> >AFAIK AC can not be used for very long lines, for instance in Sweden
> >between the power generation (in middle and north of the country) and
> >the use (mainly in the south).
>
> It is my firm belief that that is inaccurate.  In British
> Columbia, Canada,
> there is a large scale power generation facility called the WAC
> Bennett Dam
> (2.73MVA generating capacity).  The eventual destination of the
> majority of
> this power is the Greater Vancouver area.  This destination is
> approximately 770km away from the dam at the closest point.  This power
> also runs the length and breadth of Alberta and British Columbia.  On top
> of that, due to the California Energy crisis, BC Hydro (the owner of the
> WAC Bennett Dam) is selling power to the state of California.
> That is 1500
> km from the generating station.  It should further be pointed out that the
> entire North West power grid (In North America) runs from southern
> California to at least southern Yukon, which is a combined
> distance of 3300km.
>
> To the best of my knowledge, the entirety of that power grid is
> AC power of
> varying voltages (or at least all the power lines I've seen are 3 wires,
> and the lines leaving the generator are 3 wire.  If they were going to
> convert to DC, I'd expect them to do it at the generating facility rather
> than build a separate facility).  There is one exception to that that I
> know of, which is an SCR switched DC line out to an island in BC.  That is
> a relatively short run and is not along the main power stream,
> but rather a
> branch from it, and there may well be more like it.
>
> So, yes, AC power can go a long way.

        It depends on the situation. AC power can go as far as you want, the
problem is losses, after a certain distance the losses with AC overweigh the
additional costs of a DC run. There are several long lines in Canada that do
DC. In your case it's possible that there are "taps" along that 1500km
meaning no single stretch of line is long enough to warrant using DC on it.
TTYL

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