Power distribution network fault fixed point instrument and detection method

The invention provides a power distribution network fault fixed point instrument and a detection method. The power distribution network fault fixed point instrument comprises a signal source and a detector, wherein the signal source is arranged in a fault section of a power distribution network and used for injecting characteristic signals into grounding phases of a plurality of branch lines whenthe plurality of branch lines to which the fault section belongs are out of operation, and the characteristic signals form a loop through grounding points of the plurality of branch lines; and the detector is used for being connected with the plurality of branch lines, measuring the characteristic signals flowing through the plurality of branch lines so as to obtain a measurement result of each branch line in the fault area, and determining a grounding point of the fault section based on the measurement result. According to the power distribution network fault fixed point instrument and the detection method, the groun