# 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

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

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
3. Lagging

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