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06000EE301122001

With the help of a vector diagram, derive an expression for capacitance required
to improve the power factor from cos@ to ೦೦50).

Discuss the need for transposition of conductors and explain how it is done.

Derive ABCD Constants of a medium transmission lines using nominal 7
method. Also draw the phasor diagram.
With the help of a vector diagram, explain what do you mean by Ferranti effect.

PART C
Answer any two full questions, each carries10 marks.
What do you mean by sag template? Explain its necessity.

In a 33 kV overhead line, there are three units in the string of insulators. If the
capacitance between each insulator pin and earth is 11% of self-capacitance of
each insulator, find (i) voltage across the top, middle and bottom unit and (ii)
string efficiency.

Compare the volume of conductor material required in a 2 wire d.c system with a
single phase 2 wire ac system.

The core diameter of a single-core cable is 2-5 cm and resistivity of insulation is
4.5 x 1014 Q-cm. If the insulation resistance is 495 MQ per km, find the
insulation thickness.

Analyse the benefits of FACTS devices.

Illustrate the need for grading of underground cables. Explain any one method
with the help of a diagram.

PART D

Answer any two full questions, each carries 10 marks.
Explain the working of a vacuum circuit breaker with the help of a diagram.
Define the different ratings of a circuit breaker.
With the help of a block diagram, explain the working of a microprocessor-based
relay.
With necessary sketches, explain different types of AC distributors.
What do you mean by insulation co-ordination? Why is it necessary?
With the help of a neat diagram, explain the working of a percentage differential

protection of transformers.

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