Electrical tree growth retardation and acceleration model

In predicting electrical tree growth behaviour of practical insulation materials under operating alternating voltages, one must consider the effects of compressive and tensile residual stresses to retard and accelerate electrical tree growth. In this study a general model of electrical tree growth retardation and acceleration is firstly proposed. The present model combines both macroscopic and submicroscopic approaches to describe the local damage features around the tree tip and enables the effect of compressive and/or tensile residual stresses on electrical tree growth dynamics to be determined quantitatively. Electrical tree propagation rate equation and a lifetime formula that take into account the effect of the residual stresses have been derived. Taking the example of mechanically pre-stressed fibre-reinforced epoxy resins the application of the proposed model has been addressed.