Abstract: Objective: To address the issue of abnormal electric shock incidents among maintenance personnel caused by improper operations during metro vehicle workshop maintenance, a control scheme for the auxiliary highvoltage bus ring feeder in urban rail transit vehicle is proposed. Method: The proposed scheme is designed based on four aspects: highvoltage box safety circuit, feeder contact box safety loop, ring feeder control, and mediumvoltage bus control. Trip switch, workshop power socket cover position switch and grounding isolation switch are installed on the front cover of vehicle highvoltage box. A feeder contact box is added to the existing highvoltage circuit, which includes the feeder contactor, lowvoltage control circuit, and the trip switch on the box cover. A network control unit and a logic unit are set up to collect the status of highvoltage box front cover, workshop power, grounding isolation switch, and feeder contactor box cover, and perform logic diagnostics based on the cover and switch position status. Result & Conclusion: (1) When all the aforementioned status are in the normal position, the feeder contactor coil is energized, and the highvoltage feeder extends through two power units of the entire vehicle. (2) If any cover status is abnormally disconnected, the feeder contactor coils of both power units lose power, resulting in disconnection of the highvoltage feeder, providing power only within the local power unit. Simultaneously, the logic diagnostic unit controls the power loss of threephase gridrelay, disconnecting the threephase bus contactor, and the threephase bus is connected only within the local power unit. (3) In addition to highvoltage safety loop control, the threephase bus can also protect its own status. When there is no shortcircuit fault, the threephase bus contactors are closed, and in case of shortcircuit fault, the contactors are disconnected; when the auxiliary inverter diagnosis indicates an internal shortcircuit, the corresponding auxiliary inverter is cut off and reconnected to the grid. If the auxiliary inverter diagnosis indicates an external shortcircuit, the threephase contactors are disconnected. (4) In case of a network failure throughout the vehicle, and the auxiliary inverter detects an internal shortcircuit fault, the threephase contactors are disconnected.