torque converter

I think we have a problem in translating to English. By prime mover, do you mean starter? To me, the prime mover (principal source of energy) of a truck or tractor is a diesel engine, and the prime mover of an electric generator is commonly a diesel engine or a gas turbine, either of which will have a relatively small starter motor or engine.

The word usage may well be different in other countries or other industries...

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I am guessing that you are asking about a diesel starting engine system for a gas turbine. In such a system, the diesel cannot be directly clutched to the gas turbine, because the inertia of the turbine would cause the diesel to stall. A torque converter allows the diesel to run at low speed with a great deal of slip (just as a torque converter in a car functions: when you sit at a stop light in drive, first gear is fully engaged, but the torque converter slips to allow the engine to idle while transmitting very little power through the transmission to the wheels).

When the diesel speeds up to begin starting the turbine, the torque converter multiplies torque (either by a roughly fixed ratio or by a widely variable ratio, depending upon the construction of the torque converter, with some having vane angles that can be varied).

Voith makes a torque converter system for this purpose, although in the linked brochure, the starter motor is electric, but the basic idea is the same. The Voith torque converter can operate at torque multiplication of up to 10. I glanced quickly through the brochure, but it looks as if the declutching is accomplished in this case, by empting the converter of its oil.

I am guessing here, but would assume that the jaw clutch you mention disengages after the turbine starts (first becomes self-sustaining) and before it gets up to operating speed. It would make sense to have the torque converter on the diesel side of the clutch, so the the converter would not be spinning at high speed while the turbine operates. In that case, the torque converter would continue to turn with the diesel until the diesel is shut down.

There is an speed sensor in the Accessory gear box, which senses the speed and auromatically activates and EM to declutch the clutch between the AGB and the Hydraulic clutch (Must be Voith only) at a speed I think about 30% of rated or so, when the compressor becomes strong enough and the fule is fed to the turbine. From then onwards the GT is powerful enough to drive the compressor.

There is no question of stopping of the torque converter if it is on other side - between the DE and Gear Box and the Engine is stopped as the turbine picks up.