Electrical Machines Multiple Choice Questions - Mcqs - Quiz
Electrical Machines Multiple Choice Questions - Mcqs - Quiz
Electrical Machines Multiple Choice Questions - Mcqs - Quiz
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This set of Electrical Machines Multiple Choice Questions & Answers (MCQs) focuses on “Transformer
Construction”.
1. The primary and secondary of a transformer are ________ coupled but _______ connected.
a) magnetically, not electrically
b) electrically, not magnetically
c) magnetically, also magnetically
d) electrically, also electrically
View Answer
Answer: a
Explanation: Transformer is the machine which has physical spacing and has magnetic circuit to exchange
the voltage.
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Answer: a
Explanation: A transformer can be put in use upto a varying range of the power and it is usually available in
readily in market.
3. A transformer has comparitively much higher efficiency than a similar induction machine due to
a) small air gaps
b) no moving parts
c) strong coupling
d) all of the mentioned
View Answer
Answer: d
Explanation: Transformer does not has any moving components so losses are anyway reduced and also the
coupling is very strong between two sides.
4. It was needed that to isolate dc noise coming from the transmitted signal, to attain the same which machine
can be used without suffering significant loss
a) transformer
b) dc machine
c) induction machine
d) stepper motor
View Answer
Answer: a
Explanation: We should use transformer to achive the isolation of dc.
Answer: a
Explanation: CRGO has magnetization in the rolling direction and low core losses and very high permeability
than present materials.
Answer: a
Explanation: Leakage flux is meant to to be loss as it does not link two windings.
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Answer: c
Explanation: Staggering is done for the steel butt joints of the transformer to gain more mechanical strength
as the continuous air gap reduces the same.
8. Consider two transformers X and Y having exact ratings, but have flux densities of 1.5T and 2T respectively.
The weight of the transformer A per KVA will be
a) more than that of B
b) lesser than that of B
c) equal to that of B
d) can not be said from the given data
View Answer
Answer: a
Explanation: Flux density = flux/Area.
Hence A has more area than B and so weight of A will be more than that of B.
9. Consider two transformers X and Y having identical ratings, but have flux densities of 1.5T and 2T
respectively. The weight of the transformer B per KVA will be
a) more than that of A
b) lesser than that of A
c) equal to that of A
d) can not be said from the given data
View Answer
Answer: b
Explanation: Flux density = flux/Area.
Hence A has more area than B and so weight of B will be less than that of A.
11. A coupling magnetic field inside a rotating machine or static machine like transformers must involve with
a) mechanical parts
b) electrical parts
c) both electrical and mechanical
d) either of the electrical or mechanical parts
View Answer
Answer: a
Explanation: The coupling field should interact with both the electrical as well as mechanical parts in order to
achieve electromechanical energy conversion.
12. A coupling magnetic field inside a rotating machine or static machine like transformers must involve with
I. electrical system to extract energy from electrical system.
II. mechanical system to extract energy from electrical system.
a) Only I is true
b) Only II is true
c) I and II are true
d) I and II are false
View Answer
Answer: b
Explanation: The energy conversion which involves both electrical as well as mechanical systems must have
mutual field.
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Answer: c
Explanation: Pulse transformers are used in isolation transformer and need high permeablity.
15. Core type transformers have, LV and HV windings are arranged such that
a) Half LV near the core and half HV outside LV on each limb
b) LV one one limb and HV on the other
c) Half LV outside the core and half HV inside LV on each limb
d) LV and HV windings are sandwiched
View Answer
Answer: a
Explanation: Core windng has first of all both the windings on the same limb and HV is placed outside to have
tappings to the transformer.
16. The shell type transformers have, LV and HV windings are arranged such that
a) Half LV near the core and half HV outside LV on each limb
b) LV one one limb and HV on the other
c) Half LV outside the core and half HV inside LV on each limb
d) LV and HV windings are sandwiched
View Answer
Answer: d
Explanation: Shell type windng has mix of LV and HV winding sandwiched over each other.
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