Transmission and Distribution line MCQ Part-2

1. With the same maximum voltage to earth, which of the following ac system with 0.8 pf will need more copper in comparison to DC 2-wire system ?________.

a. Single-phase, 2-wire (midpoint earthed)

b. Single-phase, 3-wire (neutral half of outer) 

c. Three-phase, 3-wire

d. Three-phase, 4-wire (neutral=outer)

2. The approximate cost ratio of a 220 kV, underground cable transmission and 220 kV O/H transmission is__________.

a. 50

b. 25

c. 13

d. 5

3. 66 kV is suitable for transmission of power over____________.

a. 30 km

b. 60 km

3. 120 km

4. 200 km 

4. If 3 MW power is to be transmitted over a distance of 30 km, the desirable transmission voltage will be__________.

a. 11 kV

b. 33 kV

c. 66 kV

d. 3.3 kV

5. 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. Lenz's law

b. Faraday's law

c. Kelvin's law

d. Ohm's law

6. For high-voltage transmission lines, conductors are suspended from towers so as to __________.

a. Increase clearance from ground 

b. Reduce clearance from ground

c. Take care of increase in length

d. Reduce wind and snow effects

 

7. The supports used for transmission line should have the characteristics of ___________.

a. High mechanical strength and longer life

b. Good looking, light in weight and easily accessible for painting and erection of line conductors

c. Cheap in initial as well as maintenance cost

d. All of the above 

8. The wooden poles well impregnated with creosite oil or any preservative compound have a life of _____.

a. 25-30 years

b. 20-25 years

c. 10-15 years

d. 5-10 years

9. Steel poles for transmission lines need protective against_______.

a. Borer

b. Termites

c. Corrosion

d. All of these

10. In India for distribution of power we usually use ________.

a. Wooden poles 

b. Steel poles

c. RCC poles

d. Both (b) and (c)

 

11. Conductors used in HT line are stranded because_____.

a. Increased tensile strength 

b. Ease in handling

c. Cheaper in cost

d. Reduced resistivity

12. Which of the following property has got higher values for  Aluminium comparison  to Copper ?

a. Electrical resistivity

b. Melting point 

c. Thermal conductivity

d. Specific Gravity

13. In 7/30 ACSR conductor why is grease is put between steel and aluminium conductors ?

a. To reduce corrosion by electrolytic action between zinc and aluminium

b. To reduce friction between the strands

c. To reduce leakage of current from aluminium strands to steel strands

d. To eliminate air pockets

14. ACSR used in place of copper in overhead lines because of _________.

a. Higher current carrying capacity 

b. Being lighter in weight

c. Economy

d. Higher tensile strength

15. ACSR conductors have________.

a. All conductors made of aluminium

b. Outer conductors made of aluminium

c. Inner conductors made of aluminium

d. No conductors made of aluminium

16. "Expanded ACSR" are conductors composed of________.

a. Larger diameter individual strands for a given cross section of the aluminium strands

b. Larger diameter of the central steel strands for a given overall diameter of the conductor 

c. Larger diameter of the aluminium strands only for a given overall diameter of conductor

d. A filter between the inner steel and the outer aluminium strands to increase the overall diameter of the conductor

17. The function of steel wire in an ACSR conductor is to_______.

a. Compensate for skin effect 

b. Take care of surges

c. Provide additional mechanical strength

d. Reduce inductance

18. The material used for the manufacture of ground wire is__________.

a. Aluminium 

b. Galvanised steel

c. Cast iron 

d. Stainless steel

19. Guy wire is employed for_______.

a. Providing protection against surges

b. Providing emergency earth route

c. Supporting the pole 

d. All of the above

20. The sag of a transmission line is least affected owing to________.

a. Weight of the conductor

b. Current through the conductor

c. Atmospheric temperature

d. Ice deposition on the conductor

21. Effect of temperature rise in overhead lines is to_______.

a. Increase the sag and decrease the tension

b. Decrease the sag and increase the tension

c. Increase both

d. Decrease both 

22. The sag of a transmission line conductor in summer is________.

a. Less than that in winter

b. More than that in winter

c. Same as in winter

23. In a transmission line, sag depends upon_________.

a. Span length 

b. Tension in conductors

c. Weight of the conductor per unit length

d. All of the above

 

24. Which of the following statement is correct ?

a. Ice on conductor increases skin effect

b. Wind pressure reduces corona effect

c. Wind pressure is taken to act at perpendicular to that for ice

d. Ice on conductor reduces sag

25. Wind loading in coastal regions is in the range of________.

a. 40-5- kg/m²

b. 150 kg/m²

c. 96 kg/m²

^{Transmission and distribution line MCQ Part-1}

^{Transmission and Distribution line MCQ Part-3}

^{Transmission and Distribution line MCQ Part-4}

^{Transmission and Distribution line MCQ Part-5}

^{Transmission and Distribution line MCQ Part-6}

^{Transmission and Distribution line MCQ Part-7}