Deck 1: Electrical Power Transmission and Distribution

Question 1

If variable part of annual cost on account of interest and depreciation on the capital outlay is equal to the annual cost of electrical energy wasted in the conductors, the total annual cost will be minimum and the corresponding size of conductor will be most economical. This statement is known as

A)Kelvin's law
B)Ohm's law
C)Kirchhoffs law
D)Faraday's law

Answer 1

Kelvin's law

Question 2

are the conductors, which connect the consumer's terminals to the distribution

A)Distributors
B)Service mains
C)Feeders
D)None of the above

Answer 2

Service mains

Question 3

The underground system cannot be operated above

A)440 V
B)11 kV
C)33 kV
D)66 kV

Answer 3

66 kV

Question 4

Overhead system can be designed for operation upto

A)11 kV
B)33 kV
C)66 kV
D)400 kV

Question 5

The wooden poles well impregnated with creosite oil or any preservative compound have life

A)from 2 to 5 years
B)10 to 15 years
C)25 to 30 years
D)60 to 70 years

Question 6

Which of the following materials is not used for transmission and distribution of electrical power ?

A)Copper
B)Aluminium
C)Steel
D)Tungsten

Question 7

Galvanised steel wire is generally used as

A)stay wire
B)earth wire
C)structural components
D)all of the above

Question 8

The usual spans with R.C.C. poles are

A)40-50 metres
B)60-100 metres
C)80-100 metres
D)300-500 metres

Question 9

The corona is considerably affected by which of the following ?

A)Size of the conductor
B)Shape of the conductor
C)Surface condition of the conductor
D)All of the above

Question 10

Which of the following are the constants of the transmission lines ?

A)Resistance
B)Inductance
C)Capacitance
D)All of the above

Question 11

310 km line is considered as

A)a long line
B)a medium line
C)a short line
D)any of the above

Question 12

The phenomenon qf rise in voltage at the receiving end of the open-circuited or lightly loaded line is called the

A)Seeback effect
B)Ferranti effect
C)Raman effect
D)none of the above

Question 13

The square root of the ratio of line impedance and shunt admittance is called the

A)surge impedance of the line
B)conductance of the line
C)regulation of the line
D)none of the above

Question 14

Which of the following is the demerit of a 'constant voltage transmission system' ?

A)Increase of short-circuit current of the system
B)Availability of steady voltage at all loads at the line terminals
C)Possibility of better protection for the line due to possible use of higher terminal reactances
D)Improvement of power factor at times of moderate and heavy loads

Question 15

Low voltage cables are meant for use up to

A)l.lkV
B)3.3kV
C)6.6kV
D)llkV

Question 16

The operating voltage of high voltage cables is upto

A)l.lkV
B)3.3kV
C)6.6kV
D)llkV

Question 17

The operating voltage of supertension cables is upto

A)3.3 kV
B)6.6 kV
C)11 kV
D)33 kV

Question 18

The operating voltage of extra high tension cables is upto

A)6.6 kV
B)11 kV
C)33 kV
D)66 kV

Question 19

Which of the following methods is used for laying of underground cables ?

A)Direct laying
B)Draw-in-system
C)Solid system
D)All of the above

Question 20

Due to which of the following reasons the cables should not be operated too hot ?

A)The oil may loose its viscosity and it may start drawing off from higher levels
B)Expansion of the oil may cause the sheath to burst
C)Unequal expansion may create voids in the insulation which will lead to ionization
D)All of the above

Question 21

Which of the following D.C. distribution system is the simplest and lowest in first cost?

A)Radial system
B)Ring system
C)Inter-connected system
D)None of the above

Question 22

A booster is a

A)series wound generator
B)shunt wound generator
C)synchronous generator
D)none of the above

Question 23

Besides a method of trial and error, which of the following methods is employed for solution of network problems in interconnected system ?

A)Circulating current method
B)Thevenin's theorem
C)Superposition of currents
D)All of the above

Question 24

Which of the following faults is most likely to occur in cables ?

A)Cross or short-circuit fault
B)Open circuit fault
C)Breakdown of cable insulation
D)All of the above

Question 25

The cause of damage to the lead sheath of a cable is

A)crystallisation of the lead through vibration
B)chemical action on the lead when buried in the earth
C)mechanical damage
D)all of the above