Impedance Spectra of a Silicone Rubber in a Needle-Plane Electrode Arrangement during Electrical Tree Growth

Inhalt:
In order to assess the potential of dielectric/impedance spectroscopy as a diagnostic tool for quantifying cumulative damage due to electrical treeing in silicone rubbers, broadband impedance spectra in a needle-plane configuration at progressive stages of electrical tree degradation are presented and discussed. It is shown that the grown electrical tree is invisible to frequencies in the kilohertz range, but that tree inception (formation of first microvoids in the high-field region) strongly influences the low-frequency space charge relaxation associated with electrode polarization. In such systems, the dynamics of the electrical double layer may thus be a valuable source of information to detect/probe void formation at the electrode-insulator interface.