Insulation function in electrical equipment

Materials, in the broadest sense of the term, have played a major role in the progress made by electrical equipment. Their evolution, cumulated over almost a century, although often slow, has been considerable. They are undoubtedly key factors in the development of tomorrow's electrotechnical equipment. Insulating materials are among those whose choice and use pose the most delicate problems to be resolved in the design, manufacture and operation of such equipment.

This is due to the fact that insulating materials are a large family in nature (polymers, glass, ceramics, wood, paper, cardboard, oil, air, vacuum, gas...), come in various forms (solid, liquid, gaseous) and have diverse and varied properties. This is also, and above all, due to the fact that the function of electrical insulation is of paramount importance, in that it is one of the fundamental conditions for the operation of equipment for the production, transmission and distribution of electrical energy.

This article begins by discussing the stresses to which insulation systems can be subjected, and how these influence material behavior. It then presents the evolutionary classes of insulation systems, before turning to the field of insulation characterization, testing and modeling. It is not intended to provide recipes or ready-made solutions, but rather to illustrate approaches, comment on reasoning and argue choices, without seeking to be exhaustive.

The aim is to provide the means for engineers to navigate more easily through the mass of information contained in both equipment-specific articles and articles on insulating materials, not forgetting theoretical articles on basic phenomena (dielectric, conduction, breakdown, etc.).