Analyzing the components and concentrations of oiled-dissolved gas in transformers is the primary approach to detect and diagnose transformer faults.For ultra-high voltage(UHV)and extra-high voltage(EHV)transformers

partial discharges produce lower concentrations of dissolved gases

demanding higher precision from analysis instruments.This study focuses on developing an oil-dissolved gas analysis instrument utilizing an enhanced plasma detector with argon as the carrier gas and also verifies its performance.Results indicate that the instrument achieves repeatability better than 3%

with a minimum detection concentration reaching the 10-8 level.Compared to traditional gas chromatographs

the enhanced plasma analyzer enables ultra-trace level(10-7~10-8)detection of gas components

aiding in the timely identification of early latent transformer faults.