Prime Mover and Governors Flashcards

What is the effect of increasing the integral gain (I-term) in a PID electronic governor?

Answer: It eliminates steady-state speed error more aggressively but can cause instability if too high

Higher integral gain causes the governor to eliminate sustained speed errors more quickly but excessive integral gain can cause oscillation and instability.

Which factor most influences the 'acceleration time' of a diesel prime mover when picking up a block load?

Answer: Engine displacement and turbocharger lag time

Engine displacement determines available torque reserve, and turbocharger lag (turbo lag) delays full boost pressure, both critically affecting how quickly the engine accelerates to meet sudden load demand.

What is 'speed regulation' (also called 'steady-state frequency regulation') of a governor?

Answer: The difference between no-load and full-load speed expressed as a percentage of rated speed

Speed regulation is calculated as (no-load speed − full-load speed) / rated speed × 100%, and it is numerically equal to the droop percentage for droop governors.

On a generator set with a mechanical governor, what must be done to synchronize it with the bus before paralleling?

Answer: Manually adjust the governor speed control to match the bus frequency before closing the breaker

Before paralleling, the incoming generator's governor speed control must be adjusted so its frequency closely matches the bus frequency to enable synchronization.

What is the primary purpose of a 'load sensor' or 'load sharing line' connection between paralleled generator governor controls?

Answer: To allow each governor to sense total system load and proportionally share real power (kW)

The load sharing line allows isochronous governors to communicate current load levels so each unit proportionally shares real kW load without needing droop.

Which prime mover characteristic is described by the 'heat rate' (BTU/kWh)?

Answer: The thermal efficiency of the prime mover — how much fuel energy is converted to electrical energy

Heat rate (BTU/kWh) measures how much fuel energy (in BTUs) is required to produce one kilowatt-hour of electrical output; a lower heat rate indicates higher efficiency.

A governor's 'stability' adjustment (derivative or dashpot setting) is used to:

Answer: Dampen governor response to prevent hunting and overshoot after load changes

The stability (derivative) adjustment adds damping to the governor response, preventing it from overcorrecting and oscillating (hunting) after a load disturbance.