Question 121Electricity & Electronics - 1st Asst/Chief
70% to passAs shown in the illustrated diagnostic setup checking for a reversed field pole on a ten-pole synchronous motor, if a rotor is being checked after reassembly and the steel bolts repel each other as shown in the illustration, what condition is indicated? Illustration EL-0205
AEither coil 3 or coil 4 has a reversed polarity
BAn undetermined coil has reversed polarity
CBoth coils 3 and coil 4 have the correct polarity
DAll coils have the correct polarity
AI Explanation
The correct answer is A) Either coil 3 or coil 4 has a reversed polarity. If the steel bolts repel each other during the diagnostic setup, it indicates that the magnetic field of the rotor is reversed in one of the poles. This means that either coil 3 or coil 4 has a reversed polarity, creating an opposing magnetic field in that section of the rotor. The other options are incorrect because: B) does not specify which coil is reversed, C) would mean the repelling bolts are not indicative of a reversed polarity, and D) would not explain the repelling bolts observed in the diagnostic setup.
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