Design and Fabrication of an Inexpensive Capacitive Humidity Sensor for Smart Sub-Station Automation

This paper presents a RH smart humidity sensor fabricated using poly vinyl alcohol (PVA) as sensing film deposited on polyimide substrate. This sensor detects change in capacitance due to presence of humidity in gas insulated switchgear (GIS) application. The initial tests are conducted using moist nitrogen gas with different percentage relative (% RH). The performance of designed PVA sensor was experimentally validated and it is noticed that the sensor possesses good sensitivity with linear characteristics over the range of 0- 20% suitable for industrial practices. Further, other parameters of the sensors such as reproducibility test, transient response analysis, linearity analysis, impedance response, and dissipation factor were also conducted to test the stability and effectiveness of the designed sensor. COMSOL Multiphysics is also used to validate the design aspects of the sensor with the fabricated one. The uniqueness of the fabricated sensor is that it is demonstrated good sensitivity profile along with the excellent linear response for the measurement of low RH values. The cost effectiveness of the sensor ensures due to simple fabrication process, use of inexpensive materials and 100% yield ratio.