The distribution network transmission line suffers from various complicated environmental impacts during operation

and frequent disconnection faults

which seriously affect the stable operation of the distribution network. This paper takes the single-phase disconnection fault of the 10 kV neutral grounded distribution network as the research object

analyzes the steady-state electrical characteristics of the single-phase disconnection fault of the distribution network

including the characteristics of current and voltage changes. A diagnosis method of single-phase breakage fault with current as the main and voltage as the auxiliary is proposed. The occurrence of single-phase breakage fault is determined by analyzing whether the amplitude and phase angle of the current and voltage are within the threshold of the fault amount and its type. For the distribution network transmission line follow-up protection

it provides a reliable basis for action

and improves the stability of the distribution network operation. Finally

the feasibility and effectiveness of the diagnosis method are verified by MATLAB simulation

and the field measured data is also verified.