Question 193Electricity & Electronics - QMED

The correct answer is B) a hazardous condition will be created by the cross current between the machines. When synchronizing two AC generators, it is critical that their voltages, frequencies, and phase angles match exactly before closing the circuit breaker. If the synchroscope pointer stops at a position other than 0°, it indicates a phase difference between the generators. Closing the circuit breaker in this condition will result in a large cross-current flowing between the generators, creating a hazardous condition that could potentially damage the equipment. The other answer choices are incorrect because: A) the incoming machine will not accept all the load, as the phase mismatch will cause uncontrolled load sharing; C) the frequency mismatch is not the primary issue, as the phase angle difference is the main concern; and D) the incoming machine will not trip out on low voltage release, but rather experience the dangerous cross-current condition.