Characterization of the lightning wave

Analysis of the phenomena allows definition of the types of lightning current and voltage waves.

• 2 types of current wave are considered by the IEC standards:

  - 10/350 µs wave: to characterize the current waves from a direct lightning stroke (see Fig. J9);

Fig. J9: 10/350 µs current wave

  - 8/20 µs wave: to characterize the current waves from an indirect lightning stroke (see Fig. J10).

Fig. J10: 8/20 µs current wave

These two types of lightning current wave are used to define tests on SPDs (IEC standard 61643-11) and equipment immunity to lightning currents.
The peak value of the current wave characterizes the intensity of the lightning stroke.

• The overvoltages created by lightning strokes are characterized by a 1.2/50 µs voltage wave (see Fig. J11).

This type of voltage wave is used to verify equipment's withstand to overvoltages of atmospheric origin (impulse voltage as per IEC 61000-4-5).

Fig. J11: 1.2/50 µs voltage wave