LIMA JÚNIOR, G. B.; http://lattes.cnpq.br/9232850503920479; LIMA JÚNIOR, Geraldo Bezerra.
Resumo:
Nowadays the reliability and continuity in the electricity supply are increasingly
required. The surge arresters has an important function in this process, which is to
protect the other utility equipment against lightning and switching surges. When they
fail, usually causing the shutdown of transmission lines or transformers, severely
penalizing the power utility for the unavailability or regulator fines. As any important
equipment for the electrical system, surge arresters need effective monitoring
techniques. In the literature and industry several techniques, procedures or
equipment for their monitoring can be found. All procedures or devices have their
limitations, advantages and disadvantages, whether technical, economic or
operational. Aiming to overcome some of the limitations in existing techniques and
procedures commonly employed in the electrical industry, a methodology for
analyzing the surge arrester operational condition based on measurements of total
leakage current is proposed in this paper. With this methodology is intended to
minimize operational difficulties associated with monitoring activities, since it will only
measure the total leakage current unlike the usual techniques and procedures, which
require the measurement of the applied voltage, too. A database of leakage currents
with measurements performed in five (05) power substations was obtained.
Measurements were grouped by arresters model/manufacturer and operation time.
The measuring instrument used consists of a clamp type ammeter and a portable
digital oscilloscope. The process of field measurement was effective and practical
due to the ease of handling of the used instrument. Laboratory tests were performed
to evaluate the methodology and measuring instruments. From the database
produced, it was possible through the use of techniques of signal processing and
statistical observe the Gaussian behavior of the data and the average increase of the
3rd harmonic component of the total current as a function of operating time, which
highlights thus, the correlation between the increase of the leakage current and the
decrease of the lifetime of the surge arrester.