Sure you have your facts right Bill?
I understand the iron losses increasing, but why does copper cable 'only use
the outer quarter inch'?
My understanding is that this phenomena kicks in at much higher
frequencies - like above 50KHz.
Another factor in choosing the frequencies may have been to do with
audibility. I can imagine a (say) 800Hz transformer or motor making an
intolerable racket compared to a 50Hz model.
Regards
Ron
..
"Repeating Rifle" > wrote in message
...
> in article , Lawrence DčOliveiro
at
> _zealand wrote on 12/10/04 12:24 PM:
>
> > I heard that Tesla wanted mains frequencies to be around 300-400Hz for
> > this reason. I think the engineers who built the early power plants
> > (Edison?) felt this was impractical because they couldn't build big AC
> > generators that could spin that fast.
> >
> > Wonder how things would be different if the situation could be revisited
> > today...
>
> Very briefly, the commercial power frequency selected is a tradeoff
between
> costs of equipment and size of equipent. Core losses, from the iron in
> transformers, increase with frequency. For 60 Hz ac, only about the outer
> quarter inch of copper in cables is used. As frequency is increased, less
of
> the copper conductor is used. In the end 60 Hz is used for most European
> power while 60 Hz was selected for the USA. In aircraft, weight can be
much
> more of an economic factor then efficiency. Thus 400 Hz is popular in
> aircraft. But realize that only about 0.1 inch thickness of copper is
> useful.
>
> Bill
>