NYTRO BIO 300X: Thumbs up from grid operators
As the field experience of Nynas’ biobased transformer liquid grows, so does the positive feedback from grid operators. With many more test cases lined up, Nynas reviews the experiences so far.
Hugo Campelo
Senior Technical Advisor, Electrical Industry, Nynas AB.
A growing number of utility companies are using Nynas’ new innovative insulating liquid NYTRO® BIO 300X in their transformers. This is hardly surprising, as the novel liquid is not only bio-based, but also biodegradable, offering a sustainable and acceptable alternative for transformers located in, for instance, sensitive water protection areas.
“The feedback we are getting from the industry confirms our own findings and everything we say about the liquid in our sales brochures and data sheets,” says Hugo Campelo, Senior Technical Advisor at Nynas.
Developed as an alternative to mineral insulating oil and ester liquids and produced from bio- based by- products, NYTRO BIO 300X offers a negative carbon footprint. Fully renewable and recyclable, it is an attractive option for utilities with increasingly tough sustainability targets for their operations.
Since it was first introduced in the market in 2019, NYTRO BIO 300X has been used in multiple tests conducted mainly by transformer manufacturers in the scope of factory acceptance tests.
“Although it is now used in around two dozen power transformers and hundreds of distribution transformers, the market uptake is still in the early stages of adoption,” explains Hugo Campelo.
Due to its ultra-low viscosity and low density, NYTRO BIO 300X provides enhanced cooling in the transformers. Temperature rise tests conducted in four different power transformers show a consistent trend towards an average winding temperature reduction of 4–5°C, depending mainly on the cooling regime. In ONAF/OFAF systems, temperature reductions beyond 10°C can be achieved both in the liquid and in the hot spot.
“More transformers and more designs are expected to be tested soon with business cases also covering retrofills and/or retrofits of old units. The extra buffer offered by reduced temperatures and load losses is one of the routes to explore, along with the compatibility with existing design and maintenance behaviours adopted so far for mineral oils,” he says.
Twin transformer test
- The Spanish utility company Iberdrola tested Nynas NYTRO BIO 300X in one of two sister transformers of the same design. Their side-by-side study of temperature rise tests showed that the bio-based hydrocarbon liquid significantly enhances transformer cooling, thus improving the overall thermal performance of the transformer filled with the bio-based liquid compared to the sister one immersed in a conventional naphthenic mineral oil.
- Temperature reductions ranging from 5 to 10°C have been reported. These reductions enable a transformer to either be operating with lower losses, significantly extending its lifetime, or be operating above its nominal power. Iberdrola’s study proved that overloads of 20 percent for periods of two hours were possible without exceeding any of the standard temperature limits.
- “Previously published work had already pointed in this direction, but now this has been measured for the first time – using direct temperature measurements under steady and unsteady conditions,” comments Hugo Campelo.
Results of oil temperature rise testing (during ONAF mode) clearly demonstrate the superior performance of the bio-based liquid. Adapted figure curtesy of Iberdrola and A. Aguado et al. “Design of transformers suitable for different insulating liquids” Paper 10545 A2-PS1, Cigre Session Paris 2024.
