Portable Device for Transformer Oil Inhibitor Content Analysis Using Near-Infrared Spectroscopy Wavelength

Monitoring the insulation system of power transformers is crucial in ensuring power transformers are operating in optimal conditions. Due to the non-direct 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 on-site testing and on-line monitoring application. Therefore, this work proposed the measurement of inhibitor concentration in transformer oil using a portable optical measuring device that utilizes near-infrared spectroscopy. The fundamental studies of measuring inhibitor in transformer oil using a newly discovered wavelength at 1403nm 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 based on the data obtained from the photodetector. The measurements were then conducted along with the conventional technique for performance comparison and prototype verification. The results showed a root-mean-square-error of 0.01708 and an average error of 2.11%. This proposed prototype opens up opportunities in on-site testing and on-line monitoring of inhibitor content concentration in transformer oil.