Assessment of insulation condition of 130 kV oil-paper current transformers using return voltage measurements and an expert system

Abstract

An automated pattern recognition system for the assessment of insulation condition of 130 kV oil-paper current transformers has been developed. The system uses polarisation spectra as obtained by return voltage measurements to estimate the state of high voltage (HV) insulation. Preliminary results show that the system is very reliable, decisions are reached within few seconds and the results fully agree with tan /spl delta/ measurements upon which previous estimates of insulation degradation were based. Moreover, return voltage measurements are easy to apply, offer robust performance in field environment and the equipment is less bulky.