Andrew Gabriel wrote:
writes:
Capitol writes:
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?
400Hz means a wart small enough to fit into a high top mains plug in
many cases. It means a far smaller TF.
So lets say we cut from 30p to 20p each at the factory gates, or =A32 to
=A31.33 on the retail shelf.
Now, how many warts have you bought in total? Lets take a vague guess
at 10. Times 60 million people in UK gives us:
factory gates savings of =A360 million
and consumer savings of =A3400 million.
And thats just for warts, which are definitely not the biggest saving.
microwaves. Savings on all inductor fluorescent lights. Savingsd on
These are all going electronic anyway.
not microwaves. We might save =A35-10 retail per nuke. Say =A35, and say
a history of 5 nukes owned per person.
5 x 60 mill x =A35 =3D =A31.5 billion
Get the picture?
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.
OK, I'll rephrase the question: why can all gens not be synced by a
common time standard instead of by the neighbouring mains waveform?
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.
skin effect at 400Hz??
NT