An impulsive transient is a sudden, non–power frequency change in the
steady-state condition of voltage, current, or both that is unidirectional
in polarity (primarily either positive or negative).
Impulsive transients are normally characterized by their rise and
decay times, which can also be revealed by their spectral content. For
example, a 1.2x50-micro(s )2000-volt (V) impulsive transient nominally
rises from zero to its peak value of 2000 V in 1.2 micro(s) and then decays to
half its peak value in 50 micros. The most common cause of impulsive transients
is lightning. Figure illustrates a typical current impulsive
transient caused by lightning.
steady-state condition of voltage, current, or both that is unidirectional
in polarity (primarily either positive or negative).
Impulsive transients are normally characterized by their rise and
decay times, which can also be revealed by their spectral content. For
example, a 1.2x50-micro(s )2000-volt (V) impulsive transient nominally
rises from zero to its peak value of 2000 V in 1.2 micro(s) and then decays to
half its peak value in 50 micros. The most common cause of impulsive transients
is lightning. Figure illustrates a typical current impulsive
transient caused by lightning.
Because of the high frequencies involved, the shape of impulsive
transients can be changed quickly by circuit components and may have
significantly different characteristics when viewed from different parts
of the power system. They are generally not conducted far from the
source of where they enter the power system, although they may, in
some cases, be conducted for quite some distance along utility lines.
Impulsive transients can excite the natural frequency of power system
circuits and produce oscillatory transients.
Figure Lightning stroke current impulsive transient.
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Transient
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