A quick rundown of the A330 electrical system:
The A330 does indeed have an emergency generator powered by the RAT.
Like most aircraft the systems is divided into buses: AC1, AC2, AC ESS, DC1, DC2, DC BAT and DC ESS.
Essential bus provides power to most vital systems, and I assume (but don't know) that it includes the 5 FBW computers (or at least some of them, even if it leaves them with degraded flight control laws). AC ESS
is normally fed from the AC1 bus, but if AC1 is unpowered then AC ESS
can be fed from the AC2 bus - presumably this is an automatic switchover but I don't know for sure, although I do no there is a switch on the overhead for this function.
If both AC
buses are unpowered then the RAT is deployed automatically and feeds AC ESS
from the emergency generator.
The DC buses are fed from their respective AC
buses (i.e. AC1 powers DC1) through a Transformer Rectifier which I assume is just a fancy AC
-DC inverter. The two DC buses power the DC BAT
bus, the DC BAT
bus among other things provides power to charge the batteries when they are below a certain voltage.
If either of the AC
buses is unpowered the associated DC bus will draw power from the opposite DC bus through the DC BAT
bus. If AC1 and AC2 are unpowered then DC1 and DC2 buses are lost.
The DC ESS
bus is powered from the DC BAT
bus (which is usually powered from DC1 and DC2), however if DC1 and DC2 buses are unpowered the DC ESS
will draw power from the AC ESS
bus through the ESS
Transformer Rectifier, or failing that directly from the 2 batteries.
The RAT is disabled when landing gear is extended and in such situations the DC ESS
bus is powered directly from batteries and the AC ESS
bus is powered from the batteries through a Static Inverter. (I presume this is to ensure the continuity of supply as the aircraft slows down and the generator produces less energy - anyone tell me for sure?)
As you can see, like all modern commercial aircraft there is a lot of redundancy built into the system.
Even if the shit really hits the fan the flight crew still have direct control of the aircraft through the pitch and rudder trim, along with the throttles (which I assume would act in a mode similar to if the autothrust instinctive disconnect buttons had been held for 15 secs). I imagine the two guys up front would be very busy bees, but I have no doubt that the aircraft could be brought down with a good degree of success.
A type rated pilot or A&P will know more than me, this is just what I could muster from the limited information I have available to me - but I think it's all factually correct as it stands.
[Edited 2003-10-25 13:39:00]
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