Power Generation Equipment Flashcards

What is the primary function of an automatic voltage regulator (AVR) in a generator set?

Answer: Maintain constant output voltage under varying loads

An AVR senses output voltage and adjusts excitation current to keep generator terminal voltage stable as load changes.

In a diesel generator, what does the term 'wet stacking' describe?

Answer: Unburned fuel and oil accumulating in the exhaust system

Wet stacking occurs when a diesel engine runs at light load for extended periods, causing unburned fuel and carbon deposits to accumulate in the exhaust stack.

Which generator winding configuration provides both 120V and 240V single-phase output from the same alternator?

Answer: Center-tapped single-phase winding

A center-tapped single-phase winding allows both 120V (line-to-neutral) and 240V (line-to-line) to be derived from the same winding.

What is the purpose of a droop governor setting on a generator operating in parallel?

Answer: Allow proportional load sharing between paralleled generators

Droop governor settings cause engine speed to decrease slightly as load increases, enabling stable proportional load sharing when multiple generators run in parallel.

What is the typical standby power rating for a generator set?

Answer: Maximum power available for up to 200 hours per year with varying load

Standby rating represents maximum power for emergency use, typically not exceeding 200 hours per year at varying load with no average load factor limit.

In a brushless generator, the exciter stator receives DC from the AVR to produce AC in which component?

Answer: Exciter rotor winding

The AVR supplies DC to the exciter stator, inducing AC current in the rotating exciter rotor, which is then rectified and fed to the main rotor field.

What NFPA standard governs the installation of emergency and standby power systems?

Answer: NFPA 110

NFPA 110 is the Standard for Emergency and Standby Power Systems, covering installation, testing, and maintenance requirements.