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Join Date: Sep 2010
Location: Saudi Arabia
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Hipot Leakage Current

01/06/2012 6:26 AM

Dear Members

1) What is the Value of Maximum acceptable Leakage current for Hipot of MV Cables. I am testing 3C ,300mm2 XLPE with VLF 24KV RMS.

2) Also is this acceptable for 2KM long , 8 Joints, Cables having IR of 400 M Ohms with 5KV DC Test.

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Guru
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#1

Re: Hipot Leakage Current

01/06/2012 6:30 AM

Well, what does it say in the test procedure document against which the testing is being carried out? If it doesn't say, then how is anyone supposed to know whether the cable has passed the test or not (rhetorical question)?

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#2

Re: Hipot Leakage Current

01/06/2012 9:01 AM

There is no such limit for leakage current even in Standards. But in case of High Voltage Test with DC voltage results in <10mA. I have got almost zero value for 2.3 KM XLPE cables,tested at 60 KV DC. What is the value you have got?

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Power-User
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#3

Re: Hipot Leakage Current

01/06/2012 9:26 AM

VLF -Very Low Frequency testing (Freda/Frida equipment)

AC Test;

Here we have low voltage (below 1000V) and high voltage (1000V or above).

I assume you be testing 11 KV. First do 5 KV DC Megger Testing. If no short, then proceed with VLF. Your results must be below 10 mA, by rule of thumb (and even practically) some what 1 mA per kilometer, in your case 3 mA :)

Hope that helps....

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#4
In reply to #3

Re: Hipot Leakage Current

01/06/2012 2:06 PM

i got the value of 11 mA for single phase, with BAUR Viola Test Instrument.

the IR with 5KV Fluke was 500 m Ohms.

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Power-User
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#5
In reply to #4

Re: Hipot Leakage Current

01/08/2012 6:45 AM

Try to separate each phase to a minimum of ten centimeters apart during Megger or Insulation Resistance test. You need a higher value in giga ohms before VLF. If possible open the cable to semiconductor layer to improve results, otherwise.....

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Guru

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#6

Re: Hipot Leakage Current

01/09/2012 7:34 AM

We used to get less than 3mA on 22kV XLPE cables. Anything above 6mA, the kit used to trip.

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