Case Study on Power Transformer using Dissolved Gas Analysis Technique

Abstract

This paper discusses Dissolved Gas Analysis (DGA) in transformer oil from two 69/24 kV 24/32 MVA installed in urban areas. By detecting unusual increasing gas, then transformer oil samples were collected frequently according to Standards. First transformer was failed by inside short circuit. All loads were transfer to second transformer. The risk of failure on last transformer is very high. Standards used for DGA interpretation is IEEE C57.104. Evaluation of fault type used Key gas method, Doernenburg ratio, Rogers ratio and Duval Triangle.