Glass for electrical insulation

This article deals with glasses used in the electrotechnical field, whose main applications are in electrical insulation techniques for conductors or live elements in power transmission and distribution networks. The focus is on molded glass and glass fibers used for mechanical reinforcement of resin parts in direct contact with conductor elements, for example in composite insulators for power lines or substations, tubular structures used in substation insulators, or surge arresters for distribution or extra-high-voltage lines.

Glass tempering, the fundamental aspects of which will be explained here, has made it possible to take into account the ever-increasing tensile mechanical loads imposed on overhead power lines, making annealed glass insulation a thing of the past. In addition, insulating materials made from glass-fibre-reinforced polymeric materials enable insulation applications in which the mechanical stresses are not only tensile, but also bending or compression, or their combination.

The chemistry of glass used in electrical insulation is mainly determined by the nature of the currents applied (alternating or direct) to the molded insulators, while the chemical or electrochemical corrosion of glass fibers guides the choice of materials used for polymer reinforcement.

We will omit certain theoretical aspects for which reference documents can be consulted, and where the reader will find details of the fundamental equations and physical principles relating to the material glass in general and its properties.