Assessment of Voltage and E-Field Distribution in Outdoor Composite Insulator in 500 kV System for Interface Defects

This paper presents a simulation-based investigation using the finite element method (FEM) for a 500 kV composite insulator with conducting defect generating from the live end. The core of these insulators is Fiber Reinforced Plastic (FRP) glass which has silicone rubber as polymeric housing material around it and metal end fittings. The macroscopic interface between the core rod and polymeric housing is a weak contact and hence prone to degradation in these composite insulators. The appearance of voids at the interface could be due to improper adhesion during manufacturing. Moreover, poor handling during installation can lead to the development of internal cracks leading to permanent damage like brittle fracture. In service, the interfacial condition deteriorates due to internal defects, air-filled voids, and mechanical damage by dynamic loads (aeolian), leading to the debonding or crack at the interface. Hence, detecting internal defects at the early stages is essential for safe, reliable operation and improved service life. Engineering approaches must be employed to assess the performance of the interface to keep the insulator healthy. The field stress has been computed and improved by using a series combination of 132 kV conventional insulators to restrict the propagation of interfacial tracks. Results show a reduction in the stress at the simulated conducting channel, leading to a reduction in the electric field stress, which will restrict the propagation and improve service life.