To protect a pressure vessel against damage by comparing each comparison pressure data with a corresponding high pressure side reference pressure data every predetermined sampling time and outputting a high pressure alarm data when the former is higher.
A pressure detecting section 21 and an A/D converter 14 sample the pressure of SF6 gas base on a pressure signal at a predetermined sampling time. A control section 24 calculates a pressure rise rate data based on a pressure detection data and compares the pressure rise rate data with a plurality of preset reference pressure rise rate data. If a pressure rise rate corresponding to a pressure detection data is higher than a pressure rise rate corresponding to any reference pressure rise rate data, an impact pressure detection data is outputted to an impact pressure detection output section 54 in order to actuate an impact pressure detection relay 53. Since an impact pressure is detected based on a pressure rise rate, a small gas state monitor having simple internal structure can be obtained.
Koyatsu, Osamu
Watabe, Yukio
Nakahara, Seiichi
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