Study on the Insulation Property of Fiber Reinforced Plastics under Nanosecond Voltage Pulses

The Fiber Reinforced Plastics (FRP) with vacuum forming technology has high structural strength and excellent insulation property, and is widely used in EMP (Electromagnetic Pulse) simulation devices. In order to improve the insulation performance of FRP and meet the requirements of the supporting structure for insulating materials in MV (Megavoltage) EMP simulation equipment, the effect of groove shape on the insulation performance of FRP insulators was studied. The experimental object is the cylinder insulators with different grooving technologies. The insulation environment is 0.1 MPa SF6, and here we use the circuit to output the nanosecond pulse with the rising edge of approximate 30 ns. The result shows that in SF6, different from the vacuum condition, the concave grooves of different shapes and sizes have no significant influence on the flashover voltage along the surface of insulators, which indicates that the secondary electrons production on the surface of insulators may not be the main reason for the flashover process along the surface in SF6. The result also indicates that convex grooves can reduce the electric field on the development path of the flashover channel and change the angle between the development path of the streamer and the electric field on the surface of the insulator, thus improving the withstand voltage of the insulator. Besides, in the experiments of samples with convex grooves, the bulk breakdown phenomenon of insulator and its convex grooves were observed, showing that there is a competition between the bulk breakdown in the insulator and the flashover along the surface of insulator whose phenomenon may be related to the impurities (bubble or dust) introduced along the glass fiber during the manufacturing operation.