Re: Potato Chips (fwd)

---------- Forwarded message ----------
Date: Mon, 27 Apr 1998 20:12:35 -0700 (PDT)
From: gweaver <gweaver-at-earthlink-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Potato Chips

The main reason I removed the varnish is because when I dissambled the
transformer the varnish pealed off uneven with thick spots on some of plate
and no varnish at all on other plate.  When I try to put the laminations
back together they won't all fit any more.  If I remove the varnish then all
the plates are smooth and flat and they will all fit again.

When I worked in the transformer factory 30 years ago I was told the varnish
was used to glue all the plates together and stop transformer hum.  And in
electronics classes in college I learned about hysteresis losses and eddy
current losses in the transformer.  I was planning to coat the lamination
again with polyurethane to stop hum.  I have never heard about the varnish
being used to insulate the plates from each other.

My electronic book says the lamination act line individual magnets.  100
laminations is like having 100 magnets.  Its like taking a real bar magnet
and cutting it in half then glueing the 2 halves together.  

When I worked for the transformer company (Misners 1968) the workers would
assemble the transformers with the required number of laminations then brush
the outside edges of the laminations with varnish.  The laminations would
wick the varnish in and when it dryed everything was glued together.

Gary Weaver

>Gary - do *not* remove the varnish off the laminations!  The varnish is
there to 
>electrically isolate each metal plate from the next.  As I recall, the
>reduces either hysteresis losses or eddy current losses in the transformer.
>Bert Pool