Electrical Machines Questions and Answers_pag108

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View Answer 
Answer: d 
Explanation: At starting , the flux should be rated so that there is no abnormal situation arise. 
 
12. For a 100 hp 250 V, compound dc motor with compensating winding has a field current of 5 
A to produce a voltage of 250 V at 1200 rpm. What will be the shunt field current of this machine 
at no load? 
a) 5 A 
b) 5.6 A 
c) 4 A 
d) 0 A 
View Answer 
Answer: a 
Explanation: At no load, armature current is zero, so the internal generated voltage is 250 V. So 
5 A will be the shunt field current at no load. 
13. The torque characteristic is best described for a dc series motor with respect to armature 
current is 
a)​ 
http://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-operating-characteristics-dc-motor-q13a.png
http://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-operating-characteristics-dc-motor-q13a.png
http://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-operating-characteristics-dc-motor-q13a.png