Study on ultrasonic generation mechanism of partial discharge

Partial discharge is important reason to cause insulation deterioration, ultrasonic testing have the advantage of strong immunity, apt to realize on-line monitoring, easy to space location etc., therefore many scholars proceed ultrasonic wave to test partial discharge, also obtained a lot of results. But at present, the study of ultrasonic generation mechanism of partial discharge is not deep enough, Therefore profound study on ultrasonic generation mechanism of partial discharge have the theories guides meaning for ultrasonic method detecting partial discharge. In ultrasonics, oscillation is the major contributor to the formation of ultrasonic waves. While discharging, an impulse force will be exerted on the surrounding material, which is elastic usually, to generate oscillation, i.e. ultrasonic waves. Founded on this thought, resorting to the method of electrical-mechanical-ultrasonics analogy, the dissertation offers the analysis of the sources of electric-field-force-generated ultrasonic waves and heat-stress-generated ones and provides in-depth study on the origins of partial discharge related ultrasonic waves and the relevant model-of-gap-based equivalent circuit for partial discharge-generated ultrasonic waves, Theoretically, the derivation of the relations between ultrasonic signals and the actual discharging magnitude is helpful to make clear some problems of ultrasonic detection. The data of the tests and the experiments has positively demonstrated the validity of the analysis in the paper and confirmed the credibility of the conclusions as well, which, somehow, will be of some value and significance in terms of theory and practice to ultrasonic method of transformer on-line detection.