Abstract:
A system for monitoring and reporting power consumption in a branch circuit electrical panel is disclosed. The system uses split core transformers to sense current and voltage within the electrical panel. Each circuit within the electrical panel is sampled periodically. The periodically sampled voltages and currents are transformed into power consumption data. The power consumption data is communicated to a remote server computer. The remote server computer generates reports regarding the power consumption of the various circuits within the electrical panel. A remote computer may be used to access the reports from the server. Note that this abstract is presented to meet requirements of the USPTO. This abstract is not intended to identify key elements of the apparatus and methods disclosed herein or to delineate the scope thereof.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority and benefits of U.S. Provisional Patent Application 61/310,415 by applicant Scott L. Bassford entitled “BRANCH CIRCUIT POWER MONITORING DEVICE” filed on 4 Mar. 2010, which is hereby incorporated by reference in its entirety herein. 
     
    
     BACKGROUND 
       [0002]    1. Field 
         [0003]    This apparatus and associated methods disclosed herein relate generally to monitoring and reporting devices for use in monitoring and reporting power usage in a branch electrical circuit. 
         [0004]    2. Related Art 
         [0005]    Residential and commercial buildings typically include electrical circuit panels. These circuit panels may include breakers, and other devices for controlling electrical circuits within the building. There is a need for improved branch circuit power monitoring apparatus that can monitor individual circuits within the breaker box. 
       BRIEF SUMMARY 
       [0006]    These and other needs and disadvantages may be overcome by the apparatus and methods disclosed herein. Additional improvements and advantages may be recognized by those of ordinary skill in the art upon study of the present disclosure. 
         [0007]    A branch circuit power monitoring system is disclosed herein. In various aspects, the branch circuit power monitoring apparatus includes a current transformer adapted to communicate with a circuit that receives power from an electrical panel to detect the current within the circuit, and a converter in operable connection with the current transformer to sample intermittently a current transformer signal from the current transformer indicative of the current. The converter is adapted to generate a digital data signal indicative of the current, in various aspects. 
         [0008]    This summary is presented to provide a basic understanding of some aspects of the apparatus and methods disclosed herein as a prelude to the detailed description that follows below. Accordingly, this summary is not intended to identify key elements of the apparatus and methods disclosed herein or to delineate the scope thereof. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a schematic of an exemplary implementation of a branch circuit power monitoring apparatus; 
           [0010]      FIG. 2  is a schematic of portions of the exemplary implementation of a branch circuit power monitoring apparatus generally illustrated in  FIG. 1 ; 
           [0011]      FIG. 3  is an exemplary circuit diagram of a circuit used in the exemplary implementation of a branch circuit power monitoring apparatus of  FIG. 1 ; 
           [0012]      FIG. 4  illustrates by schematic portions of an exemplary implementation of a branch circuit power monitoring apparatus in communication with circuits within an electrical panel 
           [0013]      FIG. 5  is an exemplary display screen with a report regarding power consumption generated by a remote server according to an exemplary implementation of a branch circuit power monitoring apparatus; 
           [0014]      FIG. 6  illustrates by process flow chart an exemplary method of collecting and uploading data to a remote server; and, 
           [0015]      FIG. 7A  illustrates graphically an implementation of intermittent sampling of a current transformer signal from the current transformer indicative: and 
           [0016]      FIG. 7B  illustrates graphically an implementation of intermittent sampling of a reference voltage signal from the reference voltage transformer. 
       
    
    
       [0017]    The Figures are exemplary only, and the implementations illustrated therein are selected to facilitate explanation. The number, position, relationship and dimensions of the elements shown in the Figures to form the various implementations described herein, as well as dimensions and dimensional proportions to conform to specific force, weight, strength, flow and similar requirements are explained herein or are understandable to a person of ordinary skill in the art upon study of this disclosure. Where used in the various Figures, the same numerals designate the same or similar elements. Furthermore, when the terms “top,” “bottom,” “right,” “left,” “forward,” “rear,” “first,” “second,” “inside,” “outside,” and similar terms are used, the terms should be understood in reference to the orientation of the implementations shown in the drawings and are utilized to facilitate description thereof. 
       DETAILED DESCRIPTION 
       [0018]    In various aspects, a branch circuit monitoring apparatus may include one or more circuit monitors, which may be current transformers. Each of the one or more circuit monitors may be in communication with a corresponding circuit of an electrical panel to detect the voltage and current within the circuit. The circuit monitor may communicate one or more digital values representative of the voltage, the current, or the power within the circuit to a computer. The computer may be located generally on site (i.e. the same facility) or may be remotely located geographically with respect to the circuit. The computer may conduct various analyses of the voltage, current, or power, and the results of these analyses may be displayed graphically, in a tabular form, or otherwise communicated to a user. The computer may communicate with various devices that are in communication with the circuit to modulate the operation of these devices in order to adjust the power drawn from the circuit by these devices. 
         [0019]    In various aspects, the branch circuit power monitoring apparatus uploads usage data to a server. The branch circuit power monitoring apparatus may be installed within a branch circuit electrical panel, or may be installed near the electrical panel. The branch circuit monitoring apparatus samples multiple channels of current draw and one or more channels of AC voltage references. 
         [0020]    A voltage divider may be used to connect current transformers and the AC voltage reference transformer to a voltage midway between the ground and positive voltages. The voltage midway between the ground and the positive voltages may be about 2.5 volts or may be 1.65 volts, in various aspects. 
         [0021]    An analog to digital converter (“A-D converter”) receives inputs from the voltage divider, the AC voltage reference transformer, and the current transformers, in various aspects. In various aspects, multiple A-D converters may be used. The A-D converters may be connected to a microcontroller, and the microcontroller may upload data periodically, for example, once per minute to a remote server. The remote server may be generally on site or may be in a geographically remote location in various aspects. The microcontroller may store data for an extended period, if the remote server is unreachable due to a connection problem. 
         [0022]    The current transformers are sampled intermittently, rather than on a continuous basis, by the A/D converter in various aspects. For example, a current transformer may be sampled over a 250 milliseconds interval once per minute, and the current transformer would not be sampled for the remainder of the minute. In various aspects, the power consumption of each circuit is reported in watts. Sampling of current transformers and, thus, the sampling of the circuits being monitored by the current transformers, in various aspects, occurs once per minute for a period of about 250 milliseconds per circuit, and several hundred samples of current waveform and voltage waveform may be taken. The samples may be analyzed to provide RMS readings of voltage, volts amperes—voltage multiplied by RMS amperes and also wattage, the average of multiplying the individual samples of current waveform and voltage waveform. Sampling of current transformers may occur once per minute for a period ranging from about 100 milliseconds to about 1.5 seconds, in various aspects. The current transformers may be sampled intermittently with various other intermittencies in other aspects. In various aspects, the current transformers are split core transformers, such that it is not necessary to take the lines off load during installation. 
         [0023]    The voltage divider may be sampled intermittently by the A/D converter, in various aspects. For example, the voltage divider may be sampled for a period ranging from about 100 milliseconds to about 1.5 seconds, in various aspects. The voltage divider may be sampled intermittently with various other intermittencies in various aspects. 
         [0024]    In one aspect the present invention is directed to a branch circuit power monitoring apparatus. The circuit power monitoring apparatus includes a channel logger that has a plurality of split core current transformers adapted to sense current within a plurality of circuits in an electrical circuit panel, in this aspect, and each of the current transformers is adapted to periodically sense current within a corresponding circuit. A converter may convert the sensed currents into digital data. A microcontroller may record the digital data. The microcontroller may be adapted to communicate the digital data to a remote server. The remote server may be adapted to generate readable reports based on the data. A voltage reference transformer may be provided. The plurality of split core current transformers may include 14 or 42 current transformers, in various aspects, and the readable reports may include reports that show power consumption by watts. 
         [0025]      FIG. 1  illustrates an exemplary implementation of a branch circuit power monitoring apparatus  10 . The branch circuit power monitoring apparatus  10 , in this implementation, includes a circuit monitor  12  operably connected with a branch circuit electrical panel  14 . The electrical panel  14  controls the distribution of electricity to electrical circuits  17  to provide alternating current electrical power to outlets and appliances  19  within the building  16 . The electrical panel  14  may be supplied by mains electric. The panel  14  distributes the supplied power to electrical circuits  17  and electrical circuits  17  communicate the electrical power from the electrical panel  14 . In various implementations, the electrical circuits  17  may communicate alternating current from the electrical panel  14  through portions of a building  16 . The building  16  may be, for example, a residential building, such as a home or apartment, or may be a commercial building such as an office building, store or warehouse, a manufacturing facility, an industrial facility such as a refinery, or a farm related facility, or other facility or equipment to which the circuits of the electrical panel communicate. The electrical panel  14  may be used to control electrical distribution to the entire building  16 , or to only a portion of the building  16 . The electrical panel  14  may include a plurality of circuits, and may include circuit breakers and other controls for the various circuits. Power is distributed to the one or more circuits by the electrical panel so that the circuit(s) are powered by the electrical panel. The electrical circuits within the electrical panel  14  may be single-phase circuits, or may be three-phase circuits. An exemplary electrical panel  14  might include 42 separate electrical circuits. 
         [0026]    An electrical power source  18  provides electrical power to the electrical panel  14  through incoming wiring  20 . Typically the power source  18  will be an electric utility that transmits electricity through power lines. 
         [0027]    The circuit monitor  12  periodically samples and senses voltages and currents within the various circuits in the electrical panel  14 , as will be described in more detail below. The circuit monitor  12  determines estimated power consumption in the various circuits based on these voltages and currents. The circuit monitor  12  communicates these sensed voltages and currents as well as the estimated power consumption data to a remote server computer  22 . The server  22  is programmed to convert the data into various electronic reports, including power consumption reports in terms of watts consumed for each of the circuits within the electrical panel  14 . The electronic reports generated by the server computer  22  may be communicated to a remote computer  24  and displayed on a display screen  26  of the remote computer  24 . 
         [0028]    It should be appreciated that while the circuit monitor  12  is shown as being mounted outside the electrical panel  14 , in practice the circuit monitor  12  may be mounted within the electrical panel  14 . Additionally, it should further be appreciated that the circuit monitor  12  may be constructed as a generally single self-contained unit, or may be constructed as a collection of components that are operably connected with each other. 
         [0029]      FIG. 2  is a schematic representing an implementation of a self-contained unit for circuit monitor  12 . The circuit monitor  12  of  FIG. 2  includes an outer shell  28  that is suitable for mounting on or near an electrical panel  14 . The outer shell  28  may be provided with a cover (not shown) that can be selectively opened to provide access to the components within the circuit monitor  12 . The cover may be attached by hinges, or may be removable from the outer shell  28 . The cover may be provided with a lock in order to limit access only to authorized personnel. 
         [0030]    Provided within the shell  28  is a logger unit  30  and a power supply unit  36 . The logger unit  30  and power supply unit  36  include various components which will be described in more detail for sensing, recording, and communicating the voltage, current, and power consumption within several circuits in an adjoining electrical panel. 
         [0031]    The power supply unit  36  includes at least one voltage reference transformer  32  for sensing a reference voltage within the electrical panel. While a single voltage reference transformer  32  is shown, if the circuit monitor  12  is intended for use with a three-phase system, three voltage reference transformers would be needed. The voltage reference transformer  32  receives a reference voltage input from the circuit panel. The power supply unit  36  also includes a power supply apparatus  37  that converts AC to DC to supply power to the various components in the logger unit  30 . 
         [0032]    A plurality of current transformers  34  are also connected with the logger  30  for connection to individual circuits within the electrical panel. While only three such current transformers  34  are shown in the implementation of  FIG. 2 , in practice it would be preferred to have at least 14 of such current transformers  34 , and in one preferred implementation the logger  30  includes 42 such current transformers  34 , in order for the logger  30  to monitor up to 42 separate circuits within the electrical panel  14 . Preferably, the current transformers  34  will be split core type transformers such that they can be connected with the individual circuits without the need to rewire the circuits or remove them from load. 
         [0033]    The circuit monitor  12  includes a communications outlet  38  for communicating data to a remote server regarding the voltages and currents sensed by the transformers  32  and  34  and the power consumption of the circuits. The communications outlet  38  may be connected with a microcontroller that connects to the server via Ethernet and TCP/IP. According to a preferred implementation, the logger unit  30  will sample the various circuits to which it is connected once per minute, and communicate with the remote server  22  (see  FIG. 1 ) with information regarding each of the circuits one time per minute. Those of skill in the art will understand that other sampling frequencies may be used. Additionally, the information from a series of samplings may be saved and communicated to the remote server  22  on a less frequent basis than the samplings are taken. 
         [0034]      FIG. 3  illustrates by diagram an implementation of the electrical components within circuit monitor  12 . The implementation shown in  FIG. 3  is for use in a 14-channel logger. Therefore, the circuit includes fourteen current transformers  34 . Each of the current transformers  34  are provided with resistors  44  to bring the voltage within an appropriate range. A surge protection varistor  46  is also provided in parallel with the each current transformer  34 . According to a preferred implementation, each of the resistors  44  is a 100 ohm resistor. 
         [0035]    A voltage divider  40  connects to the current transformers  34  and the voltage reference transformer  32  at a voltage midway between ground and positive. The voltage divider is stabilized with 0.1 μF capacitors. As an alternative to the voltage divider  40 , it may be possible to utilize a voltage reference chip. 
         [0036]    The voltage reference transformer  32  is a step down transformer that feeds into a voltage divider  40  in order to reduce the output of voltage to an appropriate voltage. 
         [0037]    Each of the current transformers  34  and the voltage reference transformer  32  are connected to one of the analog to digital converters  42   a  and  b . According to a preferred implementation, each of the A-D converters  42   a  and  b  is a model sold under the brand name Microchip with Model No. MCP3208. A first channel of a first A-D converter  42   a  is used to measure the voltage divider  40 . This compensates for any variations in the manufacturing of the resistors. The second input in the first A-D converter  42   a  is used to measure the voltage reference received from the voltage reference transformer  32 . The remaining inputs on the first A-D converter  42   a  are used for current measurements received from the current transformers  34 . Preferably the A-D converter  42   a  will have a high impedance. The second A-D converter  42   b  has all of its inputs connected to current transformers  34 . 
         [0038]    The A-D converters  42   a  and  b  convert the analog signals received at the inputs and provide digital output to a microcontroller  50 . The A-D converters  42   a  and  b  may be connected to the microcontroller  50  via SPI interface. Firmware embedded on the microcontroller  50  computes the watts, volt amperes and volts for each channel, given the voltage divider input, the AC voltage references, and the multiple current inputs. According to a preferred implementation, the microcontroller may be sold under the brand name Rabbit with Model No. RCM3710. Those of skill in the art will be aware of other microcontrollers that will be suitable for the purpose. 
         [0039]    The microcontroller  50  has a communication outlet  38  that connects via Ethernet and TCP/IP to a remote server  22  (not shown, see  FIG. 1 ). According to a preferred implementation, the microcontroller  50  uploads the data to the remote server once per minute. The microcontroller  50  includes a storage medium for storing data, such that it will store several minutes of data if the server is unreachable due to a communication problem, and then upload the data quickly until it catches up to real time. 
         [0040]    In one exemplary implementation, each of the individual current transformers  34  is sampled once per minute with a sampling time for each circuit of about 250 milliseconds. Accordingly, the microcontroller  50  records current information and calculates watts, volt amperes, and volts for each channel once per minute. Different frequencies and durations may be used for sampling the individual circuits. 
         [0041]    The microcontroller  50  requests the A-D converters  42  to sample the voltage reference transformers  32  and the current transformers  34  several hundred times until 250 milliseconds has elapsed. The microcontroller  50  uses standard algorithms to compute the watts, volt amperes, and volts. 
         [0042]    The server  22  is programmed to generate a variety of reports based on the data received from the microcontroller  50 . The report generated by the server  22  may be accessed by remote computers via the Internet.  FIG. 5  shows an output screen that might be generated on the display screen  26  of a remote computer  24  (see  FIG. 1 ). The reports may be used to graphically display the power consumption within the individual circuit of the electrical panel  14 . 
         [0043]      FIG. 4  illustrates an implementation of branch circuit power monitoring apparatus  10  in communication with circuits  56  of electrical panel  75 . As illustrated, power is supplied to bus bar  54  in panel  75  through circuit  70  that communicates with mains electric. Circuits  56  extend from buss bar  54  and circuits  56  include breakers  58 , as illustrated. In this implementation, breakers  58  are positioned between current transformers  34  and the buss bar  54 . In other implementations, not shown, the current transformers  34  may be positioned between the buss bar  54  and the breakers  58 . In various implementations, the current transformers  34  may communicate with circuits  56  within panel  14  or with circuits  56  as the circuits extend forth from panel  14 . 
         [0044]      FIG. 5  illustrates an implementation of a display of consumption data. Last data updated date  81  informs the user if the data is uploading in a prompt fashion. Average watts  82  for the time period are displayed as well as a projection of Yearly KWH usage  83 . Chart display  100  displays usage data in a graphical fashion using bar chart  101  to summarize data. 
         [0045]    The system, in this implementation, analyzes power usage by sampling the current waveform and voltage waveform for approximately 250 milliseconds. This yields several hundred samples. In order to determine line voltage, an RMS algorithm is used on the samples, in this implementation. To determine Volt Amperes, an RMS value of the current draw may be determined and then multiplied by the line voltage. To determine the watts power consumption, the individual samples of voltage waveform and current waveform may be multiplied together and the divided by the number of samples. One application of the system may be to monitor power usage for individual renters in a facility. 
         [0046]      FIG. 6  represents an exemplary flow chart of operations. This exemplary process begins with 200 to start operations. With continuing reference to the exemplary process of  FIG. 6 , if there is data to upload that was not previously sent, the system will try to send data to the server  202 . If this data is sent OK  203 , it is marked sent 204. The system samples data once per minute and if it is time to sample  205 , the sampling process begins. Sampling occurs on each of 14 or 42 channels for 250 milliseconds typically  207 , and the Volts, Volt Amperes and Watts are computed  208 . Channel is incremented  209  until all channels are complete in the unit  210 . The system then tries to send the new data to the server. If there is no data to upload and it is not time to sample, the system will wait. 
         [0047]      FIG. 7A  illustrates an implementation of intermittent sampling of a current transformer signal from the current transformer  34  indicative of the current within circuit  56 . With continuing reference to the implementation illustrated in  FIG. 7A , the current transformer signal is sampled intermittently by converter  42  such that the current transformer signal is sampled during sampling period  231  and is not sampled during rest period  233 . Sampling period  231  may range from about 100 milliseconds to about 1.5 seconds, in various implementations, and rest period may range from about 10 seconds to about 59 seconds. The converter  42  may capture discrete samples  229  of the current transformer signal during the sampling period  231 . The number of discrete samples  229  of the current transformer signal may range from about 200 to over 2500, in various implementations, and the sampling rate may range from about 1000 samples per second to over 10000 samples per second. 
         [0048]      FIG. 7B  illustrates graphically an implementation of intermittent sampling of a reference voltage signal from the reference voltage transformer. With continuing reference to the implementation illustrated in  FIG. 7B , the reference voltage signal is sampled intermittently by converter  42  such that the reference voltage signal is sampled during sampling period  251  and is not sampled during rest period  253 . Sampling period  251  may range from about 100 milliseconds to about 1.5 seconds, in various implementations, and rest period may range from about 10 seconds to about 59 seconds. The converter  42  may capture discrete samples  249  of the reference voltage signal during the sampling period  251 . The number of discrete samples  249  may range from about 200 to over 2500, in various implementations, and the sampling rate may range from about 1000 samples per second to over 10000 samples per second. 
         [0049]    In various implementations, the converter  42  may sample the current transformer(s) and the voltage reference signal(s) concurrently, serially, or in various other orders. For example, sampling period  231  may be generally concurrent with sampling period  251  in some implementations or sampling period  231  may be offset from sampling period  251  in other implementations. 
         [0050]    The foregoing discussion along with the Figures discloses and describes various exemplary implementations. These implementations are not meant to limit the scope of coverage, but, instead, to assist in understanding the context of the language used in this specification and in the claims. Upon study of this disclosure and the exemplary implementations herein, one of ordinary skill in the art may readily recognize that various changes, modifications and variations can be made thereto without departing from the spirit and scope of the inventions as defined in the following claims.