This is used for locating various faults of the cables for the city cable, high frequency communication cable, buried cable and medal overhead cable line. The faults include open circuit, short circuit and poor contact. It also can be used to telemetry the position of the fault, including the leak grounding, wire breaking and poor contacting. The instrument adopts many testing methods and the most advanced electron technology fruits as well as the computer technology and the microelectronic technique. It has a high degree of intelligent, a full function, a large range of use, an accurate testing, a convenient operation and alternating-current power or direct current power source. It is especially suitable for testing different types and grades voltage cables.