Evaluation of distribution network transformer dissolved gas analysis (DGA) data

IEEE Standard C57.104-1991 IEEE Guide for the Interpretation of Gases Generated in Oil-Immersed Transformer outlines the guidelines and procedures applicable to large power transformers. This paper describes how Consolidated Edison applied this standard to underground network distribution transformers. It also describes Con Edison´s process for determining the root cause of combustible gas generation and the results of the root cause analysis for selected cases. This information will be helpful for other utilities that may wish to consider or currently perform DGA testing on distribution transformers. The information contained in this paper may be used as the basis for the inclusion of network transformers to current guide and the creation of new procedures for DGA as it applies to Con Edison´s network transformers.