Management of atmospheric gases in high reliability outdoor distribution transformers

The art and science of life assessment of liquid-filled transformers is common topic for power engineers. In a given sample group of transformers, the oil may be in excellent condition. Low percent H2O saturation can indicate dry oil and dry paper. Dryness of the paper can be confirmed by insulation power factor and polarization index measurements. These results, however, would not confirm the mechanical condition of the paper, which is usually the end point in the life of the transformer. Nominally, this can be done by correlation with either COx (CO + CO2) or furans. However there can be a paradox in the data. The COx can be very high, indicating significant degradation of the paper, while the furans at the same time are very low, indicating that the paper is in perfect condition. A possible explanation of this paradox is developed.