Hot Electron Injection Regulation in Al2O3-filled Epoxy Resin Composite Using Cr2O3 Coatings

Al2O3-filled epoxy resin has been widely used as basic materials for insulators in ac/dc power transmission applications. Under normal working condition, charges injection from electrodes accelerates the dielectric aging rate and distorts the surface electric field, which is followed by dielectric degradation and breakdown. Therefore, to restrain the charge injection is of very important significance, especially when the dielectric was operating under temperature gradients. In this paper, to regulate the charge injection of dielectrics under temperature gradient, Cr2O3 coatings composed of dense well organized Cr2O3 molecules were created on the insulation surface. The surface potential appears low increments for modified samples, which indicates less charge injection phenomenon. Only slight surface potential increment was found using samples modified by Cr2O3 coating with thickness of 1000 nm, even when the temperature of HV electrode reaching 100 degrees C. Therefore, we believe that the Cr2O3 coating can effectively suppress the charge injection from the electrode, which has excellent application significance.