EGSA Electrical Systems Troubleshooting 4

Question 1

Excessive third-harmonic distortion in a generator's output is most commonly caused by:

Accepted Answer

Non-linear loads such as UPS systems and VFDs

Answer

Incorrect governor speed setting

Answer

Worn brushes on the slip rings

Answer

Low coolant temperature

Question 2

When load testing a generator, what parameter confirms the generator is operating within its rated kVA capacity?

Accepted Answer

Both kilowatts and kVAR readings within nameplate rating

Answer

Engine coolant temperature only

Answer

Fuel consumption rate

Answer

Battery voltage during cranking

Question 3

A parallel-connected generator is importing reactive power (absorbing VArs) instead of exporting. The likely cause is:

Accepted Answer

Under-excitation of the generator field

Answer

Oversized fuel injectors

Answer

Governor set point too high

Answer

Tripped overcurrent relay on the bus

Question 4

What is the most appropriate test to verify continuity of a generator's rotor winding without disassembly?

Accepted Answer

Slip ring resistance measurement with an ohmmeter

Answer

Megohmmeter test at 5000V

Answer

Capacitance test on the stator leads

Answer

Power factor test on load bank

Question 5

Which fault condition causes unequal voltage readings across each phase of a three-phase generator but normal frequency?

Accepted Answer

Partial short in one phase stator winding

Answer

Incorrect governor calibration

Answer

Low engine oil pressure

Answer

Clogged air filter

Question 6

When a generator's voltage regulation is poor under varying loads, which component should be calibrated or replaced first?

Accepted Answer

AVR

Answer

Governor actuator

Answer

Transfer switch

Answer

Main circuit breaker

Question 7

A technician measures 0 ohms between two phase conductors in a de-energized three-phase system. This indicates:

Accepted Answer

A phase-to-phase short circuit

Answer

Normal winding resistance

Answer

An open circuit between the phases

Answer

Correct diode bridge operation