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Defects Detection of High Voltage Insulation Pull Rod Based on Ultrasonic Wave Method

Insulation pull rod is an important component in high voltage circuit breakers, but during production or under electrical and mechanical stresses for a long time, some defects such as voids and cracks may occur in the insulation poll rod and reduce the reliability of power equipment. Considering the structure characteristics of insulation pull rod and the features of typical internal defects, a model of insulation pull rod was designed in COMSOL, and simulation analysis was carried out using ultrasonic echo detection method. In addition, a series of typical defects were added to the simulation model of the insulation pull rod to study the effect of the defects on the ultrasonic echoes, and a method for evaluating defects by the propagation time and amplitude of defect echoes was proposed. The simulation results for void defects show that the amplitude of the defect echo increases with the size of the defect and the time interval between the surface echo and the defect echo increases with the depth of the defect. The simulation results for crack defects show that the orientation of the cracks have an effect on the ultrasonic echoes. In other words, 0° crack is the easiest to detect, 45° crack is second, and 90° crack is the most difficult to detect.