Yes, it's more or less the same effect. Repeated surface discharges
across contaminated thermosetting plastics also caused carbonization,
often resulting in a fireworks display when the mains voltage was
applied after testing.
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK
On 2018-08-15 20:29, Pete Perkins wrote:
John, your description sounds much like the failure mechanism seen is
circuit boards which start in a small void and develop micro-arcing
which feeds upon itself and eventually drives a large void that allows
conductors to directly contribute current and destroy the board. I’ve
investigated some destructive fires in equipment from such a source.
And the circuit boards don’t need full hipot voltages to do this, line
operated units eat themselves up quite handily.
No, I don’t mean to start anew thread here.
:>) br, Pete
Peter E Perkins, PE
Principal Product Safety & Regulatory Affairs Consultant
PO Box 23427
Tigard, ORe 97281-3427
503/452-1201
IEEE Life Fellow
p.perk...@ieee.org <mailto:p.perk...@ieee.org>
*From:*John Woodgate <j...@woodjohn.uk>
*Sent:* Wednesday, August 15, 2018 12:17 PM
*To:* EMC-PSTC@LISTSERV.IEEE.ORG
*Subject:* Re: [PSES] hipot test
I think it's not quite like that. Modern insulating materials don't
degrade, but old ones did, or at least appeared to. For instance,
oiled paper had pinholes, and a discharge caused local carbonization,
which prompted more discharges and more carbonization.
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associateswww.woodjohn.uk <http://www.woodjohn.uk>
Rayleigh, Essex UK
On 2018-08-15 18:07, Richard Nute wrote:
Their claim is that the hipot can degrade some insulation and
should be kept to a minimum.
Conventional wisdom not supported by science.
Best regards,
Rich
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