PURPOSE: To enable determination of a failure point in a underground electric wire involving connection parts of cables in a short time and with high accuracy.
CONSTITUTION: An optical fiber 1 is put inside a plastic pipe 8 installed in a tunnel 10 of an electric power cable 3, and a temperature distribution measuring apparatus 2 for measuring a longitudinal temperature distribution inside the tunnel 10 according to backward scattering light distribution in the optical fiber 1 is provided. A trigger signal is sent to a temperature distribution measuring apparatus 2 at the moment when a trip signal of a underground electric wire is received, the longitudinal temperature distribution of optical fiber 1 is directly measured. Differential values of the temperature distributions' been before and after the trip signal is received are obtained by a data Processor 7, and a position with the maximum differential value is detected as a failure point.
TSUTSUI TERUAKI
HASHIBA KEIICHI
HITACHI CABLE