Gema Romadhona, Ketut Ima Ismara, Mutiara Nugraheni
Dissolved Gas Analysis (DGA) is a key technique for detecting incipient faults in power transformers. However, conventional DGA interpretation methods were developed for mineral oil and often produce inaccurate diagnoses when applied to vegetable oil-based insulating fluids due to differences in gas generation behavior. As natural ester insulating liquids are increasingly adopted for environmental and fire safety advantages, reliable diagnostic methods tailored to these fluids are required. This study presents a systematic literature review evaluating DGA diagnostic approaches for ester-filled transformers. A PRISMA-guided protocol covering 2015–2025 identified 7,986 records, of which 24 studies met inclusion criteria after screening and quality appraisal. Extracted data included oil types, fault conditions, diagnostic methods, and reported effectiveness. Five diagnostic method families were identified: modified ratio and Duval-based methods, ester-specific graphical diagnostics, molecular simulations, ageing marker analysis, and comparative validation approaches. The findings indicate that modified Duval Triangle 3 and alternative ratios such as C2H6/CH4 provide improved diagnostic reliability compared with conventional methods, particularly for thermal faults. Ester-specific graphical methods also demonstrate enhanced performance. However, diagnostic effectiveness remains strongly dependent on oil type and limited field validation. This review highlights the need for standardized diagnostic criteria and expanded field datasets for reliable condition monitoring of ester-filled transformers. © 1994-2012 IEEE.
Universitas Negeri Yogyakarta, Yogyakarta, Indonesia
