Specifications

12
Table 4 — Thermistor Designations
LEGEND
Table 5 — Status Inputs
Table 6 — Output Relays
Table 7 — CCN Communication Bus Wiring
Sensors — The electronic control uses 2 to 7 thermistors to
sense temperatures for controlling chiller operation. See
Table 4. These sensors are outlined below. Thermistors cooler
leaving fluid, cooler entering fluid, discharge temperature, cir-
cuit A return gas temperature, outdoor-air temperature sensor
or dual LWT sensor, accessory remote space temperature sen-
sor, condenser entering fluid temperature sensor, and condens-
er leaving fluid temperature sensor are identical in temperature
versus resistance and voltage drop performance. The dual chill-
er thermistor (DLWT) is 5,000 ohmsat 77 F (25 C)thermistor.
Space temperature thermistor (SPT) is a 10,000 ohmsat 77 F
(25 C). See Thermistors section for temperature-resistance-
voltage drop characteristics.
COOLER LEAVING FLUID SENSOR (LWT) — The thermis-
tor is installed in a well in the factory-installed leaving fluid
piping coming from the bottom of the brazed-plate heat
exchanger.
COOLER ENTERING FLUID SENSOR (EWT) — The therm-
istor is installed in a well in the factory-installed entering fluid
piping coming from the top of the brazed-plate heat exchanger.
CONDENSER LEAVING FLUID SENSOR (CDLT) — The
thermistor is installed in a well in the field-installed leaving
fluid piping coming from the bottom of the brazed-plate heat
exchanger. The thermistor is a field-installed accessory. See
Table 8 for thermistor and well part numbers.
CONDENSER ENTERING FLUID SENSOR (CDET) — The
thermistor is installed in a well in the field-installed entering
fluid piping coming from the top of the brazed-plate heat
exchanger. See Table 8 for thermistor and well part numbers.
COMPRESSOR RETURN GAS TEMPERATURE SEN-
SOR (RGT.A) — This accessory thermistor can be installed
in a well located in the suction line. Use Carrier part number
HH79NZ029.
OUTDOOR-AIR TEMPERATURE SENSOR (OAT) —
This sensor is an accessory that is remotely mounted and used
for outdoor air temperature reset. See Table 4. Use Carrier part
number HH79NZ023.
DUAL LEAVING WATER TEMPERATURE SENSOR
(DLWT) — This input can be connected to the LVT. See Ta-
ble 4. For dual chiller applications (parallel only are support-
ed), connect the dual chiller leaving fluid temperature sensor
(see Table 8 for thermistor and well part numbers) to the out-
side air temperature input of the Master chiller. If outside-air
temperature is required for reset applications, connect the sen-
sor to the Slave chiller and configure the slave chiller to broad-
cast the value to the Master chiller.
DISCHARGE TEMPERATURE THERMISTOR
(D.GAS) — This sensor is only used on units with a digital
compressor. The sensor is mounted on the discharge line close
to the discharge of the digital compressor. It attaches to the dis-
charge line using a spring clip and protects the system from
high discharge gas temperature when the digital compressor is
used. This sensor is a connected to the AUX board.
REMOTE SPACE TEMPERATURE SENSOR (SPT) —
The sensor (part no. 33ZCT55SPT) is an accessory sensor that
is remotely mounted in the controlled space and used for space
temperature reset. The sensor should be installed as a wall-
mounted thermostat would be (in the conditioned space where
it will not be subjected to either a cooling or heating source or
direct exposure to sunlight, and 4 to 5 ft above the floor).
Space temperature sensor wires are to be connected to
terminals in the unit main control box. The space temperature
sensor includes a terminal block (SEN) and a RJ11 female
connector. The RJ11 connector is used access into the Carrier
Comfort Network
®
(CCN) at the sensor.
IMPORTANT: A shorted CCN bus cable will prevent some
routines from running and may prevent the unit from start-
ing. If abnormal conditions occur, unplug the connector. If
conditions return to normal, check the CCN connector and
cable. Run new cable if necessary. A short in one section of
the bus can cause problems with all system elements on the
bus.
SCROLLING
MARQUEE
THERMISTOR
DISPLAY
NAME
PIN
CONNECTION
POINT
THERMISTOR INPUT
CLWT J8-13,14 (MBB) Cooler Leaving Fluid
CEWT J8-11,12 (MBB) Cooler Entering Fluid
D.GAS
J6-12 (AUX2) Discharge Temperature
Thermistor (Digital Compres-
sor Option Only)
RGTA
J8-9,10 (MBB) Circuit A Return Gas
Temperature (accessory)
OAT/DLWT
J8-6,7 (MBB),
LVT-21,22
Outdoor-Air Temperature
Sensor (accessory) or Dual
LWT Sensor
SPT
J8-5,6 (MBB)
LVT-22,23
Accessory Remote Space
Temperature Sensor
CDET
J8-1,2 (MBB) Condenser Entering Water
Temperature Sensor
(30MPW Only)
CDLT
J8-3,4 (MBB) Condenser Leaving Water
Temperature Sensor
(30MPW Only)
LWT — Leaving Water Temperature
MBB — Main Base Board
STATUS SWITCH PIN CONNECTION POINT
Condenser Flow Switch LVT-11,17, J7-2, J6-2 (MBB)
Dual Set Point LVT-12,13, J7-3,4 (MBB)
Remote On/Off LVT-14,15, J7,8 (MBB)
Cooler Flow Switch Interlock LVT-16,17, J6-2, J7-10 (MBB)
Compressor Fault Signal, A1 J9-11,12 (MBB)
Compressor Fault Signal, A2 J9-5,6 (MBB)
Compressor Fault Signal, A3 J9-8,9 (MBB)
RELAY
NO.
DESCRIPTION
K1 Energize Compressor A1
K2 Energize Compressor A2
K3 Energize Compressor A3
K4 Energize Minimum Load Valve
K7 Liquid Line Solenoid Valve
K8 Crankcase Heater Relay (30MPA Only)
K9 Chilled Water Pump
K10 Condenser Fan/Pump
K11 Alarm Relay
MANUFACTURER
PART NO.
Regular Wiring Plenum Wiring
Alpha 1895 —
American A21451 A48301
Belden 8205 884421
Columbia D6451 —
Manhattan M13402 M64430
Quabik 6130 —