14
Table 7 — Thermistor Designations
LEGEND
Table 8 — Status Inputs
Table 9 — Output Relays
Table 10 — CCN Communication Bus Wiring
CURRENT SENSING BOARD (CSB) — The CSB is used
to monitor the status of each compressor by measuring current
and providing an analog input to the main base board (MBB)
or compressor expansion module (CXB).
ENABLE/OFF/REMOTE CONTACT SWITCH — The
Enable/Off/Remote Control switch is a 3-position switch used
to control the unit. When switched to the Enable position, the
unit is under its own control. Move the switch to the Off posi-
tion to shut the unit down. Move the switch to the Remote Con-
trol position and a field-installed dry contact can be used to
start the unit. The contacts must be capable of handling a
24 vac, 50 mA load. In the Enable and Remote Control (dry
contacts closed) positions, the unit is allowed to operate and re-
spond to the scheduling configuration, CCN configuration and
set point data. See Fig. 7.
EMERGENCY ON/OFF SWITCH — The Emergency On/
Off switch should only be used when it is required to shut the
unit off immediately. Power to the MBB, CXB, AUX, EMM,
and scrolling marquee display is interrupted when this switch is
off and all outputs from these modules will be turned off. See
Fig. 7.
HIGH PRESSURE SWITCH (HPS) — Each unit is protect-
ed with a high pressure switch to prevent excessive condensing
pressure. See Table 11 for switch details.
Table 11 — High Pressure Switch
* Available for 30MPA,MPW015-045, 30MPA050-071, 30MPW050-
071 high condensing option.
PRESSURE TRANSDUCERS — Each refrigerant circuit is
equipped with a suction and discharge pressure transducer. The
suction pressure transducers have a yellow body with a pres-
sure range of –6.7 to 420 psig (–46 to 2896 kPa) while the dis-
charge transducers have a red body with a pressure range of
14.5 to 667 psig (100 to 4599 kPa). These inputs connect to the
MBB (main base board) and are used to monitor the status of
the unit and to ensure the unit operates within the compressor
envelope. The transducers are used to protect the compressor
from operating at too low or too high of a pressure condition. In
some cases, the unit may not be able to run at full capacity. The
MBB will automatically reduce the capacity of a circuit as
needed to maintain specified maximum/minimum operating
pressures. Table 12 summarizes pressure transducer
characteristics.
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 Temp
CEWT J8-11,12 (MBB) Cooler Entering Fluid Temp
D.GAS
J6-1,2 (AUX2) Discharge Temperature
Thermistor (DTT)(Digital Com-
pressor Option Only for unit
size 020-045)
RGT.A
J8-9,10 (MBB) Circuit A Return Gas
Temperature (accessory, stan-
dard for unit sizes 050-071)
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, T55
Accessory
CDET
J8-1,2 (MBB) Condenser Entering Fluid
Temperature Sensor
(30MPW Only)
CDLT
J8-3,4 (MBB) Condenser Leaving Fluid
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
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 —
CARRIER PART
NUMBER
OPENS AT CLOSES AT
HK02ZZ001*
650 ± 10 psig
(4482 ± 69 kPa)
500 ± 15 psig
(3447 ± 103 kPa)
HK02ZZ003
558 ± 15 psig
(384 ± 103 kPa)
435 ± 29 psig
(2999 ± 200 kPa)
To Next Page
Loading...
