Materials Transactions Online

Materials Transactions, Vol.53 No.04 (2012) pp.617-620
© 2012 The Japanese Society for Non-Destructive Inspection

In-Service Aged Composite Insulators at Transmission Line Investigated by the Micro-Computerized Tomography

Pietro P. J. C. Silva1, Armando H. Shinohara1, Admilson P. Pacheco1, Zurdival P. Castro Filho2 and Sergio L. P. Monteiro2

1UFPE — Federal University of Pernambuco, Department of Mechanical Engineering, Recife-PE, 50740-530, Brazil
2CHESF — Companhia Hidroelétrica do São Francisco, Recife-PE, 50761-901, Brazil

Composite insulators aged in-service for almost 10 years at the transmission line of 230 kV, in an area where brittle fracture of a composite insulator occurred, were inspected by the micro-computed tomography, µ-CT, and by the scanning electron microscope, SEM. As a result, several cracks with different depths under pollutant scale and confined in silicone housing were detected by the µ-CT. Surface of silicone housing was observed by the SEM. Many randomly oriented cracks from micrometers size were observed. However, larger cracks detected and evaluated by the µ-CT appear essentially perpendicular to the composite rod axis. In order to explain the evolution of those large cracks in composite insulators, a model based on µ-CT and SEM data was proposed.

(Received 2009/11/13; Accepted 2011/10/29; Published 2012/03/25)

Keywords: composite insulators, transmission lines of 230 kV, silicone housing, micro-computerized tomography, brittle fracture, scanning electron microscopy

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