Alternative Insulating Liquids for High-Voltage Power Transformers
A Special Issue of Energies (ISSN 1996-1073) belonging to the section "F1: Electrical Power System".
Deadline for manuscript submissions: 31 December 2026 | Viewed by 139
Editor
Interests: high voltage; insulation materials; transformer; electric and magnetic fields; insulation oil; heat transfer; thermal properties; thermal conductivity
Special Issues, Collections and Topics in MDPI journals
Special Issue Information
Dear Colleagues,
Alternative liquids are becoming increasingly popular in high-voltage transformers. Liquids such as natural and synthetic esters are of particular interest. The reason for this is the extension of the transformer's lifetime (i), increased fire safety (ii), reduced negative impact on the natural environment (iii), and decreased oil resources.
The extension of the lifetime (i) should be associated with a higher solubility of water in esters compared to the solubility of water in oil, and in the case of a natural ester, also with the process of its hydrolysis. This results in less moisture in the transformer insulation. This translates into improvements in many key insulation properties of both the paper and the liquid itself, such as electrical strength, electrical resistivity and dielectric loss coefficient. Increased fire safety (ii) should be associated with a higher ignition and burning temperature of ester vapors compared to mineral oil. For example, the flash point of oil vapor is about 150°C, and that of natural ester is about 350°C. The reduction in the negative impact on the natural environment (iii) should be associated with a much higher biodegradability of esters compared to mineral oil. This is important in situations where the insulating liquid leaks from the transformer into the environment.
The use of alternative liquids applies to both new and operated transformers. In the case of operated units, the use of alternative liquids takes place by retrofilling, i.e., the replacement of mineral oil with esters. Despite numerous studies conducted in recent years, alternative liquids are not widely used. The reason for this is that not all the properties of esters and ester– mineral oil mixtures, which are formed as a result of retrofilling, are fully understood. These properties include dielectric, thermal, mechanical, physical and chemical properties. We hope that the scientific research published in the articles in this Special Issue will contribute to the wider use of alternative liquids in high-voltage transformers.
Although this Special Issue covers interdisciplinary research, the core focus of all submissions must remain within the field of energy.
Prof. Dr. Zbigniew Nadolny
Guest Editor
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Keywords
- alternative liquids
- power transformer
- esters
- mineral oil
- retrofilling
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