Protection against disturbances - Protective components

This article describes the criteria for selecting protection components and the different types of components:

• semiconductor components (diodes and thyristors, which provide so-called fine protection (low response time and residual voltage));

• ceramic varistors, widely used in electronics and electrical engineering;

• Gas spark gaps, which provide brutal protection against strong disturbances and are therefore rarely used alone;

• finally, thermistors, although a little apart in this field, are often used to protect against long-lasting, low-level disturbances, against which the previous components have no effect; moreover, in combination with such a component, they make protection more reliable.

The electrical and physical mechanisms responsible for the non-linear behavior of these components are explained, so that protection can be properly understood. The general conditions of use of these components are specified in the light of the various disturbances described in the theoretical section.

The various means and their service life are evaluated in the face of these disturbances, leading to a general comparison table of components.

Finally, possible combinations of components are indicated, which greatly improve protection: in such a combination, each component protects against a particular range of energy and/or rise time.