PDGA － Portable Dissolved Gas Analyzer represents a new generation of test equipment for analysis the dissolved gas in oil. PDGA adopted the advanced infrared photo-acoustic spectroscopy technology and the friendly operation interface. The concentration data of the 7 key fault gases and moisture can be drawn directly within 20 minutes in the field. It really can take place of the Gas Chromatography system in the laboratory because of the accurate, rapid, reliable results. Thus the PDGA is one of the best tools for the electric equipment asset evaluation. Analysis of dissolved gases in the oil is an established technique in this field, and is being further extended to other oil filled equipment, such as power transformers, tap-changers, circuit breakers.