Compressor overheating in failure analysis of industrial chillers
Commercial Air & Water Cooled Chillers /industrial water chiller
In order to ensure that the components of the industrial chiller will not be damaged under abnormal operating conditions, the chiller is equipped with various protection devices. When the unit fails, it can be shut down for self-protection. The compressor overheating protection function is set to prevent the compressor from being damaged due to excessive motor power.
The thermistor is embedded in the compressor motor windings of industrial chillers, and the resistance is generally 1kΩ. When the winding is overheated, the resistance value will increase rapidly and exceed the limit, and then the thermal protection module will cut off the operation of the unit, and the overheating fault indicator will light up. There are several possibilities for compressor overheating faults in industrial chillers:
(1) Excessive compressor load causes overcurrent operation. The possible reasons are: the cooling water temperature is too high, the refrigerant is charged too much, or there is non-condensable gas such as air in the refrigeration system, which causes the compressor to have a heavy load, which manifests as an overcurrent, and is accompanied by a high pressure fault.
(2) Compressor overcurrent operation caused by electrical failure. For example, the three-phase power supply voltage is too low or the three-phase unbalance causes the current of one phase to be too large; or the AC contactor is damaged and the current is too large due to contact ablation and lack of phase.
(3) The overheating protection module SSM is damp or damaged, the intermediate relay is damaged or the contacts are bad, and the fault phenomenon is that the chiller has an overheating fault and cannot be started after the chiller is turned on. There is also a possibility that the control circuit board is faulty and an error fault alarm is issued.