Wireless temperature sensor for condition monitoring of mechanical seals

This paper presents the first RF temperature sensor for condition monitoring of mechanical face seals. The sensor comprises a resonant inductor-capacitor circuit that is inductively coupled to a separate interrogating coil. The resonant circuit is mounted on the stationary face of the mechanical seal. A temperature rise is sensed as a resonant frequency increase, caused by a decrease in the sensor capacitance value. The resonant sensor is implemented using commercially-available components and has a footprint of less than 5.12 mm². Despite the very close proximity to the steel shaft (0.79 mm) and the stainless steel flange (2 mm), successful interrogation is achieved and the sensor´s frequency is increased linearly from 41.1 MHz to 41.6 MHz for a temperature increase from 25°C to 80°C. The measurements are verified by simulating the system using a combination of HFSS-ADS EM-circuit co-simulation model. The uncertainty in the measurements with respect to calibration equation was less than ±5%.