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Compressor & Motor

Chiller: Compressor

What to Look Out For

  • The total running hours of the equipment is approaching the factory recommended limits
  • Abnormal sound in the internal compressor
  • A persistently high bearing temperature
  • Excessive vibration transmitted through the chiller body
  • Lower than normal oil differential pressures
  • Metal content in the oil filter or oil analysis
  • Temperatures and pressures which are outside normal operating range


Compressors function as system drivers by taking the low pressure gaseous refrigerant from the evaporator and increasing the pressure before delivering it to the condenser. They are designed based on cooling requirements. Mostly, the compressor is the single most expensive and mechanically complex component in the system.

The delivery time for the spare parts can be quite long and can exceed four weeks in some cases. The overhaul work including pressure testing, typically takes another two to three weeks to complete. It is important that for the benefit of the customers, you should take a proactive approach through this preventive measure. This ensures that the customer will not experience an abrupt and an unexpected system failure (that may result in a prolonged downtime).

A predictive maintenance program using vibration analysis is another viable option for the customer to consider. 

Chiller: Electric Motor

What to Look Out For

  • The electric motor is in poor physical condition
  • The compressor motor actual wattage differs from that listed for the prevailing suction and discharge pressures
  • Current imbalance
  • Noisy motor bearings
  • Lower than normal insulation readings on motor windings
  • Loose motor terminals
  • Plant room temperatures above standard motor ratings.

Possible Improvement Measure(s)

  • Rewind and/or re-varnish the motor.
  • Replace the motor and/or the motor bearings.
  • Install an automatic motor bearing greasing system.

Customer Benefits

Saves energy,reduces future repair cost, and ensures health and safety:

Motors in good condition save energy and prevent damage to other equipment.

Operation Considerations

Do we need to engage a contractor to do the alignment when reinstalling the motor?


Chiller: Coupling

 The coupling transmits the power from the electric motor to the compressor shaft.It is very important that the coupling is in good condition and is properly aligned. Misaligned coupling will induce stress on the motor and the compressor shafts, which can lead to premature failure of the compressor and/or motor bearings as well as premature leakage of the compressor shaft seal. Wear and misalignment in bearings and couplings of all types of compressors must be detected early to avoid further serious and costly damage.

What to Look Out For

  • Noise in drive line/transmission
  • Worn and misaligned coupling
  • Loose bolts, broken s him pack and damaged shaft key
  • Incorrectly installed shims, i.e. motor soft foot
  • Incorrect motor to compressor shaft distance

Possible Improvement Measure(s)

  • Check and correct the alignment and tightness of the coupling.
  • Replace the coupling.
  • Correct the motor soft foot.

Customer Benefits

  • Reduces future repair cost, and ensures health and safety:
  • Replacing worn coupling and ensuring its proper alignment prevents the compressor and the electric motor from being damaged, and loose parts from causing injury.


Is the damage confined to the coupling only or has it affected the compressor and the electric motor also?




What to look out for
The system high side equipment like Condenser & Cooling water circuits auxiliary equipment like cooling tower & condenser pumping system.

Possible Improvement Measures(s)
Upgrading condenser efficiency, improve water side system & water quality.

Customer Benefits
Energy efficient system & possible break down of equipment.

Operation Considerations
Isolation of water system and/ or Shut down requirement





Oil & Oil Return System

Oil & Oil Return system