String Effeciency and methods to improve String Effeciency

The ratio of voltage across the whole string to the product of number of discs and the voltage across the disc nearest to the conductor is known as string efficiency i.e.,

where n = number of discs in the string.
String efficiency is an important consideration since it decides the potential distribution along the string. The greater the string efficiency, the more uniform is the voltage distribution. Thus 100% string efficiency is an ideal case for which the volatge across each disc will be exactly the same. Although it is impossible to achieve 100% string efficiency, yet efforts should be made to improve it
as close to this value as possible.

Various Systems of Power Transmission

It has already been pointed out that for transmission of electric power, 3-phase, 3-wire a.c. system is universally adopted.  The different possible systems of transmission are :

1. D.C. system

Comparison of D.C. and A.C. Transmission

The electric power can be transmitted either by means of d.c. or a.c. Each system has its own merits and demerits.

1. D.C. transmission.

For some years past, the transmission of electric power by d.c. has been receiving the active consideration of engineers due to its numerous advantages.

Electric Supply System

The conveyance of electric power from a power station to consumers’ premises is known as electric supply system. An electric supply system consists of three principal components viz., the power station, the transmission lines and the distribution system.