Power System Objective Questions

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Power System MCQs

Students are expected to solve these MCQs during or after the completion of this subject which will help them to analyze whether they have understood the subject or not.
Solve:
1) Which of the following is not the distribution system normally used
(A) 3 phase-4 wire
(B) 3 phase-3 wire
© Single phase - 3 wire
(D) Single phase -4 wire.

Answer: (d)

2) In overhead transmission lines the effect of capacitance can be neglected when the length of line is less than
(A) 200 km
(B) 160 km
© 100 km
(D) 80 km.

Answer: (d)

3) The skin effect of a conductor will reduce as the
(A) diameter increases
(B) frequency increases
© using stranded conductors
(d) permeability of conductor material increases

Answer: C

4) Stones are provided in the substation to:
a) To avoid fire accident by draining oil from transformer if leaks
b) To avoid growing of weeds and plants
c) To provide insulation
d) All the above

Answer: (d)

5) In order to improve the power factor ___ device is employed in the substation
a) Synchronous condenser..
b) Synchronous reactor
c) Series Capacitors
d) None of the above

Answer: (a)

6) The fact that a conductor carries more current on the surface as compared to core, is known as
(A) skin effect
(B) corona
© permeability
(D) unsymmetrical fault.

Answer: (a)

7) Earthing conductivity is affected by:
a) Moisture content in the soil
b) Chemical composition
c) Concentration of salts in the soil
d) All the above

Answer: (d)

8) With same maximum voltage to earth, which ac system (with p.f. 0.8) will require more copper as compared to dc 2 wire system
(A) single phase. 2 wire (mid point earthed)
(B) single phase. 3 wire (neutral=1/2 outer)
© three phase three wire
(D) three phase-four wire (neutral = outer).

Answer: (d)

9) The effective resistance of a conductor will be the same as ohmic resistance when
(A) current is in true sine wave form
(B) voltage is low
© power factor is unity
(D) Current is uniformly distributed in the conductor cross-section.

Answer: (d)

10) The effect of ice deposition on conductor is
(A) increased skin effect
(B) reduced corona losses
© increased weight
(D) reduced sag.

Answer: C

11) For 66 kV lines the number of insulator discs used
are
(A) 3
(B) 5
© 8
(D) 12.

Answer: (b)

12. Ten discs usually suggest that the transmission line
voltage is
(A) 11 kV
(B) 33 kV
© 66 kV
(D) 132 kV.

Answer: (d)

If you have doubts about the answers, feel free to ask