From: Paul
Date: Tue, 30 Apr 2002 14:28:53 +0100
Subject: Re: [TSSP] Secondary voltage stress factor
Bert wrote: > creeping leader surface discharges "hug" the surface of a > dielectric, and are enhanced when there's a conductive plane on the > opposite side at a different potential. As the leader propagates > along the dielectric surface, streamers fan out and collect higher > displacement current than if the leader was propagating in free air One of my favourite HV games is playing a 'hot' electrode across the surface of a pond or pool, which seems to give impressive displays - longer 'streamers' with much more branching, spreading out across the water surface. Is this a related thing? I suppose then the enhancement by a conductive surface on the opposite side occurs because of the resulting 'shunt' capacitance that the streamer current has to charge up, ie more current, therefore hotter. Is this surface leader propagation enhanced because the mobile charges in the leader have less opportunity to escape, since half of their lateral escape route is blocked by the dielectric surface across which charges cannot move. Is it this lateral confinement that makes the difference? I'd like to know the peak base current of some coils that are exhibiting racing arcs, so that we can work out what the V/cm is along the coil. I'm keen to get some examples which show how much lower than 26kV/cm the problem starts at. They would be very useful numbers for coilers. -- Paul Nicholson, --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.