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Anonymous Poster

Corona in 11kV Panel

10/17/2010 4:04 AM

We note severe corona in an indoor 11kv VCB panel. We replaced almost all insulators where corona is seen. But still some where corona continues and corrodes the panel and copper connections. The panel was cleaned several times. What is the solution?
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waldig
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Join Date: Aug 2010
Location: VA
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#1

Re: Corona in 11kV panel

10/17/2010 8:45 AM

Have you considered a high voltage paint to increase the insulation and prevent problems with humidity? Old tv sets ran 25,000 volts without issue, due to insulation systems to prevent corona discharges. Woody

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TonyS
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#2

Re: Corona in 11kV panel

10/17/2010 9:38 AM

De-humidifiers in the switch room would make sense. They would get rid of one of the main culprits.

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rcapper
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Join Date: Dec 2005
Location: Etats Unis
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#3

Re: Corona in 11kV Panel

10/17/2010 11:49 PM

Flood it with sulfur hexafluoride.

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bubbapebi
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Join Date: Apr 2007
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#4
In reply to #3

Re: Corona in 11kV Panel

10/18/2010 1:15 AM

Alas, it's a gas!
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4
Emjay4119
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Join Date: Dec 2005
Location: Queensland Coalfields Australia.
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#5

Re: Corona in 11kV Panel

10/18/2010 2:13 AM

The quality of the workmanship at the terminations can have a big bearing on corona effect. There should be no stress risers. The insulation is normally tapered rather than cut off square. Any bolts need to be the correct length and maybe packed with HV putty. Stress relief socks are a good idea 3M make them in a cold shrink silicone, ABB make them in a stretch on silicone and Raychem make heat shrinkable products. 3M also make a variety of tapes and publish instructions for their use.

If spacings are at around their minimum, bare connections can be corona prone and the above methods will fix the situation.
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Andy Germany
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#6
In reply to #5

Re: Corona in 11kV Panel

10/18/2010 6:08 AM

I am not personally a HV trained person (other than what one picks up when working on big Laser printers, CRT screens etc., which is not a lot!), but I have to feel that :-

a) you know what you are talking about

and

b) your advice sounds really good and helpful!

So I have taken the slight "risk" of giving you a GA (from someone like me who is not really "qualified" to judge fully) as I somehow feel that there are very few of us here fully qualified in this area to be around to give you one and we need more Guys like you than we would care to admit!

It all made good sense, so a GA for you from a HV amateur.........

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amitbhatia
Active Contributor

Join Date: Feb 2010
Posts: 18
#7

Re: Corona in 11kV Panel

02/25/2012 12:48 AM

Corona is nothing but ionization of air. Cover live portions with Raychem raysulate shrouds/tapes which are non halogen materials Further, ensure that sufficient clearances are maintained in the stress control region. Please contact your nearest Raychem office to assist you in this matter
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Previous in Forum: Comparison of Generator with Same Insulation Class & Different Class Temp. Rise   Next in Forum: Sizing 3 Phase Induction Generator

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