Transformer insulating oil is often exposed to high temperatures due to the high voltage electrical applications for which it is commonly used. As a result, insulating oil degrades over time, reducing its ability to act as an insulator and possibly leading to equipment failure. 2,6-di-tert-butyl-p-cresol (DBPC) and 2,6-di-tert-butyl phenol (DBP) are commonly used in transformer insulating oil as antioxidants. It is common practice for more antioxidant to be added if the level drops below 0.15%. As a result of this, regular testing of transformer oils is necessary to ensure optimum functionality of transformer units. Infrared spectroscopy provides a fast method wherein the quantity of antioxidant in a sample may be determined in less than 30 seconds while adhering to regulations set out by ASTM D2668 and IEC 60666.
This application note describes how the PerkinElmer Spectrum Two FT-IR spectrometer provides a fast, simple and cost-effective method for evaluating the levels of antioxidant in transformer insulating oil.