🚀 go-pugleaf

In article <bar> steve@pepe.aero.org (Steve Sedlacek) writes:
   Again, what is the HISTORY and WHY should
   power transmission be AC (I assume it is more than just transformers to
   step voltage up and down being easy for AC).

You hit the nail on the head.  There are two good reasons for AC
rather than DC: it's easier to generate (no make-and-break brushes in
the generator); and it's much easier to step voltage up and down.  That's
crucial because resistive losses go like the current you're transporting.
Thus you want to step up the voltage as high as you can, so you don't have
to push as much charge around.  But it doesn't make sense to have high 
voltages in the home (imagine a 30kV line in every electrical socket!),
so there's a limit there.  It's well-nigh impossible to supply a whole
city (or even small town) with a pure ~100V system.  AC lets you slip 
nicely between the horns of that dilemma.

Another good reason that springs to mind: the circuitry is (for
simple applications) apolar.  If you plug in your vacuum cleaner
backwards, it does _not_ spew dust all over the house.  So you can
make cheaper sockets and plugs.  This matters -- there are well over a billion,
and probably over 10 billion, electrical sockets in the U.S. alone!

As far as history goes, Edison and his company had established some
small DC power grids, and basically was washed under (despite Edison's
fantastic reputation and clout) by Tesla's polyphase AC system (I 
forget the company that was promoting it: GE maybe?  Westinghouse?).

The sad part of the story is that Tesla's life reads like a Charlie 
Brown cartoon:  despite his brilliant ideas, he kept getting swindled
and/or smeared by people who practically stole many of his inventions.

Towards the end, he did get a bit whacked out, though -- `telautomatics' 
was an idea far ahead of its time, and he didn't have enough nonlinear
circuit elements to make it work.
[Then Lee DeForest invented the triode and it was all over...]

--
Craig DeForest -- astrophysicist for hire.   DoD#314159; PhD#271828