Eastburn wrote:

Without a load, one doesn't want to generate G Watts - in fact
where does it go. The pop the lines and shut down the core.
The turbine plants did the same thing, only some of them take longer
to spin-up as a smaller diesel is used to power the windings of a
smaller
turbine and then it in turn electrifies the windings in others.

Naturally, they, the turbines can't be turned until there is ample
'holy' steam - the industry calls the water that. Once the burners
are up to temp and the steam is running - Then the windings are
engerized.


No, actually, the big turbo-alternator sets can't ever stop turning.
The alternator
rotors weigh 50 + tons, and the shafts will bend if they stop turning.
They have
a small motor called the turning gear that keeps the machine rotating slowly
when no steam is available. The air gap on the rotors is incredibly small
for such a huge machine, about .001" per side. The rotor on an 800 MVA
alternator is about 18-20" diameter and about 12 feet long. it is solid
steel,
with the shaft and rotor one piece. Grooves are cut into the face of the
rotor, and solid rectangular copper bars are fitted into the grooves, with
insulating paper surrounding them. They run some fantastic current through
these bars, something like 10,000 Amps at 100 V DC! They'd melt if it
wasn't for the Hydrogen cooling.

If the high pressure section of the turbines ever cool off, there is a
complicated
procedure to warm them up slowly without causing too much condensation on
the blades and guide vanes. You don't want a lot of water slinging
around inside
the turbine while parts are moving near the speed of sound, only a
fraction of
an inch apart.

Jon