Abstract:
A sensor module for a compressor, having an electric motor operating at a first voltage, the sensor module operating at a second voltage, is provided. The sensor module includes a plurality of inputs connected to a plurality of sensors that generate a plurality of operating signals associated with operating conditions of the compressor. A processor is connected to the plurality of inputs and records multiple operating condition measurements from the plurality of operating signals. A communication port is connected to the processor for communicating said operating condition measurements to a control module that controls the compressor. The processor is disposed within an electrical enclosure of the compressor, the electrical enclosure being configured to house electrical terminals for connecting a power supply to the electric motor. The second voltage is less than said first voltage.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/984,909, filed on Nov. 2, 2007. The entire disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to compressors, and more particularly, to a compressor sensor module. 
       BACKGROUND 
       [0003]    The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
         [0004]    Compressors are used in a variety of industrial and residential applications to circulate refrigerant within a refrigeration, heat pump, HVAC, or chiller system (generically “refrigeration systems”) to provide a desired heating or cooling effect. In each application, it is desirable for the compressor to provide consistent and efficient operation to ensure that the refrigeration system functions properly. To this end, it is desirable to monitor data received from various sensors that continually measure various operating parameters of the compressor. Electrical sensors may monitor electrical power. Pressure sensors may monitor compressor suction and discharge pressure. Temperature sensors may monitor compressor suction and discharge temperatures as well as ambient temperature. In addition, temperature sensors may monitor an electric motor temperature or an oil temperature of the compressor. Further sensors may monitor oil level and oil pressure of the compressor. 
         [0005]    Electrical power is delivered to the electric motor of the compressor by a power supply. For example three phase high voltage power may be used. 
       SUMMARY 
       [0006]    A sensor module is provided for a compressor having an electric motor operating at a first voltage. The sensor module may operate at a second voltage and may comprise a plurality of inputs connected to a plurality of sensors that may generate a plurality of operating signals associated with operating conditions of the compressor. The sensor module may also comprise a processor connected to the plurality of inputs that records multiple operating condition measurements from the plurality of operating signals and a communication port connected to the processor for communicating the operating condition measurements to a control module that controls the compressor. The processor may be disposed within an electrical enclosure of the compressor, with the electrical enclosure being configured to house electrical terminals for connecting a power supply operating at the first voltage to the electric motor and with the second voltage being less than the first voltage. 
         [0007]    In other features, a transformer may be located within the electrical enclosure and may generate the second voltage from the power supply. 
         [0008]    In other features, the processor may be disposed within a tamper-resistant enclosure within the electrical enclosure. 
         [0009]    In other features, the plurality of sensors may include a voltage sensor that may generate a voltage signal corresponding to a sensed voltage of the power supply. 
         [0010]    In other features, the plurality of sensors may include a current sensor that may generate a current signal corresponding to a sensed current of the power supply. 
         [0011]    In other features, the plurality of sensors may include a discharge temperature sensor that generates a discharge temperature signal corresponding to a discharge temperature of the compressor and/or a suction temperature sensor that generates a suction temperature signal corresponding to a suction temperature of the compressor. 
         [0012]    In other features, the plurality of sensors may include a discharge pressure sensor that may generates a discharge pressure signal corresponding to a discharge pressure of the compressor and/or a suction pressure sensor that may generate a suction pressure signal corresponding to a suction pressure of the compressor. 
         [0013]    In other features, the plurality of sensors may include at least one electric motor temperature sensor that may generate an electric motor temperature signal corresponding to a temperature of the electric motor of the compressor. 
         [0014]    In other features, the plurality of sensors may include an oil temperature sensor that may generate an oil temperature signal corresponding to a temperature of oil of the compressor, an oil level sensor that may generate an oil level signal corresponding to an oil level of the compressor, and an oil pressure sensor that may generate an oil pressure signal corresponding to an oil pressure of the compressor. 
         [0015]    In other features, the second voltage may be between 18 volts and 30 volts. 
         [0016]    In other features, the second voltage may be 24 volts. 
         [0017]    Another sensor module for a compressor having an electric motor connected to a three phase power supply is provided. The sensor module may be powered by single phase power derived from the three phase power supply. The sensor module may comprise a plurality of inputs connected to a plurality of sensors that may generate a plurality of operating signals associated with operating conditions of the compressor, a processor connected to the plurality of inputs that records multiple operating condition measurements from the plurality of operating signals, and a communication port connected to the processor for communicating the operating condition measurements to a control module that controls the compressor. The processor may be disposed within an electrical enclosure of the compressor and the electrical enclosure may be configured to house electrical terminals for connecting the power supply to the electric motor. An operating voltage of the single phase power may be less than an operating voltage of the three phase power. 
         [0018]    In other features, the processor may be disposed within a tamper-resistant enclosure within the electrical enclosure. 
         [0019]    In other features, a transformer may be connected to the three phase power supply to generate the single phase power. The transformer may be located within the electrical enclosure. 
         [0020]    In other features, the plurality of sensors may include a first voltage sensor that may generate a first voltage signal corresponding to a voltage of a first phase of the three phase power supply, a second voltage sensor that may generate a second voltage signal corresponding to a voltage of a second phase of the three phase power supply, and a third voltage sensor that may generate a third voltage signal corresponding to a voltage of a third phase of the three phase power supply. 
         [0021]    In other features, the plurality of sensors may include a current sensor that may generate a current signal corresponding to a current of one of the first, second, and third phases the three phase power supply. 
         [0022]    In other features, the operating voltage of the single phase power may be between 18 volts and 30 volts. 
         [0023]    In other features, the operating voltage of the single phase power may be 24 volts. 
         [0024]    A method for a sensor module with a processor disposed within an electrical enclosure of a compressor having an electric motor, the electrical enclosure being configured to house electrical terminals for connecting the electric motor to a power supply at a first operating voltage, is also provided. The method may comprise connecting the sensor module to a transformer for generating a second operating voltage from the power supply, the first operating voltage being higher than the second operating voltage, connecting the electrical terminals to the power supply operating at the first operating voltage, receiving voltage measurements of the power supply from a voltage sensor connected to the sensor module, receiving current measurements of the power supply from a current sensor connected to the sensor module, and communicating operating information based on the current and voltage measurements to a control module connected to the sensor module via a communication port of the sensor module. 
         [0025]    In other features, the method may further comprise receiving a temperature associated with the compressor from a temperature sensor connected to the sensor module and communicating operating information based on the temperature to the control module. The temperature may include a suction temperature of the compressor, a discharge temperature of the compressor, an ambient temperature, an oil temperature of the compressor, and/or an electric motor temperature of the compressor. 
         [0026]    In other features, the method may further comprise receiving a pressure associated with the compressor from a pressure sensor connected to the sensor module and communicating operating information based on the pressure to the control module. The pressure may include a suction pressure of the compressor and/or a discharge pressure of the compressor. 
         [0027]    A system is also provided that may comprise a compressor having an electric motor operating at a first voltage, a control module that controls the compressor, and a sensor module operating at a second voltage. The sensor module may have a plurality of inputs connected to a plurality of sensors that generate a plurality of operating signals associated with operating conditions of the compressor, a processor connected to the plurality of inputs that records multiple operating condition measurements from the plurality of operating signals, and a communication port connected to the processor for communicating the operating condition measurements to the control module. The processor may be disposed within an electrical enclosure of the compressor. The electrical enclosure may be configured to house electrical terminals for connecting a power supply operating at the first voltage to the electric motor. The second voltage may be less than the first voltage. 
         [0028]    In other features, the system may further comprise a transformer located within the electrical enclosure that generates the second voltage from the power supply. 
         [0029]    In other features, the processor may be disposed within a tamper-resistant enclosure within the electrical enclosure. 
         [0030]    In other features, the plurality of sensors may include a voltage sensor that generates a voltage signal corresponding to a sensed voltage of the power supply. 
         [0031]    In other features, the plurality of sensors may include a current sensor that may generate a current signal corresponding to a sensed current of the power supply. 
         [0032]    In other features, the plurality of sensors may include a discharge temperature sensor that may generate a discharge temperature signal corresponding to a discharge temperature of the compressor and/or a suction temperature sensor that may generate a suction temperature signal corresponding to a suction temperature of the compressor. 
         [0033]    In other features, the plurality of sensors may include a discharge pressure sensor that may generate a discharge pressure signal corresponding to a discharge pressure of the compressor and/or a suction pressure sensor that generates a suction pressure signal corresponding to a suction pressure of the compressor. 
         [0034]    In other features, the plurality of sensors may include at least one electric motor temperature sensor that may generate an electric motor temperature signal corresponding to a temperature of the electric motor of the compressor. 
         [0035]    In other features, the plurality of sensors may include an oil temperature sensor that may generate an oil temperature signal corresponding to a temperature of oil of the compressor, an oil level sensor that may generate an oil level signal corresponding to an oil level of the compressor, and/or an oil pressure sensor that may generate an oil pressure signal corresponding to an oil pressure of the compressor. 
         [0036]    In other features, the second voltage may be between 18 volts and 30 volts. 
         [0037]    In other features, the second voltage may be 24 volts. 
         [0038]    Another system is provided that may comprise a compressor having an electric motor connected to a three phase power supply, a control module that controls the compressor, and a sensor module powered by single phase power derived from the three phase power supply. The sensor module may have a plurality of inputs connected to a plurality of sensors that generate a plurality of operating signals associated with operating conditions of the compressor, a processor connected to the plurality of inputs that records multiple operating condition measurements from the plurality of operating signals, and a communication port connected to the processor for communicating the operating condition measurements to a control module that controls the compressor. The processor may be disposed within an electrical enclosure of the compressor. The electrical enclosure may be configured to house electrical terminals for connecting the power supply to the electric motor. An operating voltage of the single phase power may be less than an operating voltage of the three phase power. 
         [0039]    In other features, the processor may be disposed within a tamper-resistant enclosure within the electrical enclosure. 
         [0040]    In other features, a transformer may be connected to the three phase power supply to generate the single phase power. The transformer may be located within the electrical enclosure. 
         [0041]    In other features, the plurality of sensors may include a first voltage sensor that may generate a first voltage signal corresponding to a voltage of a first phase of the three phase power supply, a second voltage sensor that may generate a second voltage signal corresponding to a voltage of a second phase of the three phase power supply, and a third voltage sensor that generates a third voltage signal corresponding to a voltage of a third phase of the three phase power supply. 
         [0042]    In other features, the plurality of sensors may include a current sensor that may generate a current signal corresponding to a current of one of the first, second, and third phases the three phase power supply. 
         [0043]    In other features, the operating voltage of the single phase power may be between 18 volts and 30 volts. 
         [0044]    In other features, the operating voltage of the single phase power may be 24 volts. 
         [0045]    Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0046]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0047]      FIG. 1  is a schematic view of a refrigeration system; 
           [0048]      FIG. 2  is a schematic view of a compressor; 
           [0049]      FIG. 3  is a schematic view of an electrical enclosure of a compressor including a sensor module; 
           [0050]      FIG. 4  is a flow chart illustrating an operating algorithm of a sensor module; 
           [0051]      FIG. 5  is a perspective view of a compressor; and 
           [0052]      FIG. 6  is a top view of a compressor. 
       
    
    
     DETAILED DESCRIPTION 
       [0053]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
         [0054]    As used herein, the terms module, control module, and controller refer to one or more of the following: an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, or other suitable components that provide the described functionality. Further, as used herein, computer-readable medium refers to any medium capable of storing data for a computer. Computer-readable medium may include, but is not limited to, memory, RAM, ROM, PROM, EPROM, EEPROM, flash memory, punch cards, dip switches, CD-ROM, floppy disk, magnetic tape, other magnetic medium, optical medium, or any other device or medium capable of storing data for a computer. 
         [0055]    With reference to  FIG. 1 , an exemplary refrigeration system  10  may include a plurality of compressors  12  piped together with a common suction manifold  14  and a discharge header  16 . Compressor  12  may be a reciprocating compressor, a scroll type compressor, or another type compressor. Compressor  12  may include a crank case. The compressors  12  may be equipped with electric motors to compress refrigerant vapor that is delivered to a condenser  18  where the refrigerant vapor is liquefied at high pressure, thereby rejecting heat to the outside air. The liquid refrigerant exiting the condenser  18  is delivered to an evaporator  20 . As hot air moves across the evaporator, the liquid turns into gas, thereby removing heat from the air and cooling a refrigerated space. This low pressure gas is delivered to the compressors  12  and again compressed to a high pressure gas to start the refrigeration cycle again. While a refrigeration system  10  with two compressors  12 , a condenser  18 , and an evaporator  20  is shown in  FIG. 1 , a refrigeration system  10  may be configured with any number of compressors  12 , condensers  18 , evaporators  20 , or other refrigeration system components. 
         [0056]    Each compressor  12  may be equipped with a control module (CM)  30  and a sensor module (SM)  32 . SM  32  may monitor operating conditions of compressor  12  via communication with various operating condition sensors. For example, CM  30  may be connected to electrical voltage sensors, electrical current sensors, discharge temperature sensors, discharge pressure sensors, suction temperature sensors, suction pressure sensors, ambient temperature sensors, electric motor temperature sensors, compressor oil temperature sensors, compressor oil level sensors, compressor oil pressure sensors, and other compressor operating condition sensors. 
         [0057]    With reference to  FIG. 2 , three phase AC electric power  50  may be delivered to compressor  12  to operate an electric motor. SM  32  and CM  30  may receive low voltage power from one of the phases of electric power  50  delivered to compressor  12 . For example, a transformer  49  may convert electric power  51  from one of the phases to a lower voltage for delivery to SM  32  and CM  30 . In this way, SM  32  and CM  30  may operate on single phase AC electric power at a lower voltage than electric power  50  delivered to compressor  12 . For example, electric power delivered to SM  32  and CM  30  may be 24V AC. When low voltage power, for example 24V AC, is used to power CM  30  and SM  32 , lower voltage rated components, such as lower voltage wiring connections, may be used. 
         [0058]    CM  30  may control operation of the compressor  12  based on data received from SM  32 , based on other compressor and refrigeration system data received from other compressor and refrigeration system sensors, and based on communication with a system controller  34 . For example, CM  30  may be a protection and control system of the type disclosed in assignee&#39;s commonly-owned U.S. patent application Ser. No. 11/059,646, Publication No. 2005/0235660, filed Feb. 16, 2005, the disclosure of which is incorporated herein by reference. Other suitable protection and control type systems may be used. 
         [0059]    By communicating with SM  32 , CM  30  may monitor the various operating parameters of the compressor  12  and control operation of the compressor  12  according to protection and control algorithms and based on communication with system controller  34 . CM  30  may activate and deactivate compressor  12  according to a set-point, such as a suction pressure, suction temperature, discharge pressure, or discharge temperature set-point. In the case of discharge pressure set-point, CM  30  may activate compressor  12  when discharge pressure, as determined by a discharge pressure sensor connected to SM  32 , falls below the discharge pressure set-point. CM  30  may deactivate the compressor  12  when the discharge pressure rises above the discharge pressure set-point. 
         [0060]    In this way, SM  32  may be specific to compressor  12  and may be located within an electrical enclosure  72  of compressor  12  for housing electrical connections to compressor  12  (shown in  FIGS. 3 ,  5 , and  6 ) at the time of manufacture of compressor  12 . CM  30  may be installed on compressor  12  after manufacture and at the time compressor  12  is installed at a particular location in a particular refrigeration system, for example. Different control modules may be manufactured by different manufacturers. However, each CM  30  may be designed and configured to communicate with SM  32 . In other words, SM  32  for a particular compressor  12  may provide data and signals that can be communicated to any control module appropriately configured to communicate with SM  32 . Further, manufacturers of different control modules may configure a control module to receive data and signals from SM  32  without knowledge of the algorithms and computations employed by SM  32  to provide the data and signals. 
         [0061]    System controller  34  may be used and configured to control the overall operation of the refrigeration system. System controller  34  is preferably an Einstein Area Controller offered by CPC, Inc. of Atlanta, Ga., or any other type of programmable controller that may be programmed to operate refrigeration system  10  and communicate with CM  30 . System controller  34  may monitor refrigeration system operating conditions, such as condenser temperatures and pressures, and evaporator temperatures and pressures, as well as environmental conditions, such as ambient temperature, to determine refrigeration system load and demand. System controller  34  may communicate with CM  30  to adjust set-points based on such operating conditions to maximize efficiency of the refrigeration system. System controller  34  may evaluate efficiency of compressor  12  based on the operating data communicated to CM  30  from SM  32 . 
         [0062]    SM  32  may be connected to three voltage sensors  54 ,  56 ,  58 , for sensing voltage of each phase of electric power  50  delivered to compressor  12 . In addition, SM  32  may be connected to a current sensor  60  for sensing electric current of one of the phases of electric power  50  delivered to compressor  12 . Current sensor  60  may be a current transformer or current shunt resistor. 
         [0063]    When a single current sensor  60  is used, electric current for the other phases may be estimated based on voltage measurements and based on the current measurement from current sensor  60 . Because the load for each winding of the electric motor may be substantially the same as the load for each of the other windings, because the voltage for each phase is known from measurement, and because the current for one phase is known from measurement, current in the remaining phases may be estimated. 
         [0064]    Additional current sensors may also be used and connected to SM  32 . For example, two current sensors may be used to sense electric current for two phases of electric power  50 . When two current sensors are used, electric current for the remaining phase may be estimated based on voltage measurements and based on the current measurements from current sensors. Additionally, three current sensors may be used to sense electric current for all three phases of electric power. 
         [0065]    In the case of a dual winding three phase electric motor, six electrical power terminals may be used, with one terminal for each winding resulting in two terminals for each of the three phases of electric power  50 . In such case, a voltage sensor may be included for each of the six terminals, with each of the six voltage sensors being in communication with SM  32 . In addition, a current sensor may be included for one or more of the six electrical connections. 
         [0066]    With reference to  FIGS. 5 and 6 , CM  30  and SM  32  may be mounted on or within compressor  12 . CM  30  may include a display  70  for graphically displaying alerts or messages. As discussed above, SM  32  may be located within electrical enclosure  72  of compressor  12  for housing electrical connections to compressor  12 . 
         [0067]    Compressor  12  may include a suction nozzle  74 , a discharge nozzle  76 , and an electric motor disposed within an electric motor housing  78 . 
         [0068]    Electric power  50  may be received by electrical enclosure  72 . CM  30  may be connected to SM  32  through a housing  80 . In this way, CM  30  and SM  32  may be located at different locations on or within compressor  12 , and may communicate via a communication connection routed on, within, or through compressor  12 , such as a communication connection routed through housing  80 . 
         [0069]    With reference to  FIG. 3 , SM  32  may be located within electrical enclosure  72 . In  FIG. 3 , a schematic view of electrical enclosure  72  and SM  32  is shown. SM  32  may include a processor  100  with RAM  102  and ROM  104  disposed on a printed circuit board (PCB)  106 . Electrical enclosure  72  may be an enclosure for housing electrical terminals  108  connected to an electric motor of compressor  12 . Electrical terminals  108  may connect electric power  50  to the electric motor of compressor  12 . 
         [0070]    Electrical enclosure  72  may include a transformer  49  for converting electric power  50  to a lower voltage for use by SM  32  and CM  30 . For example, electric power  51  may be converted by transformer  49  and delivered to SM  32 . SM  32  may receive low voltage electric power from transformer  49  through a power input  110  of PCB  106 . Electric power may also be routed through electrical enclosure  72  to CM  30  via electrical connection  52 . 
         [0071]    Voltage sensors  54 ,  56 ,  58  may be located proximate each of electrical terminals  108 . Processor  100  may be connected to voltage sensors  54 ,  56 ,  58  and may periodically receive or sample voltage measurements. Likewise, current sensor  60  may be located proximate one of electrical power leads  116 . Processor  100  may be connected to current sensor  60  and may periodically receive or sample current measurements. Electrical voltage and current measurements from voltage sensors  54 ,  56 ,  58  and from current sensor  60  may be suitably scaled for the processor  100 . 
         [0072]    A discharge temperature sensor  150  may be connected to the processor  100  and may generate a discharge temperature signal corresponding to a discharge temperature of the compressor (T D ). A suction temperature sensor  152  may be connected to the processor and may generate a suction temperature signal corresponding to a suction temperature of the compressor (T S ). A discharge pressure sensor  154  may be connected to the processor  100  and may generate a discharge pressure signal corresponding to a discharge pressure of the compressor (P D ). A suction pressure sensor  156  may be connected to the processor  100  and may generate a suction pressure signal corresponding to a suction pressure of the compressor (P S ). An ambient temperature sensor  158  may be connected to the processor  100  and may generate an ambient temperature signal corresponding to an ambient temperature of the compressor (T amb ). An electric motor temperature sensor  160  may be connected to the processor  100  and may generate an electric motor temperature signal corresponding to an electric motor temperature of the compressor (T mtr ). An Oil level sensor  161  may be connected to processor  100  and may generate an oil level signal corresponding to a level of oil in compressor  12  (Oil lev ). An Oil temperature sensor may be connected to processor  100  and may generate an oil temperature signal corresponding to a temperature of oil in compressor  12  (Oil Temp ). 
         [0073]    PCB  106  may include a communication port  118  to allow communication between processor  100  of SM  32  and CM  30 . A communication link between SM  32  and CM  30  may include an optical isolator  119  to electrically separate the communication link between SM  32  and CM  30  while allowing communication. Optical isolator  119  may be located within electrical enclosure  72 . Although optical isolator  119  is independently shown, optical isolator  119  may also be located on PCB  106 . At least one additional communication port  120  may also be provided for communication between SM  32  and other devices. A handheld or portable device may directly access and communicate with SM  32  via communication port  120 . For example, communication port  120  may allow for in-circuit programming of SM  32  a device connected to communication port  120 . Additionally, communication port  120  may be connected to a network device for communication with SM  32  across a network. 
         [0074]    Communication with SM  32  may be made via any suitable communication protocol, such as I2C, serial peripheral interface (SPI), RS232, RS485, universal serial bus (USB), or any other suitable communication protocol. 
         [0075]    Processor  100  may access compressor configuration and operating data stored in an embedded ROM  124  disposed in a tamper resistant housing  140  within electrical enclosure  72 . Embedded ROM  124  may be a compressor memory system disclosed in assignee&#39;s commonly-owned U.S. patent application Ser. No. 11/405,021, filed Apr. 14, 2006, U.S. patent application Ser. No. 11/474,865, filed Jun. 26, 2006, U.S. patent application Ser. No. 11/474,821, filed Jun. 26, 2006, U.S. patent application Ser. No. 11/474,798, filed Jun. 26, 2006, or U.S. Patent Application No. 60/674,781, filed Apr. 26, 2005, the disclosures of which are incorporated herein by reference. In addition, other suitable memory systems may be used. 
         [0076]    Relays  126 ,  127  may be connected to processor  100 . Relay  126  may control activation or deactivation of compressor  12 . When SM  32  determines that an undesirable operating condition exists, SM  32  may simply deactivate compressor  12  via relay  126 . Alternatively, SM  32  may notify CM  30  of the condition so that CM  30  may deactivate the compressor  12 . Relay  127  may be connected to a compressor related component. For example, relay  127  may be connected to a crank case heater. SM  32  may activate or deactivate the crank case heater as necessary, based on operating conditions or instructions from CM  30  or system controller  34 . While two relays  126 ,  127  are shown, SM  32  may, alternatively, be configured to operate one relay, or more than two relays. 
         [0077]    Processor  100  and PCB  106  may be mounted within a housing enclosure  130 . Housing enclosure  130  may be attached to or embedded within electrical enclosure  72 . Electrical enclosure  72  provides an enclosure for housing electrical terminals  108 . Housing enclosure  130  may be tamper-resistant such that a user of compressor  12  may be unable to inadvertently or accidentally access processor  100  and PCB  106 . In this way, SM  32  may remain with compressor  12 , regardless of whether compressor  12  is moved to a different location, returned to the manufacturer for repair, or used with a different CM  30 . 
         [0078]    LED&#39;s  131 ,  132  may be located on, or connected to, PCB  106  and controlled by processor  100 . LED&#39;s  131 ,  132  may indicate status of SM  32  or an operating condition of compressor  12 . LED&#39;s  131 ,  132  may be located on housing enclosure  130  or viewable through housing enclosure  130 . For example, LED  131  may be red and LED  132  may be green. SM  32  may light green LED  132  to indicate normal operation. SM  32  may light red LED  131  to indicate a predetermined operating condition. SM  32  may also flash the LED&#39;s  131 ,  132  to indicate other predetermined operating conditions. 
         [0079]    Additional current sensors may also be used and connected to SM  32 . Two current sensors may be used to sense electric current for two phases of electric power  50 . When two current sensors are used, electric current for the remaining phase may be estimated based on voltage measurements and based on the current measurements from current sensors. Three current sensors may be used to sense electric current for all three phases of electric power  50 . 
         [0080]    In the case of a dual winding three phase electric motor, electrical enclosure  72  may include additional electrical terminals for additional windings. In such case, six electrical terminals may be located within electrical enclosure  72 . Three electrical terminals  108  may be connected to the three phases of electric power  50  for a first set of windings of the electric motor of compressor  12 . Three additional electrical terminals may also connected to the three phases of electric power  50  for a second set of windings of the electric motor of compressor  12 . Voltage sensors may be located proximate each of the additional electrical terminals. Processor  100  may be connected to the additional voltage sensors and may periodically receive or sample voltage and current measurements. For example, processor  100  may sample current and voltage measurements twenty times per cycle or approximately once every millisecond in the case of alternating current with a frequency of sixty mega-hertz. 
         [0081]    Referring now to  FIG. 4 , a flow chart illustrating an operating algorithm  400  for SM  32  is shown. In step  401 , SM  32  may initialize. Initialization may include resetting any counters or timers, checking and initializing RAM  102 , initializing any ports, including communication ports  118 , enabling communication with other devices, including CM  30 , checking ROM  104  on PCB  106 , checking other ROM  124  such as an embedded memory system, and any other necessary initialization functions. SM  32  may load operating instructions from ROM  104  for execution by the processor  100 . 
         [0082]    In step  402 , SM  32  may receive actual electrical measurements from connected voltage and current sensors  54 ,  56 ,  58 ,  60 . SM  32  may receive a plurality of instantaneous voltage and current measurements over the course of a cycle of the AC electrical power. SM  32  may buffer instantaneous voltage and current measurements in RAM  102  for a predetermined time period. 
         [0083]    In step  404 , SM  32  may receive measurements from sensors  150 ,  152 ,  154 ,  156 ,  158 ,  160 ,  161 ,  163 . SM  32  may buffer the instantaneous temperature and pressure measurements in RAM  102  for a predetermined time period. 
         [0084]    In step  406 , SM  32  may communicate electrical, temperature, and pressure measurements to CM  30 . Alternatively, SM  32  may communicate electrical, temperature, and pressure measurements to a system controller  34  or to another communication device, such as a handheld device, connected to a communication port  120 . 
         [0085]    After communicating data in step  406 , SM  32  may loop back to step  402  for continued monitoring and communication. 
         [0086]    In this way, SM  32  may thereby provide efficient and accurate operating condition measurements of the compressor to be utilized by other modules and by users to evaluate operating conditions and efficiency of the compressor.