Transmission line is a kind of installation that connects power plant, substation and electric equipment to transmit electric energy. It is divided into overhead line and cable line.High voltage transmission line is the main artery of power industry and an important part of power system.This time the secondary introduction of overhead transmission lines.

Power lines are divided into transmission lines and distribution lines.The power transmission lines transmitted from the power plant to the power load center and the contact lines between the power fragments are called transmission (transmission) lines, and the power distribution lines distributed from the power load center to each power user are called distribution lines.

Power lines are divided into high voltage, high voltage, ultra-high voltage and ultra-high voltage lines according to the voltage grade.The voltage grade below 1kV is high voltage line, 10kV and above is high voltage line, 500kV and above is ultra-high voltage line, 750kV and above is ultra-high voltage line.

Transmission lines can be divided into overhead transmission lines and cable transmission lines according to their erection data.Transmission lines are divided into ac and dc lines according to the characteristics of current.The overhead transmission line is divided into single loop, double loop and multiple loop according to the number of loops on the tower.