[en] The results are given of modelling dynamic properties by a hybrid computer of the steam generator of a WWER type reactor power plant. A model was developed of the dynamics of a horizontal and a vertical steam generator. The dynamic properties were studied in a wide range of output changes; the effect was also studied of steam pressure in the generator evaporating zone. The effect is analysed of thermal and physical processes in the vertical steam generator, such as the nonstationary boiling limit point and the dynamics of the circuit with natural secondary water circulation on the transients with the objective of finding simplification possibilities for the dynamic model. (Z.M.)