Transformer Oil Maintenance

Transformer oil, when operating the unit within its design parameters and with proper, regular maintenance and testing, will last the life of the transformer.

Transformer oil should be tested regularly (typically annually) for general oil quality (moisture content, dielectric strength, interfacial tension, acidity, specific gravity, color number) and dissolved combustible gases. This should be trended throughout the transformer's lifetime. If the oil shows a change, then diagnostics and electrical testing need to be done to determine the cause.

Do NOT just change the oil! That is only masking the symptoms, not finding the cause. It could be any of a variety of problems: overheating/overloading, insulation breakdown, corona or other discharge under the oil, arcing, leaks, contamination, oxidation, etc. You have to determine the cause and fix it first. After repair and depending on how badly the oil has deteriorated, you may just choose to keep the same oil and continue to test it regularly, reprocess it to clean it up, or replace it with new oil.

If problems are caught early enough, the oil can continue to be used. Reprocessing may be necessary if the problem was allowed to continue long enough that the oil is severely contaminated or deteriorated. It is very seldom that there is need to totally replace the oil.

Please define <...2......bad quality...>? Where does the boundary lay?

When the oil sample fails the BDV or tan/delta or moisture or DGA... testing

And the numbers and units of these TLAs, please?