Practice Test Geeks(AEP) American Electric Power Practice Test
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Troubleshooting & Diagnostics Flashcards

7 cards from real AEP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Troubleshooting & Diagnostics flashcards as text

  1. A substation bus voltage drops suddenly but feeder current remains normal. What is the most probable cause?

    Answer: Voltage regulator malfunction or tap changer failure

    A sudden voltage drop without a corresponding load change typically indicates a voltage regulator or tap changer fault.

  2. When testing a protection CT with a turns-ratio test, you find the measured ratio is 10% higher than nameplate. This most likely indicates:

    Answer: Shorted secondary turns

    Shorted secondary turns reduce the effective secondary turns, causing the measured ratio to appear higher than the nameplate value.

  3. A ground fault indicator on a distribution feeder activates, but the feeder does not trip. What type of fault is most likely?

    Answer: High-impedance ground fault

    High-impedance ground faults produce limited fault current that may activate a ground indicator but not exceed overcurrent relay pickup.

  4. You measure negative sequence current in a balanced three-phase system. What does this indicate?

    Answer: Phase transposition error or unbalanced fault

    Negative sequence current appears when there is phase imbalance caused by an unbalanced fault or wiring error such as a phase transposition.

  5. An automatic recloser operates three times and locks out. The feeder remains de-energized. What is the correct next step?

    Answer: Patrol and inspect the feeder for a permanent fault before re-energizing

    Lockout after three operations indicates a permanent fault; a physical inspection must locate and clear the fault before re-energizing.

  6. Thermal imaging of a cable termination shows a hot spot at the lug. What should you check first?

    Answer: Lug torque and connection integrity

    Hot spots at lugs are most commonly caused by loose or improperly torqued connections that increase contact resistance.

  7. A power quality meter records high total harmonic distortion (THD) on a bus supplying a VFD load. The best mitigation is:

    Answer: Install a line reactor or harmonic filter

    Line reactors and harmonic filters are standard mitigation devices that reduce harmonic currents injected by VFDs into the power system.