MCQ GK Quiz Basic Electrics - Set 07

G.K. Practice Test: Question Set - 07

1. The voltage regulation of a transformer is poor at
    (A) Unity power factor
    (B) Zero power factor
    (C) Leading power factor
    (D) Lagging power factor

2. The copper losses in a transformer at half load compared to those at full load will be
    (A) Same
    (B) Half
    (C) One-fourth
    (D) 2 times

3. It is essential that transformer oil should have no traces of moisture. The reason is that
    (A) Density of oil increases with reduces heat dissipation
    (B) Moisture will reduce the dielectric strength of the oil and hence insulation is weakened
    (C) Moisture will reduce the lubricating property of the oil
    (D) Moisture will develop rust

4. Which of the following electrical machines has the highest efficiency?
    (A) D.C shunt motor
    (B) Transformer
    (C) Induction motor
    (D) Synchronous motor

5. The condition for the maximum efficiency of the transformer is that
    (A) Copper losses are half of the iron losses
    (B) Copper losses are equal to iron losses
    (C) Copper losses are negligible in comparison to iron losses
    (D) Iron losses are zero

6. The operation of the electric generator and motor is based on the interaction between
    (A) Magnetic field and electric field
    (B) Magnetic field and electric current
    (C) Electric field and law of induction
    (D) Law of induction and dynamo-electric principle

7. Which of the following transformers will have smallest size with same electrical specifications?
    (A) Oil Natural Air Natural (ONAN) cooled transformer
    (B) Dry type transformer
    (C) Oil Natural Air Forced (ONAF) cooled transformer
    (D) Oil Natural Water Forced (ONWF) cooled transformer

8. Which parameter is increased by step up transformer?
    (A) Current
    (B) Resistance
    (C) Voltage
    (D) Frequency

9. Open circuit test on transformer measures
    (A) Impedance and insulation resistance
    (B) Voltage regulation
    (C) Eddy current loss
    (D) Core loss

10. In a step up transformer, which of the following is correct?
    (A) Secondary power is more than primary
    (B) Secondary current is more than primary
    (C) Secondary turns are more than primary
    (D) Phase shift between secondary and primary is 180°

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