The incipient fault of medium-voltage cable joint in a water-logged environment has seriously affected the reliable operation of distribution network. In view of the poor interpretability of incipient fault identification methods of cable joints in current research

this paper designed incipient fault experiments of cable joints in water-logged environment according to actual operation scenarios

and obtains the composition and change process of incipient fault scenarios. Therefore

the incipient fault is divided into two stages

the beginning and the main stage

and the time domain and frequency domain characteristics such as current amplitude

duration time

damage accumulation

and spectrum difference between stages are analyzed. On this basis

the structure of incipient fault identification device and corresponding identification logic are proposed. The identification logic consists of five steps

namely

timing threshold detection

continuity detection

harmonic sampling

harmonic content comparison

and repetitive detection. Finally

the identification logic verification is carried out based on the data from the actual scenario. The verification results show that the proposed recognition logic can effectively screen out other interference signals and has a high accuracy.