A simulation model for transformer internal faults base for the study of protection and monitoring systems

The study of internal faults in transformers, i.e. the calculation of the fault current and its external detection (phase currents) as a function of the location and the amplitude of the fault, is of great interest. This situation has led the authors to manufacture a special, multiple output transformer. This device, designed on the basis of a 100 kVA MV/LV transformer, has enabled them to carry out numerous turn-to-turn and turn-to-earth short-circuits. In association with these tests, they have developed a digital model of the transformer, validated by the actual measurements. This model, when applied to a HV network transformer, enables the efficiency of the usual protection devices to be examined, in particular that of the transformer differential protection.