In order to ensure the safe operation of transformer

reduce the accumulation of hidden dangers resulting in sudden accidents

it is an important measure to monitor and analyze the content and components of dissolved gas in transformer oil.This paper introduces the common methods to judge the latent faults in the transformer

such as dissolved gas attention value method

gas production rate method

characteristic gas method and three-ratio method. Dissolved gas chromatographic analysis in transformer oil can analyze and judge many potential faults that cannot be found in high voltage test

which plays a key role in transformer state evaluation.