Breakdown and flashover characteristics in transformer oil under nanosecond pulses

The insulation characteristics of transformer oil under nanosecond-pulse are a key issue in pulsed power technology. Hence, we experimentally researched the characteristics using an MPC-120D nanosecond-pulse power. Experimental data of breakdowns in 1-mm gap and surface flashover along PMMA surface in transformer oil were obtained. Furthermore, we also compared the flashover voltages of PMMA surface before and after treating the surface with plasma jet. The results show that the breakdown voltage of transformer oil in 1-mm gap is close to 120 kV when the applied voltage has a rise time of 40 ns and a full width at half maximum of 100 ns. The flashover voltage along untreated PMMA surface in transformer oil is 80 kV, which is lower than that in pure oil. However, the flashover voltage along the treated PMMA can be increased to 120 kV.