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# Tag Archives: High voltage

## Transformers

Please explain what is transformer and tell what is the reason behind the working of transformer that it reduces potenial when current is high and increases potential when current is low?

Explain widely and deeply with concepts.

Transformer is a device based on mutual inductance and is used to change the voltage of alternating (or varying) current. There are two types of transformers – stepup and stepdown.

A step-up transformer increases the voltage as the step-down transformer decreases the ac voltage.

When a transformer changes the alternating voltage, it is not adding any power, it only transforms the voltage.

As power is the product of voltage and current, as voltage increases, the current decreases. (and vice versa)

## Resistance of Transmission lines

A high voltage transmission line has an aluminum cable of diameter 3.0 cm , 200 km long . What is the resistance of this cable?

Use the relation R = ρ l/A

A= πr2 =πd2/4

= 3.14 x 3 x 10-2x 3 x 10-2/4

ρ= 2.82×10−8 ohm m

l = 200km = 200000 m = 2 x 105m

You can now just substitute the values and get the answer.

## Difference between Dielectric Break Down and Corona Discharge

HOW IS CORONA DISCHARGE DIFFERENT FROM DIELECTRIC BREAKDOWN IN THE CASE OF VANDEGRAFF GENERATOR

• Corona (egrejeen.wordpress.com)

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