> On Jul 17, 2025, at 12:55 PM, Carlos E Murillo-Sanchez via cctalk
> <[email protected]> wrote:
>
> Paul Koning via cctalk wrote:
>>> 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.
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
