Characteristics and Superposition Regularity of Aliasing Signal of an Inductive Debris Sensor Based on a High-Gradient Magnetic Field

The detection of wear condition is critical for the prediction of mechanical equipment failure and the avoidance of catastrophic accidents. A large-diameter inductive debris detection sensor was previously presented to satisfy the requirement of high throughput, and the characteristics of induced voltage generated by single debris were analyzed. However, in practice, plenty of wear particles carried by lubricant flowing through the sensors probably form the aliasing signal, thus affecting the evaluation of concentration and size of particles. In order to analyze the mechanism of aliasing, this paper studies the influence of the motion state of wear debris, such as velocity, relative spatial position and trajectory, on the waveform of the aliasing induction signal. The experimental results show that the aliasing induced voltage is proportional to the debris velocity and magnetic induction intensity. Additionally, the voltage peak-peak of aliasing signal is approximately proportional to the radius of the debris instead of the volume, from which the relational expression about the aliasing signal and component singles derives. Finally, the theoretical results and experimental results are performed to validate this relation.