Investigating the Output Response of the Relative Saturation (RS) Sensor for Measuring the Moisture in Transformer Oil

Abstract

This paper proposes the RS sensor fabricated using inexpensive materials to evaluate its output voltage corresponding to the moisture. The main structure of the RS sensor consists of upper and lower electrodes. The lower electrodes are made of ceramic and copper, while the upper electrodes are made of different materials: (1) porous aluminum adhesive electrode (2) 18650 battery gasket. Furthermore, the thin-film polymer is placed between the upper and lower electrodes for sensing the moisture in oil. The moisture sensing film is highly hydrophilic and is made of silicone film. For measuring the output voltage of the RS sensor, a voltage sensor is connected to Arduino Uno. The test condition is categorized into 4 ranges of the oil temperatures: (1) at 10–14 °C, (2) at 30–35 °C, (3) at 60–65 °C, and (4) at 80–85 °C. The results show that the value of the output voltage of the sensors vary directly to the value of moisture in ppm and the temperature of the oil. To integrate the effects of both factors, the output voltage of each sensor is plotted as a function of the %relative saturation(RS). The output voltage of the sensors decreases as the %RS increases. However, with R-squared (R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) value of each graph shows that the relationship of the output voltage as a function of %RS is a good linear for all three sensors. Then, this leads to a good indication to use the RS sensor for continuous moisture measurement in transformer oil.