Abstract: In order to explore the variation of sheath current on high voltage (HV) cable metal sheath multipoint grounding, a model of sheath current based on complex matrix equation was proposed by using centralized parameter circuit model. Combined with the model and mathematical theory, the calculation methods of leakage current and earth current in multipoint grounding branch were proposed. In order to verify the accuracy of the model, simulations were performed by ATP-EMTP. Comparing the simulation results with the calculated values of different grounding modes, laying ways, numbers and locations of multipoint grounding, the average relative error of the model was less than 3.26%, which could be used to calculate the sheath current accurately. The model was used to analyze the variation of sheath current on sheath multipoint grounding at cross connecting models. The results showed that the sheath current peak appeared around the phase-change point. Based on the change rule, a method according to the sheath current value monitored at the head and the end of the cable line was proposed, to judge fault phase and location

Key words: HV cable, multipoint grounding, sheath current, ATP