Prime Mover and Governors Flashcards

What is the primary function of a governor on a generator set prime mover?

Answer: To maintain engine speed by controlling fuel delivery

A governor controls fuel delivery to the prime mover to maintain a constant engine speed regardless of load changes.

In a diesel engine prime mover, what component directly actuates the fuel injection rack in response to governor signals?

Answer: The actuator (fuel control unit)

The actuator (fuel control unit) translates governor output signals into mechanical movement of the fuel injection rack.

What is 'droop' in the context of a generator governor?

Answer: The intentional speed decrease as load increases, expressed as a percentage

Droop is the engineered speed reduction (typically 3–5%) that occurs as load increases, enabling stable parallel operation of multiple generators.

A diesel generator is running at 60 Hz at no load but drops to 59.4 Hz at full load. What is the governor droop percentage?

Answer: 1%

Droop % = (no-load speed − full-load speed) / rated speed × 100 = (60 − 59.4) / 60 × 100 = 1%.

Which type of governor uses flyweights rotating with the engine to sense speed changes?

Answer: Mechanical centrifugal governor

Mechanical centrifugal governors use flyweights that move outward or inward with centrifugal force to sense engine speed and adjust fuel accordingly.

What happens to engine speed in an isochronous governor as load increases from no-load to full load?

Answer: Speed remains constant regardless of load

An isochronous governor maintains exactly the same speed from no-load to full load, unlike a droop governor which allows speed to decrease.

A magnetic pickup (MPU) used with an electronic governor is mounted near which engine component?

Answer: The flywheel ring gear

The magnetic pickup senses the passing teeth of the flywheel ring gear to generate a frequency signal proportional to engine speed.