Motor current signal analysis on programmable logic controller

Abstract

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 moder 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.

Low-Cost Diagnosis of Rotor Asymmetries of Induction Machines at Very Low Slip With the Goertzel Algorithm Applied to the Rectified Current

“…The leakage generated by the fundamental component is null at the zeros of the sinc function (14), given by the expression…”

“…In case of low cost, embedded devices, such as field programmable gate arrays (FPGAs) or digital signal processors (DSPs), this considerable computing burden and memory footprint hampers its use for the fault diagnosis of high power induction machines [7], [13]. Moreover, a growing trend is to add fault diagnostic capabilities to variable speed drive (VSD) controllers or to programmable logic controllers (PLCs) [14], what requires using the least possible resources of the controller to avoid disturbing its normal operation. Besides, diagnostic data must be sent to servers, which makes it necessary to reduce the volume of data transmitted for lower communication costs.…”