A highly precise cross-capacitive sensor for metal debris detection in insulating oil.

The presence of metal particles in lubricating oil produced during the wear and tear of mechanical equipment can harm its performance severely if not detected in time. Hence, the detection of such particles is necessary to predict and to prevent disastrous failures of the machines. This paper presents a new non-contact cross-capacitive sensor for the detection of metal particles in the lubricating oil. The sensor can detect each and every metal debris particle in the lubricating oil by monitoring the capacitance peak. The proposed capacitive sensor works on the principle of the Thompson-Lampard theorem. The sensor consists of four cylindrical electrodes with infinitesimal gaps wrapped around a hollow Teflon tube. The sensor has been modeled with finite element simulation software and then fabricated to verify the theory experimentally. Experimental results show that the capacitance value shows a sharp change in its value due to the presence of metal debris in the oil. The output of the sensor is highly precise (±0.82%) and accurate.