Electrical Power Transmission & Distribution MCQs Part-01


1. A counterpoise is buried under a transmission line:


(A) To increase the ground resistance
(B) To decrease the ground resistance
(C) To increase design strength
(D) To increase inductance

Answer: (B) To decrease the ground resistance

2. The disadvantage of Low power factor:

(A) Raises rating of transmission equipment
(B) Increased voltage drops
(C) Poor voltage regulation
(D) All of these
(E) None of these

Answer: (D) All of these

3. The resistance of a transmission line:


(A) Increase with the increase of length
(B) Increases with the decrease of length
(C) Is independent of the length
(D) Any of above

Answer: (A) Increase with the increase of length

4. The relationship between the volume of transmission line conductor to voltage:


(A) It is directly related to the voltage
(B) It is directly related to the square of the voltage
(C) It is inversely related to the voltage
(D) It is inversely related to the square of the voltage

Answer: (D). It is inversely related to the square of the voltage

5. Charging current in underground lines:


(A) Is negligible
(B) Is more than OH lines
(C) Is smaller than OH lines
(D) Is equal to OH lines

Answer: (B). Is more than OH lines

6. An increase in the length of the transmission line by 15% increases the sag by:
(A) 15%
(B) 25%
(C) 32%
(D) 48%

Answer: (C). 32%

7. Find the age of a 200 m long transmission line having 0.5 kg/km weight and working tension of 1000 kg:


(A) 2.5 m
(B) 5 m
(C) 7.5 m
(D) 10 m

Answer: (A). 2.5 m

Solution: Sag = (weight * length * length) / (8 * Tension)

8. The more practical case for transmission lines installation:


(A) Install more towers and reduce the height of each tower
(B) Install fewer towers and increase the height
(C) Install more towers and increase the height
(D) Install fewer towers and reduce the height

Answer: (A). Install more towers and reduce the height of each tower

9. Generally, overhead transmission lines insulators are made from:


(A) Glass
(B) Aluminum
(C) Porcelain
(D) Plastic
(E) Polythene

Answer: (C). Porcelain

10. Corona on transmission lines:


(A) Results energy loss
(B) Produces ozone
(C) Increases diameter of the conductor
(D) None of these
(E) All of these

Answer: (E). All of these



11. Worldwide Power transmission is done at:


(A) 100 – 500 kV
(B) 254 – 380 kV
(C) 138 – 765 kV
(D) 1000 kV – 5000 kV

Answer: (C). 138 – 765 kV


12. Single-Stage Optimization Model is limited in providing:


(A) Information on expansion timing
(B) Year by year expansion calculations
(C) Both of these
(D) None of these

Answer: (A). Information on expansion timing


13. The factors which should be considered while designing overhead lines:


(A) Voltage level
(B) Protection techniques
(C) Sag
(D) Stress
(E) All of these

Answer: (E). All of these


14. OH Power transmission comprises:


(A) 3-phase, 3-wire
(B) 3-phase, 4-wire
(C) 3-phase, 2-wire
(D) 2-phase, 2-wire

Answer: (A). 3-phase, 3-wire
Series capacitors are employed to

15. Series capacitors are employed to:


(A) Transform voltages
(B) Reduce line impedance
(C) Decrease voltages
(D) Disconnect lines

Answer: (B). Reduce line impedance


16. HVDC Transmission requires:


(A) 2 conductors
(B) 3 conductors
(C) 4 conductors
(D) 5 conductors

Answer: (A). 2 conductors


17. HVDC voltage has:


(A) No corona losses
(B) Same corona losses as in AC
(C) Lesser corona losses than AC
(D) More corona losses than AC

Answer: (C). Lesser corona losses than AC

18. Transmission lines having span 250 km or higher are considered:


(A) Short transmission lines
(B) Medium transmission lines
(C) Long transmission lines
(D) None of these

Answer: (C). Long transmission lines
Usually, electric power systems are represented via

19. Usually, electric power systems are represented via:


(A) Three-phase diagrams
(B) Single line diagram
(C) Two-phase diagram
(D) None

Answer: (B). Single line diagram


20. The nodal point of transmission networks:


(A) CTs
(B) PTS
(C) Buses
(D) Breakers

Answer: (C). Buses


21. DC transmission is _____ less expensive than a transmission for the same power ratings:


(A) 20%
(B) 33%
(C) 66%
(D) 80%

Answer: (B). 33%

22. Overhead transmission lines have a break-even distance of:


(A) 200 mile
(B) 500 mile
(C) 1000 mile
(D) 5000 mile

Answer: (B). 500 mile

23. With a decrease in the size of the conductor the corona effect:


(A) Increases
(B) Decreases
(C) Remains constant
(D) Any of above

Answer: (A). Increases

24. In stormy weather the corona effect:


(A) Occurs at a lower temperature
(B) Occurs at the high temperature
(C) Does not occurs
(D) The storm has no relationship with corona

Answer: (A). Occurs at a lower temperature

25. The safety factor of the insulator is defined as the:


(A) Puncture strength / Flash – overvoltage
(B) Puncture strength * Flash – overvoltage
(C) ( 0.5 * Puncture strength) / (0.88 Flash – overvoltage)
(D) 1 / Puncture strength

Answer: (A). Puncture strength / Flash – overvoltage

26. Power factor of dc transmission lines is:


(A) Leading
(B) Lagging
(C) Unity
(D) Zero

Answer: (C). Unity

27. Converters in dc transmission lines:
(A) Consume reactive power
(B) Produce reactive power
(C) None of above
(D) Any of above

Answer: (A). Consume reactive power

28. A punctured insulator is:


(A) Permanently damaged
(B) Partially damaged
(C) Repaired by waxing
(D) Repaired by filling

Answer: (A). Permanently damaged

29. With an increase in frequency the skin effect:


(A) Increases
(B) Decreases
(C) Remains constant
(D) Any of above

Answer: (A). Increases

30. Length of cable is halved, the capacitance will:


(A) Remain constant
(B) Halved
(C) Doubled
(D) Will increase by 1.33 times

Answer: (B). Havled





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