Three grounding fault detection schemes of HX series electric locomotives were introduced, and it was evaluated whether there were potential electrical safety hazards when single point grounding occured in different grounding ranges under different grounding detection schemes and the locomotive continued to operate after isolating the fault converter. Through simulation analysis,when a single-point ground fault occured on the motor side, the intermediate DC link side or x-terminal of the traction transformer secondary side, no matter which ground fault detection method, the fault converter can be isolated to meet the continuous power reduction operation of the locomotive without safety risk; When the grounding fault point occured at a-terminal on the secondary side of the traction transformer, there was still a risk for the continuation in low resistance grounding mode and in the operation of isolated fault converter,which shall be stopped for rescue; There was a risk for the operation of isolated grounding fault converter in high resistance grounding mode, and the continuous operation of fault shaft can be maintained. Through the above ground fault mode analysis, it was convenient to guide operators to ensure the safe operation of locomotives and vehicles under various grounding modes.