POWER SYSTEMS MCQS SET 02

POWER SYSTEMS MCQS SET 02

Transmission & Distribution of Electrical Power  

1. How many cores are used in a cable for the transmission of voltages upto 66 kV?
a. Single core.     b. Two core.     c. Three core.     d. All
ANSWER: c. Three core.
 

2. Why is the single core cables not provided with armouring?
a. Avoids excessive loss in the armour.
b. Make the cable more flexible.
c. Make the cable non hygroscopic.
d. None of the above.
ANSWER: a. Avoids excessive loss in the armour.
 

3. Which among the following cables are generally suited for the voltages upto 11 kV?
a. Belted cables      b. Screened cables     c. Pressure cables
d. None of these.
ANSWER: a. Belted cables
 

4. Which material is suitable for the manufacture of armour in a single core cable?
a. Magnetic material.
b. Non magnetic and non conducting material.
c. Non magnetic and conducting material.
d. Magnetic and non conducting material.
ANSWER: c. Non magnetic and conducting material.
 

5. Why the belted type cable constructions are not suitable for voltages exceeding 22 kV?
a. Development of both radial and tangential stress.
b. Formation of vacuous spaces and voids on loading and unloading owing to non homogeneity of dielectric in belted construction.
c. Local heating caused by power loss at the centre filling.
d. All of the above.
ANSWER: d. All of the above.
 

6. The cable best suited for the transmission of voltages from 33 kV to 66 kV 

is_______________.
a. Belted cables               b. Screened cables
c. Pressure cables           d. None of these.
ANSWER: b. Screened cables
 

7. What is/ are the advantages of using H-type cables?
a. The metallic screens assist in complete impregnation of the cable with the compound.
b. The metallic screens increase the heat dissipating power of the cable.
c. The lead sheaths in H type are thicker then S.L type cables.
d. All of these.
ANSWER: d. All of these.
 

8. What is the advantage(s) of screened type over the belted cables?
a. Reduced possibility of core to core faults.
b. Increased current carrying capacity.
c. No possibility of formation of voids within the dielectric.
d. All of the above.
ANSWER: d. All of the above.
 

9. What is the gas pressure of SF6 for a compressed gas insulated cable?
a.10 – 20 mm Hg         b. 80 – 100 mm Hg
c. 3 – 5 kg / cm2                  d. 40 – 50 kg / cm2
ANSWER: c. 3 – 5 kg / cm2
 

10. Why are the ternary lead cables used near the railway tracks?
a. Because they have high tensile strength.
b. Have a low coefficient of thermal expansion.
c. Have low specific gravity.
d. Can withstand shocks and vibrations.
ANSWER: c. Have low specific gravity.