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

Abstract

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.