Power Transformers are vital components for electrical energy transfer in a power system. In power system protection high sensitivity and fast operation of transformer protection is required while maintaining security from mal tripping. In this paper a simulation model for differential protection of three phase transformer is presented for determining its behavior during various operating conditions. Many mal-operation cases of transformer differential protection are caused by inrush and over

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... uxing problems. The proposed simulation model is tested on 2.5 MVA, 11 kV/400 V, delta-wye three phase transformer. The result shows that simulink model presented for differential protection of three phase transformer work properly and this will allow rapid modeling and testing of new algorithms in view to improve protection of transformer.