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
<mailto:[email protected]> [email protected]
From: John Woodgate <[email protected]>
Sent: Wednesday, August 15, 2018 12:17 PM
To: [email protected]
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 Associates www.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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