An electro-chemical reaction model to describe dielectric ageing and fractal behaviour

An electro-chemical reaction model is proposed in this paper to describe electrical ageing of solid dielectrics under ac voltage. The present model has the ability to predict not only the scale-invariance property of the electrical ageing function, but also the classical electrical ageing law, i.e. the electric field strength - lifetime inverse power law relationship. The micromechanisms inherent in the model enable a direct physical interpretation of the macroscopic electrical ageing behaviour in terms of the microscopic processes. We argue that the fractal behaviour of electrical ageing and breakdown processes in solid dielectrics are by essence determined by the scale-invariance of the electrical ageing evolution equation.