On multistress aging of epoxy resins: PD and temperature

The results of partial discharge (PD) aging at different temperatures performed by means of PD electrical detection on specimens with a flat cavity are reported. First, polymethylmethacrylate (PMMA) resin was used to set up a suitable test methodology under multistress conditions, e.g. in a divergent electrical field and at a temperature higher than the ambient. Next, an epoxy resin of electrical and industrial interest was tested. To analyze the aging phenomena during the life tests and to identify the PD statistical features, physical and statistical off-line analysis of the acquired data were carried out. Temperature strongly changes PD activity in pulse number and amplitude, affecting the material lifetime as well. At the examined test conditions, the skewness parameter applied to the PD phase distribution was found to be useful in the dielectric aging progression analysis, as was found earlier by other authors. The reported results are considered useful for the PD performance study of electrical systems under working conditions.