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GP Series Portable Chillers Chapter 2: Functional Description 10 of 73
Caution! Energize the crankcase heater for at least 24 hours before initial startup to
drive dissolved refrigerant from the compressor oil. Failure to do so will
damage the compressor.
High Pressure Cutout
This electro-mechanical cutout device opens the compressor control circuit if the refrigeration
system compressor discharge pressure exceeds 575 psi..
Note: The high-pressure cutout is a manual reset device typically mounted on the
compressor discharge line inside the mechanical cabinet. Call a refrigeration
service technician to analyze the problem and reset the control.
Low Pressure Cutout (no switch but done through the transducer)
There are two pressure transducers in the refrigeration piping – one on the suction line before
the compressor and one on the discharge line after the compressor. Within the program there
are four settings that warn and fault based on these two pressure transducers. The low suction
warning is set for 110 psig (758 kPa), and the compressor will fault at 100 psig (689 kPa).
The low discharge warning is set for 200 psig (1,379 kPa), and the compressor will fault at
180 psig (1,241 kPa). To prevent nuisance tripping there are delays built in to the program.
Note: Call a refrigeration service technician to analyze the problem to prevent
recurring low pressure faults.
Flow Switch
The thermal dispersion flow switch cutout device, mounted in the process piping, shuts down
the chiller if it senses that the water/glycol flow rate through the evaporator has dropped
below an acceptable level. The flow switch opens the control circuit and shuts down the
pumps and the chiller.
Remote Start/Stop Interlock
An additional contact is provided to allow the remote starting or stopping of the chiller. To
use this feature, remove the jumper between terminals 1 and 23, and supply a switch or dry
contact interlock connected in series between these two terminals. Refer to the schematic
inside the control enclosure door.
2-5 Optional Features
Options marked with “*” indicate options that can be factory installed or retrofitted in the
field.
Automatic Water Make-Up*. Not available on chillers less reservoir tank. Includes an
electric water solenoid valve, a level sensing pressure switch mounted in the reservoir tank,
and the necessary internal piping to connect the chiller to a make-up water source. See
Appendix for typical piping diagrams.
Caution! Customer piping must provide backflow protection and venting of tank to
atmosphere to prevent over-pressurization of the reservoir tank (not needed for
open tank). See Error! Reference source not found. on page Error! Bookmark
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