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Compressor Motor Burnout / Ground Fault

Likely causes

Ground short — winding in contact with compressor shell

Check: Megohm test: measure each winding-to-ground insulation resistance (normal: >1MΩ at 500V DC)

What to do: Replace compressor if insulation fails. Before replacement, analyze root cause — measure system TAN, perform power quality analysis

Open winding / winding-to-winding short — breaker does not trip but motor will not rotate

Check: Measure 3-phase winding resistance with ohmmeter — confirm deviation ≤ ±2%. Open = infinite; short = near 0

What to do: Replace compressor. If acid-contaminated oil: flush system + replace drier + change oil. Before reinstall: pull vacuum to ≤500μm and verify oil charge

Voltage imbalance >2% / liquid refrigerant ingestion — accelerated insulation degradation

Check: Measure all 3 phase voltages → imbalance = (max deviation/average voltage) × 100%. >2% = investigate power supply side

What to do: Resolve voltage imbalance (report to utility). Prevent liquid ingestion: reset TXV superheat to 5~8°C, keep crankcase heater ON at all times

Field tip

Replacing a burned compressor without fixing root cause leads to repeated failures. Before replacement: power quality analysis + TAN acid measurement. Black carbonized oil = mandatory full system flush.

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