Current-based motor condition monitoring: Complete protection of induction and PM machines

A complete summary of state-of-the-art techniques for monitoring and protecting each major component of low voltage, line-connected induction and permanent magnet synchronous motors is given in this paper. Specifically, a method for protecting the machine from thermal overload is presented, along with a method for robust stator turn-fault detection and operating fault tolerance. Current-based spectral analysis for rotor and rotating faults, as well as bearing faults is also presented. Each of these techniques are proved to provide condition- and fault-related information to the user without additional sensors.