Parametrização de HFCT para medição de descargas parciais em para-raios de ZnO.

Abstract

In this research, a parameterization of a High Frequency Current Transformer (HFCT) for measuring partial discharges in Metal Oxide Surge Arrester (MOSA) was performed. In order to achieve this, measurements of partial discharges in MOSA were made, with the arrangement proposed by the IEC 60270 (2000) simultaneously with two HFCT devices. The measurement evaluation was performed using the Phase Resolved Partial Discharge (PRPD) method. The data acquisition was performed with a digital oscilloscope with four channels, being further processed using Matlab c . From the measurements, a study of the power spectral density of the signals was conducted, followed by a filtering of the data using theWavelet Shrinkage technique. Finally, correlation curves were proposed to transform the HFCT outputs (in millivolts) to the apparent charge levels (in pC). From the results achieved by the present study, measurements in millivolt can be correlated with values defined in Electrical Engeneering standards for correct diagnosis of isolation state in the equipment.