System Troubleshooting and Maintenance Flashcards
7 cards from real EGSA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 System Troubleshooting and Maintenance flashcards as text
When troubleshooting a paralleling failure between two generators, which parameter mismatch will most commonly cause a large circulating current between units?
Answer: Voltage or frequency difference between the two sources
Voltage or frequency mismatch between two paralleled generators creates a potential difference that drives circulating currents through the windings.
A governor hunting symptom (oscillating engine speed) on a mechanical governor system is most commonly caused by:
Answer: Improper governor speed droop adjustment or linkage wear
Improper droop adjustment or worn governor linkage causes the system to over-correct repeatedly, producing speed oscillation.
Which maintenance interval task specifically addresses the degradation of diesel fuel quality in long-term storage applications?
Answer: Fuel polishing and microbial contamination testing
Fuel polishing removes water, sediment, and microbial growth that degrade stored diesel fuel quality over time.
A generator starts and runs normally but produces output voltage 15% below the nominal setting. After confirming AVR input power is present, what is the most likely fault?
Answer: Failed or misadjusted voltage sensing resistor in the AVR trim circuit
A failed or incorrectly trimmed voltage sensing circuit prevents the AVR from raising excitation to the correct level.
During a transfer switch maintenance inspection, what test verifies that the switch will correctly detect a utility outage and command generator start?
Answer: Simulated utility voltage dropout test with ATS in auto mode
A simulated utility dropout test confirms the ATS sensing circuit and time delays operate correctly before commanding generator start.
What does a high crankcase pressure reading (blowby) during engine diagnostics indicate?
Answer: Worn piston rings or cylinder liner damage allowing combustion gases to bypass
Excessive blowby indicates combustion gases are bypassing worn piston rings or damaged cylinder liners into the crankcase.
When replacing a generator set's air cleaner element, which condition in the old element would indicate an air restriction problem likely contributed to black exhaust smoke?
Answer: Element is heavily clogged, restricting airflow below manufacturer specifications
A heavily clogged air cleaner restricts the combustion air supply, causing a rich fuel-to-air mixture that produces black smoke.