The rapid wear of brushes takes place due to____________?
Correct answer: E. all of the above factors
- A. abrasion from dust
- B. excessive spring pressure
- C. rough commutator bars
- D. high mica insulation between com-mutation bars
- E. all of the above factors
Explanation
Brush wear can result from abrasive dust, excessive spring pressure, a rough commutator, or mica projecting above the copper bars. Since every listed condition can accelerate wear, the combined choice is correct.
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