[Hamid]

Study of Saturation of current transformer as one of special transformers is applicable study in power systems. Let us consider a primary current with a peak value I1p at the CT saturation limit. Let I_2p be the peak value of a primary current greater than I_1p , which is thus going to saturate the CT. Let I₁ and I₂ be the peak values of the currents at the CT secondary corresponding to I_1p and I_2p through the transformation ratio. I₂ is the design value that would be obtained if there was no saturation phenomenon. The current curves look like those in Figure below. The magnetic induction B is proportional to ?I dt . The surface designed by the current is thus proportional to B. The current I₁ being at the saturation limit, the surface S₁ designed by I₁ is proportional to the saturation magnetic induction.