大電流のインパルスアークによるOPGWの溶損量の推定

抄録

Strands of an optical fiber composite overhead ground wire (OPGW) can be broken by lightning strikes if the energy of the lightning is high. Especially, winter lightning around Japanese sea coast tends to have huge energy because of its long current duration time, therefore numbers of literatures report results of DC arc tests on OPGWs simulating winter lightning strike on them. On the other hands, short duration high current arc tests have not been conducted enough. This paper reports the results of arc tests on OPGWs using impulse current generator whose output current peak is 50kA and wave front/tail duration of 8/20μs. The arc shape was observed by high speed cameras and observation of the OPGW strand after the test was also conducted. The results seemed that the main cause of melting of the OPGW strand in the test was electric heating due to the voltage and the high current at the boundary between the strand and the arc. Taking the voltage, time variation of current density, characteristics of the material of the OPGW strand into account, simple calculation was done to estimate the melting depth and the evaporated amount of the material due to the arc. According to the results, a strand of the OPGW struck by a short-duration lightning may not be damaged seriously.