Doug Miller wrote:
In article , "Jon Danniken" wrote:

Edison was a hack. Westinghouse had the induction and polyphase generation
patents from Nikola Tesla in his pocket, which established a superior system
of electrical power generation and distribution, which we are still using to
this day.

The superiority of AC over DC for power transmission is due solely to these
two facts:
a) the higher the voltage, the lower the losses in transmission.
b) AC can drive a transformer, but DC cannot.

Thus, it's possible to step AC voltage up arbitrarily high for transmission to
minimize losses, then step it back down for distribution. This can't be done
with DC.

W/ a passive transformer that's true but solid-state devices mean can
now effectively build DC voltage step-up/down devices that couldn't
(practically) before.

AFAIK there aren't yet any long-distance DC grid transmission lines in
the existing US grid but there are at least some on/in the planning (and
maybe construction by now, been nearly 10(!!??!!) years since retired
and had direct contact w/ the particular utilities involved) so not sure
exact status. There are plans for some new lines from various
large-scale wind farms and if they're ever built in all likelihood any
lines from offshore wind will be DC.

Back when still working, studies in EPRI indicated something otoo 100
miles was about the breakeven point between AC losses and the extra cost
of DC installations for general transmission. For dedicated facilities
it could be much shorter, say 10, maybe.

--