector Values and Interrupt Priority Levels for the Software, Bus Error, Illegal Instruction, Division by Zero, Un-Initialized, and Spurious interrupts are pre-defined in the exemplary embodiment. The Exception Vector Table (Table VI above) has the Interrupt Vector Values of these interrupts. The Interrupt Vector Value and Interrupt Priority Level are user defined for the Periodic Timer interrupt.  
         [0252]    To configure the System Integration Module interrupts, the following to steps may be used. First, in the SIM Module Configuration Register (SIMCR), set the Interrupt Arbitration field (IARB) to the interrupt arbitration number you have selected for the SIM module. Valid values are from 0001 (lowest priority) to 1111 (highest priority). Second, to use the Periodic Timer interrupt, configure the PIRQL and PIV fields In the Periodic Interrupt Control Register (PICR) by setting the PIRQL field to the selected Interrupt Level. Valid values are from 001 (lowest) to 111 (highest)or by setting the PIV field to the selected Interrupt Vector Number.  
         [0253]    The Queued Serial Module consists of the Serial Communications Interface (SCI) and Queued Serial Peripheral Interface (QSPI) sub-systems. In the present embodiment, the SCI has four possible interrupt sources, but only one interrupt vector. The SCI interrupt sources are Transmit Data Register Empty, Transmit Complete, Receive Data Register Full and Idle Line Detected. When the Energy Information/Communication microprocessor  222  responds to an SCI interrupt, the SCI interrupt handler must determine the exact interrupt cause by reading the appropriate bits (TDRE, TC, RDRF, and IDLE) in the SCI Status Register (SCSR). The QSPI has three possible interrupt sources, but only one interrupt vector. These interrupt sources are QSPI Finished, Mode Fault and Halt Acknowledge. When the Energy Information/Communication microprocessor  222  responds to a QSPI interrupt, the QSPI interrupt handler must determine the exact interrupt cause by reading the appropriate bits (SPIF, MODF, and HALTA) in the QSPI Status Register (SPSR). The following steps may be used to configure the Queued Serial Module interrupts.  
         [0254]    In the QSM Configuration Register (QMCR), set the IARB field to the interrupt arbitration number you have selected for the QSM module. Valid values are from 0001 (lowest priority) to 1111 (highest priority). In the QSM Interrupt Level Register (QILR), set the ILQSPI field is set to the selected Interrupt Level for the QSPI sub-system and set the ILSCI field to the selected Interrupt Level for the SCI sub-system. Valid values are from 001 (lowest) to 111 (highest). In the QSM Interrupt Vector Register (QIVR), the INTV field is set to the selected Interrupt Vector Number. The low order bit in the INTV field is cleared during an SCI interrupt and set during a QSPI interrupt. In the QSPI Control Register  2  (SPCR 2 ), the SPIFIE bit may be set to enable QSPI interrupts. Finally, in SCI Control Register  1  (SCCR 1 ) the TIE bit is set to enable Transmit Data Register Empty interrupts, the TCIE bit is set to enable Transmit Complete interrupts, the RIE is set to enable Receive Data Register Full interrupts, and the ILIE bit is set to enable Idle Line Detect interrupts.  
         [0255]    The General Purpose Timer (GPT) Module consists of the capture/compare unit, the pulse accumulator unit and the pulse-width modulation unit. The GPT has 11 interrupt sources and 12 interrupt vectors. There are 3 Input Capture interrupts, 4 Out Compare interrupts, a programmable Input Capture 4 or Output Compare 5 interrupt, plus the Timer Overflow, Pulse Accumulator Overflow and Pulse Accumulator Input interrupts. Any one of these interrupt sources can be selected (adjusted) to have priority over all other GPT interrupt sources. The Interrupt Vector value for each interrupt source is created by combining a high nibble selected by the programmer, called the Interrupt Vector Base Address (IVBA), and a low nibble supplied by the GPT. Table VIII shows the GPT Source Number and Interrupt Vector Value for each GPT interrupt. The lower the GPT Source Number, the higher the priority of the interrupt.  
                               TABLE VIII                                   Interrupt Source   GPT Source Value   Vector Value                           Adjusted Channel   0000   IVBA: 0000           Input Capture 1 (IC1)   0001   IVBA: 0001           Input Capture 2 (IC2)   0010   IVBA: 0010           Input Capture 3 (IC3)   0011   IVBA: 0011           Output Compare 1 (OC1)   0100   IVBA: 0100           Output Compare 2 (OC2)   0101   IVBA: 0101           Output Compare 3 (OC3)   0110   IVBA: 0110           Output Compare 4 (OC4)   0111   IVBA: 0111           Input Capture 4/Output   1000   IVBA: 1000           Compare 5 (IC4/IOC5)           Timer Overflow (TO)   1001   IVBA: 1001           Pulse Accumulator   1010   IVBA: 1010           Overflow (PAOV)           Pulse Accumulator Input   1011   IVBA: 1011           (PAI)                      
 
         [0256]    The General Purpose Timer Module interrupts may be configured using the following procedure:  
         [0257]    In the GPT Configuration Register (GOTMCR), set the IARB field to the interrupt arbitration number selected for the GPT module. Valid values are from 0001 (lowest priority) to 1111 (highest priority). In the GPT Interrupt Configuration Register (ICR) set the following fields: (a) set the interrupt Priority Adjust field (IPA) to the GPT Source Number of the GPT interrupt source you wish the module to give the highest priority; (b) set the Interrupt Priority Level field (IPL) to the selected Interrupt Priority Level of GPT interrupt requests, where valid values are from 000 (lowest) to 111 (highest):(c) set the Interrupt Vector Base Address field (IVBA) to the value of the high nibble of the Interrupt Vector Values the GPT module will use. Also enable the interrupts in the Timer Interrupt Mask Register (TMASK) as follows: (a) set PAII (TMASK, bit  4 ) to enable the Pulse Accumulator Input interrupt; (b) set PAOVI (TMASK, bit  5 ) to enable the Pulse Accumulator Overflow interrupt; (c) set TOI (TMASK, bit  7 ) to enable the Timer Overflow interrupt; (d) set ICI 1  (TMASK, bit  8 ) to enable the Input Capture 1 interrupt; (e) set IC12 (TMASK, bit  9 ) to enable the Input Capture 2 interrupt; (f) set IC13 (TMASK, bit  10 ) to enable the Input Capture 3 interrupt; (g) set OCI 1  (TMASK, bit  11 ) to enable the Output Compare 1 interrupt; (h) set OCI 2  (TMASK, bit  12 ) to enable the Output Compare 2 interrupt; (i) set OCI 3  (TMASK, bit  13 ) to enable the Output Compare 3 interrupt; (j) set OCI 4  (TMASK&lt;Bit  14 ) to enable the Output Compare 4 interrupt; (k) set I 4 / 05 I (Tmask, bit  15 ) to enable the Input Capture 4/Output Compare 5 interrupt. The exemplary Interrupt Assignments are listed in Table IX.  
                               TABLE IX                           Module                   Interrupt   &amp; IARB   Level   Vector   Application                   OC1   GPT:1111   6   40   Initiates A/D conversion       IC1   GPT:1111   6   41   Signals A/D conversion                       complete       IC2   GPT:1111   6   42   Signals A/D data ready       IC3   GPT:1111   6   43   Trip Clock Signal from                       Protective μP       IC4   GPT:1111   6   48   Zero crossings for frequency                       calculation       SWI   SIM:1110   N/A    6   Used by μC/OS for context                       switching       PIT   SIM:1110   4   60   Generates the time tick                       for μC/OS       IRQ4   SIM:1110   4   14   RS-232 UART data transfer       SCI   QSM:1101   4   50   RS-485 data transfer       QSPI   QSM:1101   4   51   Protective μP/Metering μP                       data transfer                  
 
         [0258]    [0258]                               TABLE X                               Memory               Chip   Base   Block Size   Assert           Select   Address   (bytes)   Select On   Device                   Boot ROM   0000h       Reads   External EPROM select                       (high &amp; low bytes)        0       256K       not used        1               not used        2   60000h   64K   Reads &amp;   External RAM select                   Writes   (high byte)        3   60000h   64K   Reads &amp;   External RAM select                   Writes   (low byte)        4   n/a   n/a   n/a   Port Bit used as LCD CS        5   7D800h   2K   Reads &amp;   LCD                   Writes        6   7E800h   2K   Reads &amp;   A/D Converters                   Writes        7   7E000h   2K   Writes   LCD Contrast Latch        8   7F000h   2K   Reads &amp;   RS-232 UART                   Writes        9   7F800h   2K   Reads &amp;   Real Time Clock                   Writes       10   7F800h   2K   Reads   Real Time Clock (output                       enable)                    
       Operating System of the Present Embodiment  
       [0259]    All of the features described above for the Energy Information/Communications microprocessor  222  are implemented through a preemptive multi-tasking real-time program which controls microcomputer operation. In a multitasking scheme, the program is divided into blocks called tasks, each of which is written as though it has exclusive access to the processor&#39;s time. The operating system is capable of directing the processor from one task to another (this is called context switching), and manages task execution on a priority basis. Task execution management is called scheduling, and the part of the operating system that does it is called a scheduler.  
         [0260]    A preemptive multitasking system is one that is capable of interrupting a task before it has run to completion whenever a higher priority task is ready to run. The higher priority task preempts the lower priority task, and when it has finished or is suspended, the kernel returns control to the lower priority task. A multitasking approach is believed to have the following advantages: (1) tasks are scheduled according to their relative priorities since the operating system always schedules the highest priority task that is ready to run;(2) tasks that are not ready to run—those that are waiting for an event to occur—are dormant and do not consume processor time; and (3) tasks can be activated and deactivated as required for dynamic resource allocation. The program of the present embodiment consists of a main or background task and several interrupt handlers or foreground tasks. The main program uses sample values taken in response to a periodic interrupt and performs the calculations needed to generate the various monitoring values. The sampling interrupt routine samples all of the voltage and current signals over a one-second interval, squares the sample values and accumulates a sum of squares for use by the foreground task. Other interrupt handlers perform functions such as receiving communications packets from the host processor  140  and PC  117 .  
         [0261]    Each task is a section of code that performs a portion of the work of EID  200 . Each task is assigned a priority, its own stack area. The respective stack area contains the task&#39;s stack and the state of the CPU registers at the time a context switch causes the task to become dormant. Exemplary tasks are described below. The software of the present embodiment is designed to be preemptive multitasking rather than loop controlled.  
         [0262]    The scheduler determines when tasks will be executed. A Task is allowed to run until:(1) the task readies another task of higher priority;(2) an OS clock tick passes control to a higher priority task that is ready to run;(3) an interrupt service routine readies another task of higher priority; or(4) the task explicitly relinquishes control of the CPU by calling a time delay function. A task&#39;s CPU register set and its stack area is known as its context. When the scheduler decides to run a different task, it saves the context of the current task and retrieves the context of the task to be executed.  
         [0263]    Preempting involves suspending a task to execute a higher priority task that has been prepared to run. An advantage of a preemptive system is that it is deterministic, since it can be determined when the highest priority task gets control of the Energy Information/Communications microprocessor  222 . The exemplary embodiment uses a preemptive operating system. In a preemptive system, operations that are called by more than one task must be reentrant. A reentrant feature or operation can be interrupted at any time and resumed at a later time without data corruption. Reentrant operations must use only CPU registers and stack variables, or must disable interrupts when accessing global variable.  
         [0264]    With respect to the keypad, the program polls for a key press using a periodic interrupt generated by the Programmable Interrupt Timer (PIT) as a keypad poll control time base. Once a key press has been confirmed, the function Set_Key_Flag is called, which validates the key press and queues the key press into the keypad buffer. The keypad task is then activated four (4) times a second. When activated the Keypad Task checks the keypad buffer, extracts any pending key press value from the keypad buffer and makes it available to the menu software. In this way, several key presses can be queued and acted upon as time permits. In addition, if a key is held down, the key press will be reentered into the queue at a predetermined rate.  
         [0265]    As mentioned above, the Energy Information/Communications microprocessor  222  is connected to the Protective microprocessor  214  using the Serial Peripheral Interface (SPI)  258 . The SPI data is sent in 32 byte packets. Each SPI packet contains a message type byte, a data length byte, 29 data bytes and an LRC (longitudinal redundancy check) byte. The SPI packet is arranged as follows: |MESSAGE TYPE|DATA LENGTH|DATA|LRC|. The MESSAGE TYPE byte indicates the type of data the packet contains. The DATA LENGTH byte indicates the number of bytes in the data field that contain valid data. The DATA bytes are the data that is being transmitted. The LRC byte contains the least significant byte of the sum of the message type, data length, and data bytes.  
         [0266]    The SCI sub-system handles communication with the ACCESS master if circuit breaker  116  is part of an ACCESS system. In the present embodiment, this communication consists of uploading data and downloading settings. The uploaded data may consist of the breaker settings, status and current data plus the Protective microprocessor  214  and Energy Information/Communications microprocessor  222  settings, status and energy information data available from the Protective microprocessor  214  and Energy Information/Communications microprocessor  222 . The circuit breaker and metering settings can be selected remotely and downloaded to circuit breaker  116 . In the present embodiment, the ACCESS protocol operates on a serial, two-wire RS 485 network consisting of a single-bus master and up to 32 slave devices. The serial transmission format is asynchronous with one start bit, eight data bits, one stop bit and no parity. The data rate can range from 1,200 to 19,200 baud. A master device initiates all communication by sending a packet addressed to a slave device. The slave device responds with a packet if a response is required.  
         [0267]    No slave device initiates communication. Any data that does not meet the timing or structural requirements of the ACCESS protocol is ignored by all devices. Data in ACCESS format is sent in packets containing from 5 to 260 bytes, for example. These packets are defined by framing bytes contained in their headers. These consist of a synchronization byte, an address byte, a message-type byte, a length byte (packet&#39;s data field length) and a LRC byte. The SCI packet is arranged as follows: |SYNC|DEVT|MSGT|LEN|DATA|LRC|.  
         [0268]    The SYNC byte indicates the direction of the data transmission. Fourteen (14) hex is used for master to slave transmissions and twenty-seven hex is used for slave to master transmissions. The DEVT byte contains the address code for a specific device (direct addressing)or a general type of device (indirect addressing). The MSGT byte indicates what type of data the packet contains. The LEN byte indicates the number of bytes in the data field. The DATA bytes are the data that is being transmitted. This field can contain up to 225 bytes. With indirect addressing, the first byte in this field is the device address. Finally, the LRC is the checksum byte. It contains the inverted sum of all the bytes except the SYNC byte. The UART handles EIA-232 communications with a locally connected IBM PC or other personal computer. This communication consists of uploading data and down loading settings. The uploaded data consists of the circuit breaker settings, status and current data plus the metering or energy information settings status and data. The circuit breaker and energy information settings can be selected from the PC and down loaded to the trip unit.  
         [0269]    Timekeeping is performed by a real time clock  234  (RTC). The RTC  234  registers are memory-mapped I/O. They include six 8-bit time/date registers plus an 8-bit command register. When reading or writing the time/date registers, a 0 is written to the TE Bit of the command register to freeze the time and date. This allows the data to be accessed without an essentially simultaneous update. This does not affect timekeeping because the RTC  234  contains internal and external time/date registers. The external registers are frozen and during a read or a write access. After the read or write, a 1 is written to the TE bit to allow the external time/date registers to be updated again. The RTC  234  is read once each second and the new date and time information is stored in the RAM  236 . This information can then be accessed by any function, such as the Event Log, that has need of the date and time.  
         [0270]    The hardware allows sampling of the voltage and current one phase at a time. The sampling process is interrupt driven, which allows the sampling to run in the background while other tasks run in the foreground. Analog-to-Digital conversion is managed by two General Purpose Timer interrupts and their associated service routines. The interrupts are Output Compare One (OC1) and Input Capture One (IC1). When the Energy Information module needs a new sample data set for a phase, OC1 is used to start each A/D conversion. The Energy Information module uses the calculated line frequency to determine the period needed between OC1 interrupts to give exactly 64 interrupts per cycle. It then asynchronously schedules the first OC1 interrupt. The OC1 interrupt service request (ISR) reads ADC  232 A, and  232 B to start a conversion and then the next OC1 interrupt. While it is believed to be preferable to start the conversions at essentially the same time, since both ADC  232   a  and  232 B cannot be read at the same time due to bus contention, they may be read consecutively. In the present embodiment, the voltage conversion starts 2.026 μs or 0.04 degrees (at 60 Hz) after the current conversion.  
         [0271]    The IC1 interrupt is activated when both ADC  232 A and  232 B complete their respective conversions. Energy Information/Communications microprocessor  222  retrieves the result of the A/D conversions, converts the raw voltage and current data into signed data and stores the result in RAM  236 . When 384 voltage and current samples have been acquired (64 samples×6 cycles), Energy Information/Communications microprocessor  222  de-activates the OC1 interrupt and activates the Energy Information task. Thus, informing the Energy Information task that the voltage and current data sets for a particular phase are ready for processing.  
         [0272]    When sampling phase A, the IC4 interrupt is enabled so that a zero crossing of the voltage signal for phase A causes an interrupt. When the zero crossing interrupt occurs, the value of the free running timer/counter TCNT is stored in an array. Once a second, the zero crossing array is used by a routine to determine the frequency. This routine calculates the average difference between all of the TCNT values stored in the array during sampling. This average TCNT delta and the TCNT period are used to calculate the line frequency for phase A using the formula shown below. Where System Clock Frequency =16.777 Mhz, TCNT Frequency =4.194 Mhz (System Clock /4), TCNT Period =238 nSec, and  
       Line_Frequency   =     1     2   ×   Average_                 TCNT                 _Delta   ×   TCNT                 _                 Period                             
 
         [0273]    If a phase A voltage signal is not available, the frequency is set to the programmed system frequency, 50 or 60 Hz. The Output Compare 1 (OC1) interrupt is used to start each AID conversion for sample acquisition. The occurrence of this interrupt is determined by the value stored in the Timer Output Compare 1 register (TOC1). When the free running timer/counter TCNT equals the value in the TOC1 register, an asynchronous OC1 interrupt occurs. Therefore, the sampling rate can be changed by modifying the value loaded in TOC1. For the FFT algorithm used for harmonic calculation to obtain sufficiently accurate results, it is desirable to take at least about 64 samples over one cycle. Therefore, the sample period is based on the line frequency determined from the phase A voltage signal. The following equations are used to calculate the offset to be added to TCNT and stored in the TOC1 register to correctly schedule the next OC1 interrupt, where:  
         OC1                 _Offset     =     1     Line_Frequency   ×   TCNT                 _Period   ×   Samples_per      _Cycle                             
 
         [0274]    and TOC1=TCNT+OC 1_Offset.    
         [0275]    Once each second the operating system activates a task to initiate sampling. This task takes the line frequency based on the data collected by the IC4 interrupt routine. It then calculates the new offset to be used by OC1 in scheduling sampling interrupts and initiates the sampling of phase A voltage and current. Sampling continues for the next six cycles for a total of 384 samples (6×64). Each time a conversion is completed, the A/D converters activate the IC1 interrupt line. The IC1 interrupt service routine reads the conversion results and stores them. When an entire data set of 384 voltage and current samples is acquired, the IC1 ISR informs the operating system that the data is ready. When the operating system is informed the phase A data is ready, it activates the energy information task. The energy information task initiates the sampling of phase B and then processes the phase A data. An exemplary method for sampling current and voltage signals is shown in Table XI and an exemplary data memory requirement is shown in TABLE XII.  
                                   TABLE XI                       Phase       Samples   Sample   Start A/D   Read A/D       Sampled   Task   Taken   Freq.   Interrupt   Interrupt                   A   Initiate   384   64/cycle   OC1   ICI           Sampling       B   Meter   384   64/cycle   OC1   ICI       C   Meter   384   64/cycle   OC1   ICI       N   Meter   384   64/cycle   OC1   ICI                  
 
         [0276]    The sequence of events listed in the table will occur once each second. Six cycles will be sampled at 64 times per cycle. When a complete set of data for a phase has been acquired, the IC1 ISR “posts” the operating system to signal that the data set is ready for processing. For both current and voltage data, each sample requires 2 bytes of memory.  
                                                 TABLE XII                                   Source   Data Type   Bytes                                        Voltage A/D   Voltage   768           Current A/D   Current   768           Voltage Samples   Sum of Squared Voltage   4               Samples           Current Samples   Sum of Squared Current   4               Samples               Total       1544                      
 
         [0277]    FIGS.  11 A- 11 B are flowcharts outlining the ADC Sampling Interrupt. The ADC sampling interrupt maintains proper timing of the Energy Information Task (described below). A timer interrupt is used to select the phase to be sampled and set the sampling time interval. Sampling occurs 64 times per cycle based on the frequency calculation from the previous second. Whenever the frequency is unknown, the frequency is less than 35 Hz, or greater than 75 Hz, the sampling time interval is based on a selected system frequency. In the present embodiment, the selected system frequency is 50 Hz or 60 Hz.  
         [0278]    It is believed that using a sampling rate of 64 samples per cycle enables faster harmonics calculations. As is well known, for the harmonics calculations to be sufficiently accurate, the determined frequency is used. Because the frequency is calculated from Phase A voltage samples in the present embodiment, if Phase A is non-functional and the other phases are at frequencies other than the programmed system frequency, the accuracy of the energy information data may not be sufficient.  
         [0279]    Referring to FIG. 11A, at Step  1100 , the Initiate Sampling Task (described below) starts the sampling of Phase A. At Step  1101 , sampling interrupts are enabled. At Step  1102 , ADC  232 A,  232 B acquire the data from 6 cycles of voltage and current, respectively, at 64 samples per cycle for phase A. At Step  1104 , sampling interrupts are disabled. At Step  1106 , Energy Information/Communications microprocessor  222  activates the Energy Information Task (described below). At Step  1108 , the Energy Information Task changes the sampling to Phase B. At Step  1109 , sampling interrupts are again enabled. At Step  1110 , ADC  232 A,  232 B acquire the data from 6 cycles of voltage and current at 64 samples per cycle for Phase B. At Step  1112 , sampling interrupts are disabled. At Step  1114 , Energy Information/Communications microprocessor  222  activates the Energy Information Task.  
         [0280]    Referring now to FIG. 11B, the Energy Information Task changes the sampling to Phase C at Step  1116 . At Step  1117 , sampling interrupts are enabled. At Step  1118 , ADC  232 A,  232 B acquire the data from 6 cycles of voltage and current at 64 samples per cycle for Phase C. At Step  1120 , sampling interrupts are disabled. At Step  1122 , Energy Information/Communications microprocessor  222  activates the Energy Information Task. At Step  1124 , the Energy Information Task changes the sampling to Phase N. At Step  1125 , sampling interrupts are enabled. At Step  1126 , ADC  232 A,  232 B acquire the data from 6 cycles of voltage and current at 64 samples per cycle for Phase N. At Step  1128 , sampling interrupts are disabled. At Step  1130 , Energy Information/Communications microprocessor  222  activates the Energy Information Task. At Step  1132 , the ADC sampling task is complete. The ADC  232 A,  232 B will not be started again until the Initiate Sampling Task is subsequently activated.  
         [0281]    [0281]FIG. 12 is a flowchart showing the Initiate Sampling Task, which updates the Energy Information Task once per second. Once a second the Initiate Sampling Task is activated using an operating system time delay. Once activated, this task calculates the sampling time interval that will be used for the current one second time interval based on the frequency that was calculated during the previous one second time interval. The sampling time interval is set such that the voltage and current will be sampled 64 times per cycle. The sampling that occurs immediately after EID  200  is activated is calculated based on the selected system frequency. As mentioned above, in the exemplary embodiment, if the calculated frequency is less than 35 Hz or greater than 75 Hz, the selected system frequency is used to determine the sampling time interval. The Initiate Sampling Task is activated after the Energy Information Task completes the processing of the Phase N samples. This ensures that all of the per second energy information tasks are complete. Referring to FIG. 12, the Initiate Sampling Task is shown. At Step  1200 , the time between samples for a 64 sample per cycle sampling rate is calculated. At Step  1202 , ADC  232 A,  232 B sampling for Phase A is initiated At Step  1204 , the task is completed and awaits subsequent activation.  
         [0282]    [0282]FIGS. 13A to  13 C are flowcharts showing the Energy Information Task. The Energy Information Task has what are believed to be the most stringent timing constraints of any of the tasks in EID  200  because of the number of calculations that are performed every second. In the exemplary embodiment, the Energy Information Task uses approximately 500 to 600 ms of every 1000 ms process cycle. The Energy Information task does not occupy a contiguous portion of the 500 to 600 ms time, however, so that other tasks may be serviced without creating data latency problems and associated inaccuracies. In the present embodiment, it is believed that a significant and even a majority portion of time are allotted to the energy information harmonics task. This task is estimated to require approximately 90 ms per phase. In the present embodiment, the Energy Information Task is activated 4 times per second as a result of ADC signal  233  (FIG. 2C) indicating that ADC  232 A,  232 B has finished sampling a phase. To facilitate RMS computations, the system preferably uses the square root techniques of co-pending and commonly assigned case U.S. patent application Ser. No. 08/625,489, which is entitled “Fractional Precision Integer Square Root Processor And Method For Use With Electronic Circuit Breaker Systems,” and which is incorporated by reference.  
         [0283]    The energy information code essentially consists of two parts. The Energy Information task which operates in the foreground, and OC1/IC1 interrupt service routines which operate in the background. The background code (ISRs) collect the samples for the next phase while the foreground code (meter task) manipulates the samples collected for the last sampled phase. The background code is illustrated in FIG. 13A and the foreground code is illustrated in FIGS.  13 B- 13 C.  
         [0284]    Referring to FIG. 13A, at Step  1300  and OC1 interrupt occurs to activate the background sampling task. At Step  1302 , a command is sent to ADC  232 A,  232 B to collect a sample. At Step  1304 , ADC  232 A,  232 B collects a current and a voltage sample, respectively, for the currently sampled phase. At Step  1306 , an IC1 interrupt is generated. At Step  1308 , the current and voltage samples are stored. At Step  1310 , a determination is made as to whether the sample set is complete, i.e., have 384 samples been taken. If the sample set is complete Step  1312  is entered, otherwise the task waits for another OC1 interrupt at Step  1313 . Once 384 samples are collected, Step  1312  disables the OC1 and IC1 interrupts. At Step  1314 , the Energy Information task is activated.  
         [0285]    Referring to FIG. 13B, the foreground Energy Information task is outlined. At Step  1316  the Energy Information task is activated when the IC1 interrupt service routine determines a complete set of phase samples has been collected. At Step  1318 , a determination is made as to which Phase was most recently sampled. If Phase N was most recently sampled the process continues at Step  1332 , otherwise Step  1320  is executed. At Step  1320 , ADC  232 A,  232 B is instructed to begin sampling the next phase. At Step  1322 , the sum of squares for the current and voltage of the most recently sampled Phase is calculated. At Step  1324 , the harmonics most recently sampled Phase is calculated. At Step  1326 , the power of the most recently sampled Phase is calculated. At Step  1328 , RAM  236  is updated with the data calculated in Steps  1322  through  1326 . At Step  1330 , the task is completed.  
         [0286]    As mentioned above, if Step  1318  determines that the most recently sampled phase was Phase N, Step  1332  is entered. At Step  1332 , the sum of the squares of the current samples of Phase N are calculated. At Step  1334 , the harmonics of Phase N amps are calculated. At Step  1336 , the phase current for Phase N is calculated. At Step  1338 , the temperature of EID  200  is calculated. At Step  1340 , the data stored in RAM  236  at Step  1328  for each of Phase A, B, and C is read.  
         [0287]    Referring to FIG. 13C, at Step  1342  the data read from RAM  236  at Step  1340  is used to calculate the sums and averages to generate the metered quantities for display on LCD  24 . At Step  1344 , the data is stored and becomes available for display and communication. At Step  1346 , the energy registers are cleared if necessary. At Step  1348 , the energy quantities are accumulated. At Step  1350 , the demand calculations are restarted if necessary. At Step  1352 , the demand is calculated. At Step  1354 , the min/max log is cleared if necessary. At Step  1356 , the min/max log is updated if a new min/max event occurred. At Step  1358 , event data is loaded and at Step  1360 , the Event Task is posted to run at the next available processing slot. At Step  1362 , the power data is loaded and at Step  1364 , the harmonic data is loaded. At Step  1366 , a determination is made as to whether the display is in the scroll mode. If display is in the scroll mode, Step  1370  is entered and the LCD Scroll Task is posted to run. Otherwise, Step  1368  is entered and the Display Task is posted to run. After one or the other is posted, Step  1372  is entered and the Meter Task is complete.  
         [0288]    [0288]FIGS. 14A and 14B are flowcharts showing the LCD Scroll Task. The LCD Scroll Task (when in LCD scrolling mode) works in conjunction with the Display Task (when in fixed LCD mode) to provide information to LCD  240 . The Energy Information Task activates the LCD Scroll Task once a second when the scrolling mode is active. In the present embodiment, four fixed LCD displays have been selected for display on LCD  240  while LCD  240  is scrolling. When the LCD  240  is in the scrolling mode a display will remain on the LCD  240  for approximately seven seconds. LCD  240  will then be changed to the next display in the scrolling list.  
         [0289]    Referring to FIG. 14A, two ways are illustrated to enter the scrolling mode. At Step  1400 , the scroll task is entered. At Step  1402 , if power on is detected Step  1404  is entered, otherwise step  1406  is entered. At Step  1404 , a determination is made if the keypad has been inactive for 10 seconds after power up. If this determination is satisfied the scrolling mode is entered at Step  1408 . At Step  1406 , a determination is made if the keypad has been inactive for 5 minutes. If this determination is satisfied, the scrolling mode is entered at Step  1408 , otherwise Step  1406  is repeated. At Step  1408 , the first scroll display is initiated. At Step  1410 , a determination is made whether the scroll display is a new display. If the display is a new display Step  1412  is entered, otherwise Step  1416  is entered. At Step  1412  the LCD  240  is cleared to prepare for the new display. At Step  1414 , the display counter is initiated. At Step  1416 , a determination is made if the EID  200  has a system error. If a system error is detected Step  1418  is entered, otherwise processing proceeds to Step  1420  in FIG. 14B. At Step  1418 , the display is updated with the system error display.  
         [0290]    Referring now to FIG. 14B, at Step  1420 , the LCD  240  is updated with the current scroll display. At Step  1422 , the display counter is checked for a time-out. If a time-out is detected Step  1424  is entered, otherwise Step  1410  is reentered. At Step  1424 , the next scroll display is selected. At Step  1426 , the display timer is re-initiated, and Step  1410  is re-entered. During this process, a wait loop  1428  is running in the background to detect a keypad depression. When a keypad is depressed, Step  1430  is entered. At Step  1430 , the display exits the scrolling mode. At Step  1432 , the fixed display is reactivated displaying the last information prior to entry into the scroll mode. FIG. 15 is a flowchart showing the Events Task. The Events Task is activated once a second by the Energy Information Task. When activated, the Events Task maintains the states and delays for each alarm and relay function. The events task also clears the event and trip logs when requested and maintains the data written into the event and trip logs. When the Energy Information Task has completed calculating the most recent energy information data, the Energy Information Task loads the data into the Events Task. When activated, the Events Task checks the set points for each programmed alarm and relay function. When a set point is exceeded, the respective alarm or relay enters the wait state. If the delay time is exceeded, the alarm or relay function enters the active state. If an event causes several alarms to activate during a single event task, only the first alarm checked is initially entered into the event log. After the logged alarm is cleared, any other alarm that is in the active state will be logged. In this way, only one alarm at a time is logged in to prevent a single event, which may cause several alarms to become active, from overflowing the event log.  
         [0291]    Referring to FIG. 15, the Events Task is illustrated. At Step  1500  the events task is entered. At Step  1502 , a determination is made if a Clear Trip Log request is detected. If so, Step  1504  is entered, otherwise Step  1506  is entered. At Step  1504 , the Trip Log is cleared. At Step  1506 , a determination is made if a Clear Event Log request is detected. If so Step  1508  is entered, otherwise Step  1510  is entered. At Step  1508 , the Event Log is cleared. At Step  1510 , the alarms are checked, logged in the Event Log, and activated or deactivated as required. At Step  1512 , the protective relays are checked. If necessary, relay alarm data is logged in the Event Log. Also, if necessary, relay trip data is logged in the Trip Log and the circuit breaker is tripped. At Step  1514 , the SPI message task is activated if necessary and at Step  1516 , the Events Task is complete.  
         [0292]    [0292]FIG. 16 is a flowchart outlining the Keypad Task. In the present embodiment, the Keypad Task is activated every 250 ms to determine if a key has been pressed. If a key is available, the Display Task or LCD Scroll Task is informed so that the display can be updated as required. If a key is pressed, the scroll delay is reset to 5 minutes and, if LCD  240  is currently in the scrolling mode, the display mode is changed to fixed display mode. At Step  1600 , the Keypad Task is entered. At Step  1602 , a determination is made whether a new key depression occurred. If a new key depression is detected Step  1604  is entered, otherwise Step  1602  is reentered. At Step  1604 , the scroll delay is reset to 5 minutes. At Step  1606 , the current display mode is determined. If the mode is the scrolling display mode, then step  1608  is entered, otherwise Step  1610  is entered. At Step  1608 , the display mode is changed to the fixed display mode. At Step  1610 , appropriate flags are set for other tasks and the display Task is entered.  
         [0293]    [0293]FIG. 17 is a flowchart outlining the Display Task. The Display Task is activated once per second when the display is in the fixed mode or on demand in response to depressing a key. Screens that contain changing data are updated every second. Screens that contain fixed information are updated only when a key is depressed. When starting at the Main Menu, lower level menus and information/set point screens are entered when the Enter Key  412  is depressed. Likewise, when starting at a lower level screen in the menu hierarchy, higher level screens are entered when the ESC key  414  is depressed. The Up key  408  and Down key  410  are used to change the values/set points of programmed data, for example. In particular, at Step  1700 , the Display Task is entered. At Step  1702 , the area of RAM  236  containing the display data is updated based on the current display and whether a key was pressed. At Step  1704 , the SPI Message Task is activated if necessary. At Step  1706 , the display RAM is copied to the LCD interface  240 A. At Step  1708 , the Display Task is completed.  
         [0294]    [0294]FIG. 18 is a flowchart showing the RS232 Task, which determines what response needs to be transmitted after an RS232 message is received. Once the response is determined, the Transmit Message Task is activated. In the present embodiment, both the RS232 Task and the RS485 Task use the same functions to decode incoming messages and build the outgoing responses. The RS232 UART Interrupt  249  FIG. 2C receives and transmits data on the RS232 port  248 . When the last message byte is received, the RS232 UART Interrupt activates the RS232 Task so that the response to the message can be determined. Likewise, after the RS232 Task builds the response message, it activates the Transmit Message Task which causes the RS232 UART Interrupt  249  to transmit the response out the RS232 port. The RS232 Task is activated by the RS232 UART interrupt  249  after a message has been received. Again, referring to FIG. 18, the RS232 Task is illustrated. At Step  1800 , the RS232 task is entered as a result of RS232 UART interrupt  249 . At Step  1802 , the communications semaphore is acquired from the operating system (OS). At Step  1804 , the received message is processed. At Step  1806 , the SPI Message Task is activated as required. At Step  1808 , the Transmit Message Task is activated to send the response message. At Step  1810 , the communications semaphore is released to the OS.  
         [0295]    [0295]FIG. 19 is a flowchart outlining the RS485 Task. The RS485 Task determines what response needs to be transmitted after a RS485 message is received. Once the response is determined, the Transmit Message Task is activated. As mentioned above, both the RS232 Task and the RS485 Task use the same features to decode incoming messages and build the outgoing responses. The Process RS485 Task is activated by the SCI interrupt after a message has been received. The RS485 UART Interrupt receives and transmits data on the RS485 port. When the last byte of a message is received, the RS485 UART Interrupt activates the RS485 Task so that the response to the message can be determined. Likewise, after the RS485 Task builds the response message, it activates the Transmit Message Task which causes the RS485 UART Interrupt to transmit the response out the RS485 port. In particular at Step  1900 , the RS485 task is entered as a result of an RS485 interrupt. At Step  1902 , the communications semaphore is acquired from the OS. At Step  1904 , the received message is processed. At Step  1906 , the SPI Message Task is activated as required. At Step  1908 , the Transmit Message Task is activated to send the response message. At Step  1910 , the communications semaphore is released to the OS.  
         [0296]    [0296]FIG. 20 is a flowchart showing the Transmit Message Task. The Transmit Message Task determines what response needs to be transmitted after a message is received. The Transmit Message Task is activated by the RS232 Task and the RS485 Task after an incoming message has been decoded and a response message has been determined. This task activates the RS232 UART  248 A or RS485 transmitter  246  A if a response is required. In particular, Step  2000 , the Transmit Message Task is entered. At Step  2002 , it is determined whether an RS232 or RS485 task initiated the Transmit Message Task. If so Step  2004  is entered, otherwise the task is terminated at Step  2008 . At Step  2004 , it is determined whether a transmit message is necessary. If so Step  2006  is entered, otherwise the task is terminated at Step  2008 . At Step  2006 , the transmit message is sent. At Step  2008 , the Transmit Message Task is terminated.  
         [0297]    [0297]FIG. 21 is a flowchart showing the SPI Message Task. The SPI Message Task handles Inter-processor communications between the Protective microprocessor  214  and Energy Information/Communications microprocessor  222 . The SPI Message Task is activated by the tasks that need to send a message to the Protective microprocessor  214 . In particular, at Step  2100  Energy Information/Communications microprocessor  222  initiates the data transfer by first pulsing SPI interrupt line  259 . At Step  2102 , Energy Information/Communications microprocessor  222  first loads 16 bytes of data into the SPI buffer and at Step  2104 , pulses the interrupt line  259 . At Step  2106 , the Protective microprocessor  212  transfers the first 16 bytes of the message from the Energy Information/Communications microprocessor  222 . At Step  2108 , Energy Information/Communications microprocessor  222  again pulses interrupt line  259  to indicate that the data transfer is complete. At Step  2110 , Energy Information/Communications microprocessor  222  loads a second 16 bytes of data into the SPI buffer and at Step  2112 , pulses interrupt line  259 . At Step  2114 , Protective microprocessor  212  transfers the second 16 bytes of data.  
         [0298]    At Step  2116 , the 32 bytes of data are processed by the Protective microprocessor  214 . At Step  2118 , Protective microprocessor  214  sends 16 bytes of response data to Energy Information/Communications microprocessor  222 . At Step  2120 , Energy Information/Communications microprocessor  222  pulses the SPI interrupt line to suspend data transfer. At Step  2122 , Energy Information Communications microprocessor  222  stores the first 16 bytes of data and at Step  2124 , pulses SPI interrupt line  259  to continue the data transfer. At Step  2126 , Protective microprocessor  214  sends the last 16 bytes of data to Energy Information/Communications microprocessor  222 . At Step  2128 , a status message is posted to the calling task to indicate whether an error occurred during the SPI Task. At Step  2130 , the sequence is complete.  
         [0299]    Exemplary SPI messages that the Energy Information/Communications microprocessor  222  sends to the Protective microprocessor  214  include the following: (1) EEPROM Read—read an item from the Protective microprocessor&#39;s EEPROM; (2) EEPROM Write—write an item from the Protective microprocessor&#39;s EEPROM; (3) Update Status—the Energy/Communication and Protective boards swap status information; (4) Clear Trip Log—clear trip log data in the Protective microprocessor&#39;s EEPROM; (5) New Trip Log Entry—add new trip log entry to the Protective microprocessor&#39;s PROM  216 ; (6) Breaker Test—perform a breaker test; (7) System Information—get the rating plug value and protective code version; and (8) Trip Breaker—instruct Protective board to trip circuit breaker  116 .  
         [0300]    [0300]FIG. 22 is a flowchart showing the Error Task, which displays a predetermined error screen if a system error occurs. At Step  2200 , the error type is displayed. At Step  2202 , the task waits for the ESC key to be pressed. After the ESC key is pressed, Step  2204  is entered. At Step  2204 , Energy Information/Communications microprocessor  222  is reinitialized. In the present embodiment, if an error occurs, one of 6 high level error values will be displayed on the error screen. If the high level error was caused by an SPI error, then the SPI error value will be displayed after the high level error value separated by a dot (.). For example, if the error screen displays 1.4 as the error number, this is an indication that a EEPROM write message failed as a result of a EEPROM programming failure. Exemplary High Level Error values are: (1) EEPROM write error; (2) Status message error; (3) Clear trip log error; (4) Trip log update error; (5) Breaker test error; and (6) Breaker trip error. Exemplary Low Level SPI Error values are SPI errors reported by protective processor, which include: (1) Invalid message type received; (2) Bad LRC received; (3) Invalid length byte received; (4) An EEPROM programming failure occurred; and (5) An invalid test was requested. Exemplary SPI receive errors detected by Energy Information/Communications microprocessor  222  include: (6) Bad message type error; (7) Bad LRC error; (8) EEPROM read message error; (9) EEPROM write message error; (10) Update Status message error; (11) Clear Trip Log message error; (12) New Trip Log Entry message error; (13) Breaker Test message error; (14) System Information message error; and (15) Trip Breaker message error.  
         [0301]    While the present invention has been described in terms of the exemplary or present embodiment, as currently contemplated, it should be understood that the present inventions are not limited to the disclosed embodiments. Accordingly, the present inventions cover various modifications comparable arrangements, methods and structures that are within the spirit and scope of the claims.