What is the need of extra high voltage transmission lines?

Answer 1

it is cheaper to use high voltage of transmission because, it is cheaper to boost the voltage

up really high and keeps the current low, also the big pylons with huge insulators will

reduce the energy wasted. the transformer have to step the voltage up for efficient

transmissions and it bring back down to safe usable levels. the voltage is increase

by a step up transformer it's then reduced again at the consumer end using a step

down transformer.

The only thing missing from the above narrative is the reason itself:

Every conductor has some resistance. When an electric current flows through a

conductor, the resistance of the conductor causes loss of some of the energy. The

loss is LESS when the voltage is higher and the current is smaller. The big pylons,

the huge insulators, and all the step-up and step-down Transformers wouldn't be

necessary if the voltage was the same 110 volts all the way from the generating

plant to your house. But shipping it at high voltage saves more energy than the

cost of all that extra infrastructure.

Answer 2

To keep the voltage drop along the lines to a minimum, as well as to reduce the cross-sectional area of conductors and, therefore, their weight and cost, to practical levels, the load current must be as low as possible. For any given load, the higher the supply voltage, the lower the load current.

A secondary advantage is that lower load currents also mean lower line losses. But the primary reason is to reduce voltage drop and to minimise conductor size to practical values.

Answer 3

from what i can remember its so that less energy is wasted when the electricity travels through the national grid . the voltage is then decreased afterwards .