Portable NIR Spectroscopy Measuring Device for Transformer Oil DBPC Inhibitor Analysis

Monitoring the insulation system of power transformers is crucial in ensuring power transformers are operating in optimal conditions. Given the nondirect and destructive nature of conventional techniques, optical techniques have prevailed to be an effective alternative to monitor the condition of the insulation system. The recent development of small and compact optical components has also contributed to the utilization of optical techniques in onsite testing and online monitoring application. Therefore, this work proposed the measurement of inhibitor concentration in transformer oil by using a portable optical measuring device that utilizes near-infrared spectroscopy. The fundamental studies of measuring inhibitor in transformer oil by using a newly discovered wavelength at 1403 nm were validated, and its adaptation to a portable optical measuring device was discussed. A new mathematical model was formulated to estimate the inhibitor concentration in transformer oil samples on the basis of data obtained from the photodetector. Measurements and the conventional technique were conducted for performance comparison and prototype verification. Results showed a root-mean-square-error of 0.01708 and an average error of 2.11%. This proposed prototype opens up opportunities in onsite testing and online monitoring of inhibitor content concentration in transformer oil.