PARTIAL DISCHARGE CHARACTERISTICS FOR DELAMINATION DEFECT OF EPOXY CAST RESIN POWER APPARATUS

摘要

For proper insulation design of epoxy cast resin power apparatus such as moulded transformers, it is important to consider defects that might exist at the interface between resin and conductor such as delamination. Accordingly, this paper aims to investigate partial discharge (PD) characteristics for micro gap delamination defect model of epoxy cast resin power apparatus. Atmospheric nitrogen was used as a typical filled gas inside the delamination of epoxy cast resin power apparatus and the results was compared with that of SF_6 gas filled delamination at epoxy GIS spacer. Electrical and optical PD measurements were carried out. PD inception voltage (PDIV) was measured for different delamination lengths, and then, PDIV was discussed in terms of the discharge mechanism. Following PDIV measurements, the PD activity for 10 minutes at PDIV and slightly higher voltage than PDIV were acquired in the form of PD light emission intensity, PD light emission image and PD current pulse. It was found that multiple PD events were detected only by PD light emission image and could not be detected by their current pulses as a result of very small magnitudes of PD current pulses. The effect of gap length and applied voltage on PD characteristics was investigated.