turbine RPM

[Anonymous]

From what I've understood by watching the pentrex video
the turbines (at least the veranda) had the following sequence when starting up:
first the diesel engine was making electricity and feeding it into one of the generators that was serving as a motor and turning the turbine at low RPM, then when the speed got to 700 RPM the turbine was fired up and started burning diesel oil and a when it got to 5500 it started burning the main fuel.
They said that 5500 RPM was about 80% of its full power, so that would mean
that at full throttle she was spinning at about 6900RPM.

So I assume that 5500 was it's "idle" then, because that was the minimum RPM at which the turbine burned bunker C oil.

Since 5500 RPM is a lot and unless there were some gears to slow it down that would generate a lot of current, so I wonder about the way throttle was controled..

Was it controled:
a) by changing the flow of electricity as in electric locomotives
or
b) changing the RPM of the turbine as RMP is controled in diesel locomotives.
or
c) a combination of these two

the reason I ask is:
if it is a) then a lot of fuel would be wasted (the turbine would be working at full hp and power would be wasted on induced resistance unless you were working in full throttle
and if it's b, well again lots of fuel wasted on just idling at 5500 RPM

I guess what I'm asking is:
was the turbine powerplant controled by the throttle handle, or was it simply a steady powersource and the throttle handle controled only the flow of the current?
Or were there two controls, one for turbine RPM and another for flow of electricity?