The ratio of currents in the transformer, the primary winding connected to the EMF source, and the second-ary to the current source, is not equal to the transfor-mation coefficient. The current in the primary winding, with an increase in the current in the secondary, can both increase and decrease. This effect is due to the phase shift of the currents at the angle of 0-360 in con-trast to the angle shift -90...+90 when connecting capac- itive or inductive load to the secondary winding. The magnetic fluxes created by these currents in the core of the transformer have either an opposite direction, reduc-ing the total magnetic flux, or a consonant one - in-creasing it. For the purpose of studying such operating mode of the transformer the pilot study, which purpose was receiving the equation describing communication of currents in primary and secondary winding at change of the corner of shift of phases of currents was conducted. The object of the study was a single-phase two-winding transformer. Transformer power, tension brought to pri-mary winding, the module and the phase of current in a secondary winding are chosen as factors. To study composed concept, which allows using only active re-sistance can set different the module and the phase of the current in the secondary winding, the developed method. The results were processed in the programme STATGRAPHICS Plus. The regression equation was compiled, its coefficients were determined. Following the results of the analysis of the surface of the response constructed with using the equation the conclusion was drawn that current in primary winding depended more on the module and the corner of shift of the phase of the current proceeding on secondary winding of the trans-former and also on the tension given on primary wind-ing, the power of the transformer had the impact to lesser extent. Keywords: single-phase transformer, dependence of current in primary and secondary winding.