Restraining Current

PL. expline about the restraining current, when we do the transformer stability test we get the following datas.

transformer 40MVA, 66KV/11KV ,Yd1, CT HV side 400/1 , LV side 2500/1A. we give 403V AC on primary side and we short the secondry after the CT. The readings are Pr.current is 11.5,11.3,11.4A and secondry current is 71.6,70.9,70.6A.

When we saw the differencial relay display(Micom) the restraining current is 0.030,0.030,0.030A.

PL.let me know how i calculate this current ,