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From: Patent Tactics, George Brock-Nannestad

Shiffy wrote

> Prior to WWII Lionel made toy train transformers specifically designated
for
> 25 Hz operation: whatever windings they used for 60 were not applicable to
25.


----- the lower the frequency the more laminated iron you need to put into
your transformer. A lot of 110 V equipment from the US with barely sufficient
transformers were connected to the European grid at 220 V by means of
transformer, but they broke down, because the transformer could not handle
the lower induction at 50Hz. So at 25 Hz that must have been terrible.
Italian electric railroads used 14 Hz, because the motors used switches that
could function at that "high" frequency. Aircraft use 400 Hz and
comparatively little iron. Modern power supplies use 30kHz and higher, and
the price of the ferrite needed is more than offset by the minute amounts
required.

As to length of AC power lines: the grid going from the north of Sweden to
the South of Denmark once got into wild oscillations - a huge standing wave.
We, too, and the Russians, use AC-DC conversion at convenient points.

Best regards, and looking forward to seeing lots of you in Cleveland,

George