EETC - Equipment & Engine Training Council Mobile Generator Service Questions and Answers

Question 1

A technician is servicing a portable generator that starts and runs smoothly but produces no AC voltage at the receptacles.
The circuit breakers are confirmed to be in the 'ON' position.
What is the MOST likely initial diagnostic step?

Accepted Answer

Check for residual magnetism and flash the field windings if necessary.

Answer

Disassemble the generator end to inspect the stator windings.

Answer

Replace the Automatic Voltage Regulator (AVR) immediately.

Answer

Measure the engine's RPM to ensure it is at 3600 RPM.

Question 2

What is the primary function of the Automatic Voltage Regulator (AVR) on a mobile generator?

Accepted Answer

To maintain a constant output voltage under varying load conditions.

Answer

To adjust the engine speed based on the connected electrical load.

Answer

To convert AC output to DC for charging the starter battery.

Answer

To protect the generator from overload by tripping a circuit breaker.

Question 3

A contractor wants to power a 13-amp circular saw (running watts: 1560W, starting watts: 2500W) and a 10-amp air compressor (running watts: 1200W, starting watts: 2000W) with a generator rated for 4000 running watts and 5000 surge (starting) watts. Which statement is correct?

Accepted Answer

The generator can run both tools but cannot start them simultaneously.

Answer

The generator can start and run both tools without any issues.

Answer

The total running watts exceed the generator's rated capacity.

Answer

The generator can start either tool individually but cannot run both at the same time.

Question 4

A technician measures the output of a North American standard mobile generator and finds the frequency is stable at 62.5 Hz with no load connected. What is the most likely cause for this reading?

Accepted Answer

The engine speed is set slightly too high.

Answer

The Automatic Voltage Regulator (AVR) is malfunctioning.

Answer

The stator has a shorted winding.

Answer

The main circuit breaker is faulty.

Question 5

Which of the following best describes the function of a Ground Fault Circuit Interrupter (GFCI) receptacle on a portable generator?

Accepted Answer

It protects the user from electric shock by detecting small imbalances in current flow.

Answer

It prevents the generator from being overloaded by excessive current.

Answer

It regulates the output voltage to protect sensitive electronics.

Answer

It automatically bonds the neutral to the frame when a tool is plugged in.

Question 6

A technician is troubleshooting a generator with a consistently low voltage output of 95V. The engine speed is confirmed to be correct (producing 60 Hz), and swapping the AVR with a known-good unit does not fix the problem. What is the most logical next diagnostic step?

Accepted Answer

Measure the resistance of the rotor windings through the slip rings and brushes.

Answer

Perform an engine compression test.

Answer

Replace the main circuit breaker.

Answer

Test the fuel for water contamination.