# Power Systems (Transmissions & Distribution) Expected MCQ PDF 1 For VIZAG MT Exam 2017

1)   The generating voltage and frequency in India is about?

a. 11 kV and 60 Hz
b. 11 kV and 50 Hz
c. 220 kV and 60 Hz
d. 220 kV and 50 Hz

 ANSWER: 11 kV and 50 Hz
2)   Which type of system is generally adopted for the generation and transmission of electrical power?

a. 3 phase 4 wire
b. 2 phase 3 wire
c. 3 phase 3 wire
d. None of these

3)   The rated voltage of a 3 phase power system is given by ____________.

a. rms peak voltage
b. Peak phase voltage
c. rms line to line voltage
d. Peak line to line voltage

 ANSWER: rms line to line voltage
4)   Which of these systems uses the 3 phase 4 wire system?

a. Primary distribution
b. Secondary distribution
c. Primary transmission
d. Secondary transmission

5)   With the same
maximum voltage to earth, which among the following AC systems with 0.8
pf will need more copper compared to 2 wire system?

a. Single phase, 2 wire
b. Single phase, 3 wire
c. Three phase, 3 wire
d. Three phase, 4 wire

6)   Assertion (A): 3 wire dc distribution system is preferred over 2 wire dc distribution system.

Reason (R): the 3 wire dc system of distribution is more safe.

a. Both A and R are true and R is the correct explanation of A
b. Both A and R are true and R is not the explanation of A
c. A is true but R is false
d. A is false but R is true

 ANSWER: A is true but R is false
7)   Assertion (A): Transmission of electrical power by dc is economical than that with ac.

Reason (R): In case of dc transmission, there is no charging current which contributes to the continuous load, even on no load.

a. Both A and R are true and R is the correct explanation of A
b. Both A and R are true and R is not the explanation of A
c. A is true but R is false
d. A is false but R is true

 ANSWER: Both A and R are true and R is not the explanation of A
8)   In transmission system, the weight of copper used is proportional to

a. Square of voltage
b. Voltage
c. 1 / (square of voltage)
d. 1 / voltage

 ANSWER: 1 / (square of voltage)
9)   Greater the power factor the ________________ is the volume of copper required.

a. Greater
b. Smaller
c. Both are equal
d. Depending of the level of transmission

10)   Line efficiency increases for ________ transmission voltages.

a. Higher
b. Lower
c. Both (a) and (b)
d. None of these

11)   The most important disadvantage of using the high voltage for transmission is

a. The increased cost of insulating the conductors.
b. The increased cost of transformers, switchgear and the other terminal apparatus.
c. Both (a) and (b)
d. There is a reduction in the corona loss.

12)   The most suitable practical value of primary distribution is?

a. 66 kV
b. 6.6 kV
c. 230 V/ 400 V
d. 22 kV

13)   What is the main drawback of overhead system over underground system?

a. Surge problem
b. High initial cost
c. Higher charging current
d. Underground system is more flexible than overhead system

14)   For the same
conductor length, same amount of power, same losses and maximum voltage
to earth, which system requires minimum conductor area?

a. 3 wire ac
b. 2 wire ac
c. 2 wire dc
d. Single phase

15)   What is the highest possible transmission voltage in India?

a. 675 kV
b. 765 kV
c. 132 kV
d. 440 kV

16)   What is the main reason for using the high voltage for the long distance power transmission?

a. Reduction in the transmission losses
b. Reduction in the time of transmission
c. Increase in system reliability
d. None of these

 ANSWER: Reduction in the transmission losses
17)   The volume
of copper required in case of three wire two phase ac systems is how
many times to that of two wired dc system?

a. 2/cos2φ
b. 1/2 cos2φ
c. 1.457/ cos2φ
d. 6/1.457 cos2φ

18)   The volume
of copper required in case of four wire two phase ac systems is how many
times to that of two wired dc system?

a. 2/cos2φ
b. 1/2 cos2φ
c. 1.457/ cos2φ
d. 6/1.457 cos2φ

19)   By
increasing the transmission voltage double of its original value, the
same power can be despatched keeping the line losses _______________.

a. Equal to its original value.
b. Half of its original value.
c. Double the original value.
d. One – fourth of the original value.

 ANSWER: One – fourth of the original value.
20)   Which among
these is/are the fundamental economical principles that influence/s the
design of transmission lines?

a. Economic choice of conductor size.
b. Economic choice of transmission voltage.
c. Both (a) and (b)
d. Economic choice of transmission line length.

21)   The most
economical area of conductor is that for which the total annual cost of
transmission line is minimum. Which law states this?

a. Lenz’s law
b. Kelvin’s law
d. Ohm’s law

22)   The account
of interest and depreciation on the capital cost of complete
installation of transmission line is denoted by which factor?

a. Annual charge on capital outlay
b. Annual cost of energy wasted
c. Both (a) and (b)
d. Neither of these

 ANSWER: Annual charge on capital outlay
23)   The annual charge is given by

a. P1 + P2 / a
b. (P1 + P2) * a
c. P1 + P2 * a
d. P1 * a + P2

 ANSWER: P1 + P2 * a
24)   The annual cost of energy wasted is given by

a. P1 / a
b. P2 * a
c. P2 / a
d. P3 / a

25)   In the following graph what does the straight line represent?.

a. Relation between annual charge and the area of cross section.
b. Relation between annual cost of energy wasted and area of cross section.
c. Both (a) and (b).
d. None of these.

 ANSWER: Relation between annual charge and the area of cross section.
26)   In the following graph what does curve 2 represent?.

a. Relation between annual charge and the area of cross section.
b. Relation between annual cost of energy wasted and area of cross section.
c. Both (a) and (b).
d. None of these.

 ANSWER: Relation between annual cost of energy wasted and area of cross section.
27)   What does the point P refer to?.

a. Most economical power transmission.
b. Most economical area of cross section.
c. Both (a) and (b).
d. Most ideal point of transmission.

 ANSWER: Most economical area of cross section.
28)   Which among these is not the component of over head transmission lines?

a. Conductors
b. Cross arms
c. Danger plates
d. Transformers

29)   Which among these properties are not suitable for the conductor material?

a. High electrical conductivity.
b. High specific gravity.
c. Lower cost.
d. High tensile strength.

30)   What is the empirical formula to calculate the number of strands?

a. 3n (n+2n) + 2
b. 3n (n+1) + 2
c. 3n (n+1) + 1
d. 3n (3+ 3n) + 1

31)   The most ideal material for the over head conductor is copper. What are the advantages of this?

a. Smaller cross sectional area.
b. Area offered by the wind loads is reduced.
c. The price of copper is less.
d. Both (a) and (b).
e. None of these

32)   Which among the following properties has got a higher value for aluminium in comparison to that of copper?

a. Electrical resistivity.
b. Melting point.
c. Thermal conductivity.
d. Specific gravity.

33)   Why are galvanised steel conductors not suitable for transmitting large power over long distance?

a. Poor conductivity.
b. High resistance of steel.
c. More power loss.
d. Both (a) and (b).
e. None of these

34)   Why are the conductors used for higher voltage transmission stranded?

a. Ease of handling.
b. Cheaper cost.
c. Reduced resistivity.
d. Increase in tensile strength.

35)   Which material is used for the manufacture of ground wire?

a. Aluminium
b. Galvanised steel
c. Cast iron
d. Stainless steel

36)   The following materials of line conductor are given.

i. Hard drawn copper.
iii. Aluminium.
iv. Galvanised steel.

What is the correct series in descending order of their electrical conductivities?

a. a. i, ii, iv, iii.
b. B. ii, i, iv, iii.
c. C. ii, i, iii, iv.
d. D. i, ii, iii, iv.

 ANSWER: D. i, ii, iii, iv.
37)   When steel is reinforced what happens to the composite conductor?

a. 35 % more compared with equivalent weight of copper.
b. 25 % more compared with equivalent weight of copper.
c. 25 % less compared with equivalent weight of copper.
d. 35 % less compared with equivalent weight of copper.

 ANSWER: 25 % less compared with equivalent weight of copper.
38)   Why is A.C.S.R conductor used as the replacement or substitute for copper?

a. Higher current carrying capacity.
b. Economy.
c. Being less weight.
d. Higher tensile strength.

39)   What is the function of steel wire in A.C.S.R conductors?

a. Compensate for skin effect.
b. Takes care of surges.
c. Reduced capacitance and inductance.