EP0080954B1 - Connection and support arrangement for the electrodes of an arc furnace - Google Patents

Abstract

1. Arrangement for the supply of electrical energy to and for the support of the electrodes in an electric arc furnace comprising three electrodes fixed respectively in grips (14, 15, 16) placed at the respective ends of three support arms (8, 9, 10) extending horizontally from a vertical pillar, the said electrodes being connected by rigid electrical conductors to cables (13) for the supply of current, characterized in that the rigid conductors for the supply of electricity to the electrodes are constituted by the same horizontal support arms (8, 9, 10), the latter being constructed of non-magnetic metal and being provided, at their downstream ends opposite to the electrodes, with respective contact elements (11, 12) to which the cables (13) for the supply of current are connected.

Description

The present invention relates to a device for supplying electrical energy and for mechanical support of the electrodes of an electric arc furnace intended to equip a steelworks.

In an electric arc melting furnace, electric current is passed from the furnace transformer to the electrodes by flexible cables and rigid copper conductors. These conductors are generally cooled and are supported by the horizontal part, or arm, of each electrode holder. Each of these arms is made of ordinary steel and has a square or rectangular section. The construction of the conductors is quite complex in its layout, its electrical insulation and its mode of support. The conductors of each phase are arranged so as to reduce and balance their electrical characteristics, which are reactances and resistances. Such an arrangement is the subject, for example, of patent FR-A-1,569,521.

In these known devices, the support (arm) and electrical conductor (copper tubes) functions are always separate. For those skilled in the art, in fact, the electrical conduction of very intense currents is always done by means of copper tubes, because of the low resistivity of this metal. On the other hand, copper, because of its insufficient mechanical properties with the desired diameters to have a satisfactory implantation, is not used for the construction of the electrode-holder arms (see also US-A-3,433,878).

The device according to the invention allows a simpler manufacture than for these known devices, as well as a reduction in the electrical reactance of this part of the oven, which makes it possible to have, for the same power drawn from the network, a significant increase. of the power of the arcs. It is characterized in that it is equipped with non-magnetic metal electrode support arms having at the same time the function of rigid current supply conductors and the upstream end of which serves as a contact area for the supply cables current. Preferably, the metal used is stainless steel. Also preferably, the arms are constructed so as to present, on the current path, no sharp angle as well in their section as in their length.

• la figure 1 est une vue latérale schématique d'un des bras porte-électrode qui n'est pas encadré par les deux autres
• la figure 2 est une vue latérale schématique du bras porte-électrode qui se trouve encadré par les deux autres
• la figure 3 est une vue schématique dessus du dispositif de l'invention.

The invention will be better understood using the following description of a preferred embodiment, with reference to the accompanying drawings in which:

• Figure 1 is a schematic side view of one of the electrode holder arms which is not framed by the other two
• Figure 2 is a schematic side view of the electrode holder arm which is framed by the other two
• Figure 3 is a schematic top view of the device of the invention.

Referring to all of Figures 1 to 3, each of the three vertical masts (1, 2, 3) carries, conventionally, a support piece (4, 5, 6) wider, provided with a part electrically insulating 7.

According to the invention, each support piece (4, 5, 6) carries a horizontal arm (8, 9, 10) of stainless steel, the upstream end (11, 12) of which serves as a contact pad for the cables. 13 for supplying the current, and the downstream end of which is attached to the clamps (14, 15, 16) intended to grip the electrodes.

In order to avoid the phenomena of heating which would be due to accumulations of current, the arms (8, 9, 10) are constructed so as to present, on the current path, no sharp angle. Their section is circular and they are, in the direction of the length, either completely rectilinear, or presenting curves in S.

Figure 1 shows one of the two arms, such as arm 8, which is not framed by the other two. Such an arm is rectilinear and its support member (1, 4) arrives at the level of the lower part of the associated clamp 14.

Figure 2 shows the "central" arm 9, which is framed by the other two (8, 10, Figure 3). For obvious reasons of space, its support member (2, 5) arrives, in a conventional manner, at a level situated above that of the lower part of the associated clamp 15. The mast 2 is therefore higher than the two others. The three clamps (14, 15, 16) being preferably at the same level, the arm 9 has a soft curvature, S-shaped as shown, so that its downstream part is at the same level as the others.

For the realization of the invention, the use of a non-magnetic metal is essential because these metals have a "skin effect" much less than that presented by non-magnetic metals, such as ordinary steel for example. Kelvin's skin is in fact about thirty times thicker for stainless steel than for ordinary steel. Furthermore, stainless steel leads to electrode arm dimensions which are especially well suited to the desired locations for electric ovens; this metal therefore proves preferable for carrying out the invention.

Claims (4)

1. Arrangement for the supply of electrical energy to and for the support of the electrodes in an electric arc furnace comprising three electrodes fixed respectively in grips (14, 15, 16) placed at the respective ends of three support arms (8, 9, 10) extending horizontally from a vertical pillar, the said electrodes being connected by rigid electrical conductors to cables (13) for the supply of current, characterized in that the rigid conductors for the supply of electricity to the electrodes are constituted by the same horizontal support arms (8, 9, 10), the latter being constructed of non-magnetic metal and being provided, at their downstream ends opposite to the electrodes, with respective contact elements (11, 12) to which the cables (13) for the supply of current are connected.

2. Supply and support arrangement according to Claim 1, characterized in that the said arms (8, 9, 10) are constructed in such a manner as not to exhibit, on the path of the current, any sharp corner, in their section as well as over their length.

3. Supply arrangement according to Claim 2, characterized in that it includes two rectilinear arms (8) surrounding a central arm (9) including a rectilinear portion situated at a level above that of the two other arms and connected by a smooth curve in an S-shape to a downstream end for retention of the electrode situated at the same level as the ends of the other arms.

4. Supply and support arrangement according to one of Claims 1 to 3, characterized in that the said non-magnetic metal is stainless steel.

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