A multifactor stress ageing model of electrical insulation

The single stress approach in design stage and also in ageing studies offers relative simplicity, but it is inapplicable to real life operating conditions which mostly are of multistress type. The article presents a generalized model for the electrical equipment design using the multistress approach. The generality of the model lies in the fact that it can be used for designing of insulation system of all electrical components containing solid insulating materials surrounded by gas or liquid insulation or impregnated by them. At the same time, the model enables simultaneous consideration of the influences of different stresses when those loads appear as constant, variable and stochastic inputs. Besides, the inherent physical and chemical properties of the insulating materials used are also included in the model. This enables, when the changes of those properties with the operating time are known, the ageing process to be introduced in the model itself