Pressure Relief Valves are used in oil insulated power transformers. The valve protects the transformer tank integrity against internal overpressure surges. The installation of the equipment must be planned, in order to be as close as possible to the pressure generating source and so that the total volume of oil in the tank does not exceed the limit of each model. When the Valve detects a tank overpressure, it quickly opens a pathway for the transformer internal fluids to flow to the external environment, thus controlling the tank internal pressure. The valve can be equipped with an actuation indicator and can also have electrical contacts for the transformation shutdown.