Study of electric field enhancement along polymer insulators under service conditions

In recent years, the concerns about premature failures of polymer insulators have been increasing. These failures, in part, can be attributed to the high electric field (E-field) magnitude at end fittings of these insulators, which may lead to partial discharges activity. The E-field values recommended by manufacturers and researchers, to avoid this phenomenon, are not fully consensual yet, particularly when considering the insulator under service conditions, because the E-field can be affected by several factors. This paper analyzes the E-field along polymer insulators through computational simulations using finite element method to model the insulator and water drops. In association with the simulations laboratory, experiments were performed, where the corona voltage inception was observed. The experiments were made to reproduce moisture conditions on the insulator surface. The results clearly show how certain service conditions may increase the E-field.