Abstract:
A compressor assembly includes a shell, a compressor housed within the shell, and a motor drivingly connected to the compressor. In addition, a sensor assembly is provided for monitoring operating parameters of the compressor assembly. Processing circuitry, in communication with the sensor assembly, is operable to process the operating parameters of the compressor assembly according to predefined rules. Furthermore, a terminal assembly is hermetically secured to the shell and is in communication with the sensor assembly. A plug is attached to the terminal assembly outside of the shell and serves to operably connect the processing circuitry with the sensor assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/533,236, filed on Dec. 30, 2003. The disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD  
       [0002]     The present teachings relate to compressors, and more particularly, to an improved diagnostic system for use with a compressor.  
       BACKGROUND  
       [0003]     Compressors are used in a wide variety of industrial and residential applications. More particularly, compressors are often used to circulate refrigerant within a refrigeration or heat pump system to provide a desired heating or cooling effect. In addition, compressors are also used to inflate or otherwise impart a fluid force on an external object such as a tire, sprinkler system, or pneumatic tool. In any of the foregoing applications, it is desirable that a compressor provide consistent and efficient operation to ensure that the particular application (i.e., refrigeration system or pneumatic tool) functions properly. To that end, alerting when a compressor has failed or is in need of repair helps prevent unnecessary compressor damage and system failures.  
         [0004]     Compressors are intended to run trouble free for the life of the compressor and provide a consistent supply of compressed fluid. While compressors are increasingly reliable, monitoring operation of the compressor allows one to discontinue its operation should an error or fault arise. Discontinuing use of the scroll compressor under unfavorable conditions will likely prevent damage to the compressor.  
         [0005]     Faults causing a compressor to shut down may be electrical or mechanical in nature. Electrical faults generally have a direct effect on the electric motor in the compressor, and may destroy the electric motor or its associated components. Mechanical faults may include faulty bearings or broken parts, and typically raise the internal temperature of the respective components to very high levels, sometimes causing malfunction of and damage to the compressor. In addition to mechanical and electrical faults, “system” faults may occur, such as those resulting from an adverse level of refrigerant or lubricant or to a blocked flow condition. Such system faults may raise the internal compressor temperature or pressure to high levels, which may damage the compressor.  
       SUMMARY  
       [0006]     A compressor assembly generally includes a shell, a compressor housed within the shell, and a motor drivingly connected to the compressor. A sensor assembly is provided for monitoring operating parameters of the compressor assembly, including the temperature of an electrical conductor supplying current to the motor. Processing circuitry in communication with the sensor assembly processes the operating parameters of the compressor. A terminal assembly is hermetically secured to the shell and is in communication with the sensor assembly, while a connector is attached to the terminal assembly outside of the shell and serves to operably connect the processing circuitry with the sensor assembly. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The present teachings will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0008]      FIG. 1  is a perspective view of a compressor incorporating a first protection system in accordance with the teachings;  
         [0009]      FIG. 2  is a cross-sectional view of the compressor of  FIG. 1 ;  
         [0010]      FIG. 3  is a more detailed sectional view of the protection system of  FIG. 2 ;  
         [0011]      FIG. 4  is a perspective view of the protection system of  FIG. 2 ;  
         [0012]      FIG. 5  is a schematic representation of the protection system of  FIG. 2 ;  
         [0013]      FIG. 6  is an alternate schematic representation of the protection system of  FIG. 2 ;  
         [0014]      FIG. 7  is a perspective view of a compressor incorporating a second protection system in accordance with the teachings;  
         [0015]      FIG. 8  is a cross-sectional view of the compressor of  FIG. 7 ;  
         [0016]      FIG. 9  is a more detailed sectional view of the protection system of  FIG. 7 ;  
         [0017]      FIG. 10  is a perspective view of the protection system of  FIG. 7 ;  
         [0018]      FIG. 11  is a schematic representation of the protection system of  FIG. 7 ;  
         [0019]      FIG. 12  is a perspective view of a compressor incorporating a third protection system in accordance with the teachings;  
         [0020]      FIG. 13  is a perspective view of a cluster block of the protection system of  FIG. 12 ;  
         [0021]      FIG. 14  is a perspective view of the cluster block of  FIG. 13  incorporated into a current-sensor assembly;  
         [0022]      FIG. 15  is a front view of the cluster block and current-sensor assembly of  FIG. 14  incorporated into a housing;  
         [0023]      FIG. 16  is a front view of the cluster block and current-sensor assembly of  FIG. 14  incorporated into a housing and mounted to the compressor of  FIG. 12 ;  
         [0024]      FIG. 17  is a flow-chart depicting operation of a compressor in accordance with the teachings;  
         [0025]      FIG. 18  is a flow-chart depicting operation of a compressor between a run condition and a shutdown condition in accordance with the teachings;  
         [0026]      FIG. 19  is a perspective view of a compressor incorporating a fourth protection system in accordance with the teachings;  
         [0027]      FIG. 20  is a cross-sectional view of the compressor of  FIG. 19 ;  
         [0028]      FIG. 21  is a perspective view of the protection system of  FIG. 19 ;  
         [0029]      FIG. 22  is a perspective view of the protection system of  FIG. 20  showing a current-sensing arrangement; and  
         [0030]      FIG. 23  is a schematic representation of a compressor network in accordance with the teachings. 
     
    
     DETAILED DESCRIPTION  
       [0031]     The following description is merely exemplary in nature and is in no way intended to limit the teachings, its application, or uses.  
         [0032]     With reference to the figures, a scroll compressor  10  is provided and includes a compressor protection and control system  12 . The protection and control system  12  is operable to selectively shut down the compressor  10  in response to sensed compressor parameters in an effort to protect the compressor  10  and prevent operation thereof when conditions are unfavorable. While a scroll compressor  10  will be described herein, it should be understood that any compressor could be used with the protection and control system  12  of the present invention.  
         [0033]     With particular reference to  FIGS. 1 and 2 , the compressor  10  is shown to include a generally cylindrical hermetic shell  14  having a welded cap  16  at a top portion and a base  18  having a plurality of feet  20  welded at a bottom portion. The cap  16  and base  18  are fitted to the shell  14  such that an interior volume  22  of the compressor  10  is defined. The cap  16  is provided with a discharge fitting  24 , while the shell  14  is similarly provided with an inlet fitting  26 , disposed generally between the cap  16  and base  14 , as best shown in  FIGS. 2 and 8 . In addition, an electrical enclosure  28  is fixedly attached to the shell  14  generally between the cap  16  and base  18  and operably supports a portion of the protection system  12  therein, as will be discussed further below.  
         [0034]     A crankshaft  30  is rotatively driven by an electric motor  32  relative to the shell  14 . The motor  32  includes a stator  34  fixedly supported by the hermetic shell  14 , windings  36  passing therethrough, and a rotor  38  press fitted on the crankshaft  30 . The motor  32  and associated stator  34 , windings  36 , and rotor  38  are operable to drive the crankshaft  30  relative to the shell  14  to thereby compress a fluid.  
         [0035]     The compressor  10  further includes an orbiting scroll member  40  having a spiral vane or wrap  42  on the upper surface thereof for use in receiving and compressing a fluid. An Oldham coupling  44  is positioned between orbiting scroll member  40  and a bearing housing  46  and is keyed to orbiting scroll member  40  and a non-orbiting scroll member  48 . The Oldham coupling  44  is operable to transmit rotational forces from the crankshaft  30  to the orbiting scroll member  40  to thereby compress a fluid disposed between the orbiting scroll member  40  and non-orbiting scroll member  48 . Oldham coupling  44  and its interaction with orbiting scroll member  40  and non-orbiting scroll member  48  is preferably of the type disclosed in assignee&#39;s commonly-owned U.S. Pat. No. 5,320,506, the disclosure of which is incorporated herein by reference.  
         [0036]     Non-orbiting scroll member  48  also includes a wrap  50  positioned in meshing engagement with wrap  42  of orbiting scroll member  40 . Non-orbiting scroll member  48  has a centrally disposed discharge passage  52  which communicates with an upwardly open recess  54 . Recess  54  is in fluid communication with discharge fitting  24  defined by cap  16  and partition  56 , such that compressed fluid exits the shell  14  via passage  52 , recess  54 , and fitting  24 . Non-orbiting scroll member  48  is designed to be mounted to bearing housing  46  in a suitable manner such as disclosed in the aforementioned U.S. Pat. No. 4,877,382 or U.S. Pat. No. 5,102,316, the disclosures of which are incorporated herein by reference.  
         [0037]     Referring now to  FIG. 2 , electrical enclosure  28  includes a lower housing  58 , an upper housing  60 , and a cavity  62 . The lower housing  58  is mounted to the shell  14  using a plurality of studs  64  which are welded or otherwise fixedly attached to the shell  14 . The upper housing  60  is matingly received by the lower housing  58  and defines the cavity  62  therebetween. The cavity  62  is operable to house respective components of the compressor protection and control system  12 , as will be discussed further below.  
         [0038]     With particular reference to  FIGS. 1-6 , the compressor protection and control system  12  is shown to include a sensor system  66 , processing circuitry  68 , and a power interruption system  70 . The sensor system  66 , processing circuitry  68 , and power interruption system  70  cooperate to detect and correct fault conditions in an effort to prevent damage to the compressor  10  and to alert a user to the fault condition (i.e., via light emitting devices (LED) and the like). The compressor protection and control system  12  detects and responds to run winding delay, motor overload, missing phase, reverse phase, motor winding current imbalance, open circuit, low voltage, locked rotor currents, excessive motor winding temperature, high discharge temperature conditions, low oil pressure, lack of three phase power, open thermistors, welded or open contactors, and short cycling. For example, a compressor protection and control system  12  for a particular type and size compressor may be as summarized in Table 1, but other compressor types and sizes may have different thresholds, parameters, indicators and limits.  
                                   TABLE 1                       ALARM   OCCURRENCE   ACTION   LED   LOCKOUT   RESET                   Run   Excessive delay in   Trip (open   Red flashes   10 Trips   Normal run winding       Winding   energizing one   contactor relay),   one time   In a Row   operation OR Cycle       Delay   winding after a first   wait 5 minutes,   between pauses       power           winding is energized   then close               contactor relay       Missing   One phase is missing   Trip (open   Red flashes   10 Trips   All three phases       Phase       contactor relay),   two times   In a Row   present OR Cycle               wait 5 minutes,   between pauses       power               then close               contactor relay       Reverse   Three phase power   Trip (open   Red flashes   4 Trips   Phase orientation       Phase   leads are connected   contactor relay),   three times   In a Row   correct OR Cycle           improperly causing   wait 5 minutes,   between pauses       power           motor to run   then close           backwards   contactor relay       Welded   Contactor is   None   Red flashes   None   N/A       Contactor   providing three       four times           phase power to       between pauses           compressor when           contactor should           be open       Low Voltage   Supply voltage to   Trip (open   Red flashes   None   Supply voltage           AMPS is below the   contactor relay),   five times       remains in           alarm threshold   wait 5 minutes   between pauses       “normal” range       No Three   Current is not   None   Red flashes   None   Three phase current       Phase   detected at       five times       is detected when       Power   compressor       between pauses       demand is present           terminals when               OR demand is not           demand is present               present and no                           current is detected       Low Oil   Oil pressure is too   Trip (open   Red flashes   None   Oil pressure       Pressure   low for an extended   contactor relay),   one time       sensor alarm           period of time   close contactor   between pauses       relay is open               relay when oil               relay closes       Discharge   Discharge temperature   Trip (open   Red flashes   4 Trips   Discharge temps       Temperature   is too high   contactor relay),   two times   In 3 Hours   remain in “normal”               wait 30 minutes,   between pauses       range OR Cycle               then close           power               contactor relay       Motor   Motor temperature   Trip (open   Red flashes   4 Trips   Motor temps remain       Temperature   is too high OR   contactor relay),   three times   In 3 Hours   in “normal” range           motor temperature   wait 30 minutes,   between pauses       OR Cycle power           sensor is short   then close           circuited   contactor relay       Locked   Current to   Trip (open   Red flashes   4 Trips   Current to       Rotor   compressor exceeds   contactor relay),   four times   In a Row   compressor remains           300 Amps or fails   wait 5 minutes,   between pauses       in “normal” range           to decrease from   then close           OR Cycle power           initial locked   contactor relay           rotor current level           or exceeds 300 Amps           or 40% of peak           locked rotor Amps           (LRA) while running       Motor   Current to   Trip (open   Red flashes   None   Current to       Overload   compressor   contactor relay),   five times       compressor remains           exceeds maximum   wait 5 minutes,   between pauses       in “normal” range           continuous current   then close           (MCC) rating   contactor relay       Open   One or more   Trip (open   Red flashes   None   Discharge temps       Thermistor   discharge/motor   contactor relay),   six times       remain in “normal”           temperature   wait 30 minutes,   between pauses       range OR Cycle power           sensors are   then close           disconnected   contactor relay                  
 
         [0039]     As shown above in Table 1, a run winding delay is generally defined as an excessive delay in energizing one winding after a first winding is energized. When a start winding has been energized, a run winding must be energized within two seconds. If the run winding is not energized within this time period, the system  12  shuts down the compressor motor  32 . If the run winding is energized first, the start winding must be energized within two seconds. If the start winding is not energized within this time period, the system  12  similarly shuts down the motor  32 . For a plural compressor  10   c  ( FIG. 19 ) the system  12  senses both the start and run winding current at start up. When the compressor  10   c  is in the running state, if either the start or run winding completely drop out for more than two seconds, the system  12  shuts down the motor  32 .  
         [0040]     A missing phase fault is generally defined when one phase of the motor  32  is missing. Once the start winding is energized, the system  12  ensures that current is present in all phases within 700 milliseconds after current is detected in one of the phases. If current is detected in at least one phase and no current is detected in the other phase(s), then the system  12  shuts down the motor  32 . Generally speaking, a current imbalance of greater than 50 percent is required before the motor  32  is interrupted. The run winding is monitored and protected against missing phase in a similar fashion. During normal running operation (i.e., while demand is present), if a loss of current in any phase of the motor  32  is detected for a period of one second, the motor  32  is shut down.  
         [0041]     A reverse phase is generally defined when three phase power leads are connected improperly, thereby causing the motor  32  to run backwards. If the phase sequence of the three phase power is incorrect, the system  12  shuts down the compressor  10 . The phase sequence is measured roughly 700 milliseconds after the demand signal and current is sensed in the start winding. It should be noted that the motor  32  may rotate “backwards” for a short period of time after power has been removed from the compressor  10  due to pressure equalization. Due to this phenomenon, reverse phase is only monitored for roughly the first five seconds of each compressor start cycle.  
         [0042]     A welded contactor fault is declared when a contactor supplies three phase power to the compressor  10  when contactor should be open. This condition is detected after the motor  32  has been shut down. If current persists after roughly two seconds of shutdown, then it will be assumed that the contacts have welded or mechanically “jammed” shut.  
         [0043]     A motor overload condition is generally referred to a situation where current to the compressor  10  exceeds a maximum continuous current (MCC) rating. Overload current is defined as current that exceeds 110 percent rated MCC for more than 60 seconds. If the part winding motor current in any leg of either start or run winding exceeds the pre-programmed limit, then the system  12  shuts down the motor  32 . The MCC overload detection does not start until five seconds after start up and continues until shutdown. If a compressor&#39;s MCC is not programmed, overload current is detected by the a motor temperature sensor(s). The system  12  detects a missing compressor MCC parameter when it determines that the MCC value is set to zero Amps, which is the default setting for the compressor  10 .  
         [0044]     A locked rotor condition is declared when current to the compressor  10  exceeds roughly 300 Amps, fails to decrease from an initial locked rotor current level, exceeds 300 Amps, or is roughly 40 percent of peak locked rotor Amps (LRA) while running. The locked rotor current during start up is expected to decrease within one second after the motor  32  comes up to speed and settles down to a normal running current level. The system maintains a 100 millisecond buffer of the current readings for the run and start windings. When compressor demand is high, indicating the compressor has started, the highest peak current in the buffer is recorded as the locked rotor current. The peak locked rotor current is recorded as greater than 300 Amps, or as the specific peak value if less than 300 Amps.  
         [0045]     If the peak locked rotor current in the start winding is greater than 300 Amps, a second reading is taken roughly 800 milliseconds after start up (compressor demand is measured high). If the start winding current value is greater than 300 Amps 800 milliseconds after start up, then the system  12  assumes that the motor  32  is mechanically seized and that power to the motor  32  should be interrupted. If the peak locked rotor current in the start winding is less than 300 Amps, a second reading is taken roughly 800 milliseconds after start up (compressor demand is measured high). If the second reading has not dropped to a level less than 40 percent of the peak LRA measured, power to the compressor motor  32  is interrupted.  
         [0046]     For locked rotor conditions that occur after start up has completed, the peak locked rotor current measured is used. If the peak locked rotor current is greater than 300 Amps, and the running current is measured above 300 Amps for 500 milliseconds, power to the motor  32  is interrupted. If the peak locked rotor current is less than 300 Amps, and the running current is greater than 40 percent of that peak locked rotor current measured and recorded, power is similarly interrupted. If a peak locked rotor current of less than 100 Amps is measured, the locked rotor detection is disabled for that compressor run cycle. Such control eliminates nuisance trips if the timing of the start up is disrupted during troubleshooting of the equipment.  
         [0047]     A low voltage fault is declared, and the compressor  12  is shut down, if the 220 VAC supply power to the system  12  falls below 170 VAC when a compressor demand signal is present. When the voltage falls to this level, the compressor  10  is not allowed to start. Excessive arcing due to contactor coil chattering during low voltage conditions can lead to a welded contactor and therefore the compressor  10  is shut down under such circumstances. The occurrence of low voltage must persist for roughly two seconds before an alarm is recorded and power to the motor  32  is interrupted. The voltage must rise above 180 VAC for a minimum of two seconds to reset the alarm.  
         [0048]     Discharge temperature is monitored to ensure that the discharge temperature is not above a predetermined threshold value in an effort to protect the motor  32  and associated scrolls  40 ,  48 . The system  12  monitors the discharge temperature in at least two locations and, if a resistance value is greater than roughly 1.33 kΩ+/−5 percent, power to the motor  32  is interrupted. Power remains interrupted until the resistance falls below roughly 600 Ω+/−5 percent and a thirty (30) minute delay has been completed.  
         [0049]     The temperature of the motor  32  is monitored by using at least one positive-temperature-coefficient (PTC) device or negative-temperature-coefficient (NTC) device, which may be a thermistor-type sensor. If a PTC resistance value is greater than roughly 4.5 kΩ+/−5 percent, power to the motor  32  is interrupted and remains as such until the PTC resistance falls below roughly 2.75 kΩ+/−5 percent and a thirty (30) minute delay has been completed. A shorted thermistor input is read as a low resistance value and indicates the respective motor temperature sensor is jumpered or a board component has failed. Any PTC resistance below roughly 100 ohms is interpreted as a shorted thermistor.  
         [0050]     An open thermistor fault is declared, and power to the motor  32  interrupted, if any thermistor input is read as open circuit. An open circuit is defined for NTC and PTC thermistors as a resistance higher than roughly 100 kΩ. The resistance must be read at this level for 60 seconds while the compressor  10  is running.  
         [0051]     If a compressor demand input is read high for two seconds, and no current is read in any of the current transformer inputs, a no three phase power alarm is declared. Whenever current is detected in any current transformer input or if the demand inputs are read low for two seconds, the alarm is reset.  
         [0052]     In addition to detecting and reporting the above-described fault conditions (Table 1), the system  12  also detects and monitors “warning conditions.” The warning conditions are not as sever as the fault conditions, and therefore do not cause protective action (i.e., interruption of power to the motor  32 ), but the warning conditions are monitored nonetheless and are used a diagnostics and in prevention of fault conditions. The warning conditions include a high ambient temperature warning, a motor overload warning, a locked rotor warning, a low supply voltage warning, a high supply voltage warning, a high discharge temperature warning, a discharge temperature sensor short circuit warning, a high motor temperature warning, a no configuration warning, and a contactor life warning, each of which is briefly described below.  
         [0053]     A high ambient temperature warning is detected when an ambient temperature sensor measures a temperature above roughly 60 degrees Celsius for more than 60 seconds continuously. The high ambient temperature warning is reset when the ambient temperature sensor measures below 60 degrees Celsius for more than 60 seconds continuously.  
         [0054]     A motor overload warning is detected when the motor current is at 100 percent MCC current level for more than 60 seconds. The motor overload warning is reset when the motor current level has dropped below 100 percent MCC current level for more than 60 seconds or when a motor overload alarm becomes active.  
         [0055]     A locked rotor warning is detected when a locked rotor event is detected. Unlike the alarm, which requires multiple events, the warning is detected with a single event. The locked rotor warning is reset when the compressor  10  has run five minutes continuously without a locked rotor event, or when a locked rotor alarm becomes active.  
         [0056]     A low supply voltage warning is detected when the supply voltage is below 180 VAC for two seconds. A low supply voltage warning is reset when the supply voltage is above 190 VAC for two seconds or when a Low Supply Voltage Alarm becomes active.  
         [0057]     A high supply voltage warning is detected when the supply voltage is above 250 VAC for two seconds. A high supply voltage warning is reset when the supply voltage is above 240 VAC for two seconds.  
         [0058]     A high discharge temperature warning is detected when the discharge temperature is less than 10 degrees Celsius below the alarm set point for each sensor for two seconds. A high discharge temperature warning is reset when the discharge temperature is greater than 15 degrees Celsius below the alarm set point for each sensor for two seconds, or a high discharge temperature alarm becomes active.  
         [0059]     A discharge temperature sensor short circuit warning is detected when the resistance measured at the discharge temperature sensors is less than 100 Ω for two seconds. A discharge temperature sensor short circuit warning is reset when the resistance measured is greater than 1 kΩ for two seconds.  
         [0060]     A high motor temperature warning is detected when a motor temperature is less than 10 degrees Celsius below the alarm set point for two seconds.  
         [0061]     A high motor temperature warning will be reset when a motor temperature is greater than 15 degrees Celsius below the alarm set point for two seconds, or a high motor temperature alarm becomes active.  
         [0062]     A no configuration warning is detected when the compressor model number, serial number and MCC current is not programmed into the memory. A no configuration warning is reset when the compressor model number, serial number AND MCC current is programmed into the memory. There is no check for accuracy of the text entered in for model and serial number and any non-zero number for MCC value is valid.  
         [0063]     A contactor life warning is detected when the number of compressor starts equals 50,000 or a multiple of 50,000 (i.e., 100 k, 150 k, 200 k, etc.). A contactor life warning is reset when the system module is powered off and on, indicating the contactor has been inspected and/or replaced.  
         [0064]     In general, the sensor system  66  detects compressor operating conditions such as the compressor faults listed above in Table 1 and the compressor warning conditions, and provides a signal to the processing circuitry  68  indicative thereof. The processing circuitry  68  is either a microcontroller or a microprocessor such as microcontroller model number PIC18F242, manufactured by Microchip Technology of Chandler, Ariz. The processing circuitry  68  is in communication with the power interruption system  70  and selectively actuates the power interruption system  70  in response to unfavorable conditions detected by the sensor system  66  such as, but not limited to, the aforementioned “fault conditions.” More particularly, the power interruption system  70  selectively restricts power to the compressor motor  32  in response to direction from the processing circuitry  68  to prevent damage to the compressor  10  when sensed compressor operating conditions are outside of a predetermined limit.  
         [0065]     With particular reference to  FIGS. 3-6 , the sensor system  66  is shown to include a scroll sensor  72 , a motor temperature sensor  74 , and a rotor sensor  76 . The scroll sensor  72  is positioned generally proximate to the orbiting scroll member  40  and the non-orbiting scroll member  48  such that the temperature in an area surrounding the orbiting scroll member  40  and non-orbiting scroll member  48  may be detected. The motor temperature sensor  74  is positioned generally proximate to the windings  36  of the electric motor  32  and detects the temperature generally surrounding the windings  36 .  
         [0066]     The rotor sensor  76  is positioned proximate to the rotor  38  of electric motor  32  and senses when the rotor  38  is in a “locked rotor condition.” When the rotor  38  is restricted from moving relative to the windings  36 , a force is applied between the windings  36  and rotor  38  as the crankshaft  30  tries to rotate the windings  36 . As can be appreciated, when the motor  32  attempts to rotate the crankshaft  30  and is restricted from doing so due to the locked condition of the rotor  38  relative to the windings  36 , excessive current is drawn from an external power source and the rotor  38  begins to experience an elevated temperature. The increase in current draw is monitored by the rotor sensor  76  so that the compressor  10  may be shut down if a predetermined current is detected, as will be discussed further below.  
         [0067]     With particular reference to  FIG. 4 , the sensor system  66  is shown to further include a cluster block  78  and a printed circuit board (PCB)  80 . The cluster block  78  includes a housing  82 , power apertures  84 , and sensor apertures  86 . The power apertures  84  are connected to three high-voltage leads  88  extending from the housing  82 . The high-voltage leads  88  are operable to supply the electric motor  32  with power to thereby drive the crankshaft  30  and orbiting scroll member  40 . The high-voltage leads  88  extend from the housing  82  and terminate at the PCB  80 , as best shown in  FIG. 4 .  
         [0068]     The PCB  80  operably supports the motor temperature sensor  74  and rotor sensor  76  in close proximity to the electric motor  32 . The motor temperature sensor  74  is disposed on a bottom surface of the PCB  80  and is held in close proximity to the windings  36  of the motor  32  such that the motor temperature sensor  74  is able to detect temperature changes in the windings  36 . The motor temperature sensor  74  is a thermistor able to detect temperature fluctuations in the windings  36  and may be configured as either a NTC or a PTC device, depending on the particular application. If the motor temperature sensor  74  is configured as a NTC device, the signals coming from the motor temperature sensor  74  are connected in parallel. If the motor temperature sensor  74  is configured as a PTC device, then the sensed signals coming from the motor temperature sensor  74  are connected in series.  
         [0069]     The rotor sensor  76  is generally disposed on an opposite side of the PCB  80  from the motor temperature sensor  74 , as best shown in  FIG. 4 . The rotor sensor  76  generally includes a sensor pin  90  electrically connected to a terminal end of each high-voltage lead  88 . The sensor pins  90  are specially designed current carrying elements and are operable to localize an inherent electrical resistance of each pin at a specific point along its geometry indicative of the current flowing through each pin  90 . As can be appreciated, the current flowing through each sensor pin  90  is dictated by the amount of power drawn by the electric motor  32 . When the rotor  38  is in a locked condition, the motor  32  begins to draw more current through each pin  90 , thereby increasing the temperature of each pin  90  at the localized point, as will be described further below.  
         [0070]     In addition to the sensor pins  90 , the rotor sensor  76  further includes a temperature sensor  92  disposed proximate to each sensor pin  90 , as best shown in  FIG. 4 . The temperature sensors  92  detect a change in temperature along the length of the sensor pin  90 , and may be configured as either an NTC or a PTC thermistor. Generally speaking, each temperature sensor  92  is positioned along the length of each sensor pin  90  such that it is proximate to the localized spot of increased electrical resistance so as to best detect a temperature change along the length of each individual pin  90 . As can be appreciated, when more current is drawn through each sensor pin  90  by the electric motor  32 , each pin  90  will experience electric resistance at the localized point, as previously discussed. By placing each temperature sensor  92  proximate to the localized point of resistance along each sensor pin  90 , fluctuations in temperature caused by increased current draw through each sensor pin  90  will be quickly and accurately detected and may be fed back to the processing circuitry  68 , as will be discussed further below.  
         [0071]     In addition to supporting the motor temperature sensor  74  and rotor sensor  76 , the PCT  80  is also operably connected to the scroll sensor  72 , as best shown in  FIG. 4 . The scroll sensor  72  is a temperature sensor and is operable to detect temperature fluctuations proximate to, or caused by, the orbiting scroll member  40  and non-orbiting scroll member  48 . The scroll sensor  72  is a thermistor and may be configured as an NTC thermistor or a PTC thermistor, depending on the particular application.  
         [0072]     The PCB  80  serves as a termination point for the scroll sensor  72 , motor temperature sensor  74 , sensor pins  90 , and temperature sensors  92 . Specifically, the scroll sensor  72  is operably connected to the PCB  80  via low-voltage leads  94 , while the motor temperature sensor  74  and temperature sensors  92  are directly connected and supported by the PCB  80 , as best shown in  FIG. 4 . As previously discussed, each of the scroll sensor  72 , motor temperature sensor  74 , and rotor sensor  76  are operable to detect respective temperature fluctuations within the shell  14  of the compressor  10 . Because each of the scroll sensor  72 , motor temperature sensor  74 , and rotor sensor  76  terminate at the PCB  80 , the PCB  80  serves as a relay to transmit the sensed signals from each of the respective sensors  72 ,  74 ,  76 , through the shell  14  of the compressor  10  to the processing circuitry  68  and power interruption system  70 .  
         [0073]     A low-voltage lead  96  extends from the PCB  80  to the cluster block  78  and is connected to the sensor apertures  86 . As can be appreciated, the number of low-voltage leads  96  extending from the PCB  80  to the cluster block  78  will depend on the number of sensors disposed within the interior volume  22  of the compressor  10 . In other words, the number of low-voltage leads extending from the PCB  80  to the cluster block  78  will generally equal the number of sensors  72 ,  74 ,  92  disposed within the compressor  10 . However, each of the signals from the respective sensors  72 ,  74 ,  92  may be combined and sent from the PCB  80  to the cluster block  78  for transmission to the processing circuitry  68  and  70 , thereby requiring a single lead extending between the PCB  80  and the cluster block  78 . As can be appreciated, by combining the signals from the respective sensors  72 ,  74 ,  92 , a reduction in the number of leads  96  extending from the PCB  80  to the cluster block  78  may be reduced.  
         [0074]     As previously discussed, the sensor assembly  66  is in communication with the processing circuitry  68 . To maintain a hermetic seal within the volume  22  of the compressor  10 , a hermetic terminal assembly  98  is provided to establish an electrical connection between the sensor assembly  66  and processing circuitry  68 , as best shown in  FIG. 3 .  
         [0075]     The hermetic terminal assembly  98  includes a housing  100 , a plurality of high-voltage pins  102 , a plurality of low-voltage pins  104 , and a hermetic sealing material  106  surrounding the high and low-voltage pins  102 ,  104 . The housing  100  is fixedly attached to the shell  14  of the compressor  10  by a suitable means such as welding or braising. The high-voltage and low-voltage pins  102 ,  104  extend through the housing  100  such that the high-voltage and low-voltage pins  102 ,  104  extend from the interior volume  22  to an exterior surface of the compressor  10 , as best shown in  FIG. 3 . The high-voltage and low-voltage pins  102 ,  104  are surrounded by the hermetic sealing material  106  such that a hermetic seal is formed from an exterior surface of each pin  102 ,  104  and the housing  100 . In this manner, the terminal assembly  98  effectively allows communication between the sensor assembly  66  and processing circuitry  68  while maintaining the hermetic seal of the compressor  10 .  
         [0076]     The processing circuitry  68  is disposed on an outer surface of the compressor  10  and is in communication with both the terminal assembly  98  and the sensor assembly  66 . Specifically, the processing circuitry  68  is housed generally within the electrical enclosure  28  and may be incorporated into a suitable plug  108  for interaction with the hermetic terminal assembly  98 . Upon assembly, the plug  108  receives each of the high-voltage and low-voltage pins  102 ,  104  such that an electrical connection is made between the processing circuitry  68  and hermetic terminal assembly  98 . In addition, the high-voltage and low-voltage pins  102 ,  104  are received into the power apertures  84  and sensor apertures  86 , respectively, of the cluster block  78 . In this manner, an electrical connection is made between the processing circuitry  68  and sensor assembly  66  via the hermetic terminal assembly  98  and plug  108 . While a plug  108  has been described, it should be understood that any suitable connector may be used for transmitting a signal from within the compressor  10  to the processing circuitry  68 .  
         [0077]     In addition to being electrically connected to both the hermetic terminal assembly  98  and sensor assembly  66 , the processing circuitry  68  is further connected to the power interruption system  70 . The power interruption system  70  is disposed on an external surface of the compressor  10  and is operable to selectively permit or restrict power to the electric motor  32 . As can be appreciated, when the sensors  72 ,  74 ,  92  indicate that conditions are unfavorable within the compressor  10 , the processing circuitry  68  will direct the power interruption system  70  to restrict power from reaching the electric motor  32 , thereby effectively shutting down the compressor  10 . In this manner, the sensor assembly  66 , processing circuitry  68 , and power interruption system  70  are operable to shut down the compressor  10  via restricting power to the electric motor  32  when conditions in the compressor  10 , or within a system the compressor  10  may be tied to, are unfavorable for further operation.  
         [0078]     In addition to the above, the processing circuitry  68  also stores the configuration parameters of the compressor  10 . Specifically, the compressor model, compressor serial number, motor sensor type, MCC level, discharge temperature, motor temperature, current transformer calibration offset, slave addressing, and device name are all stored within the processing circuitry  68 . Of the above parameters, only the compressor model, serial number, slave addressing, and device name are field configurable.  
         [0079]     With particular reference to  FIGS. 5 and 6 , the operation of the compressor  10  and associated compressor protection and control system  12  will be described in detail. As previously discussed, the power interruption system  70  regulates power directed to the electric motor  32  of the compressor  10  by selectively engaging a contact  110  disposed external from the compressor  10  to thereby selectively restrict and permit power to the electric motor  32 .  
         [0080]     In operation, the processor  68  monitors the combined signal of both the motor temperature sensor  74  and scroll temperature sensor  72  and selectively shuts down the compressor  10  in response to detected system parameters. Specifically, if the actual value of the temperature detected by either the motor temperature sensor  74  or scroll temperature sensor  72  exceeds a preprogrammed limit such that a fault condition is detected, the processing circuitry  68  directs the power interruption system  70  to disconnect the contact  110 , thereby restricting power from reaching the electric motor  32 . In addition, the processing circuitry  68  further creates a fault signal and directs such signal to a diagnostic output  112  for recording. As can be appreciated, registered faults within the compressor  10  may be valuable diagnostic tools in tracking and preventing further faults and failures within the compressor  10 . By sending fault signals to the diagnostic output  112 , the processing circuitry  68  effectively registers each time the compressor  10  is shut down and maintains a record of each fault condition experienced.  
         [0081]     As previously discussed, the rotor sensor  76  detects when the rotor  38  is locked relative to the windings  36 . When the rotor  38  is in a “locked rotor condition” the electric motor  32  still draws current through the sensor pins  90  in an effort to rotate the crankshaft  30  and rotor  38  relative to the windings  36 . In so doing, the electric motor  32  draws a significant amount of current through each sensor pin  90  to overcome the locked condition between the rotor  38  and windings  36 , thereby increasing the temperature of each sensor pin  90 . When the sensor pins  90  realize an increase in temperature, the temperature sensors  92  relay a signal indicative of the temperature increase back to the processing circuitry  68 .  
         [0082]     When the temperature sensors  92  indicate an increase in temperature at each pin  90 , the processing circuitry  68  correlates the sensed temperature to a current flowing through each pin  90 . In this manner, the temperature sensors  92  cooperate with the processing circuitry  68  to effectively function as a current sensor to monitor the current through each pin  90  and detect a locked rotor condition. When a threshold current has been established through the pins  90 , the processing circuitry  68  is operable to direct the power interruption system  70  to restrict power to the motor  32  and shut down the compressor  10 .  
         [0083]     In addition to sending a signal to the power interruption system  70 , the processing circuitry  68  also sends a diagnostic signal to the diagnostic output  112  to record the “locked rotor” fault experienced within the compressor  10 . By storing and tracking faults, the compressor protection and control system  12  effectively allows a user to monitor and track problems experienced by the compressor  10  in an effort to prevent and detect problems in the future, as previously discussed.  
         [0084]     Compressor protection and control system  12  has thus far been described as having three temperature sensors  92 , each disposed proximate to the sensor pins  90 .  FIG. 5  schematically represents an input to the processing circuitry  68  from each one of the temperature sensors  92 . It should be understood, however, that the three temperature sensors  92  could be fed into one signal, whereby the lone signal is sent to the processing circuitry  68  via hermetic terminal assembly  98 , as best shown in  FIG. 6 . In such a relationship, the system  12  is simplified by reducing the number of signals coming from the individual temperature sensors  92 . In addition to the aforementioned sensors  72 ,  74 ,  76 , it should be understood that other sensors could be used within the compressor  10  and should be considered as part of the present invention. Specifically, it is anticipated that an oil level sensor or oil temperature sensor, generically referred to in  FIG. 6  as  114 , could also be incorporated into the compressor protection and control system  12  for use in tracking diagnostics within the compressor  10 , and should be considered with in the scope of the present invention.  
         [0085]     With particular reference to  FIGS. 7-11 , a second embodiment of the compressor protection and control system  12  will be described in detail. In view of the substantial similarity in structure and function of the components associated with the compressor protection and control system  12  and the compressor protection and control system  12   a , like reference numerals are used here and in the drawings to identify like components.  
         [0086]     The compressor protection and control system  12   a  functions in a similar fashion to that of the compressor protection and control system  12 , with respect to the scroll sensor  72  and motor temperature sensor  74 . In this manner, detailed descriptions of the scroll sensor  72  and motor temperature sensor  74  are foregone.  
         [0087]     The rotor sensor  76   a  is disposed within the electric box  28  and generally includes a sensor pin  90  electrically connected to a high-voltage lead  88 . The sensor pins  90  are a specially designed current carrying elements and localize an inherent electrical resistance of each pin at a specific point along its geometry indicative of the current flowing through each pin  90 . As can be appreciated, the current flowing through each sensor pin  90  is dictated by the amount of power drawn by the electric motor  32 . When the rotor  38  is in a locked condition, the motor  32  begins to draw more current through each pin  90 , thereby increasing the temperature of each pin  90  at the localized point, as will be described further below.  
         [0088]     In addition to the sensor pins  90 , the rotor sensor  76   a  further includes a temperature sensor  92  disposed proximate to each sensor pin  90 . The temperature sensors  92  are operable to detect a change in temperature along the length of the sensor pin  90 , and may be configured as either an NTC or a PTC thermistor. Generally speaking, each temperature sensor  92  is positioned along the length of each sensor pin  90  such that it is proximate to the localized spot of increased electrical resistance so as to best detect a temperature change along the length of each individual pin  90 . As can be appreciated, when more current is drawn through each sensor pin  90  by the electric motor  32 , each pin  90  experiences electric resistance at the localized point. By placing each temperature sensor  92  proximate to the localized point of resistance along each sensor pin  90 , fluctuations in temperature caused by increased current draw through each sensor pin  90  will be quickly and accurately detected and may be fed back to the processing circuitry  68 .  
         [0089]     The rotor sensor  76   a  allows the processing circuitry  68  to more quickly respond to an increase in current draw by the motor  32  and therefore increases the ability of the compressor protection and control system  12   a  to protect the compressor  10 . More particularly, because the rotor sensor  76   a  is disposed external from the interior space  22  of the compressor, the power drawn by the motor  32  may be monitored prior to actually entering the compressor shell  14 . Monitoring the current draw upstream from the motor  32  allows for a quicker response time as the processing circuitry  68  is not required to wait for the current to travel along the high-voltage leads  88  and through the hermetic interface  98  prior to taking a reading. The improved response time allows the processing circuitry  68  to more quickly direct the power interruption system  70  to restrict power to the motor  32 , and thus, reduces the probability of compressor damage.  
         [0090]     With particular reference to  FIGS. 12-18 , a third embodiment of the compressor protection and control system  12  will be described in detail. In view of the substantial similarity in structure and function of the components associated with the compressor protection and control system  12  and the compressor protection and control system  12   b , like reference numerals are used here and in the drawings to identify like components.  
         [0091]     The compressor protection and control system  12   b  functions in a similar fashion to that of the compressor protection and control system  12 , with respect to the scroll sensor  72  and motor temperature sensor  74 . In this manner, detailed descriptions of the scroll sensor  72  and motor temperature sensor  74  are foregone.  
         [0092]     The rotor sensor  76   b  is disposed within the electrical enclosure  28   b  such that the rotor sensor  76   b  is removed from the interior space  22  of the compressor  10 . The rotor sensor  76   b  includes a cluster block  116  that matingly engages the hermetic terminal assembly  98  and a current sensor  118  that detects a current drawn by the electric motor  32 .  
         [0093]     The cluster block  116  includes a pair of arms  120  flanking a central body  122 , as best shown in  FIG. 13 . Each of the arms  120  and central body  122  includes a high-voltage lead  88  extending therefrom. In addition, the main body  122  includes a pair of low-voltage leads  96  extending therefrom for receiving and transmitting signals from the sensor assembly  66   b , as will be described further below. As best shown in  FIG. 13 , the cluster block  116  matingly engages the hermetic terminal assembly  98  such that each of the high-voltage leads  98  engage the high-voltage pins  102  and the low-voltage leads  96  engage the low-voltage pins  104 . In this manner, the cluster block  116  effectively connects the high-voltage power leads  88  and low-voltage sensor leads  96  to the sensor system  66   a  and motor  32  disposed within the compressor  10 .  
         [0094]     The current sensor  118  is disposed proximate to the cluster block  116 , as best shown in  FIG. 14 . The current sensor  76   b  includes a series of individual sensing elements  124 , each having a high-voltage lead  88  extending therethrough. The sensor elements  124  detect a current flowing through each of the high-voltage leads  88  and produce a signal indicative thereof. The signal produced by the sensing elements  124  is sent to the processing circuitry  68   b  to compare the sensed current to a threshold limit and determine whether the electric motor  32  is in a “locked rotor state” or another fault condition.  
         [0095]     If the processing circuitry  68   b  determines that the current flowing through the high-voltage leads  88  exceeds the threshold limit, the processing circuitry  68   b  will send a signal to the power interruption system  70  to restrict power to the electric motor  32  and shut down the compressor  10 .  
         [0096]     As previously discussed, the processing circuitry  68   b  sends a signal to the power interruption system  70  to restrict power to the electric motor  32  should an undesirable condition be experienced within the compressor  10 . In addition, the processing circuitry  68   b  also alerts an operator that a system fault has occurred within the compressor  10  by illuminating a series of light-emitting devices (LED)  126 , as will be discussed further below.  
         [0097]     With particular reference to  FIGS. 14-18 , the operation of the compressor  10  and associated compressor protection and control system  12   b  will be described in detail. As previously discussed, the scroll sensor  72 , motor temperature sensor  74 , and rotor sensor  76   b  detect operating conditions and parameters of the compressor  10 . The sensed signals from the individual sensors  72 ,  74 ,  76   b  are sent to the processing circuitry  68   b  for comparison to a set of predetermined compressor operating parameters. Should the processing circuitry  68   b  determine that the sensed parameters from the individual sensors  72 ,  74 ,  76   b  exceed the predetermined compressor operating parameters, the processing circuitry  68   b  will alert the power interruption system  70  to restrict power to the electric motor  32  to thereby shut down the compressor  10 .  
         [0098]     When the compressor  10  is initially started, the system is in a ready mode, as indicated in  FIG. 17 . At this point, the processing circuitry  68   b  checks for any fault conditions. If a fault condition is detected, the processing circuitry  68   b  bypasses the run mode of the compressor  10  and causes the compressor  10  to enter a shutdown mode. In the shutdown mode, the compressor  10  attempts to recover the system without fully shutting down power to the electric motor  32 , depending on the particular fault condition experienced. However, if the fault condition experienced is a significant fault, the shutdown mode enters a lockout or a no control phase, whereby the compressor  10  will need to be shut down completely such that power is restricted from reaching the electric motor  32 . In such a condition, the compressor  10  is not be able to enter the run mode until the processing circuitry  68   b  directs the power interruption system  70  to restrict power to the electric motor  32 . Restarting the compressor  10  by restricting power often clears the fault and allows the compressor  10  to properly operate.  
         [0099]     When the compressor  10  is returned to the ready mode, or when the compressor  10  is initially started from startup and no fault conditions are detected, the compressor  10  enters the run mode, as indicated in  FIGS. 17 and 18 . The compressor  10  continues to run and the processing circuitry  68   b  will cause the diagnostic  112  to continually record each successful run. Once ten successful runs have been achieved, the processing circuitry  68   b  clears the fault memory and restarts the system anew. In this manner, the processing circuitry  68   b  receives sensed system parameters from the individual sensors  72 ,  74 ,  76   b  and selectively shuts down the compressor  10  when system conditions warrant. In addition, the processing circuitry  68   b  also collects data during an operational mode of the compressor  10  via diagnostic  112  to thereby store and track faults. As can be appreciated, by storing and tracking such faults, the processing circuitry  68   b  is able to detect and prevent possible future failures and faults by the compressor  10 .  
         [0100]     When the compressor  10  is in the run mode, the LED  126  illuminates a green light to indicate that the compressor  10  is running under normal conditions, as best shown in  FIG. 18 . In addition, a second LED  126  may also be illuminated to indicate that the contactor  110  is supplying power to the electric motor  32 . In the event that a fault is detected, a yellow LED  126  is illuminated to indicate that the compressor  10  has experienced a fault and is in need of attention. If the processing circuitry  68   b  determines that the fault condition is a significant fault, such that the compressor  10  will not be able to recover without shutting down, the processing circuitry  68   b  directs the power interruption system  70  to restrict power the compressor  10 , as previously discussed.  
         [0101]     When the power interruption system  70  shuts down the compressor  10 , a red LED  126  is illuminated to alert an operator that the compressor  10  has been shut down due to a fault condition. At this point, the green “run” and “contactor” LEDs  126  is turned off to indicate that the compressor  10  is no longer running under normal conditions, and that the contactor  110  has been disengaged from the power supply. It should be noted that at this point, the only LED  126  illuminated is the red alarm, indicating that the compressor  10  has been shut down and has logged a fault. As can be appreciated, by using such LEDs  126 , the compressor protection and control system  12   b  allows the compressor  10  to indicate when a fault condition has been experienced so that proper actions can be taken, as best shown in  FIG. 18 .  
         [0102]     Generally speaking, the LED alarms are divided into supply power alarms and compressor alarms. The respective supply power and compressor alarms are communicated to the user by denoting a specific alarm with a designated number of LED flashes. Specifically, the supply power alarms include run winding delay (one flash), missing phase (two flashes), reverse phase (three flashes), welded contactor (four flashes), low voltage (five flashes), and no three phase power (six flashes). The compressor alarms include low oil pressure (one flash), discharge temperature (two flashes), motor temperature (three flashes), locked rotor (four flashes), motor overload (five flashes), and open thermistor (six flashes). Therefore, the user can easily determine the respective fault condition by simply referring to the respective LED  126 .  
         [0103]     With particular reference to  FIGS. 19-20 , a fourth embodiment of the compressor protection and control system  12  will be described in detail. In view of the substantial similarity in structure and function of the components associated with the compressor protection and control system  12  and the compressor protection and control system  12   c , like reference numerals are used here and in the drawings to identify like components.  
         [0104]     With reference to  FIG. 19 , the plural compressor  10   c  is shown to include a generally cylindrical hermetic shell  14   c  having a pair of welded caps  16   c ,  18   c  and a plurality of feet  20   c . The caps  16   c ,  18   c  are fitted to the shell  14   c  such that an interior volume  22   c  of the compressor  10   c  is defined. In addition, an electrical enclosure  28   c  is fixedly attached to the shell  14   c  generally between the caps  16   c ,  18   c  and operably supports a portion of the protection system  12   c  therein, as will be discussed further below.  
         [0105]     A crankshaft  30   c  is rotatively driven by an electric motor  32   c  relative to the shell  14   c . The motor  32   c  includes a stator  34   c  fixedly supported by the hermetic shell  14   c , windings  36   c  passing therethrough, and a rotor  38   c  press fitted on the crankshaft  30   c . The motor  32   c  and associated stator  34   c , windings  36   c , and rotor  38   c  are operable to drive the crankshaft  30   c  relative to the shell  14   c  to thereby compress a fluid.  
         [0106]     The plural compressor  10   c  further includes a pair of orbiting scroll members  40   c , each having a spiral vane or wrap  42   c  on the upper surface thereof for use in receiving and compressing a fluid. An Oldham coupling  44   c  is positioned between orbiting scroll members  40   c  and a bearing housing  46   c  and is keyed to orbiting scroll members  40   c  and a pair of non-orbiting scroll members  48   c . The Oldham coupling  44   c  is operable to transmit rotational forces from the crankshaft  30   c  to the orbiting scroll members  40   c  to thereby compress a fluid disposed between the orbiting scroll members  40   c  and non-orbiting scroll members  48   c . Oldham coupling  44   c  and its interaction with orbiting scroll members  40   c  and non-orbiting scroll members  48   c  is preferably of the type disclosed in assignee&#39;s commonly-owned U.S. Pat. No. 5,320,506, the disclosure of which is incorporated herein by reference.  
         [0107]     Non-orbiting scroll members  48   c  also include a wrap  50   c  positioned in meshing engagement with wrap  42   c  of orbiting scroll members  40   c . Non-orbiting scroll members  48   c  have a centrally disposed discharge passage  52   c  which communicates with an upwardly open recess  54   c . Recesses  54   c  serve to store compressed fluid are disposed at opposite ends of the interior volume  22   c  such that a first recess  54   c  is positioned proximate cap  16   c  and a second recess  54   c  is positioned proximate cap  18   c.    
         [0108]     Plural compressor  10   c  is preferably of the type disclosed in assignee&#39;s commonly-owned U.S. Pat. No. 6,672,846 and U.S. patent application Ser. No. 10/600,106 filed on Jun. 20, 2003, published as U.S. 2004-0258542A1, the disclosures of which are incorporated herein by reference.  
         [0109]     The compressor protection and control system  12   c  functions in a similar fashion to that of the compressor protection and control system  12   b , with respect to the scroll sensor  72  and motor temperature sensor  74 . In this manner, detailed descriptions of the scroll sensor  72  and motor temperature sensor  74  are foregone.  
         [0110]     The rotor sensor  76   c  is disposed generally within electrical box  28   c  such that current to the motor  32   c  is sensed prior to entering the shell  14   c . The rotor sensor  76   c  is substantially identical to sensor  76   b , but requires three additional sensing elements  124  to handle an additional current draw by the motor  32   c . Specifically, because the plural compressor  10   c  drives a pair of orbiting scroll members  40   c  relative to a pair of non-orbiting scroll members  48   c , a larger motor  32   c  is required and, thus, more current is drawn. The increased power requirement causes additional high-voltage lines  88  to extend between the hermetic terminal assembly  98  and motor  32   c . In this manner, the rotor sensor  76   c  requires a total of six sensing elements  124  to accommodate the additional high-voltage leads  88 .  
         [0111]      FIGS. 21 and 22  show a perspective view of the processing circuitry  68   c  and rotor sensor  76   c . Six sensing elements  124  are shown proximate to high-voltage leads  88 , such that the current drawn by the motor  32   c  is monitored. In addition, a plurality of sensor inputs are shown such as oil level inputs  134 , motor temperature sensor inputs  136 , discharge temperature inputs  138 ,  140 , alarm relays  140 , power inputs  142 , and contactor inputs  144 . In addition, a communication port  112   c  is shown for communication with an external network, as will be discussed further below. As can be appreciated, the inputs may be varied depending on the particular application and will be largely dependent upon the sensor system  66   c  disposed within the compressor  10   c . For example, a scroll-temperature input  146  could be added if a scroll sensor  72  is used within the compressor  10   c , as best shown in  FIG. 21 .  
         [0112]     With particular reference to  FIG. 23 , the compressor  10  and associated compressor protection and control system  12  are shown incorporated into a network  128 . While the network  128  will be described with reference to compressor  10  and compressor protection and control system  12   b , it should be understood that compressor  10   c  and other protection and control systems  12 ,  12   a ,  12   c  could similarly be used in such a network. The network  128  includes a system controller  138  and a plurality of compressors  10 . Each compressor  10  is in communication with a system controller  130  via a communications port  132 . The communications port  132  may be linked to the diagnostic  112  such that faults recorded by the processing circuitry  68   b  logged in the diagnostic  112  may be supplied to the communication port  132  and system controller  130 . By doing so, the faults experienced by each individual compressor  10  may be recorded and logged so that the proper maintenance may be performed on each compressor  10 . While the compressor protection and control system  12   b  has been described incorporated into the network  128 , it should be understood that the compressor protection and control system  12  could similarly be implemented into such a network, and as such, should be considered within the scope of the present invention.  
         [0113]     As described, the compressor protection and control system  12  and compressor protection and control system  12   b  provide the compressor  10  with the ability to detect and sense system parameters, to alert potential faults through the use of LEDs  126 , and to store faults via diagnostic  112 . In addition, in the case of the locked rotor condition, each of the current sensors  76 ,  76   b  provide the system with the ability to detect current draw by the motor  32 , rather than relying solely on sensed motor temperatures. As can be appreciated, by sensing current draw, rather than waiting for a temperature signal to be produced and analyzed, the systems  12 ,  12   a ,  12   b ,  12   c  provide a quicker response time and thereby increase the productivity and performance of the compressor  10 .  
         [0114]     The description is merely exemplary in nature and, thus, variations are intended to be within the scope of the teachings and not as a departure from the spirit and scope of the teachings.