62-12259 2–8
2.3.4.5 Engine Oil Pressure Switch (ENOPS)
The ENOPS is normally open and closes on pressure rise to the signal to the APX Control System when
the engine has sufficient oil pressure for operation. There is a 15-second delay after the engine starts to
allow the oil pressure to build up before the APX Control System looks at the input from this switch. The
switch is located in the oil filter mounting assembly.
2.3.4.6 Engine Coolant Temperature Sensor (ENCT)
The ENCT is a thermistor type sensor that provides the APX Control System with engine coolant tempera-
ture information to be displayed, recorded in the DataLink data recorder and used to control the engine and
refrigeration system. The sensor is located on thermostat housing.
2.3.4.7 Rail Pressure Sensor
The Rail Pressure Sensor senses pressure in the rail that in turn signals the ECU and in turn, sends inputs
to the pressure reducing valve and the PCV. The Rail Pressure Sensor is located in the fuel rail.
2.3.5 Generator (GEN)
The generator is directly bolted to the engine and supplies nominal 460V/3Ø/60Hz power when the engine is in
high speed and nominal 345V/3Ø/45Hz power in low speed.
The generator may be fitted with a generator temperature sensor (GNT). This sensor is installed when Carrier
Transicold factory monitoring of the system is required.
2.3.6 Compressor
The unit is fitted with a scroll compressor equipped with suction and discharge service valves and an economizer
connection. The compressor draws refrigerant gas from the evaporator and delivers it to the condenser at an
increased temperature and pressure. The pressure is such that refrigerant heat can be absorbed by the surround-
ing air at ambient temperatures.
2.3.7 Compressor Switches, Transducers and Sensors
2.3.7.1 Compressor Discharge Pressure Transducer (CDP)
The CDP provides a signal to the control system equivalent to pressure leaving the compressor. The read-
ing is displayed, recorded in the data recorder and used to control the refrigeration system. It is located in
the discharge line leaving the compressor.
2.3.7.2 Compressor Suction Pressure Transducer (CSP)
The CSP provides a signal to the control system equivalent to pressure entering the compressor. The
reading is displayed, recorded in the data recorder and used to control the refrigeration system. It is
located in the suction service valve.
2.3.7.3 High Pressure Switch (HPS)
The HPS is normally closed and opens on pressure rise to signal the control system to shutdown the refrig-
eration system if the discharge pressure rises above the switch setting. It is located in the discharge ser-
vice valve.
2.3.7.4 Compressor Discharge Temperature Sensor (CDT)
The CDT is a thermistor type sensor that provides a signal to the control system equivalent to the tempera-
ture of the gas leaving the compressor. The reading is displayed, recorded in the data recorder and used to
control the refrigeration system. It is located on the compressor head.
2.3.7.5 Compressor Suction Temperature Sensor (CST)
The CST is a thermistor type sensor that provides a signal to the control system equivalent to the tempera-
ture of the gas entering the compressor suction service valve. The reading is displayed, recorded in the
data recorder and used to control the refrigeration system. It is located on the line entering the service
valve.
2.3.8 Liquid Injection Solenoid Valve (LIV)
The LIV is opened during periods of high compressor discharge temperature to inject refrigerant into the
economizer connection to cool the compressor. It is located at the front of the economizer.
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