Cause Analysis of Disoperation of Transformer Vertical Differential Protection and Its Improvement Measure

As the main differential protection of transformer, the correct moving rate is always around 55%~65%, which is harmful to the safety and stable process of transformer. According to the basic working principle of differential protection of transformer, the paper analyses the disoperation cause by unbalanced electric current, magnetizing impedance, and differential current transducer. Certain improving measures are come up with through the result of spot condition practice.