Low-voltage line power failure fault detection device

The invention discloses a low-voltage line power failure fault detection device and relates to the technical field of an electric low-voltage line electricity test device. The low-voltage line power failure fault detection device comprises an acousto-optic test pen, a screw rod, an upper insulation telescoping rod, a lower insulation telescoping rod and a positioning bolt. The acousto-optic test pen is fixedly connected with the upper insulation telescoping rod through the screw rod; the side wall of the top end of the lower insulation telescoping rod is provided with a positioning screw hole; and the positioning screw hole is internally equipped with the positioning bolt for fixing the relative position of the upper insulation telescoping rod and the lower insulation telescoping rod. The acousto-optic test pen is connected with the insulation telescoping rod, so that test personnel can realize test of the lines at high place without climbing high, and only need to use the insulation telescoping rod to contact the conductor directly to search the fault; once the power failure fault point is contacted, the rod can give an acousto-optic alarm, thereby helping line maintenance personnel to find out the line fault point quickly and greatly reducing the fault finding time; and the low-voltage line power failure fault detection device is safe, convenient and reliable to operate, high in scientificity and convenient and easy to understand.