Positioner for fault point of transmission line

A locating device for locating failure point of transmission line consists of a traveling wave signal extraction device, an amplitude-limited circuit, a three-phase rectifier circuit, a threshold compared circuit, a monostable trigger, a GPS clock module circuit and a PC. When in measurement, the failed voltage or the current traveling wave signal is not directly taken from CT or CVT of a substation but from a small reactance which is connected in series with capacitive elements of the substation, and the failure traveling wave signal from the small reactance has almost no power frequency interference. By adopting the unique traveling signal extraction device, making use of the existing capacitive device or capacitor existing in the device as a high voltage arm without any additional requirements on the device, the utility model has wide application; by adopting a low voltage arm featured with inductive elements, the utility model improves sensitivity to troubles and locating precision and dramatically increases the strength to resist interference.