/ep_edm/en/contect_396.html SHINI PLASTICS TECHNOLOGIES, INC.

Special Reports

2011 Quarter 1 Issue 6

Trouble-shooting for SICC-W Central Water Chillers

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Operation Conditions of Water Chiller
Standard conditions: 30℃ inlet temperature of cooling water, 35℃ outlet temperature of cooling water; 12℃ inlet temperature of chilled water, 7℃ outlet temperature of chilled water.


Maximum Load condition: 33℃ inlet temperature of cooling water, 38℃ outlet temperature of cooling water; 20℃ inlet temperature of chilled water, 15℃ outlet temperature of chilled water.

Low temperature condition: 16℃ inlet temperature of cooling water, 21℃ outlet temperature of cooling water; 10℃ inlet temperature of chilled water, 5℃ outlet temperature of chilled water.

The conditions mentioned above are unit operation limits. Breakdown analysis should be conducted within operation limits, or the result will be of not reference.

 

Common Faults
• High pressure protection
Details: cooling, chilled water pump run and compressor does not start after turning on machine.
Causes: no reset or faults for high pressure switch.
Solutions: reset or check, replace high pressure switch.
Details: compressor halts and cooling, chilled water pump runs after turning on machine.


Causes:
1) Deficiency in cooling water quantity
Conclusion: difference in cooling water inlet and outlet temperature is too great. (Larger than normal value 5 ℃)
Causes: flow deficiency in cooling water pump; water shortage inside water tower; filth blockage of cooling water in pipeline screening formula; valve is not fully opened; air flow in pipeline; uneven water flow.
Solutions: replace with cooling water pump with more flux; replenish cooling water (auto water replenishing device is normal); clear screening formula; open all valves in pipeline; evacuate or replace pipeline; adjust water distribution with valves.

 

2) Poor heat dissipation of condenser
Conclusion: difference in cooling water inlet and outlet temperature is lower than 5℃, feeling heat when touching lower part of condenser by hand. (Feel cooling if it is normal)
Causes: overdue maintenance of condenser.
Solutions: clean condenser through chemical or physical methods.

 

3) Inlet temperature of cooling water is too high
Conclusion: normal inlet temperature should be 30℃ and maximum below 33℃.
Causes: undersize of cooling tower; overload; no rotation or filth blockage of apron head.
Solutions: replace cooling tower; reduce load; fix cooling tower.

 

4) Memory of refrigerant system exposure to air
Conclusion: big fluctuation of high pressure gauge needle, chilled water inlet and outlet temperature is lower than 5℃, high compressor current.
Causes: no enough vacuum or air sneaking into system.
Solutions: reclaim refrigerant and re-vacuumize system with filling refrigerant.

 

5) Refrigerant system blocking
Conclusion: readings of high pressure gauge increase continuously, readings of low pressure gauge are small, temperature difference of liquid pipe before and after drying screening formula is big and condensed water forms; frosting of expansion valve.
Causes: filth blockage of drying screening formula; expansion valve fault.
Solutions: replace drying screening formula; check or replace expansion valve.

 

6) Fault of high pressure switch
Conclusion: readings of high pressure gauge remain normal value without reaching set value.
Causes: wrong set value of high pressure; fault of high pressure switch.
Solution: revise set value of high pressure protection; check or replace high pressure switch.

 

• Low pressure protection
Details: cooling, chilled water pump run and compressor does not start after turning on machine.
Causes: no reset or faults for low pressure switch.
Solutions: reset or check, replace low pressure switch.
Details: compressor halts and cooling, chilled water pump run after turning on machine.

 

Causes:
1) Blockage in refrigerant system circulation
Conclusion: low-pressure skipping takes place within seconds of compressor startup, temperature uniformity of return gas pipeline.
Causes: fault of liquid road solenoid valve; shut-off valve is not opened; fault of expansion valve.
Solutions: check or replace solenoid valve; open shut-off valve; check or replace expansion valve.

 

2) Deficiency in refrigerant
Conclusion: low-pressure skipping takes place within seconds of compressor startup, temperature of return gas pipeline is lower than normal temperature, feel cooling when touching pipeline by hand.
Causes: leakage of refrigerant.
Solutions: fill refrigerant after checking and mending leakage.

 

3) Deficiency in chilled water
Conclusion: difference in chilled water inlet and outlet temperature is too great. (Larger than normal value 5 ℃), outlet temperature is lower than 7℃.
Causes: undersize of chilled water pump, filth blockage of chilled water system pipeline; air flow inside chilled water system pipeline; valve of chilled water system is not fully opened.
Solutions: replace chilled water pump; clean pipeline screening formula; evacuate or replace pipeline; open all valves of chilled water pipeline.

 

• Overload protection of compressor
Details: cooling, chilled water pump run, compressor does not start.
Causes: no reset or fault of compressor overload relay.
Solutions: reset compressor overload relay, check or replace overload relay.
Details: compressor halts and cooling, chilled water pump run after turning on machine.
Causes: abnormal supply of main power, value mis-adjustment of overload relay; compressor fault; too high operating pressure of compressor.
Solutions: customers adjust power supply; revise set value of overload relay; replace compressor; check cooling water system and refrigerant system.