In message
<by2pr02mb16405b7796dd23601618b90f8a...@by2pr02mb1640.namprd02.prod.outlo
ok.com>, dated Fri, 12 Jun 2015, Carpentier Kristiaan
<[email protected]> writes:
Does anyone know of literature that explains this phenomenon?
It's a very old issue, so modern textbooks may not address it.
I?m also interested to understand the process of the breakdown of 2
isolations in series, like how can 1 insulation break down when the
other did not yet.
The resistance of an 'insulation' is very high but not infinite, so when
you have two insulations in series, the voltage divides according to the
resistances. The insulation with higher resistance gets the greater
volts, and that may well exceed its breakdown voltage without the total
voltage being equal to or greater than the sum of the two breakdown
voltages.
If possible, connect equal, very high value high-voltage resistors
across the insulations so as to equalize the voltages. The resistance
value clearly needs to be lower than the lower of the two insulation
resistances, but with modern insulations, you may be able to use 50
Mohms or more.
--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
When I turn my back on the sun, it's to look for a rainbow
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
-
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