Partial-Discharge Phenomena and the Effect of Their Constituents on Polyethylene

A method of investigating partial-discharge phenomena andtheir effect on polyethylene is described. A physical study was carriedout with air at atmospheric pressure and gaps between 2 and 14 mm.It is shown, that with this range of gaps and with dielectric walls, astreamer process appears as in the case of a positive point and a metallicplane.The evolution of the polyethylene samples after the aging producedby the constituents of the discharge, i.e., UV radiation and electronsand ions of low energy, was studied by means of IR spectroscopy. Ifthe discharge is of the streamer type it might be possible to attributethe deterioration to the concentration of ions at its tip; however, IRspectroscopy and scanning electron microscopy have shown thatalthough the ions were more reactive they were not sufficiently so toexplain the damage caused by corona discharges.