Response of 10 kV Insulators and Metal-Oxide Arresters Excited by MV-Level Transient Electromagnetic Disturbance

The safety of 10 kV metal-oxide arresters (MOAs) and insulators under nanosecond-level transient electromagnetic disturbances (TED) has become a critical concern as power systems develops rapidly. While current studies mainly focused on TED with peak amplitudes of hundreds kV, the electrical equipment on overhead power lines may expose to MV-level TED with nanosecond-level rise time induced by the field-to-line coupling. This article studies the responses of 10 kV MOAs and insulators under MV-level TED based on the pulsed current injection (PCI) method. Experimental results demonstrate that both the flashover voltage of insulators and the residual voltage of MOAs increase significantly with higher rate of the voltage rise and the amplitudes of injected pulses. Excited by the MV-level TED, the flashover voltage of 10 kV insulators is more than four times the lightning impulse withstand voltage, and the residual voltage of 10 kV MOAs is more than 6 times the residual voltage under the lightning impulse. Both flashover voltage and residual voltage far surpass those observed under the 200 kV TED with the roughly identical current waveforms. For the equipment on overhead lines, the results from MV-level PCI tests are more reasonable and accurate than those done with the voltage less than hundreds kV, which are mainly for the equipment along the lines near the ground. The experimental results indicate the overvoltage risks to protected equipment along overhead lines exposed to TED, and they can be referred in insulation coordination.