A Contribution to Thermal Ageing Assessment of Glass Fibre Insulated Wire Based on Partial Discharges Activity

This paper aims to evaluate a Type-II insulated wire (i.e., Glass fibre wire) as function of thermal ageing time based on partial discharges (PD) activity. Partial discharge inception voltage (PDIV), extinction (PDEV), and repetitive (RPDIV) measurements have been performed both unaged thermally aged specimens. Each specimen modelled the turn-to-turn insulation; hence it was made by pair wires wrapped in PTFE tape for mechanical purpose. The PD tests carried out under positive negative unipolar square waveform excitations using different rise times: 80, 400 800 ns. trend quantities vs exposure demonstrates that effect space charge accumulation excitation must be taken into account when specimens are compared. Results revealed although sometimes samples might show temporary superiority short run, ones always present better performance after accumulation, expected. Following statistic postprocessing collected data, shape/slope parameters Weibull distribution relevant PDIV can used an indicator wire. Finally, permittivity evaluation electrical stresses performed, relying measured capacitance each just every test. Such analysis increases long run. However, stress has impacts depending time, polarity, magnitude applied voltage.