Motor current signal analysis on programmable logic controller

Induction motors play a key role in the industrial field. Therefore, continuous monitoring and online diagnostic systems are essential to guarantee the seamless operation of modern industrial facilities. But, in modern automation installations, motor operation is controlled by programmable logic controllers (PLCs), which have become the main field controllers in automated process. This paper proposed the integration of diagnostic techniques in PLCs systems, so that their role as main controllers can be expanded to the field of motor diagnosis. This would represent an added value at a very low cost, because modern PLCs have enough computing power to process diagnostic algorithms, in parallell with the control tasks that they are performing nowadays. Besides, the integration of the control and the diagnosis in a single controller allows a faster response in case of failure, and a better integration in the SCADA systems in order to report the cause of failure and to track the number of failures. In this paper it is shown that classical motor current signature analysis can be carried out by modern PLCs, thanks to the availability of high speed data acquisition boards and new powerful processors.