EGSA Prime Mover and Governors 2

Question 1

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

Accepted Answer

To maintain engine speed by controlling fuel delivery

Answer

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

Question 2

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

Accepted Answer

The actuator (fuel control unit)

Answer

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

Question 3

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

Accepted Answer

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

Answer

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

Question 4

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?

Accepted Answer

1%

Answer

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

Question 5

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

Accepted Answer

Mechanical centrifugal governor

Answer

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

(EGSA) Electrical Generating Systems Association Certified Practice Test