Hidden danger of lightning strike disaster-induction lightning

Lightning strikes caused by lightning are a common natural phenomenon in summer. There are two types of lightning strikes in nature: direct lightning strikes and induced lightning strikes. The sound and light of direct lightning strikes are both concurrent, aggressive, and well known to all ages. Induced lightning strikes occur quietly, are not easy to detect, and have serious consequences. Direct lightning strikes are different from the objects destroyed by induced lightning strikes. The former mainly destroys buildings and transmission lines on the discharge path, kills and injures humans and animals, and the latter mainly destroys electronic equipment. For example, on April 27, 1992, Nanchang Jiangxi Medical University was struck by induction lightning, and 120 of 160 program-controlled telephones were destroyed. On the same day, all 200 program-controlled telephones of Jiangxi College of Finance and Economics were destroyed; on May 1, 1992, 200 program-controlled telephones, 6 computers, and multiple color TVs of Hunan Radio and Television University in Changsha were destroyed due to lightning strikes, resulting in losses of more than 1 million yuan On June 22, 1992, the computer room of the Beijing National Meteorological Center was struck by induction lightning, large and small computer networks were interrupted, multiple computer interfaces were damaged, the computer system was interrupted for 46 hours, and the economic loss was more than 200,000 yuan; April 1993 On the 21st, on the eve of the first East Asian Games, the Shanghai Olympic Club building was struck by lightning, and the computer controlling the program-controlled telephone in the building was damaged, resulting in a loss of tens of thousands of yuan.

Induced lightning strikes are due to the electrostatic induction of the thunderstorm cloud or the electromagnetic induction during discharge, which causes the metal objects on the building, such as pipes, steel bars, wires, and reaction devices, to induce a charge opposite to the charge of the thunderstorm cloud, causing discharge. There are four main channels for an electronic device to attract induction lightning strikes:
1. Introduction of antennas and feeders;
2. Power line introduction;
3. Signal line introduction. There are many types of signal lines, high-frequency signal transmission lines, program-controlled telephone lines, computer data processing lines, etc. may introduce powerful lightning signals and damage electronic equipment;
4. Ground wire introduction.

For the electronic equipment group in the building, there are 7 main channels for the introduction of lightning induction:
1. The antennas, feeders, power lines, signal lines, and grounding lines of all electronic equipment in the building are the lightning channels of the building;
2. Various power lines in and out of the building and "long" distance signal lines inside the building;
3. Lightning shock waves induced on the metal surface of all metal pipes in buildings with public grounding when direct lightning current flows over them
4. Lightning shock wave induced on the metal surface during lightning discharge;
5. Direct lightning strikes down the lightning high-level impact of buildings;
6. Lightning recoil current that directly strikes down a lightning point building.

This current can enter its electronic equipment through the grounding line of an adjacent building, causing a discharge phenomenon between the casing and the movement of the electronic equipment to be damaged.

Over 200 years ago, Franklin invented the “lightning rod” to prevent “direct lightning strikes”, but he was incapable of preventing “induction lightning strikes”. Because there was no electronic equipment at that time, the phenomenon of induced lightning was not obvious, and it was enough to avoid direct lightning. In modern society, with the extensive application of electronic equipment, the danger of induced lightning strikes is becoming more and more serious. Relying on the "lightning rod" lightning protection is no longer enough to meet the needs of society. Lightning protection experts have long recognized the seriousness of this problem and conducted a series of tests and studies to prevent induction lightning strikes.

The three series of electronic arresters (SPDs) for antenna feeders, signals, and power supplies that have been developed can effectively protect large, medium, and low-power communications and television equipment, microwave communications, radar, and navigation special equipment, railway equipment, satellite stations, etc Equipment, shared antennas and home appliances, program-controlled telephones, computers, power supplies and other equipment are not subject to lightning strikes and have been put into business applications. Through the promotion of new lightning protection technology, to ensure the safety of various electronic equipment and reduce lightning strike disasters.