Electrical Power Transmission & Distribution MCQ Part-4

July 02, 2021

1. The stringing charts are used for
A Finding the sag and tension in the conductor
B Finding the distance between the towers
C Design of insulator string
D Design of tower

Answer: A Finding the sag and tension in the conductor

2. The permissible voltage variation in transmission and distribution system is

A ± 0.1%

B ± 1%
C ± 10%
D ± 25%

ANSWER: C ± 10%

3. Bad weather conditions such as rain sleet

A Increases the corona loss
B Makes corona loss zero
С Decreases the corona loss
D Does not affect the corona loss

Answer: A Increases the corona loss

4. In order to lower cost of electrical generation,

A The load factor should be low and diversity the factor should be high
B The load factor should be high and diversity factor should be low
C The load factor and diversity factor should be high
D The load factor and diversity factor should be low

Answer: D The load factor and diversity factor should be low

5. Skin effect of a conductor will reduce as

A The diameter increases
B Frequency increases
C Permeability of the conductor material increases
D Resistivity of the conductor material increases

Answer: D Resistivity of the conductor material increases

6. In a 3 phase system, the area of cross section of the neutralis generally

A Same as that of the outer conductors
B Half of the outer conductors
C Quarter of the Oputer conductors
D Double of the outer conductors

Answer: B Half of the outer conductors

7. Number of insulator discs, each rated 11 kV, required in a suspension type insulator string for 66 kV line is

A 6
B More than 6
C 12
D Less than 6

Answer: D Less than 6

8. Earth wire on EHV overhead transmission line is provided to protect the line against

A Lightning surge
B Switching surge
C Excessive fault voltages
D corona effect

Answer: A Lightning surge

9. For transmission line, which one of the following relation is true?

A AD - BC = 1
B AD- BC = 1
C AD - BC = 0
D AD - BC = 3

Answer: A AD - BC = 1

10. The inductance of a transmission line is minimum when

A GMD is high
B GMR is high
C Both GMD and GMR are high
D GMD is low and GMR is high

Answer: A GMD is high

11. For a 500 Hz Frequency excitation, a 50 km long power line will be modelled as

A short line
B medium line
C long line
D data insufficient for decision

Answer: C long line

12. HVDC transmission is preferred to EHV AC because

A HVDC terminal equipment are inexpensive
B VAR compensation is not required in HVDC system
C System stability can be improved
D Harmonic problem is avoided

Answer: C System stability can be improved

13. If X is the system reactance and Rits resistance, the power transferred is maximum when

A X=R
B X = root of R
C X = root of 3R
D X = 2R

Answer: C X = root of 3R

14. A single phase transmission line of impedance 0.8 supplies aresistive load of 500 A at 300 V. The sending power factor is

A unity
B 0.8 lagging
C 0.8 leading
D 0.6 lagging

Answer: D 0.6 lagging

Load impedance Z= R = V/1 = 0.6

Line impedance = 0.8 (inductive)

Total impedance from sending = 0.6+j0.8

Power factor = R/Z= 0.6/1 = 0.6 lag

15. The power generated by two plants are; P1 = 50 MW, P2 = 40 MW. If the loss coefficients are B11 = 0.0025, B12 = -0.0005, then the power loss will be

A 5.5 MW

B 6.5 MW

С 4.5 MW

D 8.5 MW

Answer: С 4.5 MW

16. Which of the following is a series FACTS device?

А TCSC

B SVC

C STATCOM

D None of these

Answer : А TCSC

17. The function of shunt reactor is

A to control the steady state over voltage when line is lightly loaded

B to improve the transfer capability of the line

C to limit short circuit current

D None of these

Answer: A to control the steady state over voltage when line is lightly loaded

18. For a 5 Hz Frequency excitation, a 400 km long power line will be modelled as

A long line

B short line

C medium line

D data insufficient for decision

Answer: B short line

19. In AC transmission line system there is difference in phase voltage at the two ends of line due to

A earthing of line

B system voltage

C insulators

D reactance of line

Answer: D reactance of line

20. Chandrapur-Padghe HVDC Line is operated by

А MSEB

B PGVCL

C PGCIL

D Govt. Of india

Answer: А MSEB

21. Nationwide synchronous power grid, interconnecting all the five regional grids, has been established in

A 2013

B 2014

C 2015

D 2012

Answer: A 2013

22. Which of the following forms of energy has a long-term [next 50 years) estimated availability?

A Low-temperature heating from solar energy

B Synthetic oil and alcohols from coal

C Photovoltaic production of electricity

D Coal

Answer: C Photovoltaic production of electricity

23. The power transmission capability of bipolar lines is approximately

A half that of 3-phase single circuit line

B the same as that of 3-phase single circuit line

C twice that of 3-phase single circuit line

D thrice that of 3-phase single circuit line

Answer: B the same as that of 3-phase single circuit line

24. The low power factor of an industrial plant is uneconomical for

A electric supply utility only

B owner of the plant only

C both the owner of the plant and electric supply utility

D either [A] or [B]

Answer: C both the owner of the plant and electric supply utility

25. A thermal generating station has installed capacity of 15 MW and supplies a load of 10 MW for 12 hours and 5 MW For remaining 12 hours. The plant capacity factor for this station is

A 0.5

B 0.67

C 0.75

D 1

Answer: A 0.5

26. Series reactors are used to

A improve voltage regulation

B improve the PF

C improve the transmission efficiency

D bring down the fault level within the capacity of switchgear

Answer: D bring down the fault level within the capacity of switchgear

27. The voltage regulator having dead zero effect is