EP0794545A1 - Vacuum switch or circuit breaker - Google Patents

Abstract

The circuit breaker has two arc contacts housed in the two bases. One is fixed while the other slides axially in the cartridge to connect in two contact regions. One of the arc contacts is connected to one end (2a,20a) of the turns (2,20) and the other end (2b,20b) is connected to the contact region of the other contact. The turns lie outside the cartridge (C), at right angle to the spacing of the contacts. Each portion of turn of which there are normally two has a length less than one complete turn and a group of such portions forms a complete loop.

Description

The present invention relates to an electric vacuum switch intended to ensure breaking in an electric circuit in particular at low or medium voltage.

A circuit breaker is known as described in patent application FR-2,682,808 by the applicant comprising a vacuum interrupter in which two arcing contacts are housed, one of which is fixed, is secured to one of the bottoms while the other, mobile, is mounted to slide axially inside the cartridge between a closed position and a contact separation position causing the formation of an arc current. This circuit breaker further comprises a coil arranged coaxially outside the cartridge in line with the separation interval of the arcing contacts, this coil being intended to produce an axial magnetic field in the arcing region. One of the drawbacks of this type of circuit breaker is that the coil being in series with the arcing contacts, all of the main current flows through the coil. It follows that it is necessary to provide a coil of large section which therefore has a large footprint and generates considerable losses.
One of the solutions to this problem consists, as described in patent application No. 9413408 of the applicant, of interposing a bypass means between the two ends of the coil, said means being intended to derive part of the main current to through the coil during cutting, to create a reduced axial magnetic field and thus reduced loss. However, in this embodiment, the heat losses remain significant.

The present invention solves these problems and proposes a vacuum interrupter or circuit breaker, of particularly simple design, making it possible to further reduce these losses.

To this end, the subject of the present invention is an electrical switch intended to ensure breaking in an electrical circuit, of the type comprising an elongated cartridge under vacuum with a cylindrical casing closed by two bottoms, in which are housed two arcing contacts intended for be electrically connected respectively to two current supply ranges, one of which, fixed, is integral with one of the bottoms while the other, mobile, is mounted with axial sliding inside the cartridge, and at least one means intended to produce an axial magnetic field in the zone of formation of the arc, this switch being characterized in that the aforesaid means comprises at least two portions of turn mounted in parallel around the contacts, each comprising a first end electrically connected to one of the arcing contacts and a second end electrically connected to the current supply range of said contact, said portions being arranged outside the cartridge, in line with the separation gap between the arcing contacts.

The invention also relates to an electric switch intended to ensure breaking in an electrical circuit, of the type comprising an elongated cartridge under vacuum with a cylindrical envelope closed by two bottoms, in which are housed two arcing contacts intended to be electrically connected respectively to two current supply ranges, one of which is fixed, is secured to one of the aforementioned funds while the other, mobile, is mounted to slide axially inside the cartridge, and at least one means intended to produce an axial magnetic field in the arc formation zone, this switch being characterized in that the aforementioned means comprises at least two portions of turn mounted in parallel around the contacts, each comprising a first end electrically connected to the 'one of the arcing contacts and a second end electrically connected to the current supply range of said contact and in that the first and second ends of each turn portion are electrically connected by a bypass means for diverting a portion of the main current through the turn portions, during cutting.

According to a particular characteristic, each portion of turn forms a fraction of turn of length less than one complete turn.

According to another characteristic, all of the combined turn portions form a complete loop.

According to a particular characteristic, the turns are two in number.

According to a particular embodiment, the turns portions as well as the bypass means M are mounted coaxially outside the cartridge.

According to another embodiment, the turns portions as well as the bypass means are mounted coaxially inside the cartridge.

According to another characteristic, the turns portions as well as the bypass means are mounted between the fixed arcing contact and the corresponding current supply range.

According to a particular embodiment, the turns and the bypass means are an integral part of one or both of the arcing contacts.

Advantageously, the turns portions being two in number, the second end of one of the turns portions is superimposed on the first end of the other of the turns portions.

According to another particular embodiment, the switch comprises a first bell comprising several portions of turn connected electrically by one of their ends to the aforementioned area (or in arcing contact) and by their end opposite to a second conductive bell disposed coaxially with the cartridge and electrically connected to the arcing contact (or respectively to the aforementioned range).

Advantageously, the second bell also includes turns portions, the same number of turns portions as the first, electrically connected by one of their ends, respectively to the turns portions of the first bell and by their ends opposite to said contact d arc, the turns portions associated with the first and the second bell being arranged relative to each other so as to cancel the axial components of the currents passing through the portions of turns.

According to another characteristic, the aforementioned bypass means comprises a resistive element and / or an inductive element mounted in parallel with the turns portions.

• La figure 1 est une vue en perspective, illustrant une ampoule à vide conforme à une réalisation particulière de l'invention,
• La figure 2 est une vue en perspective, illustrant l'une des portions de spire utilisée dans la réalisation de l'ampoule de la figure précédente,
• La figure 3 est une vue en perspective illustrant les deux portions de spires utilisées dans cette même réalisation et constituant le moyen de création du champ axial.
• La figure 4 est une vue en perspective illustrant l'un des contacts d'une ampoule conforme à une autre réalisation de l'invention,
• Les figures 5 et 6 sont des vues partielles illustrant en coupe axiale, deux autres réalisations d'un interrupteur à vide conforme à l'invention, et
• Les figures 7 et 8 illustrent respectivement une ampoule équipée de trois portions de spire montées en parallèle, et un tiers de spire.

However, other advantages and characteristics of the invention will appear better in the detailed description which follows and which refers to the appended drawings given solely by way of example and in which:

• FIG. 1 is a perspective view, illustrating a vacuum interrupter according to a particular embodiment of the invention,
• FIG. 2 is a perspective view, illustrating one of the portions of the coil used in the production of the bulb of the preceding figure,
• Figure 3 is a perspective view illustrating the two portions of turns used in this same embodiment and constituting the means for creating the axial field.
• FIG. 4 is a perspective view illustrating one of the contacts of a bulb according to another embodiment of the invention,
• FIGS. 5 and 6 are partial views illustrating in axial section, two other embodiments of a vacuum interrupter according to the invention, and
• Figures 7 and 8 respectively illustrate a bulb equipped with three portions of turn mounted in parallel, and a third of turn.

In FIG. 1, we see a vacuum interrupter I comprising a vacuum bulb (or cartridge) C constituted mainly by a cylindrical casing 1 closed by two opposite bottoms in which are housed two arcing contacts 4 respectively fixed and movable 5 ( not visible in this figure, but visible in Figure 5). The fixed arcing contact 4 is integral with the bottom located at the top of the casing 1 while the movable arcing contact 5 is slidably mounted through the other of the two bottoms.

This switch I also comprises a means intended to create an axial magnetic field between the contacts 4, 5 in order to obtain a diffusion of the arc. In accordance with the embodiment of the invention illustrated in this figure, this means comprises two half-turns 2, 20 symmetrical such as that 2 illustrated in FIG. 2. These two half-turns 2, 20 are mounted outside of the bulb C in line with the separation gap of the arcing contacts 4, 5, so as to form a complete loop. Each turn portion 2, 20 is constituted by a half-turn having two ends 2a, 20a and 2b, 20b extending parallel to the bottoms of the cartridge C.

These ends include a first end 2a, 20a, intended to be electrically connected to the fixed contact 4, and a second end 2b, 20b, intended to be electrically connected to the pad 19 (not shown in this figure) for supplying current to the fixed arcing contact 4. As can be seen more particularly in FIG. 3, the first two ends 2a, 20a, associated respectively with the two turns portions are of complementary shape and are arranged end to end, as are the two seconds ends 2b, 20b. Advantageously, a layer of insulating material 22 with a thickness of approximately 1 mm is interposed between the first 2a, 20a and the second 2b, 20b, ends, said layer 22 extending to the bottom of the turns 2 , 20. The first ends 2a, 20a of the turn portion are electrically connected to the second ends 2b, 20b by a bypass means M mounted in parallel with said portions and constituted in this particular embodiment, by a stud 23 made of stainless steel. This means is intended to divert a sufficient part of the current through the turns 2, 20.

, $\frac{\text{1}}{\text{3}}$

, $\frac{\text{1}}{\text{4}}$

etc.) de courant qui créent un champ magnétique, le moyen de dérivation M permet d'ajuster le courant à des valeurs précises, ce qui permet de créer précisément le champ magnétique nécessaire en minimisant ainsi les pertes.While the turns allow to obtain fractions ( $\frac{\text{1}}{\text{2}}$

, $\frac{\text{1}}{\text{3}}$

, $\frac{\text{1}}{\text{4}}$

etc.) of current which create a magnetic field, the bypass means M makes it possible to adjust the current to precise values, which makes it possible to precisely create the magnetic field necessary, thereby minimizing losses.

In Figure 7, the bulb is equipped with three thirds of a turn, which are once again symmetrical. A single piece is thus used (fig. 8) to make, after mounting several sectors, a complete turn.
Note also the self-locking effect of the sectors after mounting the stud 11, obtained thanks to the particular shape of the ends of the turns portions.

Referring to Figure 4, we see that according to another embodiment of the invention, the two aforementioned two half-turns 2, 20 are formed inside one 4 of the arcing contact elements. It will be noted that in this embodiment, the two arcing contacts 4, 5 may advantageously be equipped with such portions of turns.

According to the invention, the bulb C is surrounded by several portions of turns. As a result, currents can be created whose axial component is capable of producing undesirable magnetic fields in the radial direction, these fields having the effect of repelling the arc outside the space situated between the arcing contacts. In order to compensate for these axial components, in the two embodiments described above, the two ends 2a, 2b or 20a, 20b of each portion of turn 2, 20 are offset axially, and the two second ends 2b, 20b are superimposed respectively on the first two ends 20a and 2a.

According to another embodiment described in FIG. 5, the switch I comprises a first bell 14 comprising a certain number of portions of turns 18, for example seven.

These turns portions include an end electrically connected to a current supply range 19 to the fixed contact 4 and an end electrically connected to a second conductive bell 15 mounted inside the first 14 and electrically connected to the arcing contact. fixed 4, this second bell 15 compensating the above-mentioned axial current components. Note that this second bell 15 can advantageously be an integral part of the envelope 1 of the bulb as shown in Figure 5, and be fixed to the first by soldering. It will also be noted that this second bell 15 could also have been placed outside the first. In this embodiment, the bypass means M is constituted by a resistive element 6 in the form of a disc interposed between the two aforementioned bells 14, 15.

According to another embodiment illustrated in Figure 6, the switch I comprises, as in the previous embodiment, two coaxial bells 14, 16, electrically connected to their lower part, one of which is external 14 has portions of coil 18 electrically connected to the current supply range 19 of the fixed arcing contact 4. However, in this embodiment, the compensation of the axial current components is obtained by the fact that the internal bell 16 also includes portions of coil 17, said portions 17 being located in the extension of the turns portions 18 of the outer bell 14 and electrically connected to the fixed arcing contact 4. In this case, the portions of turns belonging to the two bells are arranged relative to each other of so as to bring the current up so that the currents oriented in the axial direction cancel each other out. Thus, the ratio between the radial field and the axial field is reduced, from which it follows that the effects of the above-mentioned axial components of current are reduced.

The operation of a switch according to one or other of the abovementioned embodiments will be described briefly in the following with reference to the figures.

According to the embodiment illustrated in Figures 1 to 4 during cutting, a current bypass occurs through the coil portions 2, 20. This results in the creation of an axial magnetic field in the separation zone of the contacts. arc 4, 5. When using two portions of a turn, for a given section, each portion making a U-turn, we obtain a loss corresponding to 25% of that created in the case where the entire current passed through a complete turn .

In general, for an effective breaking capacity of 25kA, it is advantageous to obtain an axial magnetic field corresponding to a current of 10kA passing through a turn. As a result, only 40% of the available current must pass through a whorl surrounding the bulb completely.

With a single turn, and in the case where all the current crosses said turn, during the cutting, one obtains a far too strong axial magnetic field; thus, during the passage of a permanent current of 1250 A, a loss of 68 Watts is created.

By using a full turn and a bypass means, the current flowing through the turn can be adjusted and the desired axial magnetic field is obtained exactly. However, during the passage of the permanent current of 1250 A, the losses are 34 Watts.

With a system consisting of two parallel turns of the coil and a bypass means, it is also possible to adjust the branched current (up to 40% of current passing through the turns of the coil. The loss during the passage of the permanent current is then reduced and reaches only 17 Watts In the latter case, the bypass means can be achieved by a simple stud which supports the two portions of the coil and the bulb, only 20% of the current passing through this stud, which further facilitates assembly.

According to the embodiments illustrated in FIGS. 5 and 6, the derivative current first passes through the turns 18 of the first bell 14 and then through the second bell 15, 16 before crossing the arcing contacts 4, 5.

Note that an inductive shunt could just as well have been used instead of a resistive shunt or a combination of an inductive shunt and a resistive shunt.

Of course, the invention is not limited to the embodiments described and illustrated which have been given only by way of example.

On the contrary, the invention includes all the technical equivalents of the means described and their combinations if these are carried out according to the spirit.

Claims (13)

Electrical switch intended to ensure breaking in an electrical circuit, of the type comprising an elongated cartridge under vacuum with a cylindrical envelope closed by two bottoms, in which are housed two arcing contacts intended to be connected electrically respectively to two supply ranges of the current, one of which, fixed, is integral with one of the aforementioned funds while the other, mobile, is mounted to slide axially inside the cartridge, and at least one means intended to produce a magnetic field axial in the arc formation zone,
characterized in that the above-mentioned means comprises at least two portions of turn (2, 20) mounted in parallel around the contacts (4, 5), each comprising a first end (2a, 20a) electrically connected to one (4) arcing contacts (4, 5) and a second end (2b, 20b) electrically connected to the current supply range (19) of said contact (4), said portions (2, 20) being arranged at the outside of cartridge C, in line with the separation gap between the arcing contacts (4, 5). Electrical switch intended to ensure breaking in an electrical circuit, of the type comprising an elongated cartridge under vacuum with a cylindrical envelope closed by two bottoms, in which are housed two arcing contacts intended to be connected electrically respectively to two supply ranges of the current, one of which is fixed, is integral with one of the aforementioned funds while the other, mobile, is mounted to slide axially inside the cartridge, and at least one means intended to produce an axial magnetic field in the arc formation area,
characterized in that the above-mentioned means comprises at least two portions of turn (2, 20) mounted in parallel around the contacts (4, 5), each comprising a first end (2a, 20a) electrically connected to one (4) arcing contacts (4, 5) and a second end (2b, 20b) electrically connected to the current supply range (19) of said contact (4) and in that the first (2a, 20a) and second (2b, 20b) ends of each portion of turn (2, 20) are electrically connected by a bypass means M intended to divert part of the main current through the portions of turn (2, 20), during cutting. Switch according to claim 1 or 2, characterized in that each portion of the turn forms a fraction of turn of length less than one complete turn. Switch according to any one of claims 1 to 3, characterized in that all of the combined turn portions form a complete loop. Switch according to any one of claims 1 to 4, characterized in that the turns (2, 20) are two in number. Switch according to any one of claims 2 to 5, characterized in that the turns portions (2, 20) as well as the bypass means M are mounted coaxially outside the cartridge C. Switch according to any one of claims 2 to 5, characterized in that the turns portions (2, 20) as well as the bypass means M are mounted coaxially inside the cartridge C. Switch according to any one of the preceding claims, characterized in that the turns portions (2, 20) as well as the bypass means M are mounted between the fixed arcing contact (4) and the current supply range corresponding (19). Switch according to any one of Claims 1 to 5, characterized in that the turns portions (2, 20) as well as the bypass means M form an integral part of one or both of the arcing contacts (4, 5). Switch according to any one of the preceding claims, characterized in that the number of turns being two, the second end (2b, 20b) of each turn portion is superimposed on the first end (2a, 20a), of the other of the turns. Switch according to any one of the preceding claims, characterized in that it comprises a first bell (14) comprising several portions of turn connected electrically by one of their ends to the aforementioned area (19) (or in contact with arc 4) and by their end opposite to a second conductive bell (15, 16) disposed coaxially with the cartridge and electrically connected to the arcing contact (4) (or respectively to the aforementioned area (19)). Switch according to claim 11, characterized in that the second bell (16) has the same number of turns portions (17) electrically connected by one of their ends, respectively to the turns portions (18) of the first bell ( 14) and by their end opposite to said arcing contact (4), the turns portions associated with the first (14) and the second (16) bell being arranged in relation to each other so as to cancel the axial components currents crossing the portions of turns. Switch according to any one of claims 2 to 12, characterized in that the aforementioned bypass means comprises a resistive element and / or an inductive element mounted in parallel with the portions of turns (2, 20).

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