RE: ballast bobbin...again

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Pete Komen by way of Terry Fritz <twftesla-at-uswest-dot-net>" <pkomen-at-zianet-dot-com>

FWIW: I have an isolation transformer (1kva, 120v to 120v) in which the
secondary is about 3/4 to 1 inch away from the core.  It has cardboard
spacers to keep the clearance.  It works fine.

Regards,

Pete

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Tuesday, May 01, 2001 11:34 AM
To: tesla-at-pupman-dot-com
Subject: Re: ballast bobbin...again

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<jimlux-at-earthlink-dot-net>

This would work fairly well.  Very large transformers (1 MVA and up) use
laminations that are of different sizes so that they can approximate a
circular cross section. Transformers where cost is important use square or
rectangular cross sections because it is cheaper (they make those E and I
sections by the millions)

I doubt that the leakage reactance increase from spacing the windings away
from the core would be all that significant, assuming that you don't have
an air gap in the core.  HV isolation transformers are often made with the
HV winding as a separate "donut" that is slipped over the core laminations.


Tesla list wrote:
>
> Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<CTCDW-at-aol-dot-com>
>
> Hey all!
>
> I have a quick question. In my search for a suitable bobbin material, I am
> wondering how close the wire need to be from the core. I assume that right
on
> the core is the best, but can I wind on PVC pipe and put the core inside?
It
> is a straight core. I could actually get some more steel and completely
pack
> the pvc inside so it would be a more or less round cross section.. any
help
> would be appreciated! :)
>
> THanks!
>
> Chris W