When the start switch is placed in RUN position for a turbine engine with a starter-generator, which statement is true?

When the start switch is placed in RUN position for a turbine engine with a starter-generator, which statement is true?

• A. The starter relay closes to energize the ignition exciter and motor windings.
• B. The generator field relay is closed, connecting the voltage regulator to the starter-generator.
• C. The ignition system is bypassed during run.
• D. The engine is automatically connected to external power.

Answer: (B)

In RUN, the aim is to have the starter-generator act as a generator with controlled output. The crucial action is closing the generator field circuit so the voltage regulator can control the generator’s output. When the start switch is moved to RUN, the starter-generator’s field relay closes, linking the field winding to the voltage regulator. The regulator then modulates the field current based on sensed terminal voltage, establishing and maintaining the proper electrical output as engine speed increases. This is different from starting, where the focus is on powering the starter motor and ignition exciter to spin up the engine. Ignition is not simply bypassed during run, and external power connection isn’t automatic—the system generates power to supply electrical loads.

In RUN, the aim is to have the starter-generator act as a generator with controlled output. The crucial action is closing the generator field circuit so the voltage regulator can control the generator’s output. When the start switch is moved to RUN, the starter-generator’s field relay closes, linking the field winding to the voltage regulator. The regulator then modulates the field current based on sensed terminal voltage, establishing and maintaining the proper electrical output as engine speed increases. This is different from starting, where the focus is on powering the starter motor and ignition exciter to spin up the engine. Ignition is not simply bypassed during run, and external power connection isn’t automatic—the system generates power to supply electrical loads.