The lightning protection device installed on the building can only protect the building from being directly damaged by lightning. It is called external lightning protection; it cannot protect the electrical equipment in the building from being damaged by lightning overvoltage or surge voltage generated by lightning induction. , it is called internal lightning protection.
Schematic diagram of comprehensive lightning protection for buildings

Lightning overvoltage can be generated in two ways: when lightning occurs in the distance, the transient electromagnetic field generated by the lightning induces a transient surge voltage on the power supply line or signal line, which can be conducted along the line to the electrical equipment of the building. The insulation of electrical equipment is damaged; the other is that lightning or lightning strikes near the building directly strike the building. A strong transient electromagnetic field is generated around the lightning current entering the ground, which is directly induced on the power supply lines or signal lines of the electrical equipment in the building. Produce transient overvoltage and damage the insulation of electrical equipment. The energy of this surge is much greater than that of a surge induced and conducted on a wire by a distant lightning strike into a building.

After the building is equipped with an external lightning protection device, the air-termination device on the roof plays a role in guiding lightning. Although the lightning protection device can safely discharge the lightning current into the ground, protecting the building. However, the strong transient electromagnetic field generated by the lightning current caused by direct lightning strikes increases the risk that the insulation of electrical equipment in the building will be damaged by the transient overvoltage induced in power lines and signal lines. This overvoltage can also cause hazards due to impedance coupling from grounding devices along distribution lines and into adjacent buildings.

As a well-known lightning protection brand in China, Anhui Jinli has been committed to the electrical safety of electrical systems and focused on lightning protection technology for electrical systems. Among them, the research and development and production of lightning arresters are at the forefront of the industry.