Cross-Conductive Sensor for Humidity Measurement in Gas for Gas Insulated Switchgears Application

This paper presents a conductive sensor based on the extension of the Thomson and Lampard theorem for humidity measurement in nitrogen gas. Conventionally humidity sensors both resistive and capacitive types are fabricated using an interdigitated electrodes structure (IDE). In the IDE sensor, a major portion of the sensing area is covered by the electrodes when the electrodes are placed on the sensing film. The proposed sensor consists of four coaxial electrodes along the circular periphery separated by a small gap. The sensing film made of polyvinyl alcohol is deposited in the inner space of the electrodes. The cross-conductance between the two opposite electrodes is used to measure the humidity in the range of 0-S5% RH 25°C. The sensor is interfaced with a basic Opamp circuit to determine its response parameters. It shows a sensitivity of 53.76mV/% RH. The output of the sensor is found highly stable with good reproducibility.