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Re: Transformer Questions

Bob
Thanks for all the useful info, I wondered how these cores were made, now i
know. No real need to push beyond 2500w I guess since I have 4 of these
cores and can get more later.
Mike
----- Original Message -----
From: Tesla List <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, May 25, 1999 8:52 AM
Subject: Re: Transformer Questions


> Original Poster: Bob <misiura-at-nccoast-dot-net>
>
> Hi Mike,
>
> The cores you have should be good for about 2,500 watts (continuous).
> Trying to get more, out of nine square inches of iron, cross section, is
> probably asking for problems.  (at 60 HZ; raise the frequency, and you
> might stand a chance)
>
> See>  http://members.tripod-dot-com/~schematics/xform/xformer3.htm
>
> The type of core you are talking about sounds like a tape-wound core.  A
> steel band is wound on a (usually square or rectangular) mandrel and
> bound with adhesives.  The ring of metal is removed from the mandrel and
> cut into two halves, which are then polished and sometimes etched with
> acid to undercut the ends slightly to prevent eddy currents where the
> machining took place.
>
> It is very important to keep the matched halves together, and to keep
> each leg facing its own mate.  If you mix them up, it is usually easy to
> see where they are supposed to go, by looking at the coloring at the
> edges of the laminations.
>
> This type of core is very sensitive to dirt inadvertently trapped in the
> gap.  A small speck of material, can cause a great loss in inductance.
>
> Tape wound transformers, are only exceeded in efficiency, by continuous
> wound toroidal transformer cores.  (assuming 60 HZ power applications)
>
> The stainless steel clamp you intend to use, should work very well.
>
> Because you are winding a high voltage transformer, you will probably
> want to wind the secondary on an opposite part of the core from the
> primary, rather than directly over it.  This greatly simplifies
> insulation requirements, and improves cooling.  In TC operation, there
> will be less electrostaticly conducted interference from one halve to
> the other.  You will sacrifice some efficiency doing it that way (higher
> leakage inductance) but considering the benefits, it's a good
> compromise.
>
> Core length affects the amount of leakage inductance.  (reluctance is a
> magnetic property of the steel) Shorter is better, as a general rule,
> but for a TC application, the added leakage will make ballasting less
> critical.  It is typical, with this type of core, to put the windings
> over the gaps.  This tends to lower leakage inductance.
>
> No idea what they might be worth, but you can bet they would cost a
> great deal more than loose laminations of the same quantity and quality.
>
> Hope that helps
>
> Take care
>
> bob misiura
>
> Tesla List wrote:
> >
> > Original Poster: "Mad Mike" <mglass-at-netusa1-dot-net>
> >
> >   Hi all
> > I need the advice of a transformer guru. I have recently aquired 4
> > transformer cores
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