Which condition can trip the generator off by the GCU due to generator phase sequence?

• A. Generator phase sequence
• B. Overcurrent
• C. Over/Under Voltage
• D. Oil temperature

Answer: (A)

Phase sequence is the order in which the three phase voltages reach their peaks and cross zero. The generator control unit relies on this order to keep the rotating magnetic field and the grid in proper alignment. If the phase sequence is incorrect, the rotating field can become misaligned with the grid, leading to out-of-step conditions that the GCU is designed to detect and stop to prevent damage. That makes the phase sequence the condition that can trip the generator specifically because of phase sequence. Other faults like overcurrent, over/under voltage, or oil temperature involve current magnitudes, voltage levels, or heat—not the order of the phases—so they aren’t triggered by phase-sequence issues.