de Oliveira, A. C.; E OLIVEIRA, A. C.; OLIVEIRA, ADRIANO.; http://lattes.cnpq.br/0687275983941838; OLIVEIRA, Adriano Costa de.
Résumé:
The techniques used to monitor and diagnose circuit breakers currently used by
electric companies have some technical limitations, such as an invasive nature, low
reliability and difficulty of application. According to statistical data, circuit breakers are
one of the faultiest equipment in transmission/distribution systems. Hence, in this
research is presented a new radiometric monitoring method for high voltage circuit
breakers based on computational routines and the use of printed monopole antennas with
bioinspired geometry. The method facilitates the monitoring process and makes it more
efficient. The proposed methodology is based on the measurement of electromagnetic
signals radiated by the circuit breaker during current interruption operations, in statistical
techniques such as boxplot analysis, and a classifier algorithm for data processing and
decision making. For the development of the measurement system a broad research was
carried out to analyze the spectral characteristics of the signals radiated by circuit
breakers, enabling the design of optimized sensors for this application. Printed monopole
antennas were designed, manufactured and tested using gain and bandwidth optimization
techniques as well as miniaturization techniques, making them suitable for the monitoring
of different types of circuit breakers. The carried out experiments generated promising
results, allowing the detection of different types of failure, such as high level of contact
degradation, mechanical failures in the actuating system, loss of the dielectric
characteristics of the extinguishing medium and mechanical failure in the contacts. In
laboratory, comparisons with the diagnosis provided by reference techniques indicated a
100% agreement regarding the level of contact degradation. Field experiments were
performed on an SF6 circuit breaker used for the switching of a 33 MVAr reactor, attesting
the applicability of the technique.