Corona in 11kV Panel

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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 Commentator Join Date: Aug 2010 Location: VA Posts: 84 Good Answers: 4	#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 __________________ Life is short, eat your dessert first .......In theory there is no difference between theory and practice. In practice there is. Yogi Berra
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TonyS Guru Join Date: Aug 2010 Location: Resting under the Major Oak Posts: 4347 Good Answers: 181	#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. __________________ The reports of my death are greatly exaggerated.
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rcapper Guru Join Date: Dec 2005 Location: Etats Unis Posts: 1871 Good Answers: 45	#3 Re: Corona in 11kV Panel 10/17/2010 11:49 PM
	Flood it with sulfur hexafluoride. __________________ The hardest thing to overcome, is not knowing that you don't know.
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bubbapebi Power-User Join Date: Apr 2007 Posts: 414 Good Answers: 19	#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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Emjay4119 Guru Join Date: Dec 2005 Location: Queensland Coalfields Australia. Posts: 697 Good Answers: 11	#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 Guru Join Date: Sep 2006 Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E Posts: 17996 Good Answers: 200	#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......... __________________ "What others say about you reveals more about them, than it does you." Anon.
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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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