Practice Test Geeks(EGSA) Electrical Generating Systems Association Certified Practice Test
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Electrical Systems Troubleshooting 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 Electrical Systems Troubleshooting flashcards as text

  1. When a generator's output voltage collapses immediately upon applying load, the most likely cause is:

    Answer: Shorted exciter diodes

    Shorted exciter diodes prevent the field from building up sufficient current under load, causing voltage collapse when current demand increases.

  2. What is the purpose of performing a polarization index (PI) test on generator windings?

    Answer: To assess insulation condition over time by comparing resistance at 1 and 10 minutes

    The PI is the ratio of 10-minute to 1-minute insulation resistance readings; values above 2.0 generally indicate good insulation condition.

  3. A ground fault indicator lamp glows dimly on one phase of a 480V ungrounded delta system. This indicates:

    Answer: A partial ground fault on that phase

    In an ungrounded delta, a dim lamp indicates a partial or high-resistance ground fault; a solid ground fault would cause the lamp to go dark with the other two lamps glowing brighter.

  4. Which condition would cause a generator to produce voltage but fail to sustain it when a load is applied?

    Answer: Weak residual magnetism in the rotor

    Insufficient residual magnetism in the rotor prevents the field from self-exciting enough to sustain output voltage once load current is drawn.

  5. When troubleshooting a circuit with intermittent power loss, which technique is most effective for identifying a loose connection?

    Answer: Thermal imaging under load

    Thermal imaging detects heat generated by elevated resistance at loose connections under load, making intermittent faults visible before they cause failures.

  6. A generator's AVR sensing voltage input is measuring correctly, but the output voltage is too low. What should be checked next?

    Answer: Exciter field winding continuity

    If the AVR senses correct voltage but output remains low, the exciter field winding may be open or have high resistance, limiting field current to the main rotor.

  7. What happens to neutral current in a 3-phase 4-wire system when all phase currents are balanced and contain no harmonic distortion?

    Answer: Neutral current is zero

    In a perfectly balanced 3-phase system with sinusoidal currents, the phasor sum of the three phase currents cancels to zero in the neutral conductor.