Експериментальні дослідження режимів роботи зварювального трансформатора

Анотація

EXPERIMENTAL STUDY ON THE WELDING TRANSFORMER MODES

M. Bragida

Laboratory studies have shown that the winding that is placed on the magnetic circuit of regulation, can regulate the current of welding in the direction of reducing it. This means that the calculation of its parameters is performed at the maximum allowable welding current of the I_2max.

The inductive resistance of it will diminish, and hence its weight reduction will be the overall dimensions. This is important, because in welding transformers of classical execution, where the current of welding is regulated by a change in the magnitude of the air gap of the magnetic circuit, its minimum value will be absent air gap. Inductive resistance will be larger, and hence its size will increase.Laboratory studies have shown that the range of current regulation is limited, provided that the entire secondary winding encompasses the control magnet. This is due to the high intensity of the magnetic field (saturation of steel). The maximum current of welding is given, it is determined and depends on the parameters of the control magnetic circuit.At high currents of welding 200 ÷ 250 A and the number of turns 60 ÷ 80, the diameter of the transformer 250 mm, the field strength reaches up to 18000 ÷ 25000 A / m. The current control range will be insignificant even with the increase in the number of turns of the regulation winding.It is advisable to make a secondary winding distributed, that is, a part of the winding is rotated directly on the main magnetic core, and the second part covers both the main magnet and the magnet conductor.The magnitude (height) of the magnetic core will increase, and hence its magnetic capabilities will increase.The error is up to 2.5% in the direction of exaggeration in the saturated magnetic conductors, and in the weakly saturated, it increases to 5% too, in the direction of overestimation. A characteristic point when the curve obtained by the experimental way and the calculated intersect.Further increase of the current of the current leads to an increase in the current of the primary (secondary) winding. Effective current regulation can only be carried out to this value.This is confirmed by the regulatory characteristic of the welding transformer.If the steel of the magnetic conductor of the current control of the welding is saturated, then with increasing current of regulation current in the primary winding decreases practically linearly. With a lower saturation of steel, the characteristic has a minimum value to which the current of the primary winding decreases with increasing the current in the control winding. Further increase of the current of regulation leads to an increase in the current of the primary winding.For her, too, the value of the minimum is characteristic at certain control currents. In weakly saturated magnetic circuits, this point manifests itself at lower values of the current of regulation, in saturated with large, and for unsaturated, an increase in the current of the primary (secondary) winding is observed with increasing control current.The characteristics of the short circuit are noteworthy. In this type of welding transformers, we have a family of short-circuit characteristics that depend on the current of regulation.If the control winding is open, then the dependence U₁ = f (I₁) in the short-circuited secondary winding has a pronounced inductive resistance. When closing the resistance welding current winding, we have a family of characteristics with a lower saturation of the magnetic core, and with a certain current of regulation one can obtain almost linear characteristics.