Defects Analysis in Composite Insulators Associated with Brittle Fracture Aged on 230 kV Overhead Transmission Lines by the Micro-Computed Tomography

Speaker:
Shinohara, Armando; Universidade Federal de Pernambuco; Brazil

Authors:
Antonino, A.C.D.; UFPE - Federal University of Pernambuco; Brazil
Da silva junior, E.; UFPE - Federal University of Pernambuco; Brazil
Fujiwara, H.; UFPE - Federal University of Pernambuco; Brazil
Khoury, H.J.; UFPE - Federal University of Pernambuco; Brazil
Magnani, F.S.; UFPE - Federal University of Pernambuco; Brazil
Pacheco, A.P.; UFPE - Federal University of Pernambuco; Brazil
Shinohara, A.H.; UFPE - Federal University of Pernambuco; Brazil
Xavier, G.J.V.; UFPE - Federal University of Pernambuco; Brazil

ID: ECNDT-0404-2018
Session: CT-Applications 3
Room: G3
Date: 2018-06-13
Time: 13:50 - 14:10

In this work, two types of composite insulators of transmission line of 230 kV were inspected in laboratory using the technique of micro-computed tomography. One composite insulator aged for 6 years was removed after it showed three hot spots during a thermographic inspection at night, and another one was in operation for 10 years and was removed from in-service because composite rod of one of them fractured by the SCC brittle fracture mechanism.
The composite insulator that was inspected by thermography and showed three hot spots, two of them, showed the presence of defects, such as voids and detachment of silicone from composite rod. Furthermore, those defects are located in a position of injection mold of material used during the manufacturing of the insulator, that by the technique of segmentation and 3D reconstructions of the images, was possible to see clearly the mold geometry, detachment and distribution of voids inside. So, the hot spots in those two positions are attributed to partial discharge.
In the composite insulator that spent 10 years in-service and removed from the transmission line, after inspection by the micro-CT images showed presence of many fractures in the material that cover and protect the composite rod and those flaws are find perpendicularly to load due to the cable weight. The 3D images showed clearly that fracture are located only on the EPDM material region and some fractures start from interior to external surface.
As a result, two types of defects were detected and analyzed in detail by the 2D and 3D reconstructed computed tomographic imagens and a correlation was made with hot spots detected by the infrared thermographic images.