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Overvoltage characteristics of atmospheric origin

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General rules of electrical installation design
Connection to the MV utility distribution network
Connection to the LV utility distribution network
MV and LV architecture selection guide for buildings
LV Distribution
Protection against electric shocks and electric fires
Sizing and protection of conductors
LV switchgear: functions and selection
Overvoltage protection
Energy Efficiency in electrical distribution
Power Factor Correction
Power harmonics management
Characteristics of particular sources and loads
PhotoVoltaic (PV) installation
Residential and other special locations
ElectroMagnetic Compatibility (EMC)
Measurement

Lightning strokes in a few figures: Lightning flashes produce an extremely large quantity of pulsed electrical energy (see Figure J4)

  • of several thousand amperes (and several thousand volts),
  • of high frequency (approximately 1 megahertz),
  • of short duration (from a microsecond to a millisecond).

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)
95 7 9.1
50 33 24
5 65 65
1 140 95
0 270

Fig. J3Lightning discharge values given by the IEC 62305 standard

Fig. J4Example 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.