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Re: Potato Chips (fwd) Laminations (fwd)



---------- Forwarded message ----------
Date: Mon, 27 Apr 1998 21:50:06 -0700
From: Bill Noble <william_b_noble-at-email.msn-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Potato Chips (fwd) Laminations

As I understand it from years ago when I studied metalurgy, the laminations
are to control the magnetc domains, not to eliminate eddy current.  If you
look at a typical transformer, you have one secton like an "E", and another
like an "I", so together they make an "8".  Many transformers have a thin
sheet of insulator between the E and I, which I think does in fact eliminate
eddy currents by preventing the shorted turn effect.  But if you look at the
way the flux lines run (remember ILXB where "X" is the cross product) you
will see that they don't cross the laminations.
-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Monday, April 27, 1998 1:11 PM
Subject: Re: Potato Chips (fwd)


>
>
>---------- Forwarded message ----------
>Date: Mon, 27 Apr 1998 08:48:38 -0500
>From: David Huffman <huffman-at-fnal.gov>
>To: Tesla List <tesla-at-pupman-dot-com>
>Subject: Re: Potato Chips (fwd)
>
>One thing to note here is the purpose of the laminations. Laminations help
>prevent eddy currents if each laminate is electrically insulated from the
>next. Each laminate is varnished before it is used. If you remove the
>coating and assemble the core, it will get hot from the eddy currents.
>Sometimes just splitting the laminations apart pulls to coating off and
will
>cause hot spots.
>Just my 2 cents worth.
>Dave Huffman
>
>-----Original Message-----
>From: Tesla List <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
>Date: Sunday, April 26, 1998 11:58 PM
>Subject: Potato Chips (fwd)
>
>
>>
>>
>>---------- Forwarded message ----------
>>Date: Sun, 26 Apr 1998 05:08:25 -0700 (PDT)
>>From: gweaver <gweaver-at-earthlink-dot-net>
>>To: Tesla-at-pupman-dot-com
>>Subject: Potato Chips
>>
>>The laminations on one of my unpotted neons is out of square.  The thing
is
>>twisted looking and I don't like the way it looks so I took it all apart.
>>The laminations were stuck together with something like varnish or
>>polyurethane.  I decided to sand blast the laminations to remove the
>>varnish.  When the sand hit one side of the lamination it instantly curled
>>up like a potato chip. The varnish came right off.  I turned the
lamination
>>over and sand blasted the other side and the metal instantly curled up in
>>the other direction.  I tried to straighten it out by sand blasting back
>and
>>forth a little on each side but it won't straight up. I tired hammering
it,
>>but its still not flat.  I tried 3 more laminations and they did the same
>>thing.  There must be some type of stresses in the metal that cause this
to
>>happen.  WARNING, don't sand blast transformer laminations. Acetone takes
>>the glue stuff off of the lamination with no trouble at all.  Just let the
>>lamination soak about 15 minutes.  You don't even have to wipe them clean
>>with a rag.
>>
>>Gary Weaver
>>
>
>