14
CGAT-IOM01-EN
Electrical Control System
The controls used on CGAT065-215 chillers are classified either as safety or
operational controls.
Refer to the following control description for control setting
Unit Safety Controls
• Low Pressure Cutout (LPC01,
LPC02)
• High Pressure Cutout (HPC01,
HPC02)
• Reset relays (1R, 2R)
If the unit is shutdown the low pressure
cutout (or high pressure cutout, the
reset relay locks out the compressor
contactor (1M, 2M). This prevents
the system from recycling until the
condition that caused the trip is
determined and corrected.
CAUTION : To prevent unit damage,
do not reset the control circuit until
the cause of the safety lockout is
identified and corrected.
To reset 1R and 2R, open and close
the unit Low Voltage Control Circuit
Breaker (MCB).
• Frost Controller or Low
Temperature Cutout (LTC)
The Low Temperature Cutout is
designed to protect the evaporator
from freeze damage in the event of
water temperature thermostat
malfunction or if the is a restricted
water flow condition. The LTC’s
remote sensing bulbs monitors
Leaving water temperature.
Manual reset is required. Factory
Setting : 2C.
• Motor Overloads
These units have internal compressor
and condenser fan motor overloads.
These overloads protect the motors
from overcurrent and overheating
conditions and automatically reset as
soon as they cool sufficiently.
Unit Operational Controls
• Water Temperature
Thermostat (WTT)
System operation for CGAT is
controlled either by single-stage
thermostat CGAT075 - 120 or two-
stage thermostat CGAT150 - 240
• Delay Between Compressors
Prevents compressors from starting at
the same time.
Operation
Control
Electrical
Contacts
Contact
Description
designation
open
close
High Press. Cutout
HPCO1,HPC02
398+-19 psig
310+-21 psig
Low Press. Cutout
LPC01,LPC02
27+-7 psig
45.5+-7 psig
Frost controller
A27m
<35.6 deg.F
-
Delay between
TDR1,TDR2
Normally - open
3,4.5 minute
comp.
Timed to close