| 摘要 |
An electric plant comprises an electric device connected to an electric distribution or transmission network, said electric device having a magnetic circuit and at least one winding, and a measuring apparatus (10) adapted to supervise the electric device. The measuring apparatus comprises at least one capacitive sensor (11) including an inner electrode (12) and a screen electrode (14), which screens the inner electrode from disturbing electric fields. The sensor is adapted to provide voltage measurement by sensing, by means of the inner electrode (12), such a part of an electric field which penetrates into the inner electrode. The sensor (11) is directed towards an electric line connecting the electric device with the distribution or transmission network so as to sense, at insulation distance, the voltage, including overtones and transients, of this electric line via the electric field surrounding the line. Furthermore, the invention comprises a method for supervising the electric device by means of the measuring apparatus.
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