16
CHILLER CONTROL MODULE (CCM) — This module is
located in the control panel. The CCM provides the input and
outputs necessary to control the chiller. This module monitors
refrigerant pressure, entering and leaving water temperatures,
and outputs control for the guide vane actuator, oil heaters, and
oil pump. The CCM is the connection point for optional
demand limit, chilled water reset, remote temperature reset,
and motor kilowatt output.
OIL HEATER CONTACTOR (1C) — This contactor is lo-
cated in the power panel (Fig. 11) and operates the heater at
115 v. It is controlled by the PIC III to maintain oil temperature
during chiller shutdown. Refer to the control panel wiring
schematic.
OIL PUMP CONTACTOR (2C) — This contactor is located
in the power panel. It operates all 380 to 480-v oil pumps.
The PIC III energizes the contactor to turn on the oil pump as
necessary.
HOT GAS BYPASS CONTACTOR RELAY (3C)
(Optional) — This relay, located in the power panel, controls
the opening of the hot gas bypass valve. The PIC III energizes
the relay during low load, high lift conditions.
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 12 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.
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. 13.
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 LEAV-
ING CHILLED WATER temperature, its value is displayed as
0.6° F (0.33° C) below LEAVING CHILLED WATER temper-
ature. When the chiller is running, if the computed value for
CONDENSER REFRIG TEMP is less than, or within 1.2° F
(0.67° C) of the LEAVING COND WATER temperature, its
value is displayed as 1.2° F (0.67° C) above LEAVING COND
WATER temperature.
Table 3 — Standard Instrumentation Sensors
TYPE LOCATION MONITORED REMARKS
Temperature
Entering chilled water Cooler inlet nozzle
Leaving chilled water Cooler outlet nozzle
Entering condenser water Condenser inlet nozzle
Leaving condenser water Condenser outlet nozzle
Evaporator saturation Sensor well on bottom of evaporator
Compressor discharge Compressor volute
Oil sump Compressor oil sump
Compressor thrust bearing Redundant sensor provided
Motor winding Redundant sensor provided
Pressure
Evaporator Relief valve tee
Condenser Relief valve tee
Oil sump Compressor oil sump
Oil sump discharge Oil pump discharge line
Diffuser (Compressor internal) Only in machines equipped with split ring diffusers
Entering chilled water (Optional) Cooler inlet nozzle
Leaving chilled water (Optional) Cooler outlet nozzle
Entering condenser water (Optional) Condenser inlet nozzle
Leaving condenser water (Optional) Condenser outlet nozzle
Angular Position
Guide vane actuator Potentiometer inside of actuator
Split ring diffuser actuator (Optional) Potentiometer inside of actuator only on machines equipped
with split ring diffusers (split ring diffuser position not dis-
played on ICVC)
Pressure Switch High condenser (discharge) pressure Compressor volute, wired into the VFD control circuit
Temperature Switch Oil pump motor winding temperature Wired into the oil pump control circuit
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