We describe four different research activities that aim to enhance the understanding of the ageing process of dielectric insulating materials to better estimate their residual life. The first research activity investigated the behaviour of standard models that describe the dynamics of partial discharges as the evolution of a plasma at very high electric fields, close to the breakdown threshold.

In the second activity a model has been developed to represent the dynamics of a plasma within the treeing channels. Such model allows a better, and much more efficient, discretization of the problem with the objective to reduce the computational cost.

In the third research activity was outlined that calculation codes for the simulation of partial discharges, previously developed in RSE, can be successfully employed to simulate the evolution of partial discharges within defects in resin insulated transformers. In the fourth research activity, a diagnostic method for composite isolators was developed using a fully dielectric field sensor previously developed within RSE.

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