SOUZA, R. T.; http://lattes.cnpq.br/0855145610768901; SOUZA, Ronimack Trajano de.
Resumo:
The measurement and the harmonic analysis of the resistive leakage current
is an efficient technique for determining the degradation level of metal oxide surge
arresters. The arrester consists of a stack of nonlinear resistive blocks known as
varistors. A novel technique for determining the resistive component of the leakage
current of ZnO varistors has been presented. It consists of a virtual bridge that does not
require a high voltage coupling capacitor. The proposed technique has been applied to
monitor the resistive leakage current of ZnO varistors that have been degraded under
controlled conditions. The degradation has been obtained by applying high voltages and
high impulses current discharges. The resistive waveform has been measured before and
after the degradation of the varistors. Measurements and simulations are presented and
they show that the 3rd harmonic component of the resistive leakage current is a good
indicator of the level degradation of the ZnO varistors.