An On-Line Monitoring System for Gases Dissolved in Transformer Oil Using Wireless Data Acquisition

Dissolved gas analysis (DGA) is a certain method to diagnose incipient fault of transformers through the correlation between the content of gases dissolved in transformer oil and a particular malfunction. This paper developed an on-line monitoring system to detect the concentrations of H₂ and CO dissolved in transformer oil. The system mounts polyperfluoro ethylene-propylene membrane, electrochemical gas sensors, a wireless communication terminal based on RF transceiver, and data management software recording the concentration of H₂ and CO. Compared with off-line gas chromatograph results of concentrations of H₂ and CO, the concentration trend of on-line detecting results is in agreement with off-line results approximately through 8 months. For hydrogen detection, the biggest error of the system is 4 ppm when the on-line results range from 10 ppm to 21 ppm; for CO detection, the biggest error of the system is 26 ppm when on-line results range from 136 ppm to 189 ppm. The whole system provides a low cost, simple way to on-line monitor H₂ and CO dissolved in transformer oil. And the system which incorporated wireless data acquisition will definitely shorten a time gap between the changes of gas concentrations and dissolved gas analysis.