PURPOSE: To magnify a fine arc trace so as to easily detect the arc trace of an arc horn where any fault current occurs by igniting a heating agent in a metallic container fixed at the end of the arc horn with application of energy of a surge current or a fault current flowing the arc horn.
CONSTITUTION: Arc horns 1 are fixed with clamps 23 above and under an insulator string 22 to protect the string 22 from a lightning discharge toward a transmission-distribution line 21. When a fault current caused by a lightning short flows through the arc horns 1 fixed in the insulator string 22, the fault current flows in a heating agent 3 via a metallic container 2 so as to ignite the heating agent 3. The temperature at the container 2 becomes higher by the reaction heat of the heating agent 3 caused by the ignition so that the surface thereof is discolored by oxygen in the atmosphere. With this discoloring, an arc trace caused by the fault current can be displayed magnified. Therefore, the arc trace caused by the fault current can be visually detected with ease.
OOI SUKEHIRO
HIGASHIDA HIROSHI
NICHU GIKEN KOGYO KK