Question 302Electricity & Electronics - Assistant Engineer

70% to pass

As shown in the illustration of a DC machine which is configured as a generator, what is the polarity of the interpoles as compared to the main field poles? Illustration EL-0052

Diagram for USCG Electrical Assistant: As shown in the illustration of a DC machine which is configured as a...
Ain the direction of rotation, the preceding interpole should have the same polarity as the following main pole
Bin the direction of rotation, the preceding interpole should have the opposite polarity as the following main pole
Cin the direction of rotation, the following interpole should have the same polarity as the preceding main pole
Dthe polarities of the interpoles 180 degrees opposite one another should be the same, the actual polarities compared to that of the main poles does not matter
AI Explanation

The correct answer is A) In the direction of rotation, the preceding interpole should have the same polarity as the following main pole. The reason this is the correct answer is that the purpose of the interpoles in a DC generator is to create a magnetic field that opposes the armature reaction and maintains a stable commutation process. For this to work effectively, the interpoles need to have the same polarity as the main field poles in the direction of rotation. This ensures the magnetic fields of the interpoles and main poles work together to counteract the armature reaction and provide stable commutation. The other answer choices are incorrect because they either describe the wrong polarity relationship between the interpoles and main poles, or indicate the actual polarities don't matter, which is not the case for proper DC generator operation.

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