Abstract
The electric field dependence of tan δ in oil-film composite insulating system sometimes hasa peak and then decreases, which is known as Garton effect. This phenomenon is associated with that under high voltage application carriers in oil can not contribute to the conduction loss all through a phase of applied electric field. Since the separation of the loss current from the extremely large capacitive current is usually very difficult, non-linear AC dissipation current waveform caused by Garton effect has not been measured.
The authors developed a new method for the measurement of high field AC dissipation current in polymeric insulating materials. We applied this technique to the detection of non-linear dissipation current and its waveform in oil-film composite insulating system associated with Garton effect. We measured the variation of dissipation current with applied field and its frequency.
