Before condeming any semi hermetic due to a suspected short circuit I remove the terminal plate and disconnect the wires to test the windings with a megger.
The service valves must be front seated and the refrigerant recovered from the crankcase prior to removing the terminal plate.
Carlyle Service Guide
From the Thermacon Compressor Guide
Compressor Testing Guide
Please use this guide if you suspect a faulty compressor
To verify basic compressor function in a field environment the following will
demonstrate whether further investigation will be necessary or not.
1 Earth Test Using a 1000v Megger check each field winding
to earth. 1st check the earth connection is
sound by an earth to earth test & repeat this
following the motor test.
If reading < than 2 MÙ Stator probably burnt out,
but do not rule out a contaminated / damp
Reading 2 MÙ - 20 MÙ Probably not burnt out, terminal plate
contaminated or damp.
Separate terminal plate from main casting &
repeat check to casting. If fault clears then
terminal plate is faulty.
Reading > 20 MÙ No earth Fault
Precautions Do not effect Megger checks under deep vacuum.
Do not Megger overloads.
2 Field Balance Using an Ohmmeter set on Ohms verify balance
3ø motors only of motor field coils.
If balance is out by more than 10 % suspect
motor is defective.
Separate terminal plate & repeat measurements,
if readings do not improve rewind is probably