Explanation: Also, a small error in the measurement of either output or input causes the same amount of error in the computed efficiency. 3. Which of the following statements are correct regarding brush contact losses?
A. In DC machine: proportional to armature current
B. In synchronous machine: neglected
C. In induction machine: neglected
D. Any of the mentioned
Answer:A
Explanation: Also, a small error in the measurement of either output or input causes the same amount of error in the computed efficiency. 3. Which of the following statements are correct regarding brush contact losses?
A. In DC machine: proportional to armature current B. In synchronous machine: neglected C. In induction machine: neglected D. Any of the mentioned
Explanation: There is brush contact loss at the contacts between the brushes and commutator (in DC machine) or between the brushes and slip rings (synchronous and induction machines). However, in practical, the brush contact loss is neglected for synchronous and induction machines. 4. In rotating electrical machines, when the armature rotates, there are continuous magnetic reversals and power required for their reversals is called _____________