Why Earth Wire is provided in the overhead transmission lines?

Why Earth Wire is provided in the overhead transmission lines?
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1 Answer

Answer :

Earth wire is provided above the overhead transmission lines for protection against lightning strokes. The ground wire or earth wire protects the phase conductors or line conductors by attracting itself the lightning strokes which in its absence would strike the phase conductors. Also the ground wire reduces the voltage electrostatically or electromagnetically induced in the conductors by the discharge of a neighboring cloud. It also provides the additional protective effect by causing the attenuation of traveling waves set in the lines by acting a short circuit secondary of the line current
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Description : What is the difference between the lightning arrester and surge absorber?

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What is meant by protective angle? Give its value for reliable operation?

Description : What is meant by protective angle? Give its value for reliable operation?

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Description : What is the material used for overhead transmission lines?

Last Answer : Answer: ACSR conductors are employed.

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Why are overhead transmission lines not insulated?

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Last Answer : Answer: A

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Description : What for series and shunt compensation provided in EHV transmission lines?

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What can I do about a wall switch for an overhead light if the socket doesn't have a neutral wire and the switch does?

Description : What can I do about a wall switch for an overhead light if the socket doesn't have a neutral wire and the switch does?

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Differentiate between overhead transmission and underground transmission.

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Last Answer : D

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Description : An overhead transmission line has a span of 260 m. The weight of the conductor is 0.68 kg/m. The maximum allowable tension in the line is 1550 kg. Maximum sag of the line should be (a) 5.8 m (b) 4.6 m (c) 2.7 m (d) 3.7 m 

Last Answer : Maximum sag = (l^2)/8c So c = T/W c = 1550/0.68 c= 2279.4 Now Maximum sag = (260^2)/8(2279.4) = 3.7 (d)

Surge impedance of overhead transmission line is normally in the order of

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A long overhead transmission line is terminated by its characteristic...

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The time taken for a surge to travel a 600 km long overhead transmission line is?

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An overhead transmission line has a span of 240m between level ...

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Last Answer : Ans: C Xc= 1/ ωc

In a three-phase electrical system, three ground detecting lamps are provided. One lamp goes dark and the others increase in brightness. When the test button is pushed, all lamps have equal illumination. You should conclude that ____________. A. there is a ground on the line with the dark lamp B. the dark lamp must be replaced C. there are grounds on the lines with the bright lamps D. this is a normal condition

Description : In a three-phase electrical system, three ground detecting lamps are provided. One lamp goes dark and the others increase in brightness. When the test button is pushed, all lamps have equal illumination. You ... C. there are grounds on the lines with the bright lamps D. this is a normal condition

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What are the protections provided for 220 kV lines and bus bars?

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Why non-return valves are provided in the steam extraction lines?

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The leakage current in the transmission lines is referred to as the a) Resistance b) Radiation c) Conductance d) Polarisation

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What are the different relays that employed for protection of apparatus and transmission lines?

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Why, when birds sit on transmission lines or current wires doesn't get shock?

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Why, when birds sit on transmission lines or current wires doesn't get shock?

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Last Answer : A:Its true that if birds touch the single one line (phase or neutral) they don't get electrical shock... if birds touch 2 lines than the circuit is closed and they get electrical shock.. so if a human ... the air. If he is standing on the ground then touching the line (phase) he will get a shock.

The regulation of Short Transmission lines depends up on a) Distance of line b) Frequency c) Power factor d) All

Description : The regulation of Short Transmission lines depends up on a) Distance of line b) Frequency c) Power factor d) All

Last Answer : Ans: Power factor

ACSR (Aluminium Conductor Steel Reinforced) are used as (A) over head transmission lines. (B) super conductors. (C) fuse (D) underground cables.

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Description : An electric bulb is connected on a holder. One end of the wire is connected to the phase and the remaining one connected to earth instead of neutral. The bulb will glow or not? If yes then what is the need of neutral?

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Why earth switches are provided in 220 kV bays?

Description : Why earth switches are provided in 220 kV bays?  

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t consists of spike tooth cylinder, woven- wire mesh concave and upper casing provided with helical concave. a) Dummy type c) Spike-tooth type b) Hummer type d) Axial flow type

Description : It consists of spike tooth cylinder, woven- wire mesh concave and upper casing provided with helical concave. a) Dummy type c) Spike-tooth type b) Hummer type d) Axial flow type

Last Answer : Axial flow type

Copper wires are generally used for electrical power transmission instead of iron wire because (1) copper is cheaper than iron (2) copper is lighter than iron (3) copper is a better conductor of electricity than iron (4) copper can take higher power than iron

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Description : What type of balun (balanced-to-unbalanced) is used in high frequency applications? A. Transformer type balun B. A specially configured coaxial transmission line C. A specially configured parallel-wire line D. A λ/2 transformer balun

Last Answer : B. A specially configured coaxial transmission line

Which of the following is considered the most frequently used transmission line? A. Two-wire open line B. Twin lead C. Rigid coaxial line D. Flexible coaxial line

Description : Which of the following is considered the most frequently used transmission line? A. Two-wire open line B. Twin lead C. Rigid coaxial line D. Flexible coaxial line

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