Finite Element Simulation Analysis of Infrared Thermal Wave Detection on Composite Insulators

Composite insulators are now being used in wide range of power grid. However, there are still some concerns for composite insulators due to their internal faults during their in-service. Therefore, a Nondestructive Testing (NDT) method based on infrared thermal wave technology was raised. The surface information of the composite insulator about temperature field can be collected constantly by infrared detector, and there is a certain relationship between inner structure and surface temperature. In this paper, the process of internal heat conduction is analyzed by finite element simulation. The cylinder with air gaps of different depths is used to simulate the non-umbrella skirt mandrel of composite insulator, and it is simulated by Pulsed Thermography (PT) and Continuous Thermography (CT), and the records of surface's temperature field can be obtained. Based on the extracted statistics, the temperature-time curves and temperature difference-time curves can be plotted. Finally, in the case where the distance between the defect and the surface is constant, the size of the inner core is changed and experiments are repeated to demonstrate the general applicability of the method. The practical results indicate that it is feasible to employ the infrared thermal wave method on the nondestructive detection of internal defects of the composite insulators.