MEASURING METHOD FOR PARTIAL DISCHARGE AT CABLE END CONNECTION PART

摘要

PROBLEM TO BE SOLVED: To measure the partial discharge at end connection part neglecting connected electric apparatus. SOLUTION: Selecting frequency leading the impedance of an electric apparatus X to zero for measuring frequency and using this measuring frequency result in to be equal to shortening the end connection parts 12a and 12b and so the existence of electric apparatus X connected to the end connection parts 12a and 12b can be neglected. By impressing a testing voltage from the electric apparatus X side in this state, partial discharge generates near the end connection parts 12a and 12b and partial discharge signal obtained by extracting the signal of measuring frequency component selected by way of detecting foil electrodes 14a and 14b capable of regarding as capacitor and a signal detection circuit 15 can be detected with a measuring device 16. Even if external noises mix in both cables 11a and 11b, these noises are easily cancelled by differential connection of a balance circuit in the signal detection circuit 15 owing to the symmetry of the cables 11a and 11b so that only signal due to the discharge near the end connection parts 12a and 12b can be obtained with high sensitivity by the measuring device 16.