Which condition can trip the generator off by the GCU due to voltage and frequency?

• A. Over/Under Voltage/Frequency
• B. Generator and Bus Overcurrent
• C. Generator phase sequence
• D. Ground fault

Answer: (A)

Voltage and frequency levels are what the GCU uses to judge whether the generator is operating safely. The GCU continuously monitors the output voltage and the system frequency, and if either quantity strays beyond its preset limits, the protective logic trips the generator to prevent damage and maintain stability. This is precisely what “over/under voltage and frequency” refers to—the condition where voltage is too high or too low, or frequency is out of the acceptable range.

Other conditions point to different protections: overcurrent relates to excessive current, phase sequence issues involve incorrect ordering of the electrical phases, and a ground fault involves current leaking to ground. While those can trip the generator under their own fault criteria, they are not the voltage/frequency deviation condition described here.