Modeling of the Current Transformer

Electrical protection relays are sensitive to quality of input signals. The saturation of the current transformer can cause the missoperation of the protection relay especially during a short circuit with DC component. It is the reason why we have to be concerned with the problem of correct current transformer dimensioning. The model can be used to analyze the transformer behavior during high fault current or when the fault current contains a DC component. Verification of current transformers can be done by using the model, without costs of the short-circuit tests or other expensive experiments. The paper describes a created model of a current transformer and it analysis the problem of the differential protection missoperation caused by current transformer saturation.