Challenges and research areas
The transformer's performance and lifetime depend on the interplay between material properties, design, operating conditions and stresses from the power system. We investigate these relationships through research, testing and analyses. The work includes, among other things:
- failure mechanisms, damage investigations and scrapping analyses
- insulation systems, material properties and new transformer fluids
- partial discharges, electrical strength, breakdown and other insulation-related issues
- cooling, temperature and loading capability, including overload, also under Arctic conditions
- mechanical integrity, winding pre-stress, ageing and lifetime
- condition monitoring, bushings, sensors and online monitoring
- transients, overvoltages, resonances and the influence of power electronics
- specialised testing, field measurements and modelling
- technical decision support for procurement, life extension and decommissioning
The issues do not always fit neatly into one category and often span several disciplines. Many of our research and development activities start precisely with a new question from industry.
From materials to power system
Materials and electrical insulation
We study solid and liquid insulation systems and how electrical, thermal, chemical and mechanical properties affect performance and lifetime. This includes cellulose and pressboard, mineral oils and esters, moisture and ageing, tan δ measurements, partial discharges, streamers and breakdown.
Loading capability, condition and lifetime
How hard can the transformer be loaded, what limits the loading capability, and what condition is the transformer in? We work on cooling and fluid flow, temperature and dynamic load, moisture transport, bubble formation, mechanical properties and winding pre-stress. This is combined with diagnostics such as PD, acoustic measurements, dielectric response, analysis of insulation fluids and online sensors.
Electrical stresses from the power system
The transformer is also exposed to lightning, switching operations, resonances, faults and rapid voltage changes, for example from power electronic converters. We work on insulation coordination, frequency-dependent transformer models and EMT/EMTP analyses to link what the transformer actually encounters in the grid to what the insulation system can withstand.
Laboratories, measurements and models
A key strength is the combination of experiments, field measurements and modelling. Our electrical power laboratories cover material characterisation, specialised small-scale experiments and high-voltage testing of large components. Among other things, we carry out AC, DC and impulse testing, PD measurements (electrical and acoustic), testing of transformers and bushings, as well as thermal and mechanical tests.
When standard methods are not sufficient, we develop our own test setups and measurement methods. The results are combined with physics-based and data-driven models – from material and field models to thermal, mechanical and high-frequency models of the transformer and the power system.
Research in close collaboration with industry
SINTEF has for a long time worked on power transformers in collaboration with transformer owners, manufacturers, material suppliers, grid companies and power producers, both nationally and internationally.
Ongoing and recent activities include, among others:
- LiPe – electrical strength and new insulation fluids
- NewLifT – thermal properties, cooling and use of new insulation fluids
- DynaLoad & ClampIT – solid insulation materials, mechanical properties and dynamic loading
- FastTrans & SwoP – influence of rapid voltage changes and power electronics
- UPGriD – improved models and utilisation of transformers and other power components
- UpLoad – opportunities and risks associated with overloading transformers
- Spectra – ageing and diagnosis of solid insulation materials
- ProTrafo – overvoltage protection of transformers
We have a long and close collaboration with NTNU. We also participate in CIGRE, standardisation work and other professional communities. Through the User Group for Power and Industrial Transformers, we collaborate with owners and suppliers on experiences, current challenges and the need for new knowledge.
Contact and collaboration
We work both on limited testing and analysis assignments and on larger research and development projects. Please get in touch if you have a challenge, a new technology, or a question that should be investigated further.
Images
