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14
Operation
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
Control
Description
designation
High Press. Cutout
HPCO1,HPC02
Low Press. Cutout
LPC01,LPC02
Frost controller
Delay between
TDR1,TDR2
comp.
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).
Electrical
Contacts
open
398+-19 psig
27+-7 psig
A27m
<35.6 deg.F
Normally - open
Timed to close
• 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.
Contact
close
310+-21 psig
45.5+-7 psig
-
3,4.5 minute
CGAT-IOM01-EN
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