Question 187Electricity/Electronics - QMED70% to pass
You are paralleling two alternators. The synchronizing lamps grow dim and are totally darkened as the synchroscope pointer approaches the 0° position. What does this indicate?
AI Explanation
The correct answer is D) the circuit breaker can be closed.
When the synchronizing lamps grow dim and are totally darkened as the synchroscope pointer approaches the 0° position, it indicates that the voltages and frequencies of the two alternators are closely matched, and it is safe to close the circuit breaker to parallel the alternators.
The other options are incorrect because: A) the voltages being 180° apart would not result in the lamps dimming; B) the incoming alternator running too slowly would cause the lamps to remain bright; and C) a defective or broken synchroscope would not provide the necessary indication for paralleling the alternators.
Related Questions
#185 Attempting to parallel an AC generator which is out of phase with the bus will result in which of the following conditions? #186 Which of the following statements is true concerning the operation of two alternators in parallel? #188 You are attempting to parallel two AC generators, and the synchroscope pointer is revolving in the fast direction. What is the frequency of the oncoming generator relative to the bus frequency? #189 To remove an alternator operating in parallel with another unit from the main electrical bus, what must be done FIRST? #190 A main switchboard synchronizing panel is fitted with two synchronizing lamps and a synchroscope. When paralleling, if the synchroscope pointer is at the noon position and one synchronizing light is bright while the other remains dark, what does this indicate?