Chapter 7: Transformer- Single and Three phase
61. In Scott connections, the neutral point divides the teaser winding in the ratio
A.1:3
B.1:2
C.1:1
D.1:4
...
Answer is (B)
62. The secondary line voltage is maximum for which of the following connection?
A. delta-delta
B. star-star
C. delta-star
D. star-delta
63. Three units of 15 transformers are connected in
A?V to supply a 3-phase load from a 400 V. 3. source. The line voltage
on the load side is
A. 1000 V
B. 80 V
C. 3464 V
D. 803 V
...
Answer is (C)
64. The secondary of a PT is generally designed for
A. 220 V
B. 110 V
C. 150V
D. 11 V
...
Answer is (B)
66. The maximum efficiency of a 100 kVA transformer having iron loss of 900 kW and F.L. Cu loss of 1600 W occurs at
A. 56.3 kVA
B. 133.3 kVA
C. 75 kVA
D. 177.7 kVA
...
Answer is (C)
67. A good voltage regulation of a transformer means
A. difference between primary and secondary voltage is least
B. difference between primary and secondary voltage is maximum
C. output voltage fluctuation with power factor is the least
D. output voltage fluctuation form no load to full load is least.
68. Test used to determine the efficiency of two identical transformers at full load is
A. Open-circuit test
B. Short circuit test
C. Type tests
D. Back to back test
69. A 220/115 V, 25 Hz, 1-phase transformer has
eddy current loss of 100 watt which is half of the no-load loss at rated
applied voltage. If this transformer is used with primary connected to a
440 V, 50 V, 50 Hz mains, the total no-load loss would be
A. 300 W
B. 600 W
C. 1000 W
D. 400 W
70. If Cu loss of a transformer at 7/8th full load is 4900 W, then its full-load Cu loss would be
A. 5600 watts
B. 6400 watts
C. 375 watts
D. 429 watts
...
Answer is (B)
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