Electrical Machines Questions and Answers_pag42

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d) increases 
View Answer 
Answer: a 
Explanation: The current flowing in the armature will remain same so to maintain the flux 
requirements of the machine.Hence the temperature rise will also remain same as the current 
remains same. 
8. A three phase induction motor is connected to the infinite bus operating at the normal 
conditions. There occurs an unbalancing in the supply, leading to 
a) unequal heating losses 
b) stopping of motor 
c) increase in lower 
d) None of the mentioned 
View Answer 
Answer: a 
Explanation: The unbalancing in the supply phase will create an unbalanced distribution of the 
current in the phases, thereby unequal heating. 
9. A peaky voltage supply is given to the 3 phase power transformer of the connection power 
system. These results into 
a) reduction in iron losses 
b) reduction in copper losses 
c) increase in iron losses 
d) reduction in noise 
View Answer 
Answer: a 
Explanation: The flux wave will be sinusoidal in nature as the emf is peaky in nature. Sine wave 
has least losses when compared to other wave forms. 
10. The iron losses in a saturated three phase alternator is lesser than the non-saturated three 
phase alternator. 
a) True 
b) False 
View Answer 
Answer: a 
Explanation: The non-saturated reactance is greater than saturated reactance. So the reactive 
losses or iron losses will reduce due lesser contribution of the same. 
11. The hydroelectric plants in the industry are best suited with 
a) closed circuit air cooling 
b) hydrogen gas 
c) direct water 
d) any of the mentioned. 
View Answer 
Answer: a 
Explanation: The closed circuit is so used to reuse the air in the system , so that to save water 
again in the cooling system.