電子線照射架橋ポリエチレンフイルムの交流ランプ電圧印加時の高電界交流損失電流の過渡応答

抄録

To study high-field AC conduction mechanisms of nonpolar polymers, AC dissipation current waveforms are observed. The shapes of the AC dissipation current waveforms in high-field and high-temperature region become a triangle one in spite of sinusoidal voltage application, suggesting a nonlinear electric field dependence of instantaneous AC conductivity.
The fast rising AC ramp voltage application method is developed as a new technique to examine the dielectric properties in a very short time range. This method enables the measurement of the variations of the high-field dielectric properties and the dissipation current waveform immediately after the voltage application. The new measurements were carried out on electron beam (EB) irradiated crosslinked polyethylene (IR-XLPE) film. The dissipation current waveforms of IR-XLPE in high-temperature region show the peak in the former part of each half cycle of a full waveform and quick decrease in the latter half part.
In this study, in order to discuss the transient response of high-field AC dissipation current of IR-XLPE film, the dissipation current waveforms observations in very short time range were carried out under the two types of AC ramp voltage application, one electric field increasing rate is 16kVrms/mm•sec and another 80kVrms/mm•sec. The results show that the transient response of the variations of dissipation current I_XR with electric field are different between at the increasing and at the decreasing of the applied field, and in the case of increasing rate is larger, the difference between the "increasing" and the "decreasing" is emphasized. From these results, we consider that the injected homo space charge would become hetero space charge at next half cycle under AC electric field., and then the carrier injection and extraction near the electrode become a dominant conduction loss mechanism due to the formation of the hetero space charge around the electrode. Based on the above hypothesis, we tried to simulate the transient response of high-field AC dissipation current under the different electric field increasing rage. The calculated results agreed with the experimental results.