Explanation: The pulsations in flux density wave arising from slot openings cause losses in the field iron, particularly in the pole faces. This loss occurring due to relative motion, between field poles and slotted armature, is referred to as pulsation loss. 8. What percentage of the rated output for DC machine and synchronous machine is taken as stray load losses respectively?
A. 1% and 0.5%
B. 0.5% and 1%
C. 3% and 0.1%
D. 0.1% and 5%
Answer:A
Explanation: The pulsations in flux density wave arising from slot openings cause losses in the field iron, particularly in the pole faces. This loss occurring due to relative motion, between field poles and slotted armature, is referred to as pulsation loss. 8. What percentage of the rated output for DC machine and synchronous machine is taken as stray load losses respectively?
A. 1% and 0.5% B. 0.5% and 1% C. 3% and 0.1% D. 0.1% and 5%
Explanation: Stray load losses cannot be determined accurately. In DC machine, by convention, it is taken as 1% of the rated output for rating above 150 KW. For synchronous and induction machine, it is taken as 0.5% of their rated output. 9. Which of the given losses are directly proportional to square of speed?