Detecting Defects in Porcelain Postinsulator Coated With Room Temperature Vulcanized Silicone Rubber by Pulsed Thermography

• Published in: IEEE transactions on instrumentation and measurement Vol. 68; no. 1; pp. 225 - 233
• Main Authors: Liu, Lishuai, Wang, Liming, Guo, Chenjun, Mei, Hongwei, Zhao, Chenlong
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-01-2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acoustics; Coatings; Defects; Filtration; Fourier transforms; Homomorphic filtering; Image contrast; Nondestructive testing; nondestructive testing (NDT); Porcelain; porcelain postinsulator; pulsed thermography; Room temperature; room temperature vulcanized (RTV) silicone rubber; Rubber; Rubber coatings; Silicone rubber; Silicones; Temperature measurement; Testing; Thermography
• ISSN: 0018-9456; 1557-9662
• DOI: 10.1109/TIM.2018.2834157

Nondestructive testing is of great significance for preventing fracture accidents of porcelain postinsulators, especially coated with room temperature vulcanized (RTV) silicone rubber. In this paper, the feasibility of pulsed thermography for defects detection of porcelain postinsulators was investigated. 110-kV porcelain postinsulators with crack defects were tested by utilizing the investigated approach. The results show that crack defect as small as 0.4 mm under the RTV silicone rubber coating with the thickness of 1 mm can be accurately identified. Homomorphic filtering method with Fourier transform was applied to correct the nonuniform heating and improve the defect contrast in the thermal images. With the advantages of simple operation, contactless measurement, full-field imaging, and quantitative defect estimation capability, the pulsed thermography would have promising applications in live detection of porcelain postinsulators.