Thomas Tornblom wrote:

Many long distance feeds are now HVDC, which deals with the frequency
difference problem just fine.

I believe parts of Japan are 50 Hz and other parts are 60.

I've never heard about 30 Hz, but the swedish railroads use 16 2/3 Hz
(50/3) for the trains. The store behind this was that that was such a
low frequency that they could use DC motors in the early electrical
locomotives.

I live by the railroad, and when I was using a CRT monitor I could see
when a train approached from the north, as the current to drive the
train induced a strong magnetic field at 16 2/3 Hz, and the picture
would wobble slightly.

Dc motors wont work on ac of any frequency. Low frequencies used in
traction improve the motors' starting torque, and of course this is
important.

I've got a very old domestic appliance that claims to handle 25Hz, but
where 25Hz was ever found in homes in UK I dont know. I wonder if a few
old private gen plants used it at the time, and they thought theyd
corner the market, but am far from convinced.


NT