Oil contaminant detection based on differential capacitance

Oil contaminant detection is of great significance for machine fault diagnosis. However, in practical environments, there are complex electromagnetic interferences that greatly reduce the sensitivity of detection. In this paper, a capacitive oil contaminant detection method based on the differential principle is proposed. Firstly, the mathematic model of the differential capacitance principle is derived. Then, the electrode structure for contaminant detection is designed, and the detection principle is verified through physical field simulation. Finally, the feasibility of the differential capacitance detection is experimentally validated. The experimental results show that the detection method based on the differential capacitance principle can effectively suppress environmental interferences and detect sub-millimetre bubbles, which demonstrate the potential for practical applications.