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Following Test are performed :-
 1.
DC Resistance Test :
The resistance value of the coil is measured and compared with Lower
& upper limits. In case the value does not fall within the limits
NOT OK signal is flashed and test is terminated. Two limits can
be set with 2 Pot meter provided.
2. HV Test :
The test voltage 0-3 KV and the tripping current is set before starting
the test. The test voltage is applied to the winding with body as
ground for set time(0 to 60 Sec.) The Voltage and leakage Current
is display on digital meters. If there is no failure OK indication
will be given and next test will be started.
3. Insulation Test (Meggar) :
Digital Meggar is provided to give the insulation value. The lower
insulation resistance limit is set with Pot meter. In case the insulation
value is less than the limit set, NOT OK signal is given otherwise
with OK signal it proceeds for next test.
4. Surge Comparison Test :
In this test High Voltage pulse / Surge is applied to the winding
under test and Voltage delay waveform is compared with identical
winding. If winding is healthy then both waveforms will be identical.
Depending upon the type of defect the waveform will differ. Observing
the waveform one can identify the nature of defect.
Normally, for universal motors, two stator winding are identical.
Therefore two winding are compared with each
other and the waveform displayed on screen give the nature of the
fault.
Surge tester scans through the entire insulation system &
detect insulation faults such as turn-to-turn ; layer-to-layer ;
coil-to-coil ; winding-to-winding ; & phase-to-phase shorts
as well as open circuits & grounds.
5. Coil Polarity Test :
The direction of winding in stator coil is vital. If it is not proper
either heavy current will damage the winding or the direction will
be reverse. This test checks direction of both the coils (with series
shorting) and gives the decision as OK/NOT OK.
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