Torque Converter

How does a torque converter work in the starting means of a Frame 6 GE make Gas turbine with diesel engine for start up? Is there any cross sectional view of the torque converter available for reference?
 
A torque converter between a gas turbine starting means (be it a diesel engine or an electric motor) is necessary because the starting means can't be directly coupled (connected) to the turbine-generator shaft. The turbine-generator shaft is extremely heavy and the starting means develops very little power at zero RPM.

A torque converter is really two devices in one: a hydraulic pump (driven by the starting means) and a hydraulic motor (which turns the turbine-generator shaft). This allows the starting means to run at a high RPM--which is where it produces the most power while transmitting that power to the hydraulic motor turning the turbine-generator shaft at low to medium RPM. This allows the starting means to develop high power at one speed and the turbine-generator shaft to accelerate from zero RPM to self-sustaining speed during starting and firing and acceleration.

Again if the starting means we're directly connected to the turbine-generator shaft it would not be possible for the starting means to develop enough power starting at zero RPM to start the turbine -generator shaft spinning from zero RPM and accelerate it to purge and fire and self-sustaining speed. The torque converter allows for a very high speed differential between the starting means and the turbine-generator shaft so the starting means can develop high power while the turbine-generator shaft is at zero to low speed.

Once the flame is established in the gas turbine there is not enough power being developed by the hot gases flowing through the turbine and into the exhaust to keep the turbine-generator shaft spooning or to accelerate it. So, the starting means--through the torque converter--continues to provide power to help the turbine-generator shaft accelerate until the power produced by the hot gases flowing through the turbine can sustain and accelerate the unit to rated (full) speed.

Lastly, even though the starting means is producing full power while the turbine-generator shaft is at zero speed during starting the starting means cannot usually break the turbine-generator shaft away from zero speed. It's actually the "bump, from the hydraulic ratchet mechanism that breaks the turbine-generator shaft away from zero speed and once it starts turning the starting means through the torque converter gradually accelerates the turbine-generator shaft.

Everything has to work together to get the turbine-generator shaft spinning and to help it get to self-sustaining speed where the power being produced by the turbine can finish accelerating the unit to full, rated speed.

You may find a cutaway (sectional view) of the torque converter in the Operations& Service Manuals provided with the unit by the unit packager. Look in the Starting Means system description section of the manual. Another good document to study and learn is the Starting Means P&ID, which may seem intimidating but is critical to understanding the Starting Means system. All the major systems have P&Id's (Piping & Instrumentation Diagrams) which are very important to learning about and understanding the turbine and auxiliaries.

Hope this helps!
 
Take a look in your manuals, there are some very good drawings in the Spare Parts manual.

Without going into great detail, simply it is a two part device with a hydraulic pump being driven by the diesel and the produced hydraulic pressure driving a hydraulic turbine which drives the load.
 
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