"A. Melon" wrote:
>
> Tim May <[EMAIL PROTECTED]> wrote:
> > On Thursday, April 11, 2002, at 06:59 AM, Mike Rosing wrote:
> > > But the reason we have AC today is because Tesla requested no
> > > royalties on his motor/generator. Something for Brands to think
> > > about.
> >
> > No, we have AC because AC works better than DC in home wiring
> > situations.
>
> Hmmm. I always thought the reason we went with AC was because at the
> time, DC power couldn't cut it. They couldn't find any way to reliably
> transfer DC power more than a half mile or so from the power plant, and
> when trying to demonstrate it in NYC couldn't even get DC power all the
> way up a multi-story building.
You're saying the same thing. AC works for transmission over long
distances because it can be cheaply stepped up in voltage for
transmission to minimize losses, then stepped down again for safe
domestic use. We now have machinery that does that fairly cheaply for
DC, but it's still more expensive than a simple transformer with the
same capacity. Long range transmission line are now often high-voltage
DC, to take advantage of higher average power at a given peak voltage;
it is now possible to efficiently reconvert to AC at the end. In
Edison's day that was not so. If his commutated DC generators generated
32 volts (and high-voltage DC generators would have been very difficult
to build in those days), that was the transmission voltage, and you had
to have a powerplant on every block.
What held up AC as a distribution format was the absence of practical AC
motors - Tesla broke that logjam, asking little in return, and the rest
is history.
Marc de Piolenc
