1. The purpose of using transformer oil is to
(a) provide cooling.
(b) absorb heat.
(c) provide insulation.
(d) all of the above.
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2. Negative voltage regulation of transformers indicate that the load is
(a) resistive.
(b) capacitive.
(c) inductive.
(d) all of the above.
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3. If the input frequency of a transformers decreases, its magnetic flux in core will
(a) increases.
(b) decrease.
(c) remain same.
(d) none of the above.
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4. Which of the following meter is used to measure the iron loss of a transformer?
(a) low power factor wattmeter.
(b) unity power factor wattmeter.
(c) frequency meter.
(d) high power factor wattmeter.
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5. If the primary of a transformer is connected to a DC supply then
(a) nothing is happened.
(b) core losses are increased.
(c) primary may burn out.
(d) leakage flux is increased.
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6. An isolation transformer has primary to secondary turn ratio of
(a) 1 : 2.
(b) 1 : 1.
(c) 2 : 1.
(d) 1:100.
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7. When open circuit test is performed on transformer, the primary is supplied
(a) rated kVA.
(b) rated voltage.
(c) rated current.
(d) full-load current.
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8. Which of the following losses are known as variable losses?
(a) Hysteresis losses.
(b) Eddy current losses.
(c) Copper losses.
(d) Core losses.
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9. Open circuit test on transformers is conducted to determine
(a) hysteresis losses.
(b) copper losses.
(c) core losses.
(d) eddy current losses.
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10. Short circuit test on transformers is conducted to determine
(a) hysteresis losses.
(b) copper losses.
(c) core losses.
(d) eddy current losses.
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11. In a transformer, the eddy current losses are affected by
(a) frequency.
(b) thickness.
(c) flux density.
(d) all of the above.
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12. Which of the following transformer secondary winding is connected to earth?
(a) Potential Transformer.
(b) Current Transformer.
(c) Both C.T. and P.T.
(d) None of the above.
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13. The permeability of the core of an ideal transformer must be
(a) negative.
(b) zero.
(c) equal to air.
(d) infinite.
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14. The core of a high frequency transformer is sometime made of ferrite because ferrite has
(a) high hysteresis.
(b) high resistance.
(c) high specific gravity.
(d) low permeability.
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15. The secondary side of the current transformer is earthed in order to
(a) reduce losses.
(b) avoid electric shock.
(c) avoid the insulation breakdown.
(d) increase accuracy.
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