Low-cost condition monitoring sensor for used oil analysis

The development of a low cost condition monitoring sensor for used oil is described. The sensor is designed as a direct measurement of the overall quality of the used oil as compare to that of the un-used oil. The system detects the relative variation of lubricant degradation i.e. degradation of physical/chemical properties, suspended wear particles and ingested contaminants, by using the grid capacitance sensor configuration. The system consists of grid sensing unit and a multitude of small holes (1 mm in diameter) between each parallel sensing grids. The system works on a principle of measuring for the relative variation of the dielectric constant of lubricant caused by contaminants such as water, fuel dilution, water, wear debris, etc. In this particular paper, the performance of this specific sensor is assessed systematically through the utilization of statistical design of experiments (DOE).