[AMPS] HV Pole Pig Transformers

Phil (VA3UX) phil@vaxxine.com
Wed, 19 Dec 2001 20:05:13 -0500

Well this would work OK Jim if the core is made of E-I laminations.  But so 
far I haven't had any pole pigs made from E-I's : they're all hypersil, 
strip wound cores. In many cases the cores (the continuous strip) have been 
wound through the pre-fabbed coils. In other cases the cores have been 
pre-wound, then cut so the windings can be wound on the core, then the core 
is handed stacked/interleaved before binding.  I haven't seen of the 
pre-fabbed cut-cores like those used by Dahl or supplied by Magnetic Metals 

The only E-I core pole pig I have seen is an old 25 cycle 3 KVA unit.  I do 
have one transformer here where the core is made up from straight "I" 
laminations - hand stacked into a conventional "core" (as opposed to 
"shell") configuration.  This one can be (and will be) disassembled by hand 
and can be dealt with as you pointed out.


At 06:30 PM 12/19/2001 -0600, you wrote:

>"Phil (VA3UX)" <phil@vaxxine.com> mentions a very good point --
> >5) Because it will be out of oil, the transformer should be used indoors in
> >a dry location.  Might sound obvious but some people have mounted big power
> >supplies or big mono-band amplifiers in their garages.  These transformers
> >have no protection against moisture ingress once they are out of oil and  a
> >garage is subject to greater swings in temperature and humidity than a
> >house.  Indoors they seem to run for ever without a problem.
>And it goes without saying that if you rewind, it's trivial to clean the
>laminations before reassembly, and you can seal them (glyptol, varnish, or
>pigment-free lacquer)  or pot them in epoxy or polyester.  But if you don't
>disassemble and clean, potting is not going to work.
>At least, I've never found a paint that would adhere to oily metal.
>Jim N6OTQ
>lookin' for a transformer to rewind!
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