the accuracy of the ranging parameters directly affects the accuracy of fault ranging, and the ranging parameters are generally corrected by means of short-circuit tests, which are cumbersome to organize and have a large impact on the primary equipment of the substation and the contact network, and there are certain safety hazards. the transformer and feeder protection setting values are closely related to the traction load characteristics (minimum operating voltage, maximum value of feeder current, maximum incremental value of feeder current, harmonic content of feeder current, etc.), which are mainly obtained by theoretical calculation and differ from the actual field, thus affecting the action behavior of the protection device. the jda-222 traction power protection ranging analyzer developed by our company can solve the above problems. the system includes one set of traction power supply parameter analysis software, three sets of acquisition analyzers (each set contains seven current sensors and one gps receiving antenna with 30 meters long), which can meet the needs of various power supply methods for distance measurement and correction of feeder protection settings.