Sistema de aquisição de dados para monitoramento e diagnóstico remoto das condições de para-raios de óxido de zinco.

Abstract

This work has as an innovative aspect the development of a system capable of monitoring, storing, analyzing and transmitting - at distance - the information contained in the leakage current on the state of degradation of the surge arrester. For that we used: a current sensor in toroidal nucleus, manufactured with nanocrystalline alloy; one innovative discrimination of the resistive and capacitive components technique and digital signal processing techniques, as well as a data-communication system, that qualifies it to be used in the inspection of zinc oxide surge arrester. Its operation aims at to increase the exactness, the efficiency and the reliability in the monitoring of the surge arresters and, consequently, the reliability of the electrical system. A new system of acquisition of data is presented, based on the integration of techniques of analogical and digital signal processing, so as to study the electric performance of a zinc oxide surge arrester in operation, from the continuous monitoring of its leakage current. An algorithm of management and interpretation of the measured data was developed with the possibility of monitoring continuously, inside of the foreseen intervals of sampling, the occurrence of changes in the leakage current. The results of the analysis of the leakage current can directly be transmitted for an operational room through a data communication system. Additionally, an interface is added to the system to make it compatible and to allow transmission of the acquired information data registers for automatic diagnosis, by means of radio frequency, infra-red ray or optic fiber, depending on the configuration of the installed electric plant. The systems of monitoring, storage, analysis and transmission had been evaluated individually revealing efficiency and accuracy. The complete system was evaluated in the dependences of the High-Voltage Laboratory under high intensity of electric field and the transmission system was capable of sending the signals of the leakage current third harmonic by radio frequency to the reception system.