In case of interphase short circuit fault, abnormal load increase, insulation grade decrease, etc. in the power grid, the current will suddenly increase and the voltage will suddenly drop. The overcurrent protection is to set the action current of the current relay according to the requirements of line selectivity.

The lightning protection module is a kind of lightning protector, which is made into a module and stuck on the supporting base. Its base is usually installed on the guide rail. The lightning protection module connects the line with the "ground" immediately after sensing the high voltage on the line to discharge the lightning current.

Attention shall be paid to the following points when selecting semiconductor discharge tubes

The recoverable fuse is composed of specially treated polymer resin and conductive particles (Carbon Black) distributed inside.

Lightning discharge may occur between or within clouds, or between clouds and ground; In addition, the internal surge caused by the use of many large capacity electrical equipment, the impact on power supply system (Chinese low-voltage power supply system standard: AC 50Hz 220/380V) and electrical equipment, and the protection against lightning and surge have become the focus of attention.

The addition of gas discharge tube shall not affect the normal operation of the line, so it is necessary to ensure that the lower limit of the DC breakdown voltage of the gas discharge tube must be higher than the maximum normal operating voltage of the line. The nominal DC breakdown voltage of the required discharge tube is determined accordingly.