1. The value of flux involved m the e.m.f. equation of a transformer is
(a) average value.
(b) r.m.s. value.
(c) maximum value.
(d) instantaneous value.
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2. The all day efficiency of a transformer is also known as
(a) load efficiency.
(b) power efficiency.
(c) current efficiency.
(d) energy Efficiency.
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3. Power transformers are generally designed to have maximum efficiency at
(a) no load.
(b) half load.
(c) near full load.
(d) any load.
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4. Distribution transformers are generally designed to have maximum efficiency at
(a) no load.
(b) half load.
(c) near full load.
(d) any load.
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5. In a tap changing transformer, the tapping are provided on
(a) primary side.
(b) secondary side.
(c) high voltage side.
(d) low voltage side.
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6. The noise produced by a transformer is termed as
(a) zoom.
(b) hum.
(c) ringing.
(d) buzz.
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7. The most common method of cooling in a power transformer is
(a) natural air cooling.
(b) air blast cooling.
(c) oil cooling.
(d) any of the above.
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8. At what load the efficiency of a transformer will be zero?
(a) full load.
(b) half load.
(c) no load.
(d) none of the above.
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9. Efficiency of a power transformer is nearly
(a) 50 %.
(b) 80 %.
(c) 98 %.
(d) 100 %.
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10. When the load on a transformer is increases, the eddy current is
(a) increases.
(b) decreases.
(c) remain same.
(d) none of the above.
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11. When the load on a transformer is increases, the copper losses are
(a) increases.
(b) decreases.
(c) remain same.
(d) none of the above.
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12. When the load on a transformer is decreases, the hysteresis losses are
(a) decreases.
(b) increases.
(c) remain same.
(d) none of the above.
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13. Current transformers are also known as
(a) series transformers.
(b) parallel transformers.
(c) auto transformers.
(d) isolation transformers.
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14. Potential transformers are also known as
(a) series transformers.
(b) parallel transformers.
(c) auto transformers.
(d) isolation transformers.
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15. Secondary winding of which transformer should never be open circuits when primary is energized?
(a) Auto transformer.
(b) Potential transformer.
(c) Current transformer.
(d) Isolation transformer.
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