The arrester is connected between the cable and the ground, usually in parallel with the device being protected. The lightning arrester can effectively protect communication equipment, once there is an abnormal voltage, the lightning arrester will take action, play a protective role. When communication cables or equipment are in the normal operating voltage operation, the arrester will not have a role in the ground as a circuit breaker. Once there is a high voltage, and endanger the insulation of the protected equipment, the arrester immediately action, the high voltage impulse current directed to the earth, to limit the voltage amplitude, protect the insulation of communication cables and equipment. When the overvoltage disappears, the arrester quickly returns to its original state, so that the communication line works normally.
Therefore, the main role of the arrester is to trim the amplitude of the intrusion flow wave through the parallel discharge gap or the role of nonlinear resistance, to reduce the over-voltage value of the protected equipment, to protect the communication lines, and equipment.
The arrester can be used not only to protect against high voltages generated by lightning but also to protect against high operating voltages.
The role of the lightning arrester is used to protect various electrical equipment in the power system from lightning over the type of voltage, operating overvoltage, power frequency transient overvoltage impact, and damage of an electrical appliance. The type of arrester mainly has a protection gap, valve type arrester, and zinc oxide arrester. The protection gap is mainly used to limit atmospheric overvoltage, generally used in distribution systems, lines, and substations into the line protection. Valve-type arrester and zinc oxide arrester for the protection of substation and power plant, in 500kV and the following system, is mainly used to limit the atmospheric overvoltage, in the ultra-high voltage system will also be used to limit the internal overvoltage or as the internal overvoltage backup protection.