Rapid assessment of transformer insulating vegetable oil quality using FTIR spectroscopy and chemometrics

Although analytical techniques to assess the degradation of transformer insulation systems are well established, it is essential to develop fast and effective methodologies for monitoring the quality of power transformer insulating fluid. The objective of this work was to develop a fast, simple, and environmentally friendly method to evaluate and monitor the quality of insulating vegetable oil (IVO) from transformers, using multivariate control chart and infrared spectroscopy (FTIR). For the development of the method, IVO samples were subjected to electrical and thermal stress, as well as to contact with insulating paper and copper, to simulate the internal environment of a transformer before and after energizing. Control chart based on principal component analysis was developed to monitor insulating vegetable oil quality. It was possible to identify oil samples with oxidation levels that were outside the acceptable quality standards for insulating fluid in transformers. The results demonstrated the potential of FTIR spectroscopy and control charts as fast and simple tools for monitoring the quality of insulating fluids, enabling the identification of oil samples that fail to comply with regulation standards for insulating fluids, assisting in the implementation of maintenance programs for power transformers.