Protection against disturbances — Sources of disturbance

The protection of electrical and electronic equipment from electrical and electromagnetic interference has become an increasingly important issue, due to the greater sensitivity of modern electronic components to the electrical overloads created by such interference, and to the many sources of interference to which any equipment may be exposed.

In fact, it is known that an electrical overload energy of just a few microjoules is enough to destroy a highly integrated electronic component, or at least severely impair its performance, despite the built-in protections put in place by manufacturers to guard against the risks associated with electrostatic discharges.

To be effective, the protection of equipment must be taken into account from the very beginning of its design; this presupposes that the designer has a good knowledge of :

• sources of disturbance to which the equipment may be subjected (direct or indirect threat);

• modes of interaction of these threats, resulting in disturbances (electrical overload or electromagnetic influence);

• the characteristics of the disturbances created.

This article gives a detailed description of the best-known sources of disturbance (electrostatic discharges, electromagnetic pulses of nuclear origin, lightning strikes and inductive switching).