Development Of On-line Detection Device For Insulation Status Of Power Cable Joints

The manufacturing process of the cable intermediate joint is complicated,and the technical requirements of the installer are relatively high.If impurities are mixed during the installation process or the cutting is too deep when cutting the insulation,partial discharge will occur.Partial discharge is a major killer of cable insulation and an important indicator of the goodness of cable insulation.Therefore,real-time detection of the partial discharge amount of cable joint insulation is an effective means to avoid cable faults.At present,the commonly used detection methods at home and abroad are basically off-line detection,which requires power failure detection,and has been increasingly unable to meet production requirements.In this paper,the characteristics of ultrasonic waves are generated when partial discharge of cable intermediate insulation occurs,and the ultrasonic detection method is deeply studied.Firstly,the partial discharge of the insulation of the cable intermediate joint was modeled and analyzed.The propagation law of the partial discharge signal in the cable was obtained,and the important parameters to measure the insulation degree of the middle joint of the cable were obtained.Secondly,the mechanism of ultrasonic generation,waveform characteristics,amplitude-frequency characteristics and propagation law are studied,which provides a theoretical basis for the selection of ultrasonic sensors.On this basis,the cable intermediate connector model was fabricated by simulating the electrical characteristics of the cable joint in the laboratory environment,and a set of ultrasonic testing devices including ultrasonic sensors,signal processing circuits,lower-level machines and peripheral circuits,host computers and system software were developed.Wait.Finally,the experimental verification of the developed ultrasonic testing device was carried out in the laboratory.The results show that the fabricated device is feasible and effective,and can detect the amount of partial discharge,which provides an online detection method for the detection of cable joint insulation faults..