SSC JE Electrical Engineering 23 Jan 2018 Evening Paper

Question : 168 of 200

Marks: +1, -0

If a fixed amount of power is to be transmitted over a certain length with fixed power loss, then_____.

the weight of the conductor required will be proportional to the voltage
the weight of the conductor required will be inversely proportional to the voltage and that of power factor of the load
the weight of the conductor required will be inversely proportional to the square of the voltage and that of power factor of the load
the weight of the conductor will be proportional to the square of the voltage and directly proportional to the power factor of the load

Solution:

I^2R

= Power Loss (w)

I=P/{V\cosϕ}

w=P^2/{V^2\cos^2ϕ}×{ ρl}/A

A=P^2/{\V^2\cos^2ϕ}ρl

Volume

=Al={P^2ρl^2}/{V^2\cos^2ϕ}

Volume ∝ weight ∝

1/{V^2\cos^2ϕ}

So weight of conductor is inversely proportional to square of voltage and power factor.

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