Failure analysis of field-aged polymeric outdoor insulators and performance enhancement for electric stress using nonlinear field grading composites

Halloum, M-R and Reddy, BS and Reddy, GN (2023) Failure analysis of field-aged polymeric outdoor insulators and performance enhancement for electric stress using nonlinear field grading composites. In: Electrical Engineering .

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Abstract

Polymeric outdoor insulators are increasingly employed in transmission and distribution systems. The various electric and environmental stresses significantly affect their long-term performance due to their organic nature, leading to degradation and aging of the insulation materials. Experimental studies have been carried out on in-service polymeric outdoor insulators for more than 20 years (400 kV and 132 kV) to investigate the structural changes and the effects of these stresses on the degradation and aging of the housing material (silicone rubber). The silicone rubber was subjected to the following tests: Fourier transform infrared spectroscopy, scanning electron microscopy and energy-dispersive X-ray, and hydrophobicity measurements. In addition, the equivalent salt deposit density and non-soluble deposit density measurements and tensile strength measurements have been carried out. The results of the field-aged polymeric insulators are compared with fresh samples also. These investigations show some interesting results, which are presented and analyzed. Finally, a 2D axisymmetric model of the 132-kV insulator was developed using COMSOL Multiphysics and the finite element method. One mitigation technique for excessive electric stress was studied using field grading composite (FGM) based on zinc oxide microvaristors. Suitable electrical characteristics and an optimized design of field grading material have been proposed to effectively control the electric stress of the 132-kV polymeric outdoor insulators under various operating conditions. The results of the simulation demonstrate that using FGMs can significantly improve the performance of polymeric insulators in the field. Further development of FGM and experimental investigations are planned.

Item Type:	Journal Article
Publication:	Electrical Engineering
Publisher:	Springer Science and Business Media Deutschland GmbH
Additional Information:	The copyright for this article belongs to the Springer Science and Business Media Deutschland GmbH.
Keywords:	EDAX; Finite element method (FEM); FTIR; Nonlinear resistive field grading material (FGM); Polymeric outdoor insulator; SEM; Zinc oxide microvaristor.
Department/Centre:	Division of Electrical Sciences > Electrical Engineering
Date Deposited:	18 Jul 2023 11:14
Last Modified:	18 Jul 2023 11:14
URI:	https://eprints.iisc.ac.in/id/eprint/82527

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