5 May
2021
5 May
'21
8:29 a.m.
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.
--Chuck