A new inductive sensor for online health monitoring of mechanical transmission systems

Metal debris in lubricating oil contains abundant information regarding the ageing and wear of mechanical transmission systems. The health condition of the lubricated systems can be indicated by the quantity and size of the metal particles, which may provide very early warnings of faults/ failures and benefit the condition based maintenance. Generally speaking, the quantity of the metal debris in oil indicates the ageing rate of the system, while the size shows the severity of the faulty status. Particle diameter under 20μm implies normal wear condition of the system, diameter from 50 μm to 100 μm indicates the infancy failure of the system [1-2]. Inductive sensor, which transforms the quantity and size of the particles into the number and magnitude variation of pulses of coil inductance, is widely used in the online metal debris monitoring systems [1-5].