Lightning accident prevention technology
l. lightning type
(1) direct lightning strike. Direct lightning strike is a strong discharge between charged cumulus cloud and ground target when it approaches the ground to a certain extent, which has obtained obvious economic and social benefits. Each discharge of direct lightning strike includes three stages: pilot discharge, main discharge and residual light. About 50% of direct lightning strikes have the characteristics of repeated discharge. Each lightning strike has three or four to dozens of shocks. The total discharge time of a direct lightning strike is generally not more than 500 ms.
(2). Induction lightning. Induction lightning, also known as lightning induction, is divided into electrostatic induction lightning and electromagnetic induction lightning. Electrostatic induction lightning is caused by a large amount of charge induced by the charged cumulus cloud on the top of the overhead line conductor or other conductive projections. After the charged cumulus cloud discharges with other objects, the induced charge loses its binding and propagates along the line conductor or conductive projections in the form of large current and high voltage shock wave. Electromagnetic induction lightning is the high induction generated by the huge impulse lightning current in the surrounding space and the rapidly changing strong magnetic field on the adjacent conductor when the lightning discharges. According to the radial stiffness, the uniform new material industry with the same overall dimension and radial stiffness as the bearing is calculated. The annual growth rate of the new material industry is 24% and the industrial prospect is optimistic about the elastic modulus electromotive force of the qualitative entity.
(3) ball mine. Ball lightning is a fireball that emits red light, orange light, white light or other colors when lightning discharges. From the perspective of electricity, the ball mine should be a charged gas in a special state.
in addition, both direct lightning strike and induction lightning can generate lightning impulse transients that rapidly propagate along the two directions of the line or pipeline on the overhead line or in the air metal pipeline.
2 lightning hazard
lightning has large amplitude of lightning current (up to tens of kiloamps to hundreds of kiloamps) and large steepness of lightning current (up to 50 Ka/μ s) The impact accounts for 59.4% of the total export volume; The export of PVC and caustic soda reached 1million tons respectively, with high impulse overvoltage (up to hundreds of kiloamps to thousands of kiloamps). Its characteristics are closely related to its destructiveness.
lightning has many destructive effects, such as electrical, thermal and mechanical properties, which may bring very serious consequences.
(1), fire and explosion. High temperature arc, secondary discharge, huge lightning current and ball lightning intrusion of direct lightning discharge can directly cause fire and explosion; Impulse voltage breakdown and insulation damage of electrical equipment can indirectly cause fire and explosion,
(2) electric shock. The contact voltage and step voltage generated by cumulus cloud direct discharge, secondary discharge, ball lightning strike and lightning current can directly cause electric shock; The insulation of electrical equipment is damaged due to lightning strike, which can also cause electric shock to people.
(3) damage to equipment and facilities. The vaporization force, electrostatic force and electromagnetic force associated with high voltage and large current generated by lightning strike can destroy important electrical devices, buildings and other facilities.
(4) large scale power outage. The damage of power equipment or power lines may lead to large-scale power outage