Cable hi-pot withstanding time, why 15 minutes?

**moon1958moon** · Posted June 30, 2015

Hi everyone, in my instruction of cable hi-pot testing, the shield cable withstanding time is 15 minutes, un-shielded cable is 5 minutes.

It is super boring to hipot a high voltage cable, (step up time plus 15 minutes withstanding time, about half hour per cable. could we reduce the withstanding time), could somebody please explain why it needs 15 minutes?

Thank you.

**madMAX** · Posted June 30, 2015

lol

i second that! even more boring than transformer PI

Originally Posted by moon1958moon

It is super boring to hipot a hightvoltage cable, ( step on time plus 15 minutes withstanding time, about half houre per cable.

**rgrabis** · Posted June 30, 2015

Boring, agreed. Related to cable testing, Were you instructed to raise the test voltage in 5 steps to max voltage?

**JohnRaz** · Posted July 3, 2015

yes, 5 Steps.
VLF testing cable is just as much fun.

**Will Ward** · Posted July 6, 2015

Normally we do an Insulation Resistance test before and after the 15 minute High Potential Test. I was wondering if this is standard or not? Thanks.

**madMAX** · Posted July 7, 2015

Why would you need to do insulation resistance twice?

Originally Posted by Will Ward

Normally we do an Insulation Resistance test before and
after the 15 minute High Potential Test...
I was wondering if this is standard or not?
Thanks

**stevenwerynski** · Posted July 8, 2015

how were your megger readings the second time did they get worse? just curious if, and how bad the high pot damaged the insulation of the cable...

**DanielTronco** · Posted July 9, 2015

Are you an owner or an hourly paid employee? haha

Wait the 15min man and plot the readings that you take every minute. You'll see the trend of the results should reduce quickly in the beginning and then start to level out at the end of the 15min period. Almost like a wave.

Sometimes we plot these on an excel file and submit them with the report. It's a good visual to show you weren't just making up numbers.

**madMAX** · Posted July 9, 2015

tie all three cables together, do a gang test, and roll out early.

**moon1958moon** · Posted July 9, 2015

I NEED TO MEGGER BEFORE HI-POT. BUT NOT DO IT AGAIN AFTER HI-POT.

THE LEAKAGE CURRENT WILL BE STABEL OFTER TEN MINUTES OFTER GOT THE WITHSTANDING VOLTAGE. SO I DON'T THINK I NEED 15 MINUTES WITHSTANDING TIME. SUPER BORRING.

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Cable hi-pot withstanding time, why 15 minutes?

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