Surge pulses occur due to direct or indirect lightning strokes
to an external (outdoor) circuit. This leads to currents or
electromagnetic fields causing high voltage or current
transients. Another source for surge pulses are switching
transients originating from switching disturbances and systems
faults.
Due to the characteristic of the phenomenon nearly every
electrical and electronical device may suffer from such
lightning events which justifies the necessity of surge tests
being widely performed. Surge voltage can reach several
thousands of volts and surge current is seen to reach several
thousands of amps.
