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Induction motor short circuit

Trika

Feb 23, 2022
4
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Feb 23, 2022
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Hey guys I really need some help,few weeks ago I came across a shocking ground fault short circuit on 2.2KW motor. I did all the necessary tests on the motor but I didn't pick up any problems with it,but as soon as we started the motor it kept on tripping with ground fault short circuit. The motor resistance,windings and phase to earth were all ok,the fault only came when we were starting the motor. The motor cable was also ok, we decided to change the motor and the problem disappeared. So please if anyone knows what was wrong with the motor please assist me with this problem,or anyone who knows how to test such. All the motor readings were ok.
 

Minder

Apr 24, 2015
3,320
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Apr 24, 2015
Messages
3,320
You have to use a 'Megger' instrument to test the insulation.
An ordinary meter does not always show leakage, it does not take much to affect a GFI breaker.
 

Trika

Feb 23, 2022
4
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Feb 23, 2022
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How were these tested? Phase to earth and phase to phase test
What test meter was used? Megger test



Sure it was ground fault and not overload?
If ground fault, not necessarily short circuit.
 

Trika

Feb 23, 2022
4
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Feb 23, 2022
Messages
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How were these tested?
What test meter was used?



Sure it was ground fault and not overload? The VSD indicated that it was ground short circuit.
If ground fault, not necessarily short circuit.
 

Minder

Apr 24, 2015
3,320
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Apr 24, 2015
Messages
3,320
If you have the motor off, place it on something insulated, remove the earth GND conductor and see if it runs OK, if it does, test voltage from frame to earth GND.
If it runs up to speed, place the earth to the motor frame and see if it trips when up to speed.
 

ivak245

Jun 11, 2021
61
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Jun 11, 2021
Messages
61
Capacitor start motor? Centrifugal start/run switch? more info needed.
 
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