Re: potential transformer question

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Ed Phillips <evp-at-pacbell-dot-net> 

"This is very correct. Do not run the PT over +20% if you plan on
keeping
it. For instance, I have a Westinghouse 120/7200 oil filled PT 110KV
BIL, interestingly this is rated at only 750VA-at-30C, but I can run it for
hours at +2500VA. BUT, once I go over 140V in it starts groaning and at
160V in it is sucking over 6-7 amps with no load! Just try a TC load and
you'll end up with one dead PT! Really, a 0-140V supply is what only
works with these instrument transformers wired in reverse...

Regards,

David Trimmell"

	If you draw enough current from a transformer it will overheat in time,
but can be used as long as the temperature rise isn't excessive.  On the
other hand, if you apply too much voltage the core will saturate
immediately and draw huge currents of horrible waveform from the source
of power. Fried windings should follow shortly, and all without a
significant increase in output voltage.  Steel (transformer "iron") is
expensive and heavy and manufacturers of commercial products don't use
any more than is necessary.

Ed