Service Experience with Composite Line Insulators: EPRI Perspective - (PPT)

摘要

Since 2006, some utilities have experienced an increasing number of polymer insulator failures on 115 and 138 kV transmission lines. Investigations have shown that these failures can be attributed to high electric fields (E-fields) occurring close to, or on the high-voltage end fittings of these insulators. These findings suggest, contrary to common practice, that it might be necessary to consider the application of corona (also called grading) rings on polymer insulators on transmission lines with a system voltage below 161 kV. Transmission line reliability can be affected if utilities do not have measures in place to minimize the effect of corona discharges on the rubber material. EPRI utilized their experience and research results to help the affected utilities develop a strategy to address premature aging of polymer insulators on 115 and 138 kV transmission lines due to high E-fields. This included providing reference information, technical support and recommendations to assess existing insulator populations and to specify polymer insulators for new or replacement units. In this paper an overview is given of these insulator failures and the strategy that was followed to manage the situation.