Resin-bonded glass-fibre outdoor h.v. insulators

The pollution performances of a number of organic insulator materials have been studied, and, although materials have been found which withstand tracking, the erosion caused by sparking results in lowered pollution flashover voltages. An investigation of the mechanical characteristics of a resin-encapsulated glass fibre-loop in tension has shown that curing stresses can substantially reduce the ultimate strength, which is dependent on the modulus of elasticity of the resin and the shear strength of the glass-resin interface. To protect the glass component from moisture for a reasonable lifetime, a layer of 10¿20mm of epoxy resin is shown to be needed. A study of the mechanical, electrical, manufacturing and economic problems of different types of insulator leads the authors to conclude that there are good prospects for suspension and tension insulators of resinbonded glass fibre.