Avaliação das condições de operação de um contator eletromagnético utilizando sensores a fibra óptica

Abstract

This work presents the analysis and results obtained from the fiber Bragg gratting (FBG) sensors instaled in the fixed core of an electromagnetic contactor, for temperature and strain measurements. These results can be used to analyze behavior and predict future preventive maintenance of the contactor. FBGs can be used for contactor core temperature and strain measurements due to their small size and electromagnetic immunity. At the electromagnetic core contactor temperature measurement, it is observed that the thermal stability is reached in 190 minutes, with a temperature variation of 68 °C. To the strain measurement, four situations were analyzed: contactor without failure, contactor with voltage sag, contactor with obstacle in the air gap and contactor without shading rings. The electromagnetic force, obtained from the strain measurement, has a fundamental frequency of 120 Hz, which is twice the frequency of the power supply for both the contactor without failure and contactor with voltage sag. This fundamental frequency is obtained by applying the fast Fourier transform (FFT) to the steady state strain signal. For both contactor with obstacle in the air gap and contactor without shading rings, the strain waveform is non-sinusoidal, due to collisions of the fixed and movable cores. In the contactor dynamic simulation, in the Matlab® software, the electromagnetic force waveform is similar to the contactor core strain waveform under normal operating conditions.