Online Test electrical Transformers - Set 14 - ObjectiveBooks

# Practice Test: Question Set - 14

1. If a transformer is switched on to a voltage more than the rated voltage
(A) Its power factor will deteriorate
(B) Its power factor will increase
(C) Its power factor will remain unaffected
(D) Its power factor will be zero

2. The no-load current drawn by transformer is usually what per cent of the full-load current?
(A) 0.2 to 0.5 percent
(B) 2 to 5 percent
(C) 12 to 15 percent
(D) 20 to 30 percent

3. A transformer transforms
(A) Voltage
(B) Current
(C) Power
(D) Frequency

4. Spacers are provided between adjacent coils
(A) To provide free passage to the cooling oil
(B) To insulate the coils from each other
(C) Both (A) and (B)
(D) None of the above

5. The highest voltage for transmitting electrical power in India is
(A) 33 kV
(B) 66 kV
(C) 132 kV
(D) 400 kV

6. Silicon steel used in laminations mainly reduces
(A) Hysteresis loss
(B) Eddy current losses
(C) Copper losses
(D) All of the above

7. Open circuit test on transformers is conducted to determine
(A) Hysteresis losses
(B) Copper losses
(C) Core losses
(D) Eddy current losses

8. The secondary of a current transformer is always short-circuited under operating conditions because it
(A) Avoids core saturation and high voltage induction
(B) Is safe to human beings
(C) Protects the primary circuit
(D) None of the above

9. The maximum load that a power transformer can carry is limited by its
(A) Temperature rise
(B) Dielectric strength of oil
(C) Voltage ratio
(D) Copper loss

10. Buchholz's relay gives warning and protection against
(A) Electrical fault inside the transformer itself
(B) Electrical fault outside the transformer in outgoing feeder
(C) For both outside and inside faults
(D) None of the above

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