Transformer MCQ Part 4

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Transformer MCQ Questions Part 4. Electrical Engineering MCQ Questions on Transformer with brief explanatory answer and complete solution.

Numerical No 1

A 230/1100 V transformer takes no load current of 5 A and absorbs 150 W. Calcualte the core loss if the resistance of primary is 0.05 ohms:

  1. 125.5 W
  2. 148.75 W
  3. 322.98 W
  4. 485.75 W

Correct answer: 2. 148.75 W

Solution:

No load loss = 150 W

Primary Copper loss = I^2 * R = (5)^2 * 0.05 = 1.25 W

Iron loss = No load loss – Primary Copper loss

Iron loss = 150 – 1.25 = 148.75 W

The mutual flux in the transformer remains constant at all loads because

The mutual flux in transformer remains constant at all loads for the reason being:

  1. Iron core is employed in construction
  2. Leakage flux is small
  3. Eddy current losses are always same
  4. Applied voltage and frequency are constant

Correct answer: 4. Applied voltage and frequency are constant

What happens to the primary inductance of transformer when the secondary of transformer is short-circuited

What happens to the primary inductance of transformer when the secondary of transformer is short-circuited:

  1. The primary inductance decreases
  2. The primary inductance increases
  3. The primary inductance remains constant
  4. It increases in terms of logarithmic span

Correct answer: 2. The primary inductance decreases

Laminating transformer core results in

Laminating transformer core results in:

  1. Reduced Eddy current losses
  2. Reduced leakage reactance
  3. Reduced hysteresis losses
  4. Reduced copper losses

Correct answer: 1. Reduced Eddy current losses

Laminating transformer core results in reduced eddy current losses

Which of the following is correct statement about leakage flux in transformer

Which of the following is the correct statement about leakage flux in the transformer:

  1. Leakage flux helps in energy transfer
  2. Leakage flux increases the stability of the output sine wave
  3. Leakage flux introduced mutually induced emf
  4. Leakage flux can be minimized by interleaving primary and secondary

Correct answer: 4. Leakage flux can be minimized by interleaving primary and secondary

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