Contaminants in transformer oil
Transformer oil is used as liquid insulation and dissipates transformer heat. More specifically, the transformer oil is used as a coolant in transformers and as a means of arc suppression in circuit breakers (apart from its insulating properties).
Transformer oil not only helps to preserve the core and windings which are fully immersed with oil, but also prevents direct contact of atmospheric oxygen which causes oxidation of the cellulose made paper insulation around the windings.
Although individually each contaminant reduces the insulating characteristics of the oil, the combination of fibers from insulating material and water can reduce transformer performance by up to 90%, so it is imperative to maintain insulation properties of the transformer oils by rigid control over moisture, dissolved gases, and particulate contamination. The periodic and proper treatment of transformer insulating fluids will result in the improved properties of the entire insulating system of a power transformer and will extend the effective lifetime of the asset.