Mechanisms of surface potential decay on enamel wire coatings

Results of measurements of surface potential decay on coating layer of enameled wires are presented. In experiments, surfaces of winding samples were charged by dc corona of both polarities and decay of surface potential induced by charges deposited on the materials was recorded utilizing non-contact technique. The power-law type of time dependences of surface potential decay rates was obtained that indicated a dominant role of charge injection and/or dipolar polarization in the decay process. Furthermore, several decay mechanisms were employed for examining the experimental data, which revealed that potential decay was initially governed by the injection of charges due to electron transfer between the deposited charges and the material. Later on, the contribution of polarization to decay process was significant, while intrinsic conduction became the prevailing decay mechanism only at the latest stage as polarization was stabilized.