Transmission & Distribution MCQs

1. 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
(e) Possibility of carrying increased power for a given conductor size in case of long distance heavy power transmission

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Answer. a

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

(a) surge impedance of the line
(b) the conductance of the line
(c) regulation of the line
(d) none of the above

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Answer. a

3. The phenomenon of rising 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

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Answer. b

4. 310 km line is considered as

(a) a long line
(b) a medium line
(c) a short line
(d) any of the above

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Answer. a

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

(a) Resistance
(b) Inductance
(c) Capacitance
(d) All of the above

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Answer. d

6. 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

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Answer. d

7. 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

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Answer. c

8. Galvanised steel wire is generally used as

(a) stay wire
(b) earth wire
(c) structural components
(d) all of the above

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Answer. d

9. Which of the following materials are not used for transmission and distribution of electrical power?

(a) Copper
(b) Aluminium
(c) Steel
(d) Tungsten

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Answer. d

10. 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

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Answer. c

11. If variable part of the 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 the conductor will be most economical. This statement is known as

(a) Kelvin’s law
(b) Ohm’s law

(c) Kirchhoff’s law
(d) Faraday’s law
(e) none of the above

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Answer. a

12. Overhead system can be designed for operation up to

(a) 11 kV
(b) 33 kV
(c) 66 kV
(d) 400 kV

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Answer. c

13. The underground system cannot be operated above

(a) 440 V
(b) 11 kV
(c) 33 kV
(d) 66 kV

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Answer. d

14. ………………….  are the conductors, which connect the consumer’s terminals to the distribution

(a) Distributors
(b) Service mains
(c) Feeders
(d) None of the above

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Answer. b

15. By which of the following systems electric power may be transmitted?

(a) Overhead system
(b) Underground system
(c) Both (a) and (b)
(d) None of the above

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Answer. c