1. The selection of distribution transformer is based on
(a) efficiency.
(b) voltage regulator.
(c) all day efficiency.
(d) none of the above.
Answer
2. Which of the following material is used for the construction of a transformer core?
(a) Hardrawn copper.
(b) Silicon steel.
(c) Rought iron.
(d) Soft iron.
Answer
3. The primary voltage of an isolation transformer is ______ its secondary voltage.
(a) higher than
(b) smaller than
(c) same as
(d) none of the above
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4. A transformer oil must be free from
(a) sludge.
(b) moister.
(c) gases.
(d) dust.
Answer
5. As the number of turns of secondary winding increases, then its secondary current of a transformer is
(a) increases.
(b) decreases.
(c) remain same.
(d) all of the above.
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6. The main reason for generation of harmonics in a transformer could be
(a) fluctuating load.
(b) poor insulation.
(c) mechanical vibrations.
(d) saturation of core.
Answer
7. Two transformer operating in parallel will share the load depending on their
(a) leakage reactance.
(b) rating.
(c) efficiency.
(d) per unit impedance.
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8. Which of the following is not a routine test on transformers?
(a) Core insulation voltage test.
(b) Impedance test.
(c) Radio interference test.
(d) Polarity test.
Answer
9. When power transformer is operated at very high frequency then
(a) copper losses will very high.
(b) core losses will very high.
(c) primary will draw large power.
(d) all of the above.
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10. When the primary winding of a transformer is short circuited, its primary inductance is
(a) decreases.
(b) increases.
(c) remains same.
(d) none of the above.
Answer
11. The efficiency of a transformer will be maximum when
(a) copper losses are equal to hysteresis losses.
(b) hysteresis losses are equal to eddy current losses.
(c) eddy current losses are equal to copper losses.
(d) copper losses are equal iron losses.
Answer
12. In a transformer, the amount of copper in the primary as compared to secondary is
(a) less.
(b) more.
(c) about same.
(d) none of the above.
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13. At what condition the voltage regulation of a transformer can be zero?
(a) full-load.
(b) lagging power factor.
(c) leading power factor.
(d) zero power factor.
Answer
14. The value of flux in the emf equation a transformer is
(a) average value.
(b) r.m.s. value.
(c) maximum value.
(d) none of the above.
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15. The leakage flux in a transformer depends upon the value of
(a) supply frequency.
(b) core losses.
(c) mutual flux.
(d) load current.
Answer