Solve the Electrical Engineering Question Paper of 2011 Engineering Services Examination.
1. The applied voltage of a certain transformer is increased by 75%, while the frequency of the applied voltage is reduced by 25%. The maximum core flux density will.
(a) Increase by seven times
(b) Increase by three times
(c) Reduce to one quarter
(d) Remain the same
3. A 4kVA, 400 V/200 V single phase transformer has resistance of 0.02 pu and reactance referred to high voltage side are:
(a) 0.2 Ω and 2.4 Ω
(b) 0.8 Ω and 2.4 Ω
(c) 0.08 Ω and 0.24 Ω
(d) 1 Ω and 3 Ω
4. The full-load copper-loss and iron-loss of a transformer are 6400 W and 500 W, respectively. The above copper loss and iron loss at half load will be:
(a) 3200 W and 250 W respectively
(b) 3200 W and 500 W respectively
(c) 1600 W and 125 W respectively
(d) 1600 W and 500 W respectively
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