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On Sunday, in article

"Jim Michaels" wrote:

On 18 Jun 2005 22:46:09 GMT, (Andrew
Gabriel) wrote:

[Andrew's article pre-dates when I first subscribed to this group, so I'm
piggy-backing on Jim's]

In article ,
Capitol writes:
distribution circuits and products without upgrading. If we were
starting again today the world would probably settle for 230V @ 400 Hz,
giving smaller ( &cheap) transformers without significantly increased
losses.

400Hz severely reduces the maximum area of a synchronisation zone,
which makes carrying power any distance very much more expensive.
Many of the 50Hz zones are close to their size limit now, so I
don't think anyone would think of distributing at any higher
frequency in Europe. It would be OK on a small isolated island.
400Hz isn't suitable for industrial motors either. Actually, supplies
to large commercial customers at 16 2/3rds Hz and 25Hz used to be
quite common as they much prefer a lower frequency for large motors.
Transformer size is really only an issue on planes and boats, which
often do use 400Hz.

A *lot* of military hardware, neither afloat nor airborne, uses 400Hz for
power distribution, not just to cut down on the mass of transformers, but
also on their bulk.

A radar system with which I spent many years (it was first designed, but
never built, to go with a Predictor and the Vickers 3.7in AA gun,
ca.1946, but not constructed until the early/mid 1950s, and to my certain
knowledge was still being used, in a different role, right through into
the 1990s) had more than five HUNDRED power transformers operating off
"400Hz mains". Each sub-system had its own transformers for valve
heaters, HT supplies to anodes, EHT to klystrons and magnetrons, etc.

(The 400Hz "mains" came from a motor-alternator set, running off 3ph 50Hz
[which came in our instance off the public supply, but "in the field"
could arise from a pair of 27.5kVA Meadows diesel alternators]. The
startup current at switch-on was sufficient to bend the needle on the
electricity board's engineer's tong ammeter, even though it was on the
400A range: he was there to investigate our complaints of insufficient
iron in the substation transformer ;-)

--
Brian {Hamilton Kelly}
"Je n'ai fait celle-ci plus longue que parce que je n'ai pas eu
le loisir de la faire plus courte."
Blaise Pascal, /Lettres Provinciales/, 1657