Huilerie-TechThe coils and magnetic cores (formed of a stack of thin magnetic sheet metal) that enter into the composition of each item of electric machinery are subjected to many internal and external constraints when they operate: vibrations due to electromagnetic fields, differential dilation of the different materials used, to which are to be added centrifuge force, mechanical vibrations and aerodynamic forces for rotating machines (motor and alternator).

All of these effects risk generating micro-shifts in the coil loops or even the core sheet metal, over time leading to the premature wear of the insulation, the formation of short circuits between loops or between the coil and the core, local overheating, malfunctions, or the complete destruction of the machine.

In fact, to avoid these micro-shifts and their consequences, it is important that the components of these machines be closely linked together using an insulating component. This is the role of impregnation which is mainly used for rotating machine coils, but also on some transformers and magnetic circuits, coating them with suitable resins or varnishes to correctly keep all the components in position.