Degradation diagnosis of cable is one of major issues for operation and maintenance in overhead distribution power lines. The diagnostic system for overhead power lines is composed of three parts in functional aspect - a travelling unit, a sensing unit and a communication unit. Among them, sensor detects the defects such as corrosion and disconnecting of power lines. Performance of sensor is very important, and besides, the size and structure of sensor is restricted for installation to small and lightweight diagnostic system. This paper suggests an optimal eddy current sensor best suit for small and lightweight diagnostic system in consideration of detecting performance, size and ease of installation and so on. Proposed sensor has been designed by Drum core structure and can be applied to the all domestic overhead power lines regardless of the cross-sectional areas. Also, it is showed that results of mock environmental test are satisfied.

nternal corrosion of the distribution line can be detected in order to develop techniques ofnon-destructive inspection methods that operate only on the metal track eddy current diagnosis ispossible by applying the technique investigated. Sensor for the production of a finite element methodmodeled by using an eddy current sensor, a distribution line by using an accelerated aging samples ofsodium hydroxide was prepared. Sheathed cables for internal corrosion studies detected using an eddycurrent sensor is considered to be possible.