| 摘要 |
PROBLEM TO BE SOLVED: To simplify a signal treatment circuit of a vacuum pressure diagnostic device to a vacuum switching device, and realize cost reduction and improvement in reliability. SOLUTION: The vacuum switching device is constituted of a metal container 12 at a floating potential, two insulating bushings, and a contactable and separable electrode pair. A measurement terminal 50 for a vacuum pressure diagnosis is installed opposed to the metal container 12, the metal container 12 and the measurement terminal 50 are molded by an insulator 20 such as epoxy resin, and a conductive coating 21 grounded to the outer peripheral part of the insulator 20 is installed. Since an earth capacity of the metal container 12 increases by the grounded conductive coating 21, a potential of the metal container 12 in operation comes nearer to a grounded potential. If discharge is made between the main circuit and the metal container 12 in vacuum pressure deterioration, since the potential of the metal container 12 becomes equal to a system potential, deterioration detection of the vacuum pressure becomes possible by potential elevation of a system frequency generated in the metal container 12. COPYRIGHT: (C)2007,JPO&INPIT
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