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%.