Study on Simulation Design of Protected Circuit Models for Non-linear Dielectric Conductivity Measurement System Under High Electric Field Condition

When high voltage is applied to nonlinear dielectric material at the test time, due to influence of some factors (such as defects of material itself, environment temperature, humidity. etc), an accident breakdown with high voltage may happen at one moment, seriously, the high energy ns impulse discharge produced by breakdown would make the measurement failed. This work was built on the base of nonlinear conductivity platform, and designed several different kinds of RC and LC filtering protection circuits, at the same time, we had a simulation for these protection circuits by Simulink software. The simulation results showed that, the RC and LC filtering circuits all have a protection function for measurement, and can buffer the voltage amplitude changing of the megger, by comparison we know, under the same condition (the same capacitor C selected), the LC filter has a better buffering function than RC filter, it can make the output voltage of megger increased more lenitively, and improve the safety factor of measurement system in a great degree. It suggests that by comparing the simulation result between LC filter and pi filter models, the pi filter model has a best buffering function, it can make the output voltage of megger change more slowly under the high electric-field breakdown condition. Also, we analyzed the filtering principle of several typical protection circuits, and validated the correctness of simulation results by comparison.