Controlling electrical stress of polymeric insulators using zinc oxide microvaristor

Non-linear field grading materials (FGMs) based on zinc oxide (ZnO) microvaristors have been proposed to control the electric stress and prevent premature aging and degradation of high-voltage insulators near the end fittings. The current work reports on the effectiveness of using a laboratory fabricated ZnO microvaristor in controlling the electric stress on an 11 kV polymeric outdoor insulator. The proposed design involved applying a microvaristor-based compound sheet of varying dimensions onto the insulator core under the silicone rubber housing. Experimental investigations showed that the proposed FGMs improved the performance of the polymeric insulator by 38.9%.