From the editors´ desk

This issue has four articles, the first of which is titled "The Duval Pentagon???A New Complementary Tool for the Interpretation of Dissolved Gas Analysis in Transformers" by Michel Duval and Laurent Lamarre, both at IREQ, Varennes, QC, Canada. The article presents a new method for the interpretation of DGA results of mineral oil???filled transformers and similar equipment using five diagnosis gases, H₂, CH₄, C₂H₆, C₂H₄, and C₂H₂, in a single "pentagon" graphical presentation. Carbon oxides CO and CO₂ are examined separately as in other methods. The new Duval Pentagons, although they may be used alone, are not intended to replace Duval Triangles 1, 4, and 5 for mineral oils, but rather to bring complementary information, for example, in the case of mixtures of faults. Other versions applicable to nonmineral oils, i.e., natural and synthetic esters and silicones, and corresponding to Duval Triangles 3, 6, and 7, are still in the developmental stage.