On Tuesday, 29 May 2018 09:06:24 UTC+1, The Other Mike wrote:
OKOn Fri, 18 May 2018 19:53:46 +0100, tony sayer wrote:

Never hear then referring to the Alternators in a power station as
Dynamo's!..

OK rectified when fitted to a vehicle.

In a power station on the end of the alternator opposite from the turbine you'll
find a DC field excitation generator / pilot exciter that does have a
commutator.

The brushes on those are changed on load (as in hundreds of MW of main
alternator load and twirling round at 3000rpm)

Just stand on a carefully tested rubber mat, wear nice clean properly rated
rubber gloves and just don't get it wrong. But it's only about 600v or so and
there are quite a few brushes in parallel

But if you think that's dodgy they fill the stator with water and circulate
hydrogen in the gap between the stator and rotor to keep it cool.

The hydrogen being sealed on the interface between the rotating shaft and the
outside world by pressurised oil. Get a rubbing seal and it might ignite the
hydrogen make a big bang and the oil fire will burn a very big hole in the roof.

what's the uspide of H2 over N2 or burnt air?


NT