Electrical Machine - I (3140913) MCQs

MCQs of Transformers

Showing 81 to 90 out of 155 Questions
6 7 8 9 10 11
81.
The output current corresponding to maximum efficiency for a transformer having a core loss of 100 W and equivalent resistance referred to secondary of 0.25 Ω is ....... ampere.
(a) 20
(b) 25
(c) 5
(d) 400
Answer:

Option (a)

82.
At relatively light load, transformer efficiency is low because
(a) Secondary output is low
(b) transformer losses are high
(c) fixed loss is high in proportion to the output
(d) Cu loss is small
Answer:

Option (c)

83.
Distribution transformers are usually designed to have maximum efficiency
(a) at 50% of full load
(b) at 75% of full load
(c) near full load
(d) near no load
Answer:

Option (a)

84.
Distribution transformer have core losses
(a) > copper losses
(b) = copper losses
(c) < copper losses
(d) = 0.5X(copper losses)
Answer:

Option (c)

85.
The All day (energy) efficiency is the term related to
(a) Power Transformer
(b) Distribution transformer
(c) Current transformer
(d) Voltage transformer
Answer:

Option (b)

86.
The all-day efficiency of a transformer depends primarily on
(a) it's copper loss
(b) the amount of load
(c) the duration of load
(d) both (b) and (c)
Answer:

Option (d)

87.
Power transformers are usually designed to have maximum efficiency
(a) at 75% of full load
(b) near full load
(c) at 50% of full load
(d) near no load
Answer:

Option (b)

88.
The input power under no load condition of the transformer consists of
(a) Core losses in transformer
(b) Core losses and a very small amount of copper loss in primary
(c) Copper loss in transformers
(d) a significant amount of copper loss along with negligible amount of core losses
Answer:

Option (b)

89.
Iron loss in the transformer can be determined by
(a) Short Circuit Test
(b) Open Circuit Test
(c) Both Short Circuit and Open Circuit Tests
(d) None of the above
Answer:

Option (b)

90.
In a transformer
(a) OC test is conducted on the LV side and SC test on the HV side.
(b) OC test is conducted on the HV side and SC test on the LV side
(c) both OC and SC tests are conducted on the LV side
(d) both OC and SC tests are conducted on the HV side
Answer:

Option (a)

Showing 81 to 90 out of 155 Questions
6 7 8 9 10 11