Question 179Electricity & Electronics - QMED

70% to pass

If field excitation is suddenly lost to an alternator operating in parallel with another alternator, what will happen to the alternator that has experienced a loss of field excitation?

AIt will become overloaded and slow down.
BIt will lose its load and tend to overspeed.
CIt will operate at the same load, but with reduced voltage.
DIt will supply excessive current to the bus.
AI Explanation

The correct answer is B) It will lose its load and tend to overspeed. When an alternator loses its field excitation, it effectively becomes a generator that is no longer able to control its output voltage. Without field excitation, the alternator will lose its ability to regulate the voltage it produces, causing it to lose its load. This, in turn, will cause the alternator to tend to overspeed, as there is no longer a load on the generator to maintain its speed. The other options are incorrect because: A) The alternator will not become overloaded, as it has lost its load; C) The voltage will not remain the same, but will instead drop significantly; and D) The alternator will not supply excessive current to the bus, as it has lost its ability to generate power.

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