In article .com,
writes:
Andrew Gabriel wrote:
In article ,
Capitol writes:

50Hz local distribution system is purely historic and well entrenched
but the transformer sizes could be substantially reduced with 400HZ.

I don't think anyone cares about transformer size anything like to
the extent you seem to.

Cost. It may not be much per item, but add all those small cost savings
up and it comes to 1 with a long string of 0s on the end. Savings on
all domestic transformer operated gear, from wall warts to stereos to

Wall warts are purchased in bulk for figures like 30p each, so they
must already cost less than this to manufacture, including the
transformer. Maybe you could knock 5p off the price of a wall wart?

microwaves. Savings on all inductor fluorescent lights. Savingsd on

These are all going electronic anyway.

reservoir capacitors everywhere. Savings on motor caps and pf
correction caps. Etc.

If we were starting from scratch now, we could save a nice little pile
with 400Hz - or if the sync zone would not be big enough to cover UK,
maybe less, but high than 50.

Question: in this day of rf comms anad accurate time standards, why can
we not use one central standard to sync gens all across the country, or
anywhere as large as is wanted. It may have not been that way in 1900,
but accurate time standards are fairly trivial now.

It's not a time standard problem, it's a transmission line problem.
The National Grid is a large transmission line, and different parts
of it will be at slightly different phase angles due to transmission
delays. Now that might not be an insurmountable problem if it was
just a long 1-dimensional line, but it's a complex 2-dimensional
mesh, and the problem rapidly becomes unsolvable as the mesh size
grows or the frequency increases. I don't know what the wave
propagation velocity is on the National Grid, but best case it's
the speed of light, so you have a 1/4 wavelength phase shift in
around 1000 miles. At 400Hz, you shrink the max length of a synch
zone to just 1/8th size, which is 1/64th of the area, so you need
64 times as many synchronisation zones and a collosal number of
expensive conversion stations to feed power between unsynch'ed zones.

the US, local transformers on a pole appear to be the norm in a lot of
areas.

Well 120V doesn't go very far before the regulation has gone to pot.

These would certainly be lighter at 400Hz. The 400 Hz suggestion
comes from discussions with US engineers many years ago on which way
would you go today if you could start again. I certainly like it. I

I think it's a non-starter.

It is now, because of all the 50 and 60Hz kit. Theres too much of it
that wont be replaced any decade soon.

I don't think that's the only issue. Another one which just occurs
to me would be skin depth effect on large high current conductors;
not insurmountable, but you'd have to change the conductors to
multiple strands or flat tapes at 400Hz for smaller conductor sizes
than is required at 50Hz, which would make cables and terminations
more expensive.

All this to save 5p off the price of a wall wart? I have my doubts...

--
Andrew Gabriel