Feasibility of Wireless Sensors for Health Monitoring in Large Induction Motors

Wired sensor systems are currently used to monitor the performance and health of electric motors. Since the sensors need to be wired, these systems can only use few sensor modalities which are generally insufficient to detect the wide range of faults in motors. Wireless sensors, on the other hand, allow access to sensors mounted in accessible locations and on rotating parts. They are easy to install and maintain. However, the reliability of the transmission due to electromagnetic interference and the fidelity of the data due to high winding temperatures inside the motor need to be examined. This paper studies the feasibility of wireless sensors inside a 200hp AC induction motor. Two wireless sensors are attached inside the motor - one on the stator frame and one on the rotating shaft. A wired sensor is attached on the outside of the stator frame to study the fidelity of data from the wireless sensor. The packet delivery performance as a function of spatial location in terms of direction and distance with respect to the base station and the fidelity of data received by the base station are studied. The results show that an average of 97% and 87.9% of the data from the wireless sensor attached on the stator frame and shaft respectively is received at the base station, thus showing that wireless sensors can be reliably used inside the motor.