Question 192Electricity/Electronics - QMED70% to pass
When paralleling two alternators using three synchronizing lamps, the flickering of all three lamps becomes progressively slower and slower. What does this mean?
AI Explanation
The correct answer is C) The frequency of the incoming generator is approaching that of the bus.
When paralleling two alternators, the synchronizing lamps are used to indicate when the frequencies and phase angles of the two alternators are matched. If the flickering of the lamps becomes progressively slower, it means that the frequency of the incoming alternator is approaching that of the bus. This indicates that the two alternators are getting closer to being in sync, and can be safely paralleled.
The other answer choices are incorrect because:
A) Opposite phase rotation would cause the lamps to flicker rapidly, not slowly.
B) A significantly lower frequency of the incoming alternator would cause the lamps to flicker rapidly, not slowly.
D) Matching terminal voltages is not indicated by the slowing of the lamp flickering.
Related Questions
#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? #191 If the excitation of an alternator operating in parallel is decreased below normal and the other above normal, what will be the result on the alternator with the excitation decreased below normal? #193 You are attempting to parallel two AC generators and the synchroscope pointer stops at a position other than 0°. What would happen if you close the circuit breaker at this position? #194 After closing the circuit breaker to place two alternators with identical ratings in parallel, in terms of achieving a balance between the two alternators, what is the NEXT step? #195 What device is used so that the kilowatt load sharing can be adjusted on paralleled generators?