Condition monitoring of electric motors based on magnetometer measurements

Using micro-sensors in industrial applications is of great interest due to their small size, low-cost and little power consumption. However, the harsh environmental conditions encountered in an industrial environment have so far hindered the widespread use of, for example, MEMS-based sensors. Such sensors are particularly suited for mobile condition monitoring of industrial machinery as short time placement and operation of these sensors is typically unproblematic for many monitoring applications. In this paper we use a miniature triaxial geomagnetic sensor for condition monitoring of low voltage motors. The performance of the magnetometer is studied under conditions encountered in industry. Furthermore the magnetometer is used to measure magnetic fields of an electric motor in a healthy state and in case of a broken rotor bar. By frequency analysis of this data it is demonstrated that the magnetometer measurements can be employed to distinguish between these motor conditions.