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ESE EE : Electrical Machines Champion Quiz 1
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Question 1
In the core-type two winding transformer, the low voltage winding is placed adjacent to the steel core, in order to
Question 2
Sludge formation in transformer oil is due to which one of the following?
Question 3
Assertion (A): For obtaining improved magnetic properties, the transformer magnetic core is assembled using cold-rolled silicon-steel sheets.
Reason (R): The laminations for the core could be cut out of the cold-rolled silicon steel sheets, cutting either in the direction of rolling or transverse there of, without affecting the magnetic properties in any way.
Reason (R): The laminations for the core could be cut out of the cold-rolled silicon steel sheets, cutting either in the direction of rolling or transverse there of, without affecting the magnetic properties in any way.
Question 4
Two single phase transformers A and B are connected in parallel, observing all requirements of a parallel operation, except that the induced voltage Ea is slightly greater than Eb; Zea and Zeb being the equivalent impedances of A and B, both referred to the secondary side.
Under this operating condition with the primary bus-bars being energized, a circulating current will flow:
Under this operating condition with the primary bus-bars being energized, a circulating current will flow:
Question 5
If the wave form of the voltage impressed on the primary of a 
bank contains 5th harmonics, what are the wave forms of the resultant voltages of the primary and the secondary?
bank contains 5th harmonics, what are the wave forms of the resultant voltages of the primary and the secondary? Question 6
The exact equivalent circuit of a two-winding transformer is given in the figure given below. For affecting simplification, the parallel magnetising branch, consisting of RC and XO is shifted to the left of the primary leakage impedance 
This simplification introduces the inaccuracy, in the neglect of:
This simplification introduces the inaccuracy, in the neglect of: Question 7
What is the efficiency of an auto-transformer in comparison to that of a two-winding transformer of the same rating?
Question 8
Percentage resistance and percentage reactance of a transformer are 1% and 4%, respectively. What is voltage regulation at power factor 0.8 lagging and 0.8 leading?
Question 9
A 4 kVA transformer has iron-loss of 200 W and full load copper loss of 200 W. The maximum efficiency at unity power factor will be
Question 10
The percentage resistance and reactance of a transformer are 2% and 4% respectively. The approximate regulation on full load at 0.8pf lag is
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Sep 10ESE & GATE EE
