Carpathian Journal of Electrical Engineering Volume 9, Number 1, 2015 57 TRANSIENT REGIMES OF THE THREE-PHASE POWER TRANSFORMERS Olivian CHIVER, Liviu NEAMT, Eleonora POP, Cristian BARZ, Adina POP VĂDEAN, Paul Petrică POP Electrical, Electronic and Computer Engineering Department, North University Center of Baia Mare, Technical University of Cluj-Napoca olivian.chiver@cunbm.utcluj.ro Keywords: Power transformer, finite elements, transient analysis. Abstract: The transient regimes of a three-phase power transformer will be studied in this paper. The transient currents in the windings will be determined both analytically and by finite elements method (FEM). The no load and short circuit regimes will be considered. The current dependence of the instantaneous phase voltage and of the initial current value will be highlighted, by FEM. In order to determine analytically the transient currents, for inductances the analytical and FEM values will be used. The inductances are determined with FEM through the simulation of experimental tests. With FEM, the transient currents will be determined using transient analysis. Finally, the FEM and analytical results will be compared and discussed. 1. INTRODUCTION The electricity consumption in the world increases permanently. The more stringent restrictions regarding the interruption of power supply or other power quality parameters are imposed by the quality standards. The entire system of generation, transmission and distribution of electricity must work interconnected in a predictable manner and often loaded near to the maximum capacity, in order to comply with these rules. It is obvious that understanding and predicting how the entire system behaves requires thorough knowledge of the behavior of the components, separately and then interconnected. The main elements of the