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Actions For Screw Compressor Status - LG RCWW Operation & Maintenance Manual

Water-cooled screw chiller
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8-3. Actions for screw compressor status

Wire opened
Control fuse opened
High pressure switch(HPS) stopped
Loosely connected terminal
Inaccurately connected control unit
Compressor is not
Excessive lowering of voltage
Compressor motor defect
Compressor stop
Preliminary lubrication was not successful
Defective transducer
stopped due to ab-
Refrigerant insufficient
normally low pres-
Broken expansion device
Wholly/partly clogged strainer
High pressure switch abnormal operation
stopped due to ab-
Compressor discharge valve partly closed
normally high pres-
Condenser water piping clogged
Condenser scale problem occurred
Refrigerant amount-insufficient charging
Control fuse broken
Chiller operated ab-
Partly or completely clogged strainer
normally for a long
Defective insulation
Service load exceeding the designed ca-
Inefficient compressor
Pipe vibration
Expansion valve noise
Abnormal noise
Compressor noise
Compressor oil
Leakage from system
Mechanical damage in rotor
Abnormally high
Refrigerant insufficient due to leakage
temperature piping
Abnormally low
Stop valve partly closed or limited
temperature piping
Compressor loader
Electronic valve coil defect
abnomally oper-
Loading solenoid valve defect
Wrongly wired solenoid valve
To protect the compressor, 2 PTC temperature sensors are installed in
the compressor's discharge gas side and inside of motor coil. These
sensors are connected to INT69 control module to check motor coil
temperature and discharge gas temperature. In case one of the temper-
ature value is higher than the set response temperature of the PTC ther-
mistor, the sensor resistance increases, and the INT69 control module
blocks the motor contactor. The interrupting temperature of the motor
coil winding is 120℃ and the restarting temperature is 75℃. The interrupt-
ing temperature of the compressor discharge protection is 110℃ and the
restarting temperature is 60℃. The problem resolving method of the
compressor is described in the table above.
Check unconnected areas
Check control circuit's grounding or short circuit
status, replace fuse
Initialize present alarm using navigator
Check connection from CCP to contact point
Check wire and reconnect wire
Check wire voltage
Judge voltage lowering point and correct defect
Check whether motor coil winding is open or
If needed, replace compressor
Operate oil pump, Check oil pressure transducer,
Check oil solenoid valve movement
Repair leakage area and charge again
Replace transducer
Add refrigerant
If needed, repair/replace
Disengage strainer and clean
Replace switch
If valve is open or defective, replace
Check piping. If defective, repair or replace
Clean condenser
Add refrigerant
Replace control unit
Clean or replace
Replace or repair
Examine load condition
Check loader solenoid valve. If needed, replace
If needed, install supportive piping
Add refrigeran
Check clogged piping strainer
Replace compressor(worn out bearing)
Check for loosened compressor bolts for attach-
ing compressor to chiller.
Find leakage and repair
Replace compressor
Repair leakage area and charge again
Open valve or remove jam
Replace coil
Replace valve
Connect wire again correctly



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