Use of Alternative Fluids in Very High-Power Transformers: Experimental and Numerical Thermal Studies

• Main Authors: Ramazan Altay, Agustin Santisteban, Cristian Olmo, Carlos J. Renedo, Alfredo Ortiz Fernandez, Felix Ortiz, Fernando Delgado
• Format: Article
• Language: English
• Published: IEEE 2020-01-01
• Series: IEEE Access
• Subjects: Computational fluid dynamics; ester-based liquids; experimental setup; mineral oil; power transformers; thermal modeling
• Online Access: https://ieeexplore.ieee.org/document/9257425/
• ISSN: 2169-3536

The very high-power transformer lifespan depends mainly on the temperature that cellulose insulation reaches during its operation. Traditionally, its cooling has been carried out using mineral oil as coolant. Nowadays, alternative ester-based liquids are under study as substitutes due to their better environmental and fire-safety properties. This paper compares the cooling capacity of two ester-based fluids with that of a mineral oil using a 3D numerical model of a 100 MVA low voltage winding of a power transformer with axial cooling system and ONAN cooling mode. Heat-run test results with mineral oil have been used to validate this model. As a first approximation, according to the comparison developed, ester-based fluids could replace mineral oils in this type of transformers when they are going to work in a range of powers close to the rated one.