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Topic Title: HV Cable Testing Procedure
Topic Summary: Test between conductors
Created On: 13 March 2014 07:45 AM
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 13 March 2014 07:45 AM
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Avatar for timothyboler                                      .
timothyboler

Posts: 230
Joined: 25 July 2008

Hi all,

If you were to perform a HV cable test (dielectric withstand) on a multicore HV cable where the conductors have individual screens would you test:

a) between L1 and L2, L3, screens, armour all connected to earth (repeated for each phase) or

b) between three conductors L2, L2, L3 connected together at the same time and screens and armour connected to earth.

Some are suggesting b) is ok as the individual screens negate phase to phase testing. Any comments?

Thanks Tim

-------------------------
Everyone loves a fireman - but hates the fire inspector.
 13 March 2014 01:00 PM
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dlane

Posts: 690
Joined: 28 September 2007

Hi Tim,

I would use test a, testing each phase individually with the other 2 phases and all screens and armour shorted together and earthed.

Doing it that way I am recording the leakage current for each individual phase so I will know if I have a problem on a specific phase.

If I short all three phases together and test as one, I don't know if all 3 phases have a similar leakage or if the leakage is different between phases.

Kind regards

Donald Lane
 13 March 2014 07:05 PM
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neilmcd84

Posts: 56
Joined: 02 June 2003

A lot is dependent on why you are testing. I work for a DNO, where I am usually testing either to determine whether a particular section is faulty, or possibly before returning to service after carrying out work eg cable diversion. Both of these are against the clock - I might have customers off or just be approaching the end of the working day. In those cases a single 'three phases to earth' test would do as I really just need to know whether the circuit will trip when energised.
However if I was acting as a contractor carrying our commissioning tests on a high profile HV customer's private network then I would probably carry out individual phase to earth tests, recording leakage results etc.
 13 March 2014 07:09 PM
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Avatar for OMS.
OMS

Posts: 19900
Joined: 23 March 2004

a) between L1 and L2, L3, screens, armour all connected to earth (repeated for each phase)


That's the way it should be done - recording leakage values as you go

Regards

OMS

-------------------------
Failure is always an option
 15 March 2014 09:28 AM
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Avatar for timothyboler                                      .
timothyboler

Posts: 230
Joined: 25 July 2008

Ok, makes perfect sense; thanks for the comments. I'll have to try and convince our contractor to do it properly; unfortunately they're a Korean shipbuilder and they always try and do the minimum. They're arguing the test criteria is "no disruptive discharge" therefore they're not interested in leakage :-/ Disappointing that the Lloyd's Register Rules don't spell out the details of the test either.

Regards, Tim

-------------------------
Everyone loves a fireman - but hates the fire inspector.
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