About the degradation of polymer films due to surface partial discharges at different humidity levels

This paper outlines a simplified model to explain the influence of the relative humidity (RH) on the behaviour of polymer films subjected to partial discharges (PD). The proposed model hinges on the role of the films surface conductivity variations with RH and its validity is supported by the results of life tests performed on two different polymer films and by the examination of optical microscope images of the PD damaged areas. The assumptions of the model are basically consistent with the outcome of surface conductivity measurements performed on non PD aged films. This model can be useful in the selection of polymer films and/or of surface treatments for industrial applications where the “resistance” to PD at different RH levels is critical