Insulating Choke Coils (fwd)
---------- Forwarded message ----------
Date: Mon, 27 Apr 1998 08:11:56 -0400
From: Thomas McGahee <tom_mcgahee-at-sigmais-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Insulating Choke Coils
Your post shows an elegant way to insulate the choke coil from its
surroundings, but I am afraid that someone reading it might get
the impression that the need for insulating the wire from the
coil is non-existent. I note you are using very few turns. Some
coilers are using many more turns. When the choke is working properly
it will have quite large voltages across the windings. Four issues
need to be taken into consideration.
1) You have already mentioned the need to insulate the entire choke
from its surroundings.
2) The inter-turn insulation must be sufficient to prevent breakdown
between adjacent turns.
3) the insulation between windings and core must be sufficient to
prevent breakdown to the core.
4) The ends of the windings must be spaced far enough apart to
prevent breakdown between the ends.
In general a multi-layer winding is going to be hard to properly
insulate, as the voltage between layers can be tremendous.
Techniques that are useful include: Use space between windings. Use
additional insulation, such as teflon spaghetti. Wrap core with a few
layers of tape before applying windings. Especially, keep the
*ends* of the windings as far apart as possible.
Hope this helps.
Fr. Tom McGahee
> ---------- Forwarded message ----------
> Date: Mon, 27 Apr 1998 01:59:38 -0600
> From: "D.C. Cox" <DR.RESONANCE-at-next-wave-dot-net>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Re: AMIDON toroids?? (fwd)
> to: Ed
> We usually apply 4-5 turns on the ferrite before the resistor in series
> with the HV bushing. This helps clip some of the higher freq RF feedback.
> The easiest way to insulate it is to not really insulate the toroid and
> windings itself at all. Just use a nylon bolt to attach it to the top of a
> 4 in long x 3/4 in dia piece of delrin or other suitable plastic. Cut a
> few notches in the delrin to make the creepage path longer if necessary.
> We use a small 2 x 2 inch piece of flat plastic on top to the toroid to
> clamp it down to the top of the delrin rod. Works well this way.