Análise da aplicabilidade de sensores de acoplamento capacitivo no monitoramento de disjuntores de alta tensão.

Abstract

In this work, is evaluated the applicability of capacitive coupling sensors in the detection of signals emitted by electric arcs in circuit breaker contacts. In addition, the possibility of correlating these signals with the arcing contacts degradation level is investigated. The sensors applicability is investigated by comparing the signals detected by them with the signals detected by a broadband directional antenna in both time and frequency domain. For the analysis of the correlation between the arcing contacts degradation level and the detected signals, descriptive statistical attributes of the duration and energy of the signals were evaluated. The analysis of the results showed that the capacitive coupling sensors are able to detect the signals emitted by the electric arcs. It was also evidenced that the sensor detection sensitivity depends on the position in which they are installed along the analyzed pole. In the case of the circuit breakers used in this work, the best position for the installation of the sensors was the one closest to the lower terminal of the pole. The flexibility and value of the dielectric constant must be evaluated when choosing the material used in the construction of the sensors, since weak sensors can be damaged when installed at the pole of the circuit breaker, and high dielectric constants can affect the gains of the respective sensors. The correlation between the electric arcs signals detected by the sensors and the arcing contacts degradation level is possible, when the statistical attributes of the mean, standard deviation, kurtosis and median obtained from the energy of these signals are evaluated.