Summary
This paper investigates how hotspot conditions influence dissolved gas analysis results in both conventional and new insulating liquids, using an improved tube heating setup designed to eliminate headspace. Dissolved gas analysis is widely used to detect transformer faults because gases generated during thermal degradation provide insight into fault type and severity. With the increasing use of novel insulating liquids, it is important to understand whether established diagnostic tools such as IEC 60599 and the Duval Triangles remain reliable.
Read more Read lessHeadspace in experimental systems has been shown to distort key gas ratios because gases with low solubility, such as hydrogen, migrate out of the liquid into the headspace more readily than heavier hydrocarbons. This affects ratios such as methane to hydrogen and ethylene to methane and can cause misclassification of thermal fault levels.
To address this, a test rig based on the tube-heating method with no headspace was used to simulate thermal faults at 550°C, corresponding to a T2 fault. Three liquids were tested: an inhibited mineral oil, a re-refined mineral oil, and a bio-based hydrocarbon liquid.
Results show that eliminating the headspace from the system resulted in an overall better agreement between the simulated thermal fault and the interpretation using IEC 60599 and the
Duval Triangle 1. The results confirm that the dissolved gas profiles of the tested alternative liquids are similar to those of the mineral oil, indicating possibilities of same diagnostic interpretations.
Additional informations
| Publication type | Session Materials |
|---|---|
| Reference | D1_11424_2026 |
| Publication year | |
| Publisher | CIGRE |
| Country | Sweden |
| Study committees | |
| File size | 956 KB |
| Price for non member | 30 € |
| Price for member | 30 € |
Authors
WEDIN Pär - NYNAS AB; MINCHAK Elena - NYNAS AB; FAIRHOLM Robert - NYNAS AB; SINGH Jessica - NYNAS AB; NORRBY Thomas - NYNAS AB; CAMPELO Hugo - NYNAS AB
Keywords
Transformer, dissolved gas analysis, DGA, thermal fault, mineral oil, bio-based, re-refined
