Influence of carbon particles on the breakdown and partial discharge inception voltage of aged mineral based transformer oil

This paper reports on experimental investigations dealing with the influence of carbon particles on the breakdown voltage of aged transformer oil in a temperature range between 20 and 110°C and on the partial discharge inception voltage (PDIV) at 20°C. The oil samples were carbonized and afterwards subjected over periods of 1000 and 2000 h to different accelerated ageing conditions at 20 and 90°C in the presence of metallic catalysts. The results reveal that the breakdown voltage of carbonized oil samples is slightly increased by the ageing whereas the PDIV experiences a significant improvement