Efficiency in Single-Phase Transformer - MCQs with Answers

Efficiency in Single-Phase Transformer - MCQs with Answers

Q1. For maximum efficiency in a transformer

a. Core losses = 2 * copper losses
b. Core losses = copper losses / 2
c. Core losses = copper losses
d. Core losses = copper losses ∧ 2

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Q2. If the power factor of a transformer is increases, then its efficiency will

a. Increases
b. Decreases
c. Remains constant
d. Not related to each other

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Q3. When a transformer is supplied by full load at 0.8 p.f. lagging its copper losses is given by P_cu. if it is supplied by half load then copper losses will be

a. P_cu.
b. 2P_cu.
c. P_cu / 2.
d. P_cu / 4.

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Q4. A 600 kVA transformer has iron losses of 400 kW and copper losses of 500 kW. Its kVA rating for maximum efficiency is given by

a. 537 kVA
b. 548 kVA
c. 555 kVA
d. 585 kVA

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Q5. In a 20 kVA, 2200 / 220 volts transformer iron and copper losses are 300 and 400 watts respectively. Its efficiency at half load and unity power factor is

a. 95.11%
b. 96.15%
c. 97.77%
d. 98%

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Q6. A 500 kVA single phase transformer has 90% efficiency at both half load and full load at unity power factor. Then iron losses will be

a. 12.55 KW
b. 13.55 kW
c. 16.55 kW
d. 18.55 Kw

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