Transformer MCQ Questions Set 3

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Transformer MCQ Questions Set 3
Transformer MCQ Questions Set 3

Transformer MCQ

  1. The highest voltage for transmitting electrical power in India is
    (a) 33 kV.
    (6) 66 kV
    (c) 132 kV
    (d) 400 kV
    Ans: d
  2. In a transformer the resistance between its primary and secondary is
    (a) zero
    (b) 1 ohm
    (c) 1000 ohms
    (d) infinite
    Ans: d
  3. A transformer oil must be free from
    (a) sludge
    (b) odour
    (c) gases
    (d) moisture
    Ans: d
  4. A Buchholz relay can be installed on
    (a) auto-transformers
    (b) air-cooled transformers
    (c) welding transformers
    (d) oil cooled transformers
    Ans: d
  5. Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature
    exceeds
    (a) 50°C
    (b) 80°C
    (c) 100°C
    (d) 150°C
    Ans: d
  6. The main reason for generation of harmonics in a transformer could be
    (a) fluctuating load
    (b) poor insulation
    (c) mechanical vibrations
    (d) saturation of core Ans: d
  1. Distribution transformers are generally designed for maximum efficiency around
    (a) 90% load
    (b) zero load
    (c) 25% load
    (d) 50% load
    Ans: d
  2. Which of the following property is not necessarily desirable in the material for transformer core ?
    (a) Mechanical strength
    (6) Low hysteresis loss
    (c) High thermal conductivity
    (d) High permeability
    Ans: c
  3. Star/star transformers work satisfactorily when
    (a) load is unbalanced only
    (b) load is balanced only
    (c) on balanced as well as unbalanced loads
    (d) none of the above
    Ans: b
  4. Delta/star transformer works satisfactorily when
    (a) load is balanced only
    (b) load is unbalanced only
    (c) on balanced as well as unbalanced loads
    (d) none of the above
    Ans: c
  5. 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
    Ans: a
  1. The magnetising current of a transformer is usually small because it has
    (a) small air gap
    (b) large leakage flux
    (c) laminated silicon steel core
    (d) fewer rotating parts
    Ans: a
  2. Which of the following does not change in an ordinary transformer ?
    (a) Frequency
    (b) Voltage
    (c) Current
    (d) Any of the above
    Ans: a
  3. Which of the following properties is not necessarily desirable for the material for transformer
    core ?
    (a) Low hysteresis loss
    (b) High permeability
    (c) High thermal conductivity
    (d) Adequate mechanical strength

Ans: c

  1. The leakage flux in a transformer depends upon
    (a) load current
    (b) load current and voltage
    (c) load current, voltage and frequency
    (d) load current, voltage, frequency and power factor
    Ans: a
  2. The path of the magnetic flux in transformer should have
    (a) high reluctance
    (b) low reactance
    (c) high resistance
    (d) low resistance
    Ans: b
  3. Noise level test in a transformer is a
    (a) special test
    (b) routine test
    (c) type test
    (d) none of the above
    Ans: c
  4. Which of the following is not a routine test on transformers ?
    (a) Core insulation voltage test
    (b) Impedance test
    (c) Radio interference test
    (d) Polarity test
    Ans: c
  5. A transformer can have zero voltage regulation at
    (a) leading power factor
    (b) lagging power factor
    (c) unity power factor
    (d) zero power factor
    Ans: a
  6. Helical coils can be used on
    (a) low voltage side of high kVA transformers
    (b) high frequency transformers
    (c) high voltage side of small capacity transformers
    (d) high voltage side of high kVA rating transformers
    Ans: a

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