RE: [TCML] transformer theory questions

["Brian" <brianv@xxxxxxxx>]

Gary,

Having the cores welded on a transformer will work fine if the welds are
placed properly, usually you will see the welds near the corners, the reason
is the flux in a core will not stretch out to the corners so it may seem
that the transformer laminations are shorted and in reality they are, but as
long as you don't weld them in the path of the flux all is good, we used to
do it all the time on commercial transformers. You can even weld them near
the center leg on the "I" section as long as you weld on either side of it,
and do not weld real deep, there should be no problem with core losses going
up. If you weld too deep especially at the center leg then you can expect
core losses to rise up.

BrianV

-----Original Message-----
From: Lau, Gary [mailto:Gary.Lau@xxxxxx] 
Sent: Monday, September 21, 2009 10:48 AM
To: Tesla Coil Mailing List
Subject: RE: [TCML] transformer theory questions

Hi David,

I had thought about the possibility of eddy current losses, but I also
recall seeing some cores having a weld tying all of the laminations
together, clearly shorting the laminations.  It may be that to get eddy
currents, the laminations may need to be shorted in two different places?  I
don't recall if the welded cores I've seen had a single bead or not, and
it's unclear if a hack saw hack job would also short in multiple places.
But "don't do it" is surely the safest course of action!

Regards, Gary Lau
MA,  USA

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of David Rieben
> Sent: Monday, September 21, 2009 11:09 AM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] transformer theory questions
> 
> 
> Hi Thomas, Gary, all,
> 
> I would also suspect some unwanted eddy current losses/heating of the core
> to result from
> "cutting across the laminations", too, as this would almost certainly
short
> some of the
> laminations together, electrically.
> 
> 
> >> What happens if you cut into the frame of a transformer, cutting the
> >> across
> >> the iron lamination?
> 
>  > I wouldn't do that.  I expect that the consequences are largely
> mechanical - like you won't be able to get it back together again after
the
> laminations are mangled.
> 
> \
> > Many thanks
> >
> > Thomas
> 
> > Regards, Gary Lau
> > MA, USA
> 
> David Rieben
> 
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