Electrical Machines Questions and Answers_pag61

Text Material Preview

1. Choose the correct representation, which depict a non-zero torque in the armature. 
a)​ 
b)​ 
c)​ 
d) any of the mentioned 
View Answer 
Answer: a 
Explanation: Torque is produced when the net force is zero and there is a couple generated. 
The directions must obey Lorentz’s law and vector product. 
2. What is the principle of torque production in a dc machine? 
a) Lorentz’s law 
b) Lenz’s law 
c) Faraday’s law 
d) Self inductance 
View Answer 
Answer: a 
Explanation: Though all the mentioned laws contribute towards the torque generation, but 
primarily its the Lorentz’s forces which initiate and define the torque direction. 
3. The torque induced beyond the pole shoes in the DC machine is 
a) 0 
b) 2/pi *phi *i 
c) 4/pi *phi *i 
d) none of the mentioned 
View Answer 
http://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-dc-machine-torque-q1a.png
http://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-dc-machine-torque-q1a.png
http://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-dc-machine-torque-q1a.png
http://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-dc-machine-torque-q1b.png
http://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-dc-machine-torque-q1b.png
http://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-dc-machine-torque-q1b.png
http://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-dc-machine-torque-q1c.png
http://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-dc-machine-torque-q1c.png
http://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-dc-machine-torque-q1c.png