Comparison of Electrostatic-Field and Transient-Field Distributions for Insulators in Pulsed Power Systems

Abstract

The difference between transient-field distribution (TFD) and electrostatic-field distribution (EFD) is investigated by establishing models for a coaxial line with a supporting dielectric in it and a vacuum insulator with an equivalent load. By simulating the coaxial line model, it is found that the TFD is totally different from the EFD in that the maximum electric field strength ( $E_{\mathrm {max}}$ ) of the TFD is almost 2 times of the $E_{\mathrm {max}}$ of the EFD. It is considered that the wave reflection leads to the increase of $E_{\mathrm {max}}$ of the TFD. By simulating the vacuum insulator model, it is found that the TFD on the insulator surface is dependent on the impedance of the load ( $Z_{\mathrm {load}}$ ), whereas the EFD keeps constant as $Z_{\mathrm {load}}$ changes. Factors such as load impedance, gap between insulator and metal, pulsewidth, and pulse rise time are selected to further research the differences between the TFD and the EFD methods. It found that the load impedance and the gap between insulator and metal influence the TFD greatly, whereas the pulsewidth and pulse rise time have less influence on the TFD. The difference of TFD and EFD can be used to calculate the impedance distribution of an insulator in practice.