cclist at sydex.com
Wed May 5 10:29:45 CDT 2021
On 5/5/21 8:07 AM, Grant Taylor via cctalk wrote:
> I have found the Motor Generator thread to be fascinating and
> enlightening. But it has made many a reference to the 400 Hz or other
> frequency much higher than mains line frequency. Despite the comments
> about the frequency, I'm still confused as to why the higher than mains
> frequency was used.
Iron and filtering. 400Hz means far less iron needed in transformers
and variacs (CDC used a three-phase variac at the CPU cabinet for
adjustment of voltage). Compare the sizes and it's obvious.
Filtering the ripple out of a 2400 Hz 92% DC rectified supply is
comparatively simple. A 360Hz supply, less so.
In my salad days, I worked at a steel mill where a fair amount of
equipment ran from 25 Hz voltage. The transformers were huge in
comparison to their 60 Hz cousins.
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