Alienating in the same axis

摘要

PROBLEM TO BE SOLVED: To detect highly sensitively a damage part of a conductor of an overhead distributing insulated wire or a snow accretion preventive insulated wire.;SOLUTION: Two sides of a bridge circuit 2 are constituted from a pair of flaw detection coils L1, L2 arranged coaxially and mutually separately along a wire 1 to be measured, and the bridge circuit 2 wherein, when the impedance of either flaw detection coil is changed, the equilibrium state of the bridge circuit 2 is disordered and a detection signal S is outputted, is constituted. A resonant coil L3 is arranged between the pair of the flaw detection coils L1, L2 so as to compensate a magnetic flux generated by the pair of the flaw detection coils L1, L2 when the bridge circuit 2 is in the equilibrium state. A resonance circuit 6 for resonating at a prescribed frequency is connected to the resonant coil L3, and an amplifying circuit 8 for amplifying an exciting current to the pair of the flaw detection coils L1, L2 is connected to the resonance circuit 6.;COPYRIGHT: (C)2003,JPO