Question 73Electricity & Electronics - Assistant Engineer

The correct answer is B) the incoming alternator is in synchronism with the bus. When paralleling two alternators, the synchronizing lamps grow dim and become totally darkened as the synchroscope pointer approaches the 0° position. This indicates that the incoming alternator is in synchronism with the bus, meaning its voltage, frequency, and phase are matched with the bus. At the 0° position, the alternators are perfectly in phase, allowing for a smooth and safe paralleling operation. The other answer choices are incorrect because: A) 180° apart would indicate the alternators are out of phase, C) running too fast would cause the synchronizing lamps to remain bright, and D) a defective synchroscope would not provide the appropriate synchronization indications.