Space charge accumulation process in PET film at high temperature under high electric stress

Dynamic behavior of charge accumulation in PET film at high temperature under high electric stress has been investigated using pulsed electro-acoustic (PEA) method. Since dielectric materials such as an electric motor and a generator are sometimes used in environment of high temperature, the performance of the dielectric strength at high temperature is important. There are a few reports, however, about space charge accumulation process in dielectrics at high temperature. In this report, time dependent space charge accumulation process was observed using PEA method at temperature up to 150 degree with electric stress of 25 kV/mm. When the high electric stress was applied to PET film at high temperature, negative charges were observed near anode electrode. The amount of negative charge increased with increase of temperature and stress application time. After the polarity reversal of electric stress at high temperature, the immediate polarity reversal of the accumulated charge was observed.