Overvoltage characteristics of atmospheric origin
From Electrical Installation Guide
| Lightning strokes in a few figures:|
Lightning flashes produce an extremely large quantity of pulsed electrical energy (see Fig. J4)
Between 2000 and 5000 storms are constantly undergoing formation throughout the world. These storms are accompanied by lightning strokes which represent a serious hazard for persons and equipment. Lightning flashes hit the ground at an average of 30 to 100 strokes per second, i.e. 3 billion lightning strokes each year.
The table in Figure J3 shows the characteristic lightning strike values. As can be seen, 50% of lightning strokes have a current exceeding 33 kA and 5% a current exceeding 65 kA. The energy conveyed by the lightning stroke is therefore very high.
|Cumulative probability (%)||Peak current (kA)||Gradient (kA/µs)|
Fig. J3: Lightning discharge values given by the IEC 62305 standard
Fig. J4: Example of lightning current
Lightning also causes a large number of fires, mostly in agricultural areas (destroying houses or making them unfit for use). High-rise buildings are especially prone to lightning strokes.