Transformers Archives - Page 7 of 13 - MCQ and Quiz for Exams

61. The dielectric strength of transformer oil is expected to be

lkV

33 kV

100 kV

330 kV

Detailed SolutionThe dielectric strength of transformer oil is expected to be

62. The use of higher flux density in the transformer design

reduces weight per kVA

reduces iron losses

reduces copper losses

increases part load efficiency

Detailed SolutionThe use of higher flux density in the transformer design

63. Sumpner’s test is conducted on transformers to determine

temperature

stray losses

all-day efficiency

none of the above

Detailed SolutionSumpner’s test is conducted on transformers to determine

64. Which motor is preferred for use in mines where explosive gases exist?

Air motor

Induction motor

Shunt motor

Synchronous motor

Detailed SolutionWhich motor is preferred for use in mines where explosive gases exist?

65. Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is

approximately equal to one

less than one

great than one

none of the above

Detailed SolutionAuto-transformer makes effective saving on copper and copper losses, when its transformation ratio is

66. The maximum efficiency of a distribution transformer is

at no load

at 50% full load

at 80% full load

at full load

Detailed SolutionThe maximum efficiency of a distribution transformer is

67. An ideal transformer has infinite values of primary and secondary inductances. The statement is

TRUE

nan

nan

nan

Detailed SolutionAn ideal transformer has infinite values of primary and secondary inductances. The statement is

68. The path of a magnetic flux in a transformer should have

high resistance

high reluctance

low resistance

low reluctance

Detailed SolutionThe path of a magnetic flux in a transformer should have

69. For a transformer, operating at constant load current, maximum efficiency will occur at

0.8 leading power factor

0.8 lagging power factor

zero power factor

unity power factor

Detailed SolutionFor a transformer, operating at constant load current, maximum efficiency will occur at

70. In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of

less than 15 A

more than 15 A

15 A

none of the above

Detailed SolutionIn a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of

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