The Insulation Status Assessment of High Voltage Cable Joints by Decision Tree Method

A simple decision-making mechanism was described in this paper, which could be used to help the maintenance personnel to judge the equipment insulation status, so as to avoid the occurrence of unanticipated accidents. The research method was to conduct PD (partial discharge) deterioration test on two kinds of defects of underground cable joints with three specimens respectively. The measured PD signal in each test was subject to noise suppression, dimension reduction, feature extraction and moving average methods, and finally became 104 kinds of feature curves. The results showed that one feature, phase center of negative discharge area of sum of discharge, has common aging characteristic among 6 test data. It approached the starting margin (180 degrees) of the third quadrant along with evolution of degradation. A decision tree method was utilized to make rules to judge the insulation state and produced overall identification success rate as high as 83.47%.