Space Charge Characteristics in ZnO Microvaristors-Doped Silicone Rubber Composite

The accumulation of space charge in insulating material under high electric fields can trigger critical insulation failures, including electrical breakdown and material aging, posing severe threats to the safe and stable operation of power equipment. Zinc oxide (ZnO) doped silicone rubber (SiR), with nonlinear conductivity and permittivity, can adaptively control the electric field distribution in power equipment and suppress space charge injection in the insulating material. However, the charge transport and accumulation mechanisms in such nonlinear composite remain insufficiently understood, requiring further investigation. This study employs the LaserInduced Pressure Pulse (LIPP) method to investigate the space charge characteristics in SiR with 0, 20, and 40 vol% ZnO microvaristors-doped. Compared to pure SiR, ZnO microvaristors-doped SiR exhibits enhanced injection of homocharge in the voltage application test, and the injection magnitude showing a positive correlation with ZnO doping concentration. In the voltage removed test, ZnO microvaristorsdoped SiR demonstrates faster charge dissipation rate. These findings hold substantial importance for advancing the practical application of nonlinear composite in power equipment.