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Commentator

Join Date: May 2011
Posts: 91

why HI-POT test is done after HT termination..????

04/10/2012 12:53 PM

we did hi-pot test in 6.6KV HT cables, before tat we removed cables from busbars, after hi-pot test it is very difficult to connect those cables to tat busbars again...

the allignment changes between cables and busbar's when we re-connect those cables lugs to busbars

so my question is do its possible to do hi-pot before HT termination by removing the cable insulations, so that cables removning from adapter box again and again...????

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Guru
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Join Date: Jun 2008
Location: Alabama
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#1

Re: why HI-POT test is done after HT termination..????

04/10/2012 1:56 PM

It is normal to remove cable from the termination point so that you will only be testing the cable. If you left the cable connected you would apply the test voltage to anything that was attached to the busbar. You would not get a correct reading plus you may damage the other equipment..

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Power-User
Engineering Fields - Electrical Engineering - New Member

Join Date: Aug 2007
Location: Toronto
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#2

Re: why HI-POT test is done after HT termination..????

04/10/2012 2:33 PM

The intent of the hi-pot test is to verify that there are no assembly or connection faults. Therefore, the test should be done after all connections are done. In some cases, where this could cause component failure, it is allowed to disconnect those components. Difficulty should not be a consideration in omitting this final assembly test.

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Guru

Join Date: May 2010
Location: Liverpool, NY
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#3

Re: why HI-POT test is done after HT termination..????

04/11/2012 2:15 PM

You cannot do the hipot test on the cables before installing the terminations, because one of the main purposes of the test is to assure that the termination has been done properly and the cable insulation has not been compromised by that work. If you try to hipot the cable without the termination, the high voltage will probably flash across the end of the insulation at the cut cable end, and fail your test anyway. There is no getting around doing the hipot after terminations are done.

As the other contributors have said, doing the hipot with the cables still connected to the busbars and equipment includes those items in the test, so you cannot isolate a faulty component.

If the cables were originally connected to the busbars, you need to do a better job of supporting them so that when disconnected, they don't slip back and give you difficulty reconnecting. However, that is the way things are in the real world sometimes.

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