Oil Debris Detection Using Capacitance and Ultrasonic Measurements

Abstract

This paper aims at the use of a capacitance sensing approach using a RLC meter to detect oil debris contents and experimental results are compared to those obtained using an ultrasonic device. It was found that both capacitance and ultrasonic measurement can both detect particles as small as 4 mils (101 μm) in diameter. Experimental results show that the measured capacitance increases linearly with the increase of particle size while the ultrasonic wave amplitude decreases linearly with the increase of particle size. While some measurable differences can be detected by both capacitance and ultrasonic measurements between the ferrous and the nonferrous particles, a systematic difference between the data point cannot be developed. In addition, the existence of nonconductive particles cannot be readily detected using the capacitance measurements but their existence can be observed by the ultrasonic measurement.