The present invention refers to a system and method for monitoring and controlling the operational condition of a power transformer. The system for monitoring and controlling the operational condition of a power transformer comprised in a single substation comprising acontrol and data processing station linked to the transformers containing detection devices of the indicative signals of the measurements of parameters of the transformer; the signals being continuously detected by said devices; a user interface linked to said control station, the interface allowing a user to follow the measurements of the parameters of the transformer and determine ranges of desirable values of said parameters, said control station comprises a database that stores the data referring to the indicative signals of the measurements of the parameters of the transformer only when the measurements of the parameters differ from a range of parameters values previously defined as desirable. The method of the present invention comprises the steps of (a) continuously measuring parameters of a power transformer; and (b) storing the data referring to the measurements performed in step (a) only when said measurements are not within a range of previously determined as desirable for the measurements of said parameters.