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RE: Re: Cascading Transfo
Subject: RE: Re: Cascading Transfo
Date: Mon, 28 Apr 1997 19:46:22 -0700 (PDT)
From: "Edward V. Phillips" <ed-at-alumni.caltech.edu>
To: tesla-at-pupman-dot-com
" Your point on running 500V into a 120V primary is interesting. I
have a beefy transformer producing only 5kV or so on its secondary. I
will try doubling its input voltage (while monitoring primary current
of course) to see whether the core is sufficient. The insulation
easily looks good enough on the secondary side. I had been planning
to elevate the secondary voltage by other means but this would be
much simpler."
Was reading an article today on new (glass-like steel)
magnetic materials for transformer cores. In passing the author
mentioned that National Electrical Manufacturers Association (NEMA)
specifications on power transformers state that the magnetizing
current " must not increase more than 10 TIMES REPEAT 10 TIMES
when the primary voltage is increased 10 PERCENT REPEAT 10 PERCENT
over the rated value"!!!!!!!!!!!!!!!!!!!!!!!!!! The manufacturers
back off from saturation flux density in the core at rated voltage
just enough to meet this spec, no more. When you talk about
doubling the voltage on the primary you are talking madness!!!
I have been reading notes to this effect and can't see how anyone
can get away with it. Transformer iron is just too expensive and
too heavy for anyone to afford to use more of it than is absolutely
necessary.
Ed