The ATP-EMTP simulation model of cross-interconnected grounded cable is established to study the impact of induction voltage of the sheath on the sheath insulation and the protector itself under the defect of cable sheath grounding disorder, and to analyze the sheath grounding box breakdown under the disorder of the sheath grounding mode from the perspective of the short-time absorbed energy size of the sheath protector. Finally, according to the change law of the current at the grounding box under the normal grounding mode of the sheath and the chaotic grounding mode, it is proposed to use the identification of the sudden change of the grounding box current to determine the grounding chaotic fault and supply the protection device as the tripping basis. It is found that when the wrong grounding mode at J1 and J2 grounding box leads to the loss of grounding of the cable sheath at the first end of the sheath to J1 junction box, the system will induce a large overvoltage at the first end and J1 junction box, and the maximum overvoltage can reach 12.22kV after stabilization, and the overvoltage at the junction box of the cable sheath that loses grounding is the largest, and it is more likely to have a protector breakdown accident.