Análise de falhas de comutação em contator AC utilizando redes de Bragg em fibra óptica como elemento sensor

Abstract

Electrical circuits work based on switching loads using electromechanical switches. Switching devices are used in power systems at different voltage levels and, to ensure the safety of electrical installations, it is necessary to monitor the operating condition of these equipment. This work proposes the real-time study of the switching conditions of an AC contactor. For this purpose, the Fiber Bragg Grating (FBG) was used as sensor element and an ABB electromechanical contactor AX40-30-10-75 as switching device. The usage of the Support Vector Machine (SVM) as the primary method to recognize the degradation pattern of mechanisms and contacts was also proposed. Recurring failures in elements of switching artifacts were researched só that they can be properly simulated. The contactor, instrumented with only one FBG sensor element, was subjected to simulated failure conditions to validate the use of the Bragg gratings as a sensor element, based on the method already applied in previous experiments using DC relays. After the successful validation, additional tests were proposed for the analysis of mechanical switching blockage and tests with the absence of contact pressure springs. With the mechanical vibration signals acquired by FBG both in the validation and in the final tests, it was possible to extract their main characteristics and create a scatter plot through which the Gaussian Kernel function was applied in the SVM. The results indicated a probability of misclassification of 0% between samples with integrity and with switching blockage, however, for samples related to contact pressure, an additional analysis of the frequency spectrum was necessary. Through the various tests performed, it was observed that the FBG is an adequate sensor to detect the signal variations and the SVM an efficient method to acquire the patterns of each fault condition.