EGSA Electrical Systems Troubleshooting 2

Question 1

A generator shows high AC voltage output but the frequency is correct. What is the most likely cause?

Accepted Answer

Faulty AVR

Answer

The Automatic Voltage Regulator (AVR) controls output voltage; a faulty AVR can cause voltage to rise above set point while frequency remains governed correctly.

Question 2

When troubleshooting a generator that trips on overcurrent, which test should be performed first?

Accepted Answer

Megohmmeter test on windings

Answer

A megohmmeter test identifies insulation breakdown in windings, which is a common cause of sustained overcurrent trips.

Question 3

A transfer switch fails to transfer to the emergency source after generator start. The most likely cause is:

Accepted Answer

Faulty sensing relay in the transfer switch

Answer

The transfer switch sensing relay monitors utility voltage loss and initiates the transfer; a faulty relay prevents the switching sequence from completing.

Question 4

What does a high resistance measurement across a closed circuit breaker indicate?

Accepted Answer

Damaged or pitted contacts

Answer

High resistance across a closed breaker indicates damaged, burned, or pitted contacts that increase contact resistance and cause voltage drop.

Question 5

A three-phase generator produces balanced voltage but one phase has no load current. What is the most likely fault?

Accepted Answer

Open circuit on the load side of that phase

Answer

Balanced voltage with zero current on one phase points to an open circuit on the load distribution side for that phase, not within the generator itself.

(EGSA) Electrical Generating Systems Association Certified Practice Test

(EGSA) Electrical Generating Systems Association Certified Practice Test

EGSA Electrical Systems Troubleshooting 2