Performance of Transmission Line

The transmission lines are categorized as three types-

1) Short transmission line– the line length is up to 80 km.

2) Medium transmission line– the line length is between 80km to 160 km.

3) Long transmission line – the line length is more than 160 km.
Whatever may be the category of transmission line, the main aim is to transmit power from one end to another. Like other electrical system, the transmission network also will have some power loss and voltage drop during transmitting power from sending end to receiving end. Hence, performance of transmission line can be determined by its efficiency and voltage regulation.

Power sent from sending end - line losses = Power delivered at receiving end.
Voltage regulation of transmission line is measure of change of receiving end voltage from no-load to full load condition.

Every transmission line will have three basic electrical parameters. The conductors of the line will have electrical resistance, inductance, and capacitance. As the transmission line is a set of conductors being run from one place to another supported by transmission towers, the parameters are distributed uniformly along the line.

The electrical power is transmitted over a transmission line with a speed of light that is 3X108 m ⁄ sec. Frequency of the power is 50Hz. The wave length of the voltage and electric current of the power can be determined by the equation given below,
f.λ = v where f is power frequency, &labda is wave length and v is the speed of light.

Hence the wave length of the transmitting power is quite long compared to the generally used line length of transmission line.