The utility model discloses a steady state zero sequence current feeding device, which has solved the defects that the amplitude of the electrical quantity is quite small and is not easily detected by using the steady state quantity earthing selection and positioning measure for the fault signals when the system is broken down. After the electricity grid happens to the grounding fault in single phase, instantaneously enlarge the steady state quantity of the fault signals so as to ensure the earthing selection and positioning device that is based on the steady state quantity of the single phase grounding fault can be accurate to act, thereby achieving the targets of positioning and earthing selection. The structure of the utility model is shown as follows: the utility model comprise a busbar that protects the power distribution system, while a steady state zero sequence current feeding device is arranged on the busbar. The device is also connected with a pressure transformer that is connected with the busbar. The current feeding device consists of a power capacitor unit, a switching switch and a control device. The control device monitors whether the power distribution system occurs to the single phase grounding fault. The power capacitor unit feeds in the grounding current and the control device controls the switching of the power capacitor unit through the switching switch.