The state of the art for dissolved gas analysis based on interpretation techniques

Abstract

Dissolved gas analysis (DGA) is an important method and widely used for assessment the conditions of transformer insulations. The dissolved gases interpretation is one of the most significant procedures to identify the failure causes and/or degree of insulation degradation. The aim of this paper is to represent the performance of various DGA test result interpretation techniques i.e. Doernenburg Ratio, Roger Ratio, IEC Ratio, MSS ratio, Duval Triangle and Duval Pentagon. Fifty six fault cases occurring in transformers obtained from IEC TC 10 database were employed to evaluate the performance of the DGA interpretation techniques. It was found that the Duval triangle method provided the most accuracy DGA interpretation compared with other methods. However, some engineering points of view for evaluation the performance of DGA interpretation techniques for examples normal ageing insulation condition, correct and incorrect fault case identification, and unclear fault case identification including no identification of the fault cases have to be taken into account. Therefore, the performance of the Duval triangle method may be reduced while that of Duval Pentagon may be increased when such parameters are considered.