Re: electrically insulating varnish (fwd)

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Original poster: Steven Roys <sroys@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Wed, 24 May 2006 07:34:13 -0700 (PDT)
From: Tim S <stm800@xxxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: electrically insulating varnish (fwd)

  Yes i agree about the dv/dx potential.
   
  the origional question was i already used magnet wire coated with the red high temp enamel or varnish coating.
  i bought a few thousand feet from a guy 3 years ago at a flea market sale for 50 bucks,but this year he is not selling and is at the old folks home(retired) and everything he had has been sold at an estate sale.
  but i did find a 5000 foot spool of #20 soft copper and 500 foot spool of #22 awg.
  this wire is not coated with anything just bare wire.
  i like winding coils and running high voltage tests and things.
  but to wind a tight pancake discharge coil the wire needs some coating or else the tight turns would short together .
  marine grade spar urethane has worked good but i was asking does anybody else use something different that i am not aware of.
   
  tim
  
Hi Malcolm, Tim,

If going space-wound with bare wire, one should consider the following:

The inter-turn potential difference (dv/dx) is on the order of 2000 
volt/turn.
This implies a minimum spacing of 1 mm in free air, and 2 to 3 mm surface 
distance to avoid so-called "surface creep".