FR2511187A1 - ELECTRICAL SWITCH COMPRISING EXTINGUISHING SHEETS MADE OF AN ELECTRICALLY CONDUCTIVE MATERIAL AND WHICH MAY BE MAGNETIC, IN WHICH THE FRONTAL FACE HAS AT LEAST ONE RECESS - Google Patents

Abstract

The extinguishing chamber of the switch is provided with electrically conductive arc splitter plates which can be magnetised. According to the invention, that end (6) of each of the arc splitter plates (8) which faces the rear wall (10) of the extinguishing chamber (12) is provided with at least one essentially V-shaped recess (14). As a result of this measure, the arc gases within the housing can flow away more easily, and recombination of the arc elements is at the same time prevented.

Description

Electric switch.

 The present invention relates to an electric switch comprising an arc extinguishing chamber or blowing cage, which contains extinguishing sheets made of an electrically conductive material and which can be magnetized.

 Arc extinguishing devices are known for electric power switches, devices which contain extinguishing sheets made of a material which conducts electricity and which can be magnetized. On their front face facing the introduced electric arc, the extinguishing plates have entry slots for the arc, which have substantially the shape of a V. The pack of extinguishing plates can be surrounded by a tightly fitting cladding, in which gas outlet openings are provided as well as days. A shaped mask, which has corresponding orifices and slots, is placed on part of the cladding.

Said cladding is made of a material which gives off a gas under the action of an electric arc. As a result of this evolution of gas, the electric arc and the elements of the wall of the extinguishing chamber, as well as the extinguishing sheets themselves, are cooled, and the output of the arc on the front faces of the sheets extinguishing, which are associated with the rear wall of the extinguishing chamber, is prevented.

Arc returns can therefore only occur in the area of the V-shaped entry slots (German patent application 2,410,049).

 An arc extinguishing device is also known in which the gases of the arc can pass through recesses formed in the front faces of the extinguishing plates, which are turned towards the rear wall of the extinguishing chamber.

These recesses are provided, alternately offset from each other, in the corners of the extinguishing plates.

This provision prevents partial arcs from joining (German patent application 1,690,463).

 The object of the present invention is to improve this known arc extinguishing device, which comprises extinguishing sheets which can be magnetized, which have recesses in their front faces facing the rear wall of the casing, and in particular to allow easier flow of lwarc gases inside the casing, while at the same time preventing partial arcs from meeting at the rear wall of the casing or by bringing about a rapid return of the arc in the chamber containing the sheets of extinction.

 The present invention makes it possible to solve this problem, in the case of an electrical switch of the type described at the start of this patent application by the fact that the front face of the extinguishing plates, which is turned towards the rear wall of the extinguishing chamber, has at least one recess having substantially the shape of a V.

 According to an additional characteristic of the present invention, the recesses of the extinguishing plates are provided one above the other.

 In the case of a preferred embodiment of the switch according to the present invention, the recesses, which have substantially the shape of a V, are alternately offset with respect to each other in the direction of the flat side of the sheets of extinction. Thanks to this design, the path of the gases from the arc inside the casing is substantially elongated and the gases are cooled intensively.

 According to an additional characteristic of the electric switch proposed by the present invention, the front face of the extinguishing plates, which faces the rear wall of the extinguishing chamber, has several recesses.

The present invention will be better understood with the aid of the detailed description of an embodiment of an arc extinguishing chamber, taken as a nonlimiting example and illustrated schematically by the appended drawing, in which
fig. 1 is a view of an arc extinguishing chamber;
fig. 2 is a view of an extinguishing plate having a V-shaped recess in the center of its front face;
fig. 3 is a view of the extinguishing plates, having V-shaped recesses, which are offset with respect to each other; and
fig. 4 is a view of an extinguisher plate having several V-shaped recesses.

 According to fig. 1, a fixed contact 2, which is provided with a contact support 4, and a movable contact 16, provided with a contact support 18, as well as extinguishing sheets 8, which are arranged, insulated, in the plane of movement of contact 16, so that they are approximately perpendicular to an electric arc, not shown in the figure, which occurs after opening of contacts 2 and 16, are provided in an extinguishing chamber 12. The front faces 6 of the extinguishing sheets 8, which are turned towards the rear wall 10 of the extinguishing chamber 12, have recesses 14 which have substantially the shape of a V, and which are formed in the middle of the front faces 6 and, therefore, superimposed in the sheet pack. When the short-circuit currents are too high, the partial arcs can leave the extinguishing sheets and short-circuit outside the sheet pack, between the wall rear 10 of the extinguishing chamber 12 and the front faces 6 of the extinguishing plates 8, faces which are turned towards said rear wall 10. As soon as the arc is reformed in front of the rear wall 10 of the extinguishing chamber 12, the sheets which are close to it are magnetized so as to produce a magnetic field of great intensity in the V-shaped recess 14, a field by which the arc is drawn towards the interior of the recess and brought between the extinguishing plates to be further subdivided there.

In the embodiment of the extinguishing plate 8 according to FIG. 2, the recess 14 is formed in the center of the front face 6 of the extinguishing plates 8. The conditions required for the combined action of factors, such as the entry of the arc, the increase in tension of the arc and in particular the protection against re-ignition or return of the arc, is done in a particularly favorable manner are established by the fact that the V-shaped recess extends inside an angle of OC opening which is, for example between 45 and 900, with a particularly advantageous initial opening width

This refers to a direct current ID, the factor a being a function of the arc current, the difference between the plates and the properties of the material of the switching chamber, and which can, for example, be between 2 and 4. An electric arc 20 enters, in the direction of the arrow, in a V-shaped split extinguisher plate. Through the existing recess 14, which narrows in a V shape, the arc undergoes intensive cooling and a necking phenomenon during its entry. Therefore, the voltage drop increases until it is sufficient for the formation of the root of the arc and therefore for the subdivision thereof, this without elongation of the whole of the bow.

 In the embodiment of the extinguishing plate 8 according to FIG. 3, the recess 14 is offset towards the edge zone of the front face 6 of the extinguishing sheets 8. Said extinguisher sheets 8 are arranged in such a way that the recesses 14 are alternately offset from one another. Thanks to this arrangement, the path of the arc gases is substantially elongated inside the casing and the gases are cooled intensively. In addition, the presence of the recesses 14 avoids the existence, in the switching chamber, of pressures which are unfavorable for the movement of the arc.

 Fig. 4 shows an embodiment of the extinguishing plate 8 for relays, in which the arc current is generally less than that of a power switch. For this reason, the cross-sectional areas of the recesses 14 are smaller and preferably arranged over the entire length of the front face 6 of the extinguishing sheet 8, so that the arc has the possibility of passing over the sheet of extinction 8.

Claims (4)

 1. Electric switch comprising an arc extinguishing chamber which contains extinguishing plates made of an electrically conductive material and which can be magnetized, characterized in that the front face (6) of the extinguishing plates (8) , which faces the rear wall (10) of the extinguishing chamber (12), has at least one recess (14) having substantially the shape of a V.  2. Electric switch according to claim 1, characterized in that the recesses (14) of the extinguishing plates (8) are provided one above the other.  3. Electric switch according to claim 1, characterized in that the recesses (14) are alternately offset from each other in the direction of the flat side of the extinguishing plates (8).  4. Electric switch according to claim 1, characterized in that the front face (6) of the extinguishing plates (8), which faces the rear wall (10) of the extinguishing chamber (12), has several recesses (X4).