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Standard Limit for Leakage Current

01/11/2018 1:28 AM

Good Day!

Anybody can help me if this test result pass or fail. Is there Standard limit for Leakage Current. Thank you very much.

I. DC HIGH POTENTIAL TEST

APPLIED VOLTAGE (KV)

LEAKAGE CURRENT (micro amps)

PHASE A

PHASE B

PHASE C

10KV

6.3 1.2 -1,8

20KV

7.4 -0.1 -2.3

30KV

11.7 5.6 2.5

35KV

12.6 6.7 3.6

35KV/1min

12.5 6.6 3.6

EQUIPMENT USED

HAEFELY HIPOTRONICS, DC HIPOT, MODEL NO: 880PL-DC and 840PL-DC

REMARKS

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#1

Re: Standard Limit for Leakage Current

01/11/2018 1:52 AM
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#2

Re: Standard Limit for Leakage Current

01/11/2018 2:38 AM

If the pass/fail boundary has not been determined beforehand, then there is no point in carrying out the test.

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#3
In reply to #2

Re: Standard Limit for Leakage Current

01/11/2018 2:45 AM

Good Day Sir PWAlack,

Can you explain further what do you mean.

Thank you very much.

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#4
In reply to #3

Re: Standard Limit for Leakage Current

01/11/2018 2:48 AM

It's simple.

  • A test of some sort has been carried out, and no-one knows the pass fail boundary is? So why carry out the test in the first place (rhetorical question - NNTR)?

How abstruse.

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#10
In reply to #2

Re: Standard Limit for Leakage Current

01/11/2018 7:35 PM

The unit that been tested is 35KV Cradle of Vacuum Circuit Breaker. The test result above was done after the item was undergo drying due to humidity. Before the Cradle was undergo drying the Leakage current was 451 micro amps.

Thanks

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#25
In reply to #10

Re: Standard Limit for Leakage Current

01/16/2018 5:00 AM

See #24⇓.

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#5

Re: Standard Limit for Leakage Current

01/11/2018 8:58 AM

Try this.

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#6

Re: Standard Limit for Leakage Current

01/11/2018 10:52 AM

There is no standard for leakage current on an unknown item because the item is unknown. For most motors and transformers this looks reasonable but I'll be damned to say it is acceptable.

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#8
In reply to #6

Re: Standard Limit for Leakage Current

01/11/2018 6:53 PM

The unit that been tested is 35KV Cradle of Vacuum Circuit Breaker. The test result above was done after the item was undergo drying due to humidity. Before the Cradle was undergo drying the Leakage current was 451 micro amps.

Thanks

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#14
In reply to #8

Re: Standard Limit for Leakage Current

01/12/2018 8:00 AM

That's nice. Do you have any idea why or how "humidity" either entered into the vacuum or provided alternate current paths? Your data implies to me that this breaker should be used only in a well controlled environment. Most power distribution devices do not have that luxury.

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#15
In reply to #14

Re: Standard Limit for Leakage Current

01/12/2018 11:14 AM

I'll answer for him.

"Not a clue."

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#16
In reply to #15

Re: Standard Limit for Leakage Current

01/12/2018 12:07 PM

I thought so. Does this matter? Possibly not but when one gropes in the dark one can easily get a face slapped.

DILLIGAF.

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#19
In reply to #16

Re: Standard Limit for Leakage Current

01/12/2018 1:25 PM

Maybe it's just me, but it seems that members from some countries try to squeeze the last gram of profit out of every operation.

No PM, no fundamental understanding of operation of equipment, electricity or even how to find help, except to grope their way here, somehow when it would be just as easy to ask the seller of the equipment or even RTFM!

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#9
In reply to #6

Re: Standard Limit for Leakage Current

01/11/2018 7:33 PM

The unit that been tested is 35KV Cradle of Vacuum Circuit Breaker. The test result above was done after the item was undergo drying due to humidity. Before the Cradle was undergo drying the Leakage current was 451 micro amps.

Thank you sir.

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#24
In reply to #9

Re: Standard Limit for Leakage Current

01/16/2018 4:59 AM

Two issues:

1) What has been carried out is a measurement, not a <...test...>. Such activity can only be a <...test...> if the pass/fail or accept/reject boundary for <...testing...> has been established before the activity starts.

2) What other useful information that might guide the forum into coming up with a worthwhile answer to this thread has been withheld from it?

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#7

Re: Standard Limit for Leakage Current

01/11/2018 2:15 PM

Personally, leakage current on any HI POT test could be an indication of insulation failure, or at least near failure. Can you live with that?

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#11
In reply to #7

Re: Standard Limit for Leakage Current

01/11/2018 7:53 PM

Yes I understand that the leakage current is the indication of insulation failure. But is there any establish standard or rule of thumb for leakage current limit?

Like the test result above. here is the item that undergo testing.

The unit that been tested is 35KV Cradle of Vacuum Circuit Breaker. The test result above was done after the item was undergo drying due to humidity. Before the Cradle was undergo drying the Leakage current was 451 micro amps.

Thanks

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#18
In reply to #11

Re: Standard Limit for Leakage Current

01/12/2018 12:50 PM

If you look at the Phase C data, I suspect that one is the one that completely dry, and most likely unaffected from your "event".

Keep working on the other two, until you get better uniformity of leakage for each Phase.

I say everything should show up less than 5 micro ampere, but I am being strictly arbitrary in saying that.

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#22
In reply to #7

Re: Standard Limit for Leakage Current

01/15/2018 9:13 AM

There is always going to be some leakage current unless you can find a perfect insulator. The OP's measurement is getting 3 to 12 microamps of leakage at 35kV. That is insulation resistance in the gigohms range, which is generally quite acceptable for pretty much any medium-voltage apparatus. Aside from the manufacturer's expected values stating otherwise, I would have to say this test is giving acceptable values. However, that doesn't mean that there may not be some other problem with this item, which other tests and inspections could reveal...

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#12

Re: Standard Limit for Leakage Current

01/11/2018 10:42 PM
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#17
In reply to #12

Re: Standard Limit for Leakage Current

01/12/2018 12:48 PM

Lyn: that leakage current standard is with regards to medical devices, a slightly different scenario than what is being considered here.

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#20
In reply to #17

Re: Standard Limit for Leakage Current

01/12/2018 1:29 PM

Yep, you're right.

Question is did OP notice that, if they even looked?

As I've said before, we sew the crop, it's up to the harvester to separate the wheat from the chaff.

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#13

Re: Standard Limit for Leakage Current

01/12/2018 7:41 AM

So, what has been described isn't a <...test...>; it's a "measurement".

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#21

Re: Standard Limit for Leakage Current

01/15/2018 9:03 AM

Have you contacted the manufacturer, or at least queried the instruction manual for the circuit breaker you are testing? You do not state the manufacturer or model of breaker, so I have no reference. The manufacturer should be able to tell you what is the maximum acceptable leakage current value. Just by comparison with other medium-voltage apparatus (cables, instrument transformers, circuit breakers I have examined), these values are "reasonable," but I would qualify that the manufacturer may have different limits.

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#23

Re: Standard Limit for Leakage Current

01/15/2018 9:16 AM

Also, the end Client may have pass/fail boundary details in some standard that cannot be seen from here.

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