1996 Volume 116 Issue 11 Pages 1415-1421
It is feared that the very high and steep lightning impulse voltage may cause electrical breakdown of the suspension insulators used in power lines. For investigation of dielectric breakdown mechanism on the suspension insulators, different porcelains were tested by applying the impulse voltage. It was found that the porcelain with non-uniformly distributed corundum had voids, resulting in lower dielectric breakdown strength. And the test results on the suspension insulator revealed partial breakdown in the porcelain before overall dielectric breakdown. The partial breakdown is considered due to high electrical stress concentration around the voids and will progress by application of repetitive impulse voltages. Also analyzed in the investigation were influences of other insulator components on the dielectric breakdown. There was found the optimum coordination of dielectric constant among porcelain, glaze and sand. In addition, electric field calculation showed that the field strength was affected by the configuration of each component.