| 摘要 |
PROBLEM TO BE SOLVED: To provide a new method for measuring space charge by which the defective part of a cable for power, communication, etc., can be detected easily and inexpensively without using advanced measurement signal/electric noise isolating technologies, measurement signal processing technology, etc., by measuring the space charges accumulated in the part. SOLUTION: A space-charge measuring method is used for measuring the space charges in the insulator layer of a cable 5, which has the insulator layer between a conductor 51 and a metal layer coated with a corrosion-proof layer. In the method, the space charges in the insulator layer are measured in such a way that, after an electrode is attached to the surface of the corrosion-proof layer and surface charges are induced on the boundary between the corrosion- proof layer and a shield layer 55 by applying a DC voltage across the electrode and layer 55, a pressure pulse based on the surface charges is generated, by applying a pulsative voltage across an electrode 11 and shield layer 55 and the displacement current which flows, in response to the space charges in the insulating layer fluctuated by the pressure pulse, is measured.
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