Methodology to differentiate type of single-phase line break fault in 10kV ungrounded distribution networks

10kV distribution network is always a neutral point ungrounded system. Single-phase line break and grounding fault frequently occurs in 10kV distribution networks, threats the safe and stable operation of power grid and damages people's lives and properties. A methodology to differentiate type of single-phase line break fault is proposed in this paper, which uses sequence network and symmetrical components method to analyze and summarize the voltage and current variation when various single-phase line break fault occurs, then draw the voltage phasor diagram and current phasor diagram. The voltage and current variation and phasor diagrams will provide criteria for the detection and identification of single-phase line break fault in ungrounded distribution networks. Simulation results show the accuracy of the theoretical analysis in this paper.