Using a remote system to study the thermal properties of a vegetable oil filled power transformer: How does operation differ from mineral oil

There has been much discussion on the properties of natural esters and how they can be best applied as a transformer dielectric. The thermal properties of natural esters are different from those of mineral oil. A difficulty with investigating the thermal properties is that it is uncommon to find the same transformer design filled with different fluids. Two 90MVA power transformers were manufactured to the same design and installed in the south east of England, UK, where they were connected to the internet via a private connection. The transformers have been filled with different dielectrics, one being mineral oil and the other a natural ester. Remote monitoring has allowed us to perform a field study on the thermal properties of a natural ester and their effect on the operation of the transformer. The investigation shows that despite the viscosity affecting the cooling capability a power transformer can be designed so that there is little effect on its temperature. This study also demonstrates the advantage of remote monitoring, where a team in Australia can oversee a transformer on the other side of the world.