The DYN-III-10KV-R low residual voltage busbar protection cabinet provides more comprehensive busbar overvoltage protection and PT protection for the system. The low residual voltage overvoltage protector in the device is used to undertake busbar overvoltage protection, providing better overvoltage protection for equipment connected to the busbar. The residual voltage protection is reduced by more than 30% compared to conventional lightning arresters. For example, in a 10kV system, it can be reduced from 45kV to below 30kV. As a primary protection for the busbar, the residual voltage reduction of 30% will greatly improve the effectiveness of secondary protection such as lightning arresters, provide more complete protection for cables, and greatly improve the service life of cables. The suppression effect of low residual voltage technology on bus overvoltage is increased by more than 30%, which will significantly reduce the occurrence of insulation flashover accidents inside the cabinet, extend the service life of solid insulation equipment, and improve the stability of system operation.