Udarne struje koje se javljaju prilikom uklopa energetskog transformatora mogu doseći vrlo velike iznose te uzrokovati mnogobrojne probleme u elektroenergetskom sustavu. Za istraživanje ove pojave razvijen je matematički model transformatora s uračunatim efektima zasićenja, histereze i zaostalog magnetskog toka, a opisan je i algoritam za određivanje povoljnog trenutka uklopa s ciljem smanjenja udarnih struja. Za metodu mjerenja zaostalog magnetskog toka, predložena je integracija napona sekundara pri prethodnom isklopu. Realizirana je laboratorijska maketa sustava za upravljani uklop trofaznog transformatora na kojoj su mjerenjem potvrđeni rezultati simulacija.Inrush currents that occur during the energization of a three-phase power transformer can reach very high values and cause many problems in an electrical power system. A mathematical model of a transformer has been developed for the investigation of this problem, taking into account the effects of saturation, hysteresis and remanent magnetic flux. An algorithm has been described for the determination of the optimal instant of energization, with the goal of reducing inrush currents. As a method for measuring remanent magnetic flux, integration of the secondary voltage during the previous de-energization is proposed. A circuit model has been prepared of a system for the controlled energization of a three-phase transformer in which the simulation results are confirmed by measurement
