Re: Self-built power transformer

To: tesla-at-pupman-dot-com
Subject: Re: Self-built power transformer
From: Mark Finnis <mefinnis-at-medicine.adelaide.edu.au> (by way of Terry Fritz <terryf-at-verinet-dot-com>)
Date: Tue, 06 Oct 1998 20:07:30 -0600
Approved: terryf-at-verinet-dot-com

At 08:08 6/10/98 -0600, OttFritz wrote:

>Hi Coilers,
>
>you often desciribe the insulation in this discussion, but what kind of
>material is the best choice for it. (especially between the winding layers)
>
>LDPE for example might be not so good, the high dielectric konstant means a
>relativ high parasitic capacitance in the selfmade pig. (if it works under
>oil, more higher)

I suggested in a private e-mail to Malcolm that I intended using LDPE.  To
which he replied, its OK but beware it melts at relatively low temperatures.

Given I have bought my 5kVA (dry) unit to rebuild and am going to be
putting in a *lot* of work, I thought I would go "indestructible" ....

My Wire/Insulation shop sells "Slot Insulation" in various compositions.
Specifically I thought I might use "Pyrolam", which is a composite short
fibre polyester mat, bonded to both sides of a polyester film:

	Dielectric strength:	14 kV
	Thickness:		15 mil
	Temp class:		"F"

I figured I could use 2 turns of this per winding layer (about 1200 VPL)
and about 6 sheets between pri/sec.  As it is a mat, it will help wick the
oil when I submerge the beast.  This is overkill, I know, but for the sake
of $30 of insulation I suspect it will be worth it (or a bloody hope so !!).

( You recall the wife won't let me buy a PP ......... snuck this in under
the radar, little does she realise its really just a pig out of oil ! )

Will put up some pictures as I go ....

>Sorry for my english! ;-)

Its better than my German ;-)

Cheers,