Film Thickness Dependence of Dissipation Current for LDPE Film under Trapezoid Waveform Application

Polyethylene is widely used as an insulating material for power cable. We have already reported that the dissipation current waveform depends on not only the electric field but also the changing rate of electric field. It is considered that to clarify the influence of the changing rate of electric field into the dissipation current waveform, and to examine whether this is the bulk dominant role or the surface dominant role are very important. By carrying out the film thickness dependence of dissipation current under trapezoid waveform application, the electric field E versus the current density J properties under the constant changing rate of electric field is estimated. As the results of experiments, not only the effect of changing rate of electric field but also the film thickness dependence was confirmed. Though the conduction mechanism under AC high field is pretty complex, it will be discussed based on the results which mentioned above.