THERMAL SUBSYSTEM OF VOLTAGE DISTRIBUTION TRANSFORMER

Improving of the technical level of modern distribution transformers (DT) by reducing of their weight and dimen-sions, increasing of specific power are inevitably associated with the development of method which takes into ac-count the thermal processes and technical means of intensifying the existing and new systems of their cooling. Par-ticularly important rises the question of effective cooling of small and medium power distribution transformers, which constitute the bulk of the complete switchgear in power supply systems.The result of the study is the substan-tiation of expediency for simulation results implementation of heat balance equations drawn up for the active part of the voltage distribution transformer, at the stage of its final and qualifying design. The active part is located in the transformer oil environment, and heat emission is carried out by heat transfer and convection. The heat balance mathematical model corresponds to the equivalent thermal equivalent circuit, consisting of two adjacent units with heat sinks - generalized coils and ferromagnetic core and of the third node adjacent to them - moving matter from the oil, which additionally contact with the infinite heat capacity environment. The solution of equations obtained for the mean temperatures of the winding, magnetic conductor rod and oil in function of time, allows setting of their expected values during transformer operation and especially with the uneven schedule of its loading, and to exercise grounded choice of magnetic induction in the magnetic rod and the current density in the windings according to the parameters of allowable for them heating temperatures