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You’re sitting at a Sunday family lunch and someone asks what you actually do. How would you explain your research topic?
Transformers are all around us. They are used to convert high voltage into lower voltage. They consist of windings, magnetic steel sheets, and insulation. The entire system is immersed in oil, which serves both as insulation and cooling. The most commonly used option is mineral oil, but it has several drawbacks — it is toxic, flammable, and derived from a non-renewable source. The idea is therefore to replace it with natural or synthetic alternatives, so-called esters, which could eliminate these disadvantages. And that is exactly what my work focuses on.

You say mineral oil is toxic and flammable. So why do we keep pouring it into transformers when we know this?
Like with most things, it mainly comes down to the balance between cost and performance. Mineral oil has very good properties, especially when it comes to cooling, and because it is the most widely used option, it is also the cheapest. The entire infrastructure has historically been designed around it. If we wanted to replace it with natural oils, transformer designs would need to be modified because these oils have different density and higher viscosity, which affects cooling. But first, these oils need to be chemically modified in the laboratory. You cannot simply pour supermarket rapeseed oil into a transformer.

So how exactly do you improve the properties of natural oils? And could these modified oils eventually introduce a new, still unknown problem?
They have to be chemically adjusted to achieve the best possible insulating properties, transfer heat efficiently, and avoid negative reactions with other materials inside the transformer, such as seals. We already know that these oils extend transformer lifespan thanks to better interaction with insulating materials. They also offer higher fire safety and are environmentally friendly. The disadvantages are higher viscosity, poorer performance at low temperatures — they solidify at around minus 27 degrees Celsius — and oxidation stability, which still needs further improvement.

Where in practice would this greener solution make sense first?
Primarily near water sources or in protected zones. Also in important buildings such as hospitals or shopping centres, or in protected natural areas. They are already commonly used in smaller distribution transformers, for example on utility poles or in public lighting systems. The problem arises with very high voltage applications, where their disadvantages become more significant.

Do you hope your research could make these environmentally friendlier fluids the standard one day, or are we still far from that?
They are already being used around the world, for example in the London Underground or in Brazil, where soybean oils are used. In the Czech Republic we are still rather conservative. However, we do have a test transformer in Olešná in Moravia that uses a rapeseed-based natural ester. It was developed in cooperation with EGD, EGU, Trafo.cz, and our faculty, and it has been operating without any issues. So this is definitely a viable path, but large-scale adoption across the country will still take time.

What does a typical day in the life of a PhD student look like?
One advantage is the high level of independence. Working hours are flexible and depend on what we are currently doing. When we are conducting measurements in the laboratory, we need to get there as early as possible because the lab is in high demand. I sometimes spend up to ten hours a day there. I teach four practical classes a week, which is about six hours. Writing papers can also be done from home, and I find it relatively easy, so I spend less time on that.

What role do you think money plays in deciding whether to pursue a PhD?
The situation today is better than it used to be. Scholarships have increased from around 11,000 Czech crowns to roughly 25,000 crowns gross, which is already motivating, even though it still does not compare to salaries in industry. Scholarships are tax-free, they now also count towards pensions, and PhD students are newly entitled to maternity benefits. However, the studies must be completed successfully.

What should people consider before applying for a PhD?
They should be sure they really want to do it. The programme lasts four years and there is no room for hesitation. It is also important to be able to write academic papers and to be willing to travel to conferences.

And where do you see yourself after finishing your PhD?
I would like to stay in research. It does not necessarily have to be at the faculty, and I do not have to focus only on transformer oils. I am also interested in other fields, such as mechanical engineering, metallography, or the interaction of materials with hydrogen.

Three words that best describe a PhD, in your opinion.
Independence, uniqueness, community.

What is the best advice your supervisor has given you?
A piece of work is either perfect or finished.

What is the biggest myth about PhD students?
That people do it just to prolong their youth.

What would you change about doctoral studies tomorrow if you could?
The funding system.

Are you studying for a follow-up Master’s degree, interested in science, and unsure what to do next? Stay and discover more. Applications for doctoral studies at the Faculty of Electrical Engineering are open until 31 May 2026.