International Journal of Advances in Applied Sciences
Vol 14, No 4: December 2025

Methods used to enhance the physicochemical properties of natural ester insulating oils for transformers: a review

Johal, Muhammad Syahrani (Unknown)
Ghani, Sharin Ab (Unknown)
Ahmad Khiar, Mohd Shahril (Unknown)
Sutan Chairul, Imran (Unknown)
Abu Bakar, Norazhar (Unknown)



Article Info

Publish Date
01 Dec 2025

Abstract

Natural ester insulating oils, derived from vegetable-based feedstocks, are increasingly regarded as sustainable alternatives to conventional mineral oils due to their high fire point, biodegradability, and lower environmental impact. However, their widespread adoption in high-voltage equipment is constrained by their inherent limitations, such as lower oxidation stability, higher viscosity, and poor low-temperature performance. In this review, the three principal enhancement strategies developed to address these shortcomings are examined. The use of antioxidants is analysed for its role in improving oxidative resistance and flow characteristics. Transesterification is evaluated as a chemical modification method to alter the molecular structure, thereby enhancing viscosity and thermal stability. Refining and adsorbent treatments are discussed with respect to oil purification and regeneration, emphasising their adsorption efficiency and influence on dielectric performance. A comparative evaluation of these methods highlights their relative effectiveness, scalability, and practical challenges in implementation. This review underscores that no single approach is sufficient, and a combination of different methods is desirable to achieve optimal performance. These insights provide researchers with clear directions for further investigation while offering practitioners a knowledge base to guide the selection and application of enhanced natural ester insulating oils for reliable, long-term transformer operation.

Copyrights © 2025






Journal Info

Abbrev

IJAAS

Publisher

Subject

Earth & Planetary Sciences Environmental Science Materials Science & Nanotechnology Mathematics Physics

Description

International Journal of Advances in Applied Sciences (IJAAS) is a peer-reviewed and open access journal dedicated to publish significant research findings in the field of applied and theoretical sciences. The journal is designed to serve researchers, developers, professionals, graduate students and ...