Transformer Base Oil

About This Product

Transformer Base Oil is sold as a raw material for insulating oil manufacture, not as a ready-to-use transformer oil. A finished oil has two tasks inside the tank: to insulate, by occupying every gap between the windings and saturating the paper wrap so that no air pockets are left, and to cool, by moving heat from the core and coils out to the tank walls and radiators. Bringing the stock up to that standard is the blender's job. It is dried, filtered and degassed, dosed with oxidation inhibitor if the target grade calls for it, and then tested electrically as a finished oil. Two finished insulating oils, EIOS T2-U and EIOS T2-HI, have their own entries in this catalogue.

Viscosity governs heat transfer, and here it is limited to max 10.0 cSt at 40 °C. A thin oil moves quickly through the cooling ducts; a heavier one circulates sluggishly and allows hot spots to develop in the windings. The stock also carries a flash point (PMCC) of min 130 °C, a viscosity index of min 95 and ASTM colour of max 1.5, the colour limit pointing to thorough refining. Acidity starts low, at a total acid number of max 0.05 mg KOH/g, which matters because the acids generated as an insulating oil ages degrade cellulose insulation and promote sludge. One figure needs planning: a pour point of max -9 °C is well above the limit in most finished insulating oil specifications, so check the certificate of analysis and allow for pour point treatment.

Besides transformers, oils made from this stock serve switchgear, reclosers and circuit breakers, insulating live components and extinguishing arcs. The electrical and ageing properties a buyer of finished oil looks for, such as breakdown voltage, dielectric dissipation factor, water content and oxidation stability, are created by the finishing process and measured on the finished oil, so none of them appears in this base stock specification.

Spindle Oil and Base Oil 65N-HVI fall in the same light viscosity range, but both are made to lubricate. Transformer Base Oil, by contrast, has a ceiling on viscosity and no floor. A lubricant must be thick enough to separate moving surfaces, whereas an insulating oil cools best when it is as thin as possible. Buy it as an insulating oil feedstock; it is not a substitute for a finished grade.

BG Petro Chemicals supplies this stock from Pakistan, allocating volumes from a combined lube base oil output of 16,500 MT per month across all grades. An insulating oil feedstock must be protected from moisture, so receiving tanks and containers need to be clean and dry. Supply options include bulk, ISO tanks, IBC tanks, flexi bags and drums, as well as custom packaging. A certificate of analysis travels with every lot, and the technical datasheet and SDS are available on request.