Graphic approaches for faults diagnosis for Camellia insulating liquid filled transformers based on dissolved gas analysis

As vegetable insulating liquids have different chemical compositions from mineral oils, dissolved gas characteristics under thermal and electrical faults have differences; thus fault diagnostic methods based on dissolved gas analysis (DGA) used for mineral oil-filled transformers may not be suitable to vegetable oil-filled transformers. This paper presents experimental results of dissolved gases in Camellia insulating liquid under typical thermal and electrical faults in transformers. Thermal fault simulation experiments include three parts, which are low temperature, medium temperature and high temperature faults, and the electrical fault simulation experiments also include three parts, which are partial discharge, breakdown discharge and arc discharge. Experimental results show that apart from CO and CO
₂
, H
₂
and C
₂
H
₆
are the main characteristic gases under thermal faults, and the percentage of H
₂
decreases while CH
₄
, C
₂
H
₄
and C
₂
H
₆
increases with temperature. In addition, H
₂
and CH
₄
are the main characteristic gases under partial discharge faults; C
₂
H
₂
is the main characteristic gas under breakdown faults, and C
₂
H
₂
and C
₂
H
₄
are the main characteristic gases under arc discharge faults. Furthermore, graphic fault diagnostic methods based on DGA of Camellia insulating liquid including Triangle and Pentagon diagnostic methods are proposed. Compared with the current diagnostic method, the proposed methods in this paper have higher diagnostic accuracy.