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 _____________
A. Eddy current loss
B. Hysteresis loss
C. Resistance or ohmic losses
D. Mechanical loss
Answer:A
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 _____________
A. Eddy current loss B. Hysteresis loss C. Resistance or ohmic losses D. Mechanical loss
Explanation: Hysteresis loss is directly proportional to the number of magnetic reversals per second or the speed. 5. The usual lamination thickness selected to minimize the eddy current loss in rotor is _____________