Top 60 MCQs of transformer | Objective type questions of transformer #2

(21) What is the range of current density for small and medium power transformer ?

(a) 1 to 2 A per mm2

(b) 1 to 2.5 A per mm2

(c) 1.1 to 2.2 A per mm2

(d) 1.1 to 2.3 A per mm2

Answer is (d)

(22) What is the range of current density for a large power transformer ?

(a) 5.4 to 6.3 A per mm2

(b) 6 to 8 A per mm2

(c) 1.5 to 2.6 A per mm2

(d) 2.4 to 3.4 A per mm2

Answer is (a)

(23) What is the condition for minimum cost of transformer ?

(a) Cost of iron equal to cost of copper

(b) Cost of iron not equal to cost of copper

(c) Cost of iron is greater than cost of copper

(d) Cost of iron is less than cost of copper

Answer is (a)

(24) What is the condition for minimum loss in transformer ? OR What is the condition for maximum efficiency of transformer ?

(a) Iron loss is not equal to copper loss

(b) Iron loss equal to copper loss

(c) Iron loss is twice of copper loss

(d) None of above

Answer is (b)

(25) CRGO_____

(a) cool rolled grain oriented

(b) Cold rolled grain output

(c) Cold rolled grain oriented

(d) Cold rotation grain oriented

Answer is (c)

(26) Leakage reactance of the transformer depends upon _____

(a) Distance between adjacent limbs

(b) The cross-section area of core

(c) the cross-section area of winding

(d) All of above

Answer is (a)

(27) Window space factor (Kw) will_______ with increase in kVA rating

(a) Increase

(b) Decrease

(c) Remain the same

(d) None of above

Answer is (a)

(28) The basic function of a transformer is to change

(a) The power factor

(b) The frequency

(c) The power level

(d) The level of the voltage

Answer is ( d)

(29) Which of the following parameter does not change in transformer ?

(a) Current

(b) Voltage

(c) Frequency

(d) None of above

Answer is ( c)

(30) Minimum voltage regulation occurs when the power factor of the load is

(a) Zero

(b) Lagging

(c) Unity

(d) Leading

Answer is ( d)

(31) The maximum load that a transformer can carry is limited by it’s

(a) Temperature rise

(b) Copper loss

(c) Voltage ratio

(d) Dielectric strength of oil

Answer is ( c)

(32) The noise produced by a transformer is called

(a) Buzz

(b) Hum

(c) Zoom

(d) Ringing

Answer is ( b)

(33) The efficiency of two identical transformer under load conditions can be determined by

(a) Back-to-Back test

(b) Short-circuit test

(c) Open circuit test

(d) All of above

Answer is ( c)

(34) In transformer for given applied voltage , losses which remain constant irrespective of load changes are

(a) Iron losses

(b) Copper losses

(c) Hysteresis and eddy current losses

(d) Friction and windage losses

Answer is (c)

(35) Open circuit test on transformer is conduct determine

(a) Core losses

(b) Copper losses

(c) Hysteresis losses

(d) Eddy current losses

Answer is ( a)

(36) Short circuit test on transformer is conducted to determine

(a) Hysteresis loss

(b) Copper loss

(c) Core loss

(d) Eddy current loss

Answer is (b)

(37) Negative voltage regulation is indicative that the load is

(a) Capacitive

(b) Inductive

(c) Inductive and resistive both

(d) None of above

Answer is (a)

(38) Harmonics in transformer result in

(a) Increased i2R losses

(b) Increased core loss

(c) Magnetic interference with communication circuits

(d) All of the above

Answer is (d)

(39) Noise level test in transformer is a

(a) No load test

(b) Routine test

(c) Type test

(d) None of the above

Answer is (c)

(40) The inductive reactance of a transformer depends on

(a) Electromotive force

(b) Magnetomotive force

(c) Magnetic flux

(d) leakage flux

Answer is (d)

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