Power System - Transmission & Distribution Test Set - 2

1)   What is the general ratio of the cross sectional area of the two metals used in the A.C.S.R conductors?

a. 1 : 8
b. 1 : 4
c. 4 : 3
d. 2 : 1
Answer  Explanation  Related Ques

ANSWER: 1 : 4

Explanation:
No explanation is available for this question!


2)   Assertion (A): The maximum operating temperature of overhead line conductors made of aluminium or copper is restricted to 75 °C.
Reason (R): conductors beyond this limit may shatter the insulator.


a. Both A and R are true and R is the correct explanation of A
b. Both A and R are true and R is not the explanation of A
c. A is true but R is false
d. A is false but R is true.
Answer  Explanation  Related Ques

ANSWER: A is true but R is false

Explanation:
No explanation is available for this question!


3)   For high voltage transmission lines, why are conductors suspended from towers?

a. Increase the clearance from ground.
b. Reduce clearance from ground.
c. Take care of increase in length.
d. Reduce the environmental effects.
Answer  Explanation  Related Ques

ANSWER: Increase the clearance from ground.

Explanation:
No explanation is available for this question!


4)   In India, which types of poles are commonly used for distribution?

a. Wooden poles
b. RCC poles
c. Steel poles
d. Both (b) and (c)
e. None of these
Answer  Explanation  Related Ques

ANSWER: Both (b) and (c)

Explanation:
No explanation is available for this question!


5)   Which among these are the properties for the line supports?

a. Higher mechanical strength
b. Light in weight
c. Easy accessibility of conductors for maintenance
d. All of these
Answer  Explanation  Related Ques

ANSWER: All of these

Explanation:
No explanation is available for this question!


6)   What is the maximum permissible limit of voltage for the line supports?

a. 30 kV
b. 20 kV
c. 11 kV
d. 44 kV
Answer  Explanation  Related Ques

ANSWER: 20 kV

Explanation:
No explanation is available for this question!


7)   To prevent rotting oil the wooden poles which oil is impregnated to it?

a. Kerosene oil
b. Mineral oil
c. Creosote oil
d. All of these
Answer  Explanation  Related Ques

ANSWER: Creosote oil

Explanation:
No explanation is available for this question!


8)   Steel poles are painted so as to prevent it from ____________.

a. Corrosion
b. Borer
c. Termites
d. All of these
Answer  Explanation  Related Ques

ANSWER: Corrosion

Explanation:
No explanation is available for this question!


9)   Which among these is not a type of steel poles?

a. Rail poles
b. Tubular poles
c. Rolled steel joints
d. None of these
Answer  Explanation  Related Ques

ANSWER: None of these

Explanation:
No explanation is available for this question!


10)   What is the usual span of the RCC poles?

a. 250 – 400 m.
b. 80 – 150 m.
c. 50 – 105 m.
d. 10 – 75 m.
Answer  Explanation  Related Ques

ANSWER: 80 – 150 m.

Explanation:
No explanation is available for this question!


11)   What is the main purpose for guy wire?

a. Supports the pole
b. Protects against the surges
c. Provides emergency earth route
d. All of these
Answer  Explanation  Related Ques

ANSWER: Supports the pole

Explanation:
No explanation is available for this question!


12)   Sag depends on which factor?

a. Span length
b. Weight of the conductors
c. Tension in the conductors
d. All of these
Answer  Explanation  Related Ques

ANSWER: All of these

Explanation:
No explanation is available for this question!


13)   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
Answer  Explanation  Related Ques

ANSWER: Catenary

Explanation:
No explanation is available for this question!


14)   Conductor sag should be kept

a. Minimum
b. Maximum
c. Zero
d. None of these
Answer  Explanation  Related Ques

ANSWER: Minimum

Explanation:
No explanation is available for this question!


15)   What is the minimum safety factor in respect of the conductor tension?

a. 1
b. 3
c. 2
d. 1.5
Answer  Explanation  Related Ques

ANSWER: 2

Explanation:
No explanation is available for this question!


16)   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
Answer  Explanation  Related Ques

ANSWER: 13.7 m

Explanation:
No explanation is available for this question!


17)   Sag is directly proportional to the square of span.

a. True
b. False


Answer  Explanation  Related Ques

ANSWER: True

Explanation:
No explanation is available for this question!


18)   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
Answer  Explanation  Related Ques

ANSWER: The higher support

Explanation:
No explanation is available for this question!


19)   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.
Answer  Explanation  Related Ques

ANSWER: Breaking stress to working stress.

Explanation:
No explanation is available for this question!


20)   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
Answer  Explanation  Related Ques

ANSWER: Increase the sag and decrease the tension

Explanation:
No explanation is available for this question!


21)   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
Answer  Explanation  Related Ques

ANSWER: 14 and 8.39

Explanation:
No explanation is available for this question!


22)   Why is stringing chart useful?

a. For finding the sag in the conductor
b. In the design of insulator string
c. In the design of tower
d. To find the distance between the towers
Answer  Explanation  Related Ques

ANSWER: For finding the sag in the conductor

Explanation:
No explanation is available for this question!


23)   Which line represents the tension in the given graph?
Temperature vs Tension and sag


a. I
b. II
c. III
d. IV
Answer  Explanation  Related Ques

ANSWER: II

Explanation:
No explanation is available for this question!


24)   In the following graph which curve represents the sag?
Temperature vs Tension and sag


a. I
b. II
c. III
d. IV
Answer  Explanation  Related Ques

ANSWER: I

Explanation:
No explanation is available for this question!


25)   Hot template curves are a plot between

a. Temperature and humidity
b. Conductors sag and span lengths
c. Conductor weight and sag
d. None of these
Answer  Explanation  Related Ques

ANSWER: Conductors sag and span lengths

Explanation:
No explanation is available for this question!


26)   Galloping in transmission line conductors arises due to

a. Asymmetrical layers of ice formation.
b. Vortex phenomenon in light winds.
c. Heavy weight of the line conductors.
d. Adoption of horizontal conductor configuration.
Answer  Explanation  Related Ques

ANSWER: Asymmetrical layers of ice formation.

Explanation:
No explanation is available for this question!


27)   What is the frequency of aeoline vibrations?

a. fα = 2 * (Vp / d) * 1000
b. fα = 2 * (Vp * d) * 1000
c. fα = 2 / (Vp * d) * 1000
d. fα = 2 / (Vp / d) * 1000
Answer  Explanation  Related Ques

ANSWER: fα = 2 * (Vp / d) * 1000

Explanation:
No explanation is available for this question!


28)   What are the different types of vibrations in the vertical plane?

a. Aeoline vibrations
b. Galloping
c. Both (a) and (b)
d. None of these
Answer  Explanation  Related Ques

ANSWER: Both (a) and (b)

Explanation:
No explanation is available for this question!


29)   What is the minimum clearance of HV lines from ground across the streets?

a. 3 m.
b. 6 m.
c. 5 m.
d. 8 m.
Answer  Explanation  Related Ques

ANSWER: 6 m.

Explanation:
No explanation is available for this question!


30)   What is the minimum horizontal clearance of a LV line from a residential building?

a. 0.6 m.
b. 0.9 m.
c. 1.2 m.
d. 1.6 m.
Answer  Explanation  Related Ques

ANSWER: 1.2 m.

Explanation:
No explanation is available for this question!


31)   If a 132 kV line passes over a residential building, what shall be the minimum vertical clearance from the roof of the building?

a. 3 m.
b. 4.57 m.
c. 6.38 m.
d. 9.27 m.
Answer  Explanation  Related Ques

ANSWER: 4.57 m.

Explanation:
No explanation is available for this question!


32)   What is the minimum clearance provided for the 132 kV line from the ground?

a. 3.2 m.
b. 6.4 m.
c. 7.5 m.
d. 10.5 m.
Answer  Explanation  Related Ques

ANSWER: 6.4 m.

Explanation:
No explanation is available for this question!


33)   What is the horizontal spacing between phase conductors of 132 kV line?

a. 8 m.
b. 11 m.
c. 14 m.
d. 17 m.
Answer  Explanation  Related Ques

ANSWER: 8 m.

Explanation:
No explanation is available for this question!


34)   Which type of insulator is used on 132 kV transmission lines?

a. Pin type
b. Disc type
c. Shackle type
d. Pin and shackle type
Answer  Explanation  Related Ques

ANSWER: Disc type

Explanation:
No explanation is available for this question!


35)   Where are the strain type insulators used?

a. At dead ends
b. At any intermediate anchor tower
c. On straight runs
d. Either (a) or (b)
Answer  Explanation  Related Ques

ANSWER: Either (a) or (b)

Explanation:
No explanation is available for this question!


36)   Porcelain is produced by firing at high temperature due to mixtures of _________.

a. Kaolin
b. Feldspar
c. Quartz
d. All of these
Answer  Explanation  Related Ques

ANSWER: All of these

Explanation:
No explanation is available for this question!


37)   What is the dielectric strength of porcelain?

a. 55 kV/cm.
b. 60 kV/cm.
c. 75 kV/cm.
d. 80 kV/cm.
Answer  Explanation  Related Ques

ANSWER: 60 kV/cm.

Explanation:
No explanation is available for this question!


38)   Why is the wavy structure of pin insulators used?

a. Increases mechanical strength.
b. Increases puncture strength.
c. Increases flash over voltage.
d. Increases thermal strength.
Answer  Explanation  Related Ques

ANSWER: Increases flash over voltage.

Explanation:
No explanation is available for this question!


39)   The number of discs in a string of insulators for 400 kV ac over head transmission line lies in the range of

a. 32 – 33
b. 22 – 23
c. 15 – 16
d. 9 – 10
Answer  Explanation  Related Ques

ANSWER: 22 – 23

Explanation:
No explanation is available for this question!


40)   What is the maximum voltage level upto which the pin type insulators can be used?

a. 22 kV
b. 33 kV
c. 66 kV
d. 132 kV
Answer  Explanation  Related Ques

ANSWER: 33 kV

Explanation:
No explanation is available for this question!