Digital protective relay

摘要

The present invention relates to a digital protective relay for a three-phase electrical AC voltage system having the phases R, S and T, wherein use is made of a transformation of the three-phase system R, S, T into symmetrical components. A description is given of how, using suitable voltage parameters and current parameters ULoop and ILoop, respectively, derived from the symmetrical components of the phase voltages and phase currents, a correct fault decision can be made uniformly in all possible fault situations. <IMAGE>