Effect of transformer oil color on breakdown voltage

Insulation in high voltage applications is crucial, especially transformer oil. Transformer oil plays a key role in electrical power systems as an insulating medium. Over time, transformer oil undergoes a color change, which can serve as an indicator of oil degradation due to the formation of acids, resins, and sludge. This study aims to analyze the effect of transformer oil color changes on the decrease in its breakdown voltage. The methodology involves accelerating the color change of transformer oil through additional heating. The results of this experiment will provide an empirical relationship between the color change of transformer oil and its breakdown voltage. By establishing this color-versus-breakdown voltage relationship, the evaluation (maintenance) of transformer oil can be done quickly (without breakdown voltage testing). In general, the oil remains suitable for use up to a breakdown voltage of 70%. The experimental results show that as the oil color becomes darker, the content of amorphous carbon and other components (especially water) increases. The breakdown voltage decreases by 27.22% when the oil reaches a darker color, and this reduction in breakdown voltage increases exponentially.