In this article, an attempt is made to put together developments in digital relays for protection of power transformer. Efforts have been made to include all the techniques and philosophies used to that end. The article includes the most recent techniques, like artificial neural network (ANN) and fuzzy logic concepts, as well as other conventional methods used for transformer protection. Only a brief mention is made about conventional methods, while more emphasis is given on the application of ANN and fuzzy techniques for the protection of power transformer. This article presents a set of references of all concerned papers and provides a brief summary of the work presented in them.It also presents the results of these techniques as provided in the respective references.