Carrier 19XRV Start-Up, Operation And Maintenance Instructions Manual page 12

3.3.2 - 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.
3.3.3 - oil heater contactor (1C)
This contactor is located in the power panel 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.
3.3.4 - oil pump contactor (2C)
This contactor is located in the power panel. It operates all
380 to 480 V oil pumps. The PIC III energises the contactor
to turn on the oil pump as necessary.
3.3.5 - 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 energises the relay
during low load, high lift conditions.
3.3.6 - Control transformers (t1, t2)
These transformers convert incoming control voltage to
4 V a.c. power for the three power panel contactor relays,
CCM, and ICVC.
3.3.7 - optional transformer (t3)
This transformer provides 0 V a.c. control power to
DataPort/DataLINK modules.
Type Location mointored
Temperature Entering chilled water
Leaving chilled water
Entering condenser water
Leaving condenser water
Evaporator saturation
Compressor discharge
Oil sump
Compressor thrust bearing
Motor winding
Pressure 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)
Angular position Guide vane actuator
Split ring diffuser actuator (optional)
Pressure switch High condenser (discharge) pressure
Temperature switch Oil pump motor winding temperature
1
Table 2 - Standard instrumentation sensors
Remarks
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
3.3.8 - Sensors
The PIC III control determines refrigerant temperature in
the condenser and evaporator from pressure in those vessels,
read from the corresponding pressure transducers. The
pressure values are converted to the equivalent saturation
temperatures for R-134a refrigerant. When the chiller is
running, if the computed value for EVAPORATOR
REFRIG TEMP is greater than, or within 0.33 K) of the
LEAVING CHILLED WATER temperature, its value is
displayed as 0.33 K below LEAVING CHILLED WATER
temperature. When the chiller is running, if the computed
value for CONDENSER REFRIG TEMP is less than, or
within 0.67 K of the LEAVING COND WATER tempera-
ture, its value is displayed as 0.67 K above LEAVING
COND WATER temperature.
A refrigerant saturation temperature sensor (thermistor)
is located in the base of the evaporator, sensing refrigerant
temperature directly. Evaporator and condenser water side
differential pressure transducers are not standard and are
not required. The ICVC software uses the evaporator satu-
ration refrigerant temperature in place of differential pres-
sure flow detection to provide evaporator freeze protection.
Approach temperatures are shown in the HEAT_EX screen.
EVAPORATOR APPROACH is defined as LEAVING
CHILLED WATER temperature minus EVAP SATURA-
TION TEMP (from the temperature sensor). CONDENSER
APPROACH is defined as CONDENSER REFRIG TEMP
(derived from condenser pressure) minus LEAVING
CONDENSER WATER temperature. When the chiller is
running, the displayed value for either approach will not
be less than 0.1 K. If either approach value exceeds the
value configured in the SETUP1 screen, the corresponding
Approach Alert message will be entered into the Alert
History table.