The chorus dancers of the grid
A reliable and cost-effective solution, uninhibited oils such as Nynas NYTRO® Libra and Taurus represent the most tried and tested insulating liquids for transformers of all sizes.
THOMAS NORRBY
Technical Manager Lubricants and Electrical Industry at Nynas, and Adjunct Professor in Tribochemistry at KTH Royal Institute of Technology.
“Although NYTRO Libra and NYTRO Taurus are suitable for transformers of all sizes, they are mainly targeted at network transformers under medium load. These are the chorus dancers of the grid, rather than the ballerinas,” says Professor Thomas Norrby, Nynas Technical Manager for Lubricants & Electrical Industry.
Considering the number of transformers used in electricity grids, there is little wonder operators are keen to use transformer liquids requiring minimal attention at prices that fit tight budgets. In particular, the transformers making up the distribution network need to function trouble-free for as long as possible.
“The operational behaviour of uninhibited transformer liquids such as our NYTRO Libra and Taurus products is well-established and hence more predictable than that of rivalling inhibited liquids. This is of course highly appreciated, not least among service and asset management personnel,” adds Thomas Norrby.
Unlike inhibited transformer liquids, uninhibited alternatives do not contain added synthetic antioxidant additives. Instead, the oxidation stability of uninhibited liquids relies on the natural antioxidant properties of the naphthenic base oil.
“The antioxidants in inhibited liquids will indeed protect against oxidation, but additives always add costs. Moreover, additives don’t last forever, so concentrations need to be monitored, adding maintenance steps and potential costly top-up service,” says Thomas Norrby.
Uninhibited transformer liquids, on the other hand, have a long, proven track record. Extensive studies monitoring their performance show that they will function well for decades. There are examples of transformers operating for 60 years with the same original uninhibited liquid.
“Uninhibited liquids will age alongside the rest of the equipment in the transformer. There is very seldom any need for even minor interventions or maintenance,” explains Thomas Norrby.
Both NYTRO Libra and NYTRO Taurus meet the technical standard IEC 60296:2020 Type B as well as many requirements and standards of OEMs and external test laboratories such as Doble and Engie Laborelec. Both products also meet strict HSE requirements and have a lower Product Carbon Footprint than similar products in the market.
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Optimised refinement
Crafted from naphthenic base oil, NYTRO Libra and NYTRO Taurus are uninhibited transformer liquids that require no added synthetic inhibitors. Instead, they rely on natural antioxidants such as aromatic and sulfur-based molecules that are already present in the oil and then carefully preserved through a finely balanced refining and production process. Whereas uninhibited oils are refined to an optimal degree, the formulation of inhibited liquids stipulates a very high degree of refining to ensure an effective response to added inhibitors. Severely refined oils are used for making high-quality, premiumgrade inhibited transformer liquids. These would also exhibit very good electrical properties. However, a limited content of aromatic molecules could impact on the hydrogen gas absorption performance, another desirable property. An optimum degree of refining will result in a carefully balanced liquid that retains the right amount of aromatic and sulfur-based molecules to ensure both good electrical properties and oxidation stability. |
