Control Transformers (T1, T2); Optional Transformer (T3) - Carrier AquaEdge 19XRV series Operation, Maintenance And Installation Manual

CONTROL TRANSFORMERS (T1, T2) — These transform-
ers convert incoming control voltage to 24 vac power for the
3 power panel contactor relays, CCM, and ICVC.
OPTIONAL TRANSFORMER (T3) — This transformer pro-
vides 20 vac control power to DataPort™/DataLINK™
modules.
SENSORS — Two types of temperature sensors are used:
Figure 16 shows a typical temperature sensor for which
sensor wells are used, in systems having an ICVC controller.
For this type, the sensor cable cannot be separated from the
sensor itself, but the sensor can be readily removed from the
well without breaking into the fluid boundary.
SHRINK WRAP
STRAIN RELIEF
REMOVABLE
TEMPERATURE
SENSOR
Fig. 16 — Temperature
Sensor Used
TYPE
TEMPERATURE
PRESSURE
ANGULAR POSITION
PRESSURE SWITCH
TEMPERATURE
SWITCH
1/8" NPT
THERMOWELL
a23-1624
Table 3 — Standard Instrumentation Sensors
LOCATION MONITORED
Entering chilled water
Leaving chilled water
Entering condenser water
Leaving condenser water
Evaporator saturation
Compressor discharge
Oil sump
Compressor thrust bearing
Motor winding
Evaporator
Condenser
Oil sump
Oil sump discharge
Diffuser (Compressor internal)
Entering chilled water (Optional)
Leaving chilled water (Optional)
Entering condenser water (Optional)
Leaving condenser water (Optional)
Guide vane actuator
Split ring diffuser actuator (Optional)
High condenser (discharge) pressure
Oil pump motor winding temperature
The second type of temperature sensor is a thermistor,
which is installed either in the motor windings or at the thrust
bearing within the compressor. Both of these have redundant
sensors such that if one fails, the other can be connected exter-
nal to the machine. See Table 3 for a list of standard instrumen-
tation sensors.
The PIC III control determines refrigerant temperature in
the condenser and evaporator from pressure in those vessels,
read from the corresponding pressure transducers. See Fig. 17.
The pressure values are converted to the equivalent saturation
temperatures for R-134a refrigerant. When the chiller is run-
ning, if the computed value for EVAPORATOR REFRIG
TEMP is greater than, or within 0.6 F (0.33 C) of the LEAVING
CHILLED WATER temperature, its value is displayed as 0.6 F
(0.33 C) below LEAVING CHILLED WATER temperature.
When the chiller is running, if the computed value for CON-
DENSER REFRIG TEMP is less than, or within 1.2 F (0.67 C)
of the LEAVING COND WATER temperature, its value is dis-
played as 1.2 F (0.67 C) above LEAVING COND WATER
temperature.
a19-957ef
Fig. 17 — Control Sensors
(Pressure Transducers, Typical)
Cooler inlet nozzle
Cooler outlet nozzle
Condenser inlet nozzle
Condenser outlet nozzle
Sensor well on bottom of evaporator
Compressor volute
Compressor oil sump
Redundant sensor provided
Redundant sensor provided
Relief valve tee
Relief valve tee
Compressor oil sump
Oil pump discharge line
Only in machines equipped with split ring diffusers
Cooler inlet nozzle
Cooler outlet nozzle
Condenser inlet nozzle
Condenser outlet nozzle
Potentiometer inside of actuator
Potentiometer inside of actuator only on machines equipped
with split ring diffusers (split ring diffuser position not dis-
played on ICVC)
Compressor volute, wired into the VFD control circuit
Wired into the oil pump control circuit
21
REMARKS