AN APPARATUS FOR LOCATING HIGH RESISTANCE FAULTS IN ANY CORE OF A MULTICORE UNDERGROUND ELECTRIC POWER CABLES

摘要

An apparatus for locating of high resistance faults in any core of a multicore underground electric power cable having a sheath, comprising an ammeter, one end of the ammeter connected to one end of a core adjacent to the core whose fault is to be located, the opposite and of the said adjacent core being connected to he sheath of the cable by means of a jumper cable, the opposite end of the said ammeter connected to one terminal of a battery through a switch, the other terminal of the said battery connected to a voltmeter of high input resistance, which said terminal of the battery also connected to the said sheath, the opposite end of the said voltmeter being connected to the core whose fault is to be detected, recoding the potential drop along the sheath from point of fault in the core to the end of the said core where the said voltmeter is connected said potential drop being indicated by the equationwhere Ss denotes the resistance per unit length of the sheath, I denotes the direct current passed through the said core and returned through the sheath and LP is the distance from the end where the said voltmeter is connected to the point of fault and determining the potential drop in the same manner at the opposite end of the faulty core and determining the distance of the point of fault by the equation:(Chemical formula)and since LP+LQ=D by the equation as follows(chemical formula)where Vp and Vq are the potential drops indicated by the voltmeter at each of the two determining ends, D is the total length of the cable between the two determining ends and LP is the distance from the determining end to the point of fault.