Electrical Machine - I (3140913) MCQs

MCQs of Transformers

Showing 31 to 40 out of 155 Questions
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31.
The primary of a transformer is connected to a 230 V battery. The turns ratio is 1:2 and the secondary resistive load 100 Ω. The voltage across the load is.
(a) 115
(b) 230
(c) 460
(d) 0
Answer:

Option (d)

32.
If a transformer is fed from a 220V and dc supply rather than a 1-phase ac supply, then the transformer will
(a) burn its windings.
(b) operate normally.
(c) will not operate
(d) will give very small output
Answer:

Option (a)

33.
A transformer with a 110 V primary has a 15:1 turns ratio. The load resistance is 120 Ω. What is the approximate voltage across the load?
(a) 7.3
(b) 1650
(c) 73
(d) 16.50
Answer:

Option (a)

34.
In a certainly loaded transformer, the secondary voltage is one-fourth the primary voltage. The secondary current is.
(a) one-fourth the primary current.
(b) four times the primary current.
(c) equal to the primary current.
(d) one-fourth the primary current and equal to the primary current.
Answer:

Option (b)

35.
If the supply frequency of a transformer increases the output voltage of the transformer will
(a) decrease.
(b) increase proportionately.
(c) remain the same.
(d) increases very rapidly.
Answer:

Option (b)

36.
Two transformers with identical ratings are designed with flux densities of 1.2 and 1.4 Wb/m2 respectively. The weight of the first transformer per KVA is
(a) less than that of the second transformer.
(b) equal to that of the second transformer.
(c) more than that of the second transformer.
(d) None of these.
Answer:

Option (c)

37.
The flux involved in the emf equation of a transformer has
(a) r.m.s value.
(b) maximum value.
(c) average value.
(d) total value.
Answer:

Option (b)

38.
If in a sub-station there is one 132/33 kV transformer whose secondary is connected with primary of one 33/11kV transformer, the total transformation ratio of the sub–station will be,
(a) 0.25
(b) 0.33
(c) 0.083
(d) 12
Answer:

Option (c)

39.
If secondary numbers of turns in a transformer increases, the secondary output voltage of the transformer
(a) decreases.
(b) increases.
(c) remains the same.
(d) decreases slightly.
Answer:

Option (b)

40.
In an electrical power transformer.
(a) emf per turn in primary = emf per turn in secondary.
(b) emf per turn in primary > emf per turn in secondary.
(c) emf per turn in primary < emf per turn in secondary.
(d) emf per turn in primary = (2/3)Xemf per turn in secondary.
Answer:

Option (a)

Showing 31 to 40 out of 155 Questions
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