Comparative Study of DGA for Transformer Service Life

Abstract

This paper investigates the accuracy and reliability of each DGA method via dissolved gases. Key Gas Method, Doernenburg Ratio Method, Rogers Ratio Method, IEC Ratio Method, and Duval Triangle Method are used to test the 100 sample units. The results obtained are Doernenburg and IEC 94% accuracy each, Duval Triangle 80% accuracy, Rogers 79% accuracy, and Key Gas 75% accuracy. The said individual ratio methods are combined to proceed with newly developed hybrid testing methods that could probably improve the existing DGA methods. The first hybrid method is a combination between Doernenburg and Rogers which produced a slight improvement of 86% accuracy. Then a combination between Doernenburg and IEC delivered a stable prediction result of 94%. It seems that Doernenburg and IEC are the most accurate DGA methods. Although both methods are combined, they still produced a constant accuracy result. While the other methods, such as Key Gas, Rogers, and Duval Triangle, do not achieve satisfactory results.