Transformer MCQs Part 13

Transformer MCQs Part 13

The all-day efficiency of a lighting transformer is always _________ its power efficiency

The all-day efficiency of a lighting transformer is always _________ its power efficiency:

1. Less than
2. Equal to
3. Higher than
4. None of these

Correct answer: 1. Less than

A 3000/150 V, 30 kVA transformer has 50 turns in secondary. What is full load primary current of transformer

A 3000/150 V, 30 kVA transformer has 50 turns in secondary. What is full load primary current of transformer:

1. 1 A
2. 2 A
3. 5 A
4. 10 A

Correct answer: 4. 10 A

Solution: I = kVA/Primary Voltage = 30*1000/3000 = 10 A

Which of the following combination of two things remains same for primary and secondary of a transformer

Which of the following combination of two things remains same for primary and secondary of a transformer:

1. Resistance and leakage reactance
2. Ampere-turns and voltage per turns
3. Currents and induced voltages
4. None of these

Correct answer: 2. Ampere-turns and voltage per turns

Which loss of transformer is decreased with decrease in load

Which loss of transformer is decreased with decrease in load:

1. Copper losses
2. Eddy current losses
3. Friction losses
4. Hysteresis losses

Correct answer: 1. Copper losses

A transformer doesn’t possess changing property for

A transformer doesn’t possess changing property for:

1. Voltage
2. Current
3. Power
4. Impedance

Correct answer: 3. Power