Transformer MCQ’s

Electrical Engineering XYZ provides transformer MCQ’s part 1 which are very important for competitive tests. Prepare these MCQ before appearing in interviews, job tests, university exams and develop your basic concepts on transformers.

1. Auto-transformer is recommended for the transformation ratio:

  1. 1
  2. 5
  3. 1.1
  4. 5

Correct answer: c. 1.1 is the right answer.
Explanation: An autotransformer is used for smaller transformation ration. e.g 21 kV to 21.5 kV stepping is required.

2. From no load to full load condition, the Iron losses in real transformer:

  1. Are constant
  2. Increase upto 25% of orginal losses
  3. Decrease by 13% of original losses
  4. None of these

Correct answer: a. Are constant
Explanation: The iron losses depend on the core flux which remains constant from no load to full load.

3. The Eddy losses depends on:

  1. Frequency
  2. Flux density
  3. Thickness
  4. All of these

Correct answer: d. All of these
Explanation: The formula of Eddy current losses is: P = kef2Bmax2τ2

4. Scott connection in transformers are used when:

  1. Three-phase to two-phase transformation is required
  2. Single-phase to two-phase transformation is required
  3. Three-phase to two and three-phase transformation is required
  4. For of these

Correct answer: b. Three-phase to two and three-phase transformation is required

5. Scott connection in transformers are used when:

  1. Three-phase to two-phase transformation is required
  2. Single-phase to two-phase transformation is required
  3. Three-phase to two and three-phase transformation is required
  4. For of these

Correct answer: b. Three-phase to two and three-phase transformation is required

6. The PF of the transformer is:

  1. Unity
  2. Leading
  3. Lagging
  4. Depends on load

Correct answer: d. Depends on load
Explanation: The PF depends on PF of the connected load

7. The transformer oil should have:

  1. Low viscosity and Low volatility
  2. Low viscosity and High volatility
  3. High viscosity and Low volatility
  4. High viscosity and High volatility

Correct answer: a. Low viscosity and Low volatility
Explanation: Viscosity is the resistance against friction, whereas volatility is the tendency to vaporize a good oil should have low viscosity as well as low volatility.

8. Figure the samllest transformer:

  1. 5 kVA, 1000 Hz
  2. 5 kVA, 2000 Hz
  3. 5 kVA, 3000 Hz
  4. 5 kVA, 4000 Hz

Correct answer: d. 5 kVA, 4000 Hz
Explanation: Size of transformer is inversely proportional to the frequency.

9. Which one is a stepup transformer:

  1. CT
  2. PT
  3. Tesla coil
  4. None of these

Correct answer: c. Tesla coil is the right answer

10. The primary winding of a transformer can be considered as:

  1. A powered inductor
  2. A powered capacitor
  3. Both of these
  4. None of these

Correct answer: a. A powered inductor

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