Electrical Machines Questions and Answers_pag409

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a) h.v side at one end of the winding 
b) l.v. side at one end of the winding 
c) h.v side at middle 
d) l.v side at middle 
View Answer 
Answer: c 
Explanation: High voltage side winding has more voltage so the variation of the voltage will be 
more and better applicable. And it is better 
to place at the middle because it gives uniform voltage distribution by eliminating axial forces. 
14. In a transformer, we place the tapping windings at the middle because 
a) of radial forces on the windings 
b) axial forces on the windings 
c) insulation level of the winding 
d) to provide a mechanical balance to the windings 
View Answer 
Answer: b 
Explanation: Due to two different voltages, different currents will flow in the windings and it will 
cause the axial forces due to currents interaction 
appear causing damage. 
15. When a transformer winding suffers a short circuit, then inter turns of the same winding 
experience ______ forces. 
a) an attractive 
b) a repulsive 
c) no force 
d) may be attractive or repulsive type 
View Answer 
Answer: a 
Explanation: As the current will flow in one direction, attractive force will appear across the inter 
turns as per Biot-savart’s law. 
16. Two tranformer having same voltage but different KVA are operating in parallel. For a good 
load sharing, 
a) impedance must be equal 
b) pu impedances must be equal 
c) pu impedance and X/R ratios must be equal 
d) impedance and X/R ratios must be equal 
View Answer 
Answer: c 
Explanation: Both the conditions are to be met in order to have an efficient operation while in 
parallel condition.