Our team at Oil Store is pleased to stock high performance transformer oils from the best brands in the business, such as Nynas. These specialist lubricants have been devised to offer operators an impressive level of oxidation stability, which in turn contributes to a protracted transformer life with less frequent incidences of breakdown. The ingredients also ensure superior resistance to oil degradation.
What is transformer oil?
Sometimes referred to as insulating oil, transformer oil is a highly refined synthetic or mineral oil. Manufactured by leading global suppliers such as Nynas and Q8, it is specifically engineered to remain stable even at high temperatures and to prevent electricity from flowing to areas where it is not required or wanted. It is used to fill a range of high-voltage equipment, including large switches, circuit breakers and power transformers.Key functions of transformer oils
Providing high dielectric strength, transformer oils act as electrical insulators by creating a non-conductive barrier between live components and grounded parts, helping to prevent short circuits and unwanted electrical breakdown. Transformer oil also absorbs thermal energy created by copper and core losses, taking heat away from windings and transferring it to radiators or other cooling surfaces to help prevent overheating. When internal faults or electrical discharges occur, transformer oil can vaporise slightly, generating gas bubbles that may help suppress electrical arcs and reduce the risk of catastrophic failures. Transformer oil also protects components such as solid cellulose insulation and internal metal parts from corrosion, moisture and oxidation.Common types of transformer oils
Derived from refined crude oil, mineral oil is the industry standard for transformer oil and is a relatively low-cost solution. Its subtypes include naphthenic oil, which has high moisture and gas solubility and a low pour point, and paraffinic oil, which has a higher boiling point and improved oxidation resistance but a higher pour point. Natural ester oil is a bio-based fluid formulated from renewable vegetable oils such as rapeseed and soya. Fully biodegradable and offering superior moisture tolerance, it also has an extremely high fire point of more than 300°C. However, it is more expensive than conventional mineral oil. A man-made solution, synthetic ester oil is formulated using polyol esters engineered for more demanding environments. It offers biodegradability, high oxidation stability and a wide operating temperature range, but, like natural ester oil, comes at a significantly higher price than mineral oil. Silicone oil is another synthetic fluid, but it is formulated from silicone polymers. While non-biodegradable, it offers low flammability, extreme thermal stability and high dielectric strength. It is generally the most expensive option available.
The top-grade inhibited transformer oils we can supply have been thoroughly tested, and typically have passed corrosion tests including ASTM D1275, DIN 51353 and IEC 62535, as well as conforming to ASTM D3487-16 and IEC 60296 Edition 4.0. Such products are perfect for use in oil-filled electrical equipment - typically circuit breakers, rectifiers, power transformers and switch gear systems.
The lubricants are capable of start up even at the lowest temperatures, negating the need for pour point depressants, while a high dielectric strength means the oils can ably cope with extreme demands. Where required, heat removal from transformer cores and windings is enabled by specially formulated lubricants, and additionally a low index of viscosity assures the outstanding conduction and transfer of heat.
If you would like any advice on the right transformer oil for your equipment and intended usage, please feel free to ask the experts at Oil Store. We are happy to give guidance on this, or any of the other oil products we stock, upon request.