Abstract
The authors describe in this paper the application of a semiconductor pressure device for a pressure monitoring sensor, applicable to both continuous monitoring and fault locating of a gas insulated switchgear (GIS). Improvements required for these purposes are long term stability against temperature and supersensitivity for detecting a minute pressure variation caused by the fault. To get high sensitivity over a wide range, the amplifier having changeable ranges are presented. To compensate the output fluctuation due to temperature, we introduce a current driven circuit, a current source designed to have opposite characteristics to the piezzo resistance of the semiconductor and a digital compensation method. Offset drift by temperature is solved by use of AC drive. The temperature stability of the sensor consequently come at 0.01%. For high SN ratio required for the fault locating, we adopt digital filters, and pattern matching. The sensor is achieved 10Pa sensitivity with 700kPa dynamic range.
