SAG and SAG calculation - MCQs with answers

SAG and SAG calculation - MCQs with answers


Q1. Sag depends on which factor?

a. Span length.
b. Weight of the conductors.
c. Tension in the conductors.
d. All of the above.

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ANSWER: d. All of the above.



Q2. What is the shape that is attained by the conductors if suspended from the same height?

a. Parabola.
b. Catenary.
c. Semi circle
d. None of these.

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ANSWER: b. Catenary.



Q3. Conductor sag should be kept

a. Minimum
b. Maximum.
c. Zero.
d. None of these.

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ANSWER: a. Minimum



Q4. What is the minimum safety factor in respect of the conductor tension?

a. 1
b. 3
c. 2
d. 1.5

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ANSWER: c. 2



Q5. A 132 kV transmission line, with the weight of conductor = 680 kg/km, length of span = 260 m, ultimate strength = 3100 kg, safety factor =2. Calculate the height above ground at which the conductor should be supported. Ground clearance required is 10 m.

a. 10.7 m
b. 13.7 m
c. 20.83 m
d. 18.75 m

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ANSWER: b. 13.7 m



Q6. Sag is directly proportional to the square of span.

a. True
b. False.

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ANSWER: a. True



Q7. The maximum tension in a section of overhead line conductor between two supports of unequal height occurs at

a. The higher support.
b. The lower support.
c. Midpoint of the conductors.
d. None of these.

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ANSWER: a. The higher support.



Q8. Safety factor is the ratio of

a. Working stress to breaking stress.
b. Breaking stress to working stress.
c. 1 / breaking stress.
d. 1 / working stress.

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ANSWER: b. Breaking stress to working stress.



Q9. What is the effect of temperature rise on the over head lines?

a. Increase the sag and decrease the tension.
b. Decrease the sag and increase the tension.
c. Both increases.
d. Both decreases.

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ANSWER: a. Increase the sag and decrease the tension.



Q10. A transmission line has a span of 250 metres between the line supports. The conductors has a cross sectional area of 1.29 cm2 and weighs 1170 kg/km and has a breaking stress of 4218 kg/cm2. Calculate the sag and vertical sag with a safety factor of 5, with a wind pressure of 122 kg per square metre of the projected area.

a. 14 and 5.37
b. 16 and 8.39
c. 14 and 8.39
d. 15 and 5.37

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ANSWER: c. 14 and 8.39


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