SU886331A1 - Secondary current lead-in of electric arc furnace - Google Patents

Description

one

The invention relates to electrometallurgy, in particular, can be used in the design of the secondary electrical power supply of an electric arc furnace.

The design of a secondary current lead for a three-phase arc furnace, comprising compensators, a rastsirovtka bridge, fixed and movable shoes connected by flexible cables, pipes, contact elements and electrodes, is known. To reduce the reactance of the phases and to balance them in order to reduce the power transfer between the phases of the structure, various conductor connections are provided from the terminals of the transformer to the connecting points in a triangle: on the razshymutka bridge or on movable shoes of the electrode holders 1. .

The disadvantage of this design, as shown by studies carried out on an electric furnace for refining steel with a capacity of 150 tons, is that the degree of asymmetry in the distribution of power between the phases was 12% and this contributed to the uneven heating of the metal and the height of the lining. Moreover, oj:; a new reason for the transfer of power curled asymmetry

inductive resistances of individual phases, reaching 8-9%.

Closest to the proposed technical essence of the structure

5 secondary arc power supply

an electric furnace containing a razsiftovka bridge, the elements of which are located in the same plane and are connected on one side with low-voltage terminals

0 voltage corresponding to the phase of a three-phase transformer, and on the other - with fixed shoes. This secondary supply design allows it to be triangulated and to significantly improve phase balancing 2.

The disadvantage of this design is that this increases the reactivity of the secondary current lead,

20 which degrades the electrical characteristics of the furnace. In addition, this structure is difficult to manufacture and maintain. .

The purpose of the invention is to improve

25 balancing the reactances of the phases and simplifying the structures.

Claims (2)

The goal is achieved by the fact that each element of the rasmishtovka bridge is made in the form of a hollow metal box of rectangular cross section, with the boxes of two phases located inside the box of the third phase, and the axes of the box are mutually parallel. FIG. Figure 1 shows a section of the secondary current lead from the transformer to the point of connection with fixed shoes, top view; in fig. Section A-A in FIG. 1. The low voltage terminals 1 of the three phase transformer 2 are connected via compensators 3 to a rastsirovka bridge made in the form of hollow metal boxes 4.5 and b of rectangular section. In this case, the ducts 4 and 5 of the two phases are located adjacent to the inside of the third phase duct b. The axes of symmetry of all three boxes of the bridge are located in the same plane and mutually parallel. Boxes 4, 5 and b are connected to compensators 3, terminals 7, located either in the horizontal (Fig. 1) or vertical planes (Fig. 2) depending on the location of the low voltage terminals 1 of the transformer 2. Connection of the ducts 4 , 5 and b with fixed shoes (not shown) are conducted with the help of terminals The proposed design of the secondary current lead works as follows. Since to each of the three bridges of the razshyhivka bridge connects the conductors of the two poles of the phases of the low voltage transformer (a – Z, b – X, c – y), the razshirovtka bridge connects these conductors in a triangle. currents shifted in phase relative to each other by 120. The box, located geometrically, has a reduced, in comparison with other arrangement, inductive resistance, since the mutual induction between any duct and two other ducts is subtracted is from the intrinsic inductance of the duct, and the magnitude of this mutual induction is increased due to the proximity of the ducts of different phases. The mutual induction of the busbar trunks so arranged is almost completely compensated and the reactance is reduced to the minimum. Thus, the proposed secondary current lead allows to improve the CJ measurement of the reactance of the phases and simplify the design. Claims of the invention Secondary electric power supply of an electric arc furnace containing a razschitovka bridge, whose elements are located in the same plane and are connected on one side with the low voltage leads of the corresponding phase of a three-phase transformer, and on the other with fixed shoes, in order to improve the reactive resistances phases and simplify the design, each element of the razsiftovka bridge is made in the form of a hollow metal box of rectangular cross section, with the box of two phases located inside wipe the boxes of the third phase, and the axes of the boxes are mutually parallel. Sources of information taken into account during the examination 1. England patent number 1166148, cl. H 05 B 7/18, 1969. 2. USSR author's certificate number 465758, cl. H 05 B 7/02, 1975. T