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72
Upon building pressure, the compressor is allowed to start
(after 15 seconds). For across-the-line (XL) start chillers, the
compressor starts and comes up to full speed within 1 to 3 sec-
onds. For Wye-Delta start chillers, contactors 1M and S (starter
contactor assembly) are closed and the compressor is started in
a Wye configuration. This method reduces the locked rotor
current requirements by approximately 60% while maintaining
enough torque to bring the compressor up to full speed.
FIELD WIRING
Field wiring is shown in Fig. 40-54.
LEGEND FOR FIG. 40-54
* Dependant on control circuit power supply voltage.
ALM
—
Alarm
CFR
—
Condenser Fan Relay
CMP
—
Chiller Water Pump
CNFS
—
Condenser Flow Switch
CNPI
—
Condenser Pump Interlock
CNP-R
—
Condenser Pump Relay
CWP
—
Chilled Water Pump
EMM
—
Energy Management Module
EWT
—
Entering Water Thermistor
FIOP
—
Factory-Installed Option
FSR
—
Flow Switch Relay
FU
—
Fuse
GFI-CO —
Ground Fault Interrupter Convenience Outlet
GND
—
Ground
LLSV
—
Liquid Line Solenoid Valve
LWT
—
Leaving Water Thermistor
MBB
—
Main Base Board
MLV
—
Minimum Load Valve
NEC
—
National Electrical Code
OAT
—
Outdoor-Air Thermistor
SCB
—
Screw Compressor Board
SPT
—
Space Temperature Sensor
SW
—
Switch
TB
—
Terminal Block
Field-Wired
Factory Wired
FIELD CONTROL POWER SUPPLY
NEC FUSED DISCONNECT
230 V CONTROL CIRCUITS
USE 15 AMP MAXIMUM FROM
SEPARATE POWER SUPPLY
115 V CONTROL CIRCUITS
USE 30 AMP MAXIMUM FROM
SEPARATE POWER SUPPLY
2
1
GND
TB4
Fig. 40 — Power Supply Wiring
MBB
MBB
Fig. 41 — Remote Alarm Relay Accessory Wiring; All Models, 115 or 230 V*
Fig. 42 — Chilled Water Pump Relay Wiring; All Models, 115 or 230 V*
Fig. 43 — Optional Ground Fault Interrupter; Convenience Outlet Accessory Wiring