EP2565890B1 - Electrical switchgear with high making capacity - Google Patents

Description

Technical area :

The present invention relates to a high-power shut-off device provided with a control module associated with at least one cut-off module corresponding to a phase of an electrical network, this cut-off module comprising at least one associated mobile contact. at least one pair of fixed contacts, said movable contact being coupled to an actuation mechanism controlled by said control module to be moved between at least one triggered position in which the movable contact is remote from the pair of fixed contacts and the electrical circuit is open, and an engaged position in which the movable contact bears against the pair of fixed contacts and the electrical circuit is closed.

Prior art:

An example of this type of electric switchgear is described in the publications FR 2 818 434 and FR 2 891 395 of the same applicant and particularly concerns switches, fuse switches, switches, reversing switches, circuit breakers, or the like.

To establish an electric current, an electrical apparatus has at least one pair of fixed contacts and a movable contact. When closing the electrical circuit, the movable contact is brought against the fixed contact. To ensure the quality of the electrical contact, ensuring proper operation of the device, the movement of the movable contact in its docking stroke must be independent of any external actions. To do this the electrical device comprises a mechanism for closing and opening the contacts, also called actuating mechanism, which consists of a so-called abrupt closure mechanism independent of the operator. When closing, this mechanism transmits to the moving contact a moving speed of the order of a few m / s. During this period, the moving contact acquires a certain amount of kinetic energy. When the moving contact comes into contact with the fixed contact, a shock ensues. The kinetic energy of the moving contact is transformed into deformation of the materials and a reversal of the speed having the effect of re-opening the moving contact, causing a rebound of the moving contact. The reopening stroke will depend on the berthing speed, the nature of the materials, the pressing force holding the moving contact against the fixed contact. During this reopening, there arises an electric arc which, depending on its intensity, will cause a local melting of the materials of the contact areas. Depending on the conditions, the rebound may be single or consist of several consecutive rebounds, of damped amplitude, until the kinetic energy of the moving contact has dissipated. At the end of rebounds, the electrical contact is established on a melt which, with time will solidify. The risk of welding of the moving contact on the fixed contact is latent. In any case, it follows erosion of the contact areas which, if repeated, can become damaging to the normal operation of the electrical appliance.

One of the solutions to avoid these risks of welding is to differentiate the docking zone from the permanent contact zone. When the contacts are slippery, the docking area may correspond to the entry chamfer as in the publications FR 2,524,195 , FR 2,638,017 and EP 1 026 710 . The closing power of the sliding contacts on short-circuit currents is limited to the power of the actuating mechanism which must oppose the Laplace forces. In addition, the closure of the contacts by sliding is under power, which inevitably causes erosion of the permanent contact areas, limiting the endurance of the device. A solution used in the case of pressure contacts is to equip the contact areas pellets, rivets or the like made of different materials, one of them is generally refractory to limit the risk of welding, or to provide a relief playing the role of spark arrester as in the publication EP 1 085 610 . The implementation of these achievements is relatively expensive.

The publication WO 2006/137687 A1 proposes a switching device provided with a separate moving phase contact and a moving contact of neutral, having different lengths to generate different strokes so as to shift in time the docking of said movable contacts. The time offset obtained is greater than 0.1s to allow time for the relays to analyze the current in order to detect a possible malfunction. However, this arrangement does not solve the problem.

Presentation of the invention

The present invention aims to overcome these drawbacks by proposing an electrical switching device provided with pressure contacts with high closing power even on short-circuit currents, in which the risks of welding and / or erosion at the zones permanent contact are considerably reduced or even eliminated, to achieve a high number of cycles and this without altering the quality of the electrical contact.

For this purpose, the invention relates to an electric switchgear according to claim 1.

This particular construction makes it possible in particular to differentiate the spark arrester zone from the permanent contact zones and to minimize the presence of the electric arc at closing by desynchronizing the rebounds by the creation of temporal docking delays of the order of 100 μs. between two mobile contacts that succeed one another in the same set.

The number of moving contacts can be determined according to the rating of said switchgear so that the moving contact current density does not exceed an intensity value of 15kA peak current.

Depending on the size of said switchgear, said assembly may comprise two central movable contacts.

In the same set, the movable contacts are advantageously arranged symmetrically with respect to a median axis passing through the center of said assembly, and the lateral movable contacts offset two by two with respect to said central movable contact to form stages.

In the preferred form of the invention, the central movable contact comprises a central boss which, when said breaking module is in the engaged position, extends in the free space between the fixed contacts of said pair. According to the templates, the central mobile contact may be associated with an insulating screen that replaces or adds to said boss.

Each set of multiple moving contacts may be carried by an electrically insulating carriage coupled to said actuating mechanism.

This carriage advantageously comprises a housing for each movable contact, in which each movable contact is biased towards said pair of fixed contacts by a return member. These housings preferably have different depths to position said moving contacts of the same set in stages.

Brief description of the drawings:

• la figure 1 est une vue en perspective d'un appareil de coupure électrique selon l'invention comportant un module de commande associé à trois modules de coupure, dans lequel le dernier module de coupure est ouvert,
• la figure 2 est une vue en coupe d'un module de coupure de l'appareil de la figure 1 en position enclenchée,
• la figure 3 est une vue en perspective d'un ensemble de contacts mobiles selon un premier calibre de courant,
• la figure 4 est une vue similaire à la figure 3 d'un ensemble de contacts mobiles selon un second calibre de courant, et
• les figures 5A à 5C sont des vues de côté des contacts fixes et mobiles du module de coupure de la figure 2, dans trois positions d'accostage pendant la fermeture du circuit électrique.

The present invention and its advantages will appear better in the following description of an embodiment given by way of non-limiting example, with reference to the appended drawings, in which:

• the figure 1 is a perspective view of an electrical switching device according to the invention comprising a control module associated with three breaking modules, in which the last breaking module is open,
• the figure 2 is a sectional view of a cutoff module of the device of the figure 1 in the engaged position,
• the figure 3 is a perspective view of a set of movable contacts according to a first current template,
• the figure 4 is a view similar to the figure 3 a set of movable contacts according to a second current template, and
• the FIGS. 5A to 5C are side views of the fixed and moving contacts of the break module of the figure 2 , in three docking positions during closing of the electrical circuit.

Illustrations of the invention and different ways of making it:

With reference to the figure 1 , the electrical switching device 1 referred to in the invention usually consists of a control module 2 associated with one or more cutoff modules 3 each corresponding to a phase of an electrical network. In the example illustrated, the device 1 comprises three cut-off modules 3. Each cut-off module 3 comprises in known manner an insulating housing 30 inside which are housed at least two fixed contacts 4, forming a pair, extended to outside said housing by connection terminals 40, and at least one contact mobile 5 coupled to an actuating mechanism 6 controlled by the control module 2 to be moved between at least one triggered position in which it is remote from the fixed contacts and the electrical circuit is open, and an engaged position in which it is in support against the fixed contacts and the electrical circuit is closed. The control module 2 can be operated manually by a handle 20 and / or automatically by a motor (not shown). The cut-off device 1 comprises in the example shown fractionating chambers 7 arranged above the fixed contacts 4 and the movable contact 5 to capture, stretch, cool and then extinguish the electric arc generated by the current at each change of state of said apparatus.

This switching device 1 must be able to establish and cut currents 1 called normal or fault of a value of 0 to 10In, In being the value of the nominal current that can pass through the device permanently. This device must also be able to establish, and if necessary cut, short-circuit currents whose value can reach 100 to 300 times the rated current In, without altering the permanent contact zones in order to guarantee a constant quality of electrical contact in the weather.

The solution of the invention is described with reference to an electrical apparatus whose breaking modules have a specific internal architecture, object of another patent application filed simultaneously, but can of course apply to any other known internal architecture. In the example shown in Figures 1 and 2 the fixed contacts 4 and the movable contact 5 are arranged to form an omega-shaped current loop, symmetrical with respect to a median axis A coinciding with the axis of displacement Fd of the moving contact 5, in which the so-called Laplace forces, also called compensation forces Fc, generated by the current flowing in the current loop. The conductive parts forming the fixed contacts 4 are rigidly fixed to the housing 30, folded approximately S, arranged in opposition and separated by a free median space. The conductive part forming the movable contact 5 has a width greater than the free space between the two fixed contacts 4 for, in the engaged position, to be pressed against the fixed contacts 4. These conductive parts each offer a contact area C located in a plane inclined relative to the central axis A of an angle substantially equal to 45 °. This example is not limiting since the contact areas C can be included in a plane inclined with respect to the median axis A at an angle that can be between 0 ° and 90 ° in which the value 0 ° is excluded .

The switching device 1 according to the invention is distinguished from the state of the art by its movable contact 5 which is in fact constituted by an assembly 5, 5 'of a plurality of movable contacts 5A-C, 5A-F, parallel and staggered for staggering in time the docking of the movable contacts on the fixed contacts 4 and not to exceed an intensity value of 10 to 15 kA peak current per moving contact. Correspondingly, the fixed contacts 4 are sized to provide a contact area C adapted to receive the plurality of movable contacts of the same set 5, 5 '. The number of movable contacts per set 5, 5 'can be determined according to the nominal current rating In. Figures 3 and 4 illustrate two alternative embodiments of a set of movable contacts, including a first assembly 5 which has five movable contacts 5A-C and corresponds to a 250A rating with a peak value of 50 to 75 kA, and a second set 5 ' which has twelve movable contacts 5A-F and corresponds to a rating of 1600A with a peak value of 120 to 150 kA. The assemblies 5, 5 'are symmetrical with respect to the central axis A of the breaking device 1 and comprise one or two movable contact (s) central (s) 5A different (s) other 5B movable contacts -F lateral. In the whole of the figure 3 , the central movable contact 5A is centered on the median axis A and in the whole of the figure 4 , the two central movable contacts 5A are symmetrical to the central axis A. Each central movable contact 5A is larger and / or positioned in advance of the others to be the first to dock the fixed contacts 4 in order to establish the current, and the last to leave the fixed contacts 4 to turn off the power. It is he who undergoes the electric arc and therefore plays the role of spark arrester.

In the examples shown, the central movable contact 5A consists of a conductive part in the form of a blade having in its upper part a central boss 50 conferring a substantially triangular shape symmetrical with respect to the median axis A. Well Of course, any other form may be suitable. When the breaking module 3 is in the engaged position, the boss 50 extends in the free space between the fixed contacts 4 outside the current loop. This boss 50 is connected to the contact areas C by a shoulder 51 forming a nose on which the electric arc generated by the current clings to the closing and opening of the electric circuit, thus rapidly releasing the contact areas C This boss 50 then defines a slope 52 which rises in the direction of the compensating forces Fc and accompanies the displacement of the electric arc pushed by these compensating forces Fc towards the fractionating chambers 7. The central movable contact 5A can be completed by an insulating screen (not shown) which extends in place of the boss 50 or adds to this boss 50 to facilitate the extinction of the electric arc especially in low current of the order of 0.1 In by example.

The other lateral movable contacts 5B-F consist of a conductive part in the form of a blade symmetrical with respect to the central axis A and provided laterally with two contact zones C. They may have identical dimensions or not. They are at least identical two by two symmetrically with respect to the median axis A.

The movable contacts 5A-C, 5A-F of the same assembly 5, 5 'are housed in an electrically insulating carriage 8, delimiting separate and parallel housings 80, of different depths for the lateral movable contacts 5B-C, 5B -F are shifted two by two with respect to the prominent central movable contact 5A and form stages E1, E2. The race from one floor to another may be equal or not. This carriage 8 can be formed in one piece or in several assembled parts, these parts can be made for example by molding plastics. The carriage 8 is coupled to the actuating mechanism 6.

In the example shown, the actuating mechanism 6 of the set 5, 5 'of movable contacts comprises a drive shaft 60 connected in rotation with the handle 20 by an angle gear (not visible) and / or controlled by a second member (not shown) fitted into the square bore 61. A system for converting the rotational movement of the drive shaft 60 into a translation movement makes it possible to move a carriage 64 carrying the carriage 8 into the median axis A. This motion transformation system comprises a pair of rods 62, 63 hinged, but any other equivalent means is conceivable. The first link 62 is integral with the drive shaft 60 and rotatably coupled to the second link 63 by a first link B1. The second connecting rod 63 is coupled in rotation with the carriage 64, and simultaneously with the carriage 8, by a second articulation B2. The carriage 64 is guided in translation relative to the housing 30 by means of rails, ribs or any other equivalent means, in which the projecting ends of the axis forming the articulation B2 circulate.

A return member 65 is interposed between the carriage 64 and each movable contact 5A-C, 5A-F to exert a determined pressing force on each of the movable contacts when it is pressed against the fixed contacts 4. In the configuration illustrated, this pressure force is added to the compensation forces Fc generated by current I.

The FIGS. 5A to 5C illustrate in three steps the docking of the set 5 of movable contacts 5A-5C of the figure 3 on the fixed contacts 4 of a breaking module 3 to close the electrical circuit. On engagement of the breaking module 3, when the carriage 64 is moved in the direction Fd towards the fixed contacts 4 by the actuating mechanism 6, the docking of the fixed contacts 4 is effected by the central movable contact 5A. which is ahead of the others and undergoes the first rebound (cf. Fig. 5A ). Some 100μs later, the second movable contacts 5B surrounding the central movable contact 5A close on the fixed contacts 4, short-circuiting the electric arc that arose during the rebound of the movable contact central 5A, and in turn undergo a rebound (cf. Fig. 5B ). Then some 100μs later, the third movable contacts 5C that follow, are closed in turn on the fixed contacts 4, short-circuiting the electric arc that arises during the rebounds of the second movable contacts 5B (cf. Fig. 5C ), and in turn undergo a rebound. The central movable contact 5A, which was the first to close, ends its rebound stroke, short-circuiting the electric arc that arises during rebounds of the third movable contacts 5C. And so on, until rebound stabilization. The total duration of the presence of the electric arc as well as the specific duration of the presence of the electric arc at each docking are greatly reduced, making it possible to achieve a high number of closing cycles and increased endurance.

Furthermore, when the electrical circuit is opened, the lateral movable contacts 5B-C, 5B-F are totally arc-free, the electric arc being established only on the central mobile contact 5A when it leaves lastly the fixed contacts 4. Therefore, the lateral movable contacts 5B-C, 5B-F undergo no wear, erosion or local melting due to the electric arc, and participate fully in the permanent passage of the electric current.

It is clear from this description that the invention achieves the goals set, including the multiplication of mobile contacts and their time offset to minimize the adverse effects of bounces generated during the closure of the electrical circuit. This offset actually makes it possible to desynchronize the bounces of each moving contact and to minimize the time during which no moving contact is in physical contact with the fixed contact. The electrical endurance of the switchgear is thus greatly improved.

The present invention is not limited to the embodiments described but extends to any modification and variation obvious to a person skilled in the art while remaining within the scope of protection defined in the appended claims.

Claims (10)

1. Electrical cut-off device (1) with high making capacity provided with a control module (2) associated with at least one cut-off module (3) corresponding to a phase of an electrical network, said cut-off module including at least one moving contact (5) associated with at least one pair of fixed contacts (4), said moving contact (5) being coupled with an actuator mechanism (6) controlled by said control module (2) so as to be moved between at least one switched-off position in which the moving contact is distant from the pair of fixed contacts and the electrical circuit is open, and a switched-on position in which the moving contact is resting on the pair of fixed contacts and the electrical circuit is closed, characterized in that it comprises at least one set (5, 5') of several moving contacts (5A-C ; 5A-F) associated with said pair of fixed contacts (4), the moving contacts of said set (5, 5') being parallel and offset in space with respect to each other in order to stagger in time the approach of said moving contacts on said pair of fixed contacts when closing the electrical circuit, said set (5, 5') including at least one central moving contact (5A) that is ahead of the other moving contacts (5B-C ; 5B-F) arranged laterally around said central moving contact (5A), so that it is the first to establish the current when closing the electrical circuit and the last to cut off the current when opening said circuit.
2. Device according to claim 1, characterized in that said set (5, 5') comprises a number of moving contacts (5A-C; 5A-F) determined according to the rating of said cut-off device (1), so that the current density for each moving contact does not exceed an intensity value of 15kA for the peak current
3. Device according to claim 1, characterized in that said set (5') comprises two central moving contacts (5A).
4. Device according to any of the previous claims, characterized in that in said set (5, 5'), said moving contacts (5A-C ; 5A-F) are arranged symmetrically with respect to a centerline passing through the center of said set.
5. Device according to claim 4, characterized in that in said set (5, 5'), said lateral moving contacts (5B-C ; 5B-F) are offset two by two with respect to said central moving contact (5A) in order to form stages (E1, E2).
6. Device according to any of the previous claims, characterized in that said central moving contact (5A) includes a central boss (50) that, when said cut-off module (3) is in its switched-on position, extends in the free space between the fixed contacts (4) of said pair.
7. Device according to any of the previous claims, characterized in that said central moving contact (5A) is associated with an insulating screen that, when said cut-off module (3) is in its switched-on position, extends in the free space between the fixed contacts (4) of said pair, outside of said current loop.
8. Device according to claim 1, characterized in that each set (5, 5') of several moving contacts (5A-C ; 5A-F) is carried by an electrically insulating carriage (8) coupled with said actuator mechanism (6).
9. Device according to claim 8, characterized in that said carriage (8) includes a seat (80) for each moving contact, in which each moving contact is pressed against said pair of fixed contacts (4) by a return means (65).
10. Device according to claim 9, characterized in that the seats (80) of a same carriage (8) have different depths for positioning said moving contacts (5A-C ; 5A-F) of a same set (5, 5') in stages.

Images