Winding Temperature Measurement in a 154 kV Transformer Filled with Natural Ester Fluid

Abstract – This paper measures the hot spot temperatures in a single-phase, 154 kV, 15/20 MVA power transformer filled with natural ester fluid using optical fiber sensors and compares them with those calculated by conventional heat run tests. A total of 14 optical fiber sensors were installed on the high-voltage and low-voltage windings to measure the hot spot temperatures. In addition, three thermocouples were installed in the transformer to measure the temperature distribution during the heat run tests. In the low-voltage winding, the hot spot temperature was 108.4 °C, calculated by the conventional heat run test. However, the hot spot temperature measured using the optical fiber sensor was 129.4 °C between turns 2 and 3 on the upper side of the low-voltage winding. Therefore, the hot spot temperature of the low-voltage winding measured using the optical fiber sensor was 21.0 °C higher than that calculated by the conventional heat run test