Combined Inspection and PAT Testing
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This again is carried out at pre-determined intervals. For the checking of electrical safety, one will require a PAT Tester. There are many PAT Testers available but the ones with pass/fail indications are quite easy to use. All one has to do is plug the appliance into the tester, connect a test lead and press a button. The tester will carry out the required tests and indicate whether the appliance is safe or not.
When a compressor fails short, what happens is that insulation on the wires has worn off or burned off or broken Very Low Frequency AC Hipots. This allows a wire on a motor winding to touch something it should not touch - most commonly itself a turn or two further along on the motor winding. This results in a "shorted winding" which will stop the compressor immediately and cause it to heat up and burn internally.
Bad bearings can cause a failed short. Either the rotor wobbles enough to contact the stator, resulting in insulation damage that shorts the rotor either to ground or to the stator, or end bearing wear can allow the stator to shift down over time until it begins to rub against the stator ends or the housing.