17 Jul
2025
17 Jul
'25
2:55 p.m.
On Jul 17, 2025, at 12:55 PM, Carlos E Murillo-Sanchez
via cctalk <cctalk(a)classiccmp.org> wrote:
Paul Koning via cctalk wrote:
Yes, I can see that for utility transformers, which are carefully optimized for the task.
But I would think that power supply transformers are likely to have larger margins so they
aren't operated so close to the limits.
paul
> I wonder about "they were certain it
would not work". That should be a question of fact, not belief.
-snip-
For power supply transformers, 50 vs. 60 Hz is
unlikely to matter. People with CDC mainframes that want 400 Hz power do need a solution,
with motor-generators as the traditional answer. I wonder if a VFC would work for that,
perhaps with post-VFC filtering to turn the waveform into something closer to a sine
wave.
paul
Operating a 60Hz transformer at 50Hz will require a higher magnetizing
current (and flux density) in order to maintain the same operating voltage. This is very
likely to send the transformer into a B vs H region with reduced permeability, thus
creating a much more distorted magnetizing current waveform with sizable peaks. This will
in turn increase primary copper losses, and overheating can happen easily, depending on
the transformer specifics. For power distribution and transmission transformers, this is
definitely a no-no. There is a reason that 50Hz utility transformers have roughly 20%
more iron and copper in them than 60Hz ones.