EP0003447A1 - Device for current limiting and circuit breaking - Google Patents

Abstract

1. Device for current limiting and current breaking comprising : - a current limiting block (16) having fast opening contacts (48, 50 ; 62, 26) by electrodynamic effect, - a protective circuit breaker block (10) with a molded case having contacts (24, 26) and an automatic contact (24, 26) opening mechanism by an overload and/or short circuit, said blocks (10, 16) being electrically connected for a series connection of said fast opening contacts (48, 50 ; 62, 26) and said circuit breaker contacts (24, 26), and being mechanically joined so that a wall (14) of the molded case separates the latter from the limiting block, - a first movable conductor (52), the word movable being understood with respect to stationary elements, said first movable conductor (52) carrying a movable contact (50, 62) of said fast opening contacts (48, 50 ; 62, 26) and extending insides said limiting block (16) parallel to said wall (14) in closed position of said fast opening contacts (48, 50 ; 62, 26), - a second stationary conductor (44) extending insides said limiting block (16) parallel to said first conductor (52) in closed position said first (52) and second (44) conductors being electrically series connected for flowing of currents therethrough which create an electrodynamic force moving said first movable conductor (52) in the open position of said fast opening contacts (48, 50 ; 62, 26), - a third conductor (28) extending insides said circuit breaker block (10) and being electrically connected in series with said first (52) and second (44) conductors, characterized in that said third conductor (28) extends in closed position of said circuit breaker (10) contacts (24, 26 ; 62, 26) near said wall (14), parallel to said first (52) and second (44) conductors of the limiting block (16) and in that said first (51) and third (28) conductors are electrically connected in series for flowing of currents therethrough creating an additional electrodynamic force moving said first movable contact (52) into the open position of said fast opening contacts (48, 50 ; 62, 26).

Description

• - un bloc limiteur de courant à ouverture rapide de contacts par effet électrodynamique,
• - un bloc disjoncteur standard de protection, notamment un disjoncteur à boitier moulé, ayant des contacts et un mécanisme d'ouverture automatique des contacts sur défaut, lesdits blocs étant connectés électriquement en série et solidarisés mécaniquement par accolement dos à dos,
• - un premier conducteur mobile portant un contact mobile et s'étendant à l'intérieur dudit bloc limiteur parallèlement auxdits dos en position de fermeture desdits contacts à ouverture rapide,
• - un deuxième conducteur fixe s'étendant à l'intérieur dudit bloc limiteur parallèlement audit premier ponducteur en position de fermeture, lesdits premier et deuxième conducteurs étant connectés électriquement en série pour être parcourus par des courants engendrant une force électrodynamique de déplacement dudit premier conducteur mobile en position d'ouverture desdits contacts à ouverture rapide,
• - un troisième conducteur s'étendant à l'intérieur dudit bloc disjoncteur en étant connecté électriquement en série desdits premier et deuxième conducteurs.

The invention relates to a current limiting and cutting device comprising:

• - a current limiting block with rapid opening of contacts by electrodynamic effect,
• - a standard circuit breaker protection block, in particular a molded case circuit breaker, having contacts and an automatic contact opening mechanism on fault, said blocks being electrically connected in series and mechanically secured by back-to-back coupling,
• a first movable conductor carrying a movable contact and extending inside said limiter block parallel to said backs in the closed position of said quick-opening contacts,
• a second fixed conductor extending inside said limiter block parallel to said first weigher in the closed position, said first and second conductors being electrically connected in series so as to be traversed by currents generating an electrodynamic displacement force of said first movable conductor in the open position of said quick-opening contacts,
• - A third conductor extending inside said circuit breaker block while being electrically connected in series with said first and second conductors.

The performance of a conventional circuit breaker can be increased by connecting a limiter block in series, intended to limit the peak value of a short current circuit and relieve the action of the conventional circuit breaker. These limiting circuit breaker assemblies can replace special circuit breakers with high breaking capacity and allow the marketing of a range of devices based on a standard device.

There is already known a device for limiting and interrupting current with associated circuit breaker and limiter blocks, of the type corresponding to the preamble of claim 1 (French patent No. 2,272,479). The circuit breaker and limiter blocks are simply juxtaposed and no interaction by electromagnetic or electrodynamic effect between the blocks is exploited. Certain copper elements and circuits implemented in this known device are duplicated and the advantage of the circuit breaker block limiter assembly compared to a circuit breaker with high breaking capacity is reduced by a higher manufacturing cost. .

The object of the invention is to remedy this drawback and to achieve interaction between the circuit breaker and limiter blocks, more particularly between the circuits of these blocks to generate rapid opening of the contacts of the limiter and / or of the circuit breaker.

The present invention is based on the observation that the limitation of the current results from a rapid opening of the contacts by electrodynamic effect, due to a repulsion or attraction between conductors traversed by short-circuit currents, this effect being sensitive on conductors separated by a wall of insulating material and which can be reinforced by magnetic yokes for concentration of the flux. Electrodynamic blowing of the drawn arcs increases the desired limiting effect.

The limiting device according to the invention is characterized in that said third conductor extends in closed position of the circuit breaker contacts near said joined backs, parallel to said first and second conductors of the limiter block and in that said first and third conductors are electrically connected in series to be traversed by currents generating an additional electrodynamic force of displacement of the first movable conductor in the open position of said quick opening contacts.

The advantages obtained by the favorable arrangement of the circuits according to the invention consist on the one hand in the use of the circuit breaker circuit to increase the electrodynamic force of opening of the limiter contacts and on the other hand in an increased blowing of the 'bow drawn. According to an important development, an action of the circuit of the limiter block on the movable contact of the circuit breaker is provided to accelerate its opening and generate an additional limitation of the current. The blocks being placed back to back, the conductors are separated by the bottom of the molded case of the circuit breaker, and possibly the bottom of the limiter block, if this bottom exists, but in large-caliber devices interactions remain sufficient. For small sizes, the presence of magnetic yokes in the limiter block and / or the circuit breaker block allows a channeling of the magnetic flux and compensation of the spacing between the conductors, due to the presence of the bottom of the shoemaker. The circuit breaker is preferably stripped of cylinder heads in order to keep a standard device.

The electrical circuit in the limiter and circuit breaker blocks is advantageously in the form of 'f, the central fixed conductor being surrounded by the movable conductors of the circuit breaker and of the limiter.

The limiter block and the circuit breaker block may each comprise a pair of independent contacts and the associated interrupting chambers are advantageously opposite. According to a development of the invention, the fixed contact of the circuit breaker can be replaced by a mobile contact carried by an appendage of the mobile conductor of the limiter block, which crosses the bottom of the housing and cooperates with the mobile contact of the circuit breaker. This arrangement has the advantage of rapid separation of the two movable contacts of the circuit breaker and the elimination of the flexible connection between the limiter block and the circuit breaker block.

According to another development of the invention, the limiter-circuit breaker assembly comprises a single pair of contacts, one of which belongs to the circuit breaker block and the other of which is carried by an appendage of the movable conductor of the limiter block. This avoids the presence of two contact zones in series and the resulting risks of overheating, in particular in large-caliber devices. The overall size can also be reduced.

The conductors and in particular the current supply (s) are arranged to exert on the arc a blowing effect, favoring the elongation and the entry of the arc into the breaking chamber. The association of the circuit breaker block limiter block is particularly simple and does not require any significant modification of the standard circuit breaker. This is limited to replacing the conductor of the 4 fixed contact of the circuit breaker with a connection piece or in certain cases by removing this fixed contact. The ϕ structure of the electrical circuit retains the classic arrangement on the opposite sides of the input and output terminals, which facilitates connections and mounting in standard boxes and panels.

In the following, the invention is explained in more detail at _. using drawings representing different modes of execution.

• ensemble bloc disjoncteur - bloc limiteur selon l'invention;
• la figure 2 est une coupe suivant la ligne II-II de la figure 1;
• les figures 5 et 4 sont des vues analogues à celle de la figure 1, illustrant deux variantes de réalisation.

Figure 1 is a schematic section of a

• circuit breaker block - limiter block assembly according to the invention;
• Figure 2 is a section along line II-II of Figure 1;
• Figures 5 and 4 are views similar to that of Figure 1, illustrating two alternative embodiments.

In FIGS. 1 and 2, a circuit breaker block 10 with molded boot 12 is joined by its bottom 14 to a limiter block 16 with molded housing 18 with the same basic dimensions, but with an open bottom. In the assembled position of the boxes 12, 18, for example by screws (not shown), the bottom 14 constitutes a partition wall between the two blocks 10, 16 having an orifice 20 for passage of a flexible connection in the form of a braid 22 .

The circuit breaker 10, of a well-known type, comprises in its part close to the bottom 14, a fixed contact 24 which cooperates with a movable contact 26, carried by an elongated arm 28, mounted for rotation on a pivot 30 adjacent to the contact 26 A control mechanism 32, diagrammatically represented by a block, controls the opening and closing of the movable contact 26 by moving, for example, the pivot 30, the interaction between the mechanism 32 and the movable contact 26 being shown diagrammatically in the figures by a double arrow. A trip unit 34 controls the control mechanism 32 to trip the circuit breaker in the event of a fault, and a handle (not shown), allows manual control. A pair of contacts 24, 26 is associated with a breaking chamber 36 advantageously comprising deionization sheets (not shown). The rear part of the contact arm 28, opposite the movable contact 26 relative to the pivot 30, is framed by two magnetic yokes 36, 36 ', attached to the side walls and to the bottom 14 of the shoemaker 12. A braid 38 connects this rear part from arm 28 to an output range 40 and a spring (not shown) requests the movable contact 26 in the closed position. When the circuit breaker 10 is used, only the fixed contact 24 is connected or ends with a contact pad 42, shown in broken lines. In combination with the limiter block 16, the area 42 is eliminated or, more precisely, the contact assembly 24, area 42 is replaced by a contact 24 allowing the connection of the braid 22. It is unnecessary to describe in detail the structure and operation of the circuit breaker 10 which are well known to specialists.

The limiter block 16 comprises a fixed conductor 44, which carries at one of its ends, opposite the output range 40 of the circuit breaker 10, an input range 46 and at the other end a fixed contact 48. In position assembly of the boxes 12, 18 the fixed conductor 44 is pressed against the bottom 14 and extends parallel to the contact 24 and to the contact arm 28 of the circuit breaker 10. The fixed contact 48 cooperates with a movable contact 50, carried by an contact 52, the latter being articulated on an axis 54 disposed on the side of the input pad 46. In the closed position, the arm 52 extends parallel and at a short distance from the fixed conductor 44. The contact arms 28, 52 are thrust in the same plane perpendicular to the bottom 14 and containing the fixed conductor 44. A spring 56 biases the arm 52 in the closed position of the contacts 48, 50 and the end of the arm 52, opposite the contact 50, is connected to the braid 22. Contacts 48, 50 cooperate with an interrupting chamber 58 arranged opposite of the chamber 36. The arm 52 is framed by magnetic yokes 60, 60 ′ attached to the side walls of the housing 18 and to the bottom 14, these yokes being arranged as an extension of the yokes 36, 36 ′ of the circuit breaker block 10 and having an air gap in which the arm 52 is inserted in the closed position of the contacts 48, 50.

• En position fermée du dispositif, représentée sur les figures 1 et 2, le courant entre par la plage 46, parcourt le conducteur fixe 44, dans le sens indiqué par la flèche, les contacts fermés 48, 50, le bras de contact 52, la tresse 22, les contacts 24, 26, le bras 28, la tresse ₃8 et la plage de sortie 40. Il est facile de voir que le sens de parcours du courant dans le bras de contact 52 est opposé à celui dans le conducteur fixe 44, engendrant une force de répulsion électrodynamique qui tend à faire pivoter le bras de contact 52 dans le sens horaire d'ouverture des contacts 48; 50 à l'encontre du ressort 56. Le sens de parcours du courant dans le conducteur fixe 44 et le bras 28 est par contre le même et une force électrodynamique d'attraction s'exerce entre ces conducteurs 44, 28. La partie postérieure du bras 28 est plus longue que la partie antérieure qui porte le contact 26 et est disposée du côté opposé du pivot 30 de façon que la résultante des forces électrodynamiques tende à faire pivoter le bras 28 dans le sens horaire correspondant à l'ouverture des contacts 24, 26. En fonctionnement normal les contacts 48, 50 et 24, 26 sont maintenus fermés par les ressorts de pression de contact dont l'action est prépondérante. Lors de l'apparition d'un court-circuit, les efforts électrodynamiques deviennent prépondérants et déplacent d'une part le bras de contact 52 en position d'ouverture des contacts 48, 50 et d'autre part le bras 28 en position d'ouverture des contacts 24, 26, cette dernière ouverture étant confirmée par la suite par le mécanisme 32 commandé par le bloc déclencheur 34 qui a vu le court-circuit. Après extinction des arcs tirés entre les contacts 24, 26 et 48, 50, ces derniers contacts se referment sous l'action du ressort 56 le circuit étant interrompu par la séparation des contacts 24, 26 restés ouverts. L'ouverture des contacts 24, 26 et 48, 50 est extrêmement rapide et engendre une limitation efficace du courant. Les courants de même sens parcourant le conducteur fixe 44 et le bras 28 agissent tous deux sur le bras de contact 52 parcouru par un courant de sens inverse pour le déplacer rapidement et le sens du courant dans les conducteurs 24, 52, 28 et la plage 40 est favorable à un soufflage magnétique de l'arc, tiré entre les contacts 48, 50 dans la chambre de coupure 58. Le circuit magnétique, constitué par les culasses 36, 36' prolongées par les culasses 60, 60' capte et concentre le flux magnétique pour accroître l'action des forces électrodyna- mi^ques s'exerçant sur le bras de contact 52. Il est à noter que la présence de toutes ou de certaines de ces culasses 36, 36', 60, 60' n'est pas indispensable dans les appareils de gros calibre où les forces électrodynamiques engendrées sont suffisamment fortes pour déplacer rapidement les contacts.

The current limiting device according to the invention works as follows:

• In the closed position of the device, shown in FIGS. 1 and 2, the current enters through the area 46, flows through the fixed conductor 44, in the direction indicated by the arrow, the closed contacts 48, 50, the contact arm 52, the braid 22, the contacts 24, 26, the arm 28, the braid ₃ 8 and the output range 40. It is easy to see that the sense current path in the contact arm 52 is opposite to that in the stationary conductor 44, generating an electrodynamic repulsion force which tends to rotate the contact arm 52 in the clockwise direction of opening of the contacts 48; 50 against the spring 56. The direction of current flow in the fixed conductor 44 and the arm 28 is however the same and an electrodynamic force of attraction is exerted between these conductors 44, 28. The rear part of the arm 28 is longer than the front part which carries the contact 26 and is arranged on the opposite side of the pivot 30 so that the result of the electrodynamic forces tends to rotate the arm 28 clockwise corresponding to the opening of the contacts 24 , 26. In normal operation the contacts 48, 50 and 24, 26 are kept closed by the contact pressure springs whose action is predominant. During the appearance of a short circuit, the electrodynamic forces become preponderant and move on the one hand the contact arm 52 in the open position of the contacts 48, 50 and on the other hand the arm 28 in the position opening of the contacts 24, 26, this latter opening being subsequently confirmed by the mechanism 32 controlled by the trip unit 34 which has seen the short circuit. After extinction of the arcs drawn between the contacts 24, 26 and 48, 50, these latter contacts close under the action of the spring 56 the circuit being interrupted by the separation of the contacts 24, 26 which remain open. The opening of the contacts 24, 26 and 48, 50 is extremely rapid and generates an effective limitation of the current. Currents alike direction traversing the fixed conductor 44 and the arm 28 both act on the contact arm 52 traversed by a current of opposite direction to move it quickly and the direction of the current in the conductors 24, 52, 28 and the range 40 is favorable to a magnetic blowing of the arc, drawn between the contacts 48, 50 in the breaking chamber 58. The magnetic circuit, constituted by the yokes 36, 36 'extended by the yokes 60, 60' captures and concentrates the magnetic flux to increase the action of electrodynamic mid ^q ues forces on the contact arm 52. It should be noted that the presence of all or some of these yokes 36, 36 ', 60, 60 is not essential in large gauge devices where the electrodynamic forces generated are strong enough to quickly move the contacts.

The action exerted by the current flowing through the fixed conductor 44 on the arm 28 accelerates the opening of the contacts 24, 26 and contributes to the limiting effect of the limiting block 16. The combination according to the invention, of the limiting block 16 and of the standard circuit breaker block 10 allows interaction of the conductors arranged in these blocks which promotes the effect of limiting the current and the blowing of the arcs. The transformation of the standard circuit breaker is limited to the replacement or adaptation of the fixed contact 24 and the fixing of the braid 22. In the majority of cases the cylinder heads j6, 36 'are superfluous.

Different alternative embodiments are conceivable and FIG. 3 illustrates one of them, which has the advantage of eliminating the braid 22 and of opening the contacts of the circuit breaker as fast as that of the contacts of the limiter. In FIGS. 3 and 4, the same reference numbers designate parts similar or identical to those identified by these numbers in FIGS. 1 and 2. The fixed contact 24 of the circuit breaker 10 is eliminated and replaced by a movable contact 62 carried by a appen dice 64 of the contact arm 52, which passes through the orifice 20 formed in the bottom 14. The operation of the device naturally remains the same, but the speed of opening of the contacts 62, 26 of the circuit breaker block 10 is increased. As soon as the movement of the contact arm 52 carrying the device 64 begins, the contacts 62, 26 separate at an increased speed by the almost simultaneous movement of the two contacts 62, 26 in opposite directions.

Appendix 64 facilitates the assembly of blocks 10, 16 and avoids any additional electrical connection. In Figure 3 only the cylinder heads 60, 60 'of the limiter block have been retained.

In large-caliber devices the presence of two contact zones 62, 26; 48, 50 may be the cause of excessive heating and FIG. 4 illustrates an alternative embodiment derived from that of FIG. 3 and making use of a single pair of contacts 62, 26. The support appendage 64 of the contact 62, which cooperates with the movable contact 26 of the circuit breaker 10, belongs to a contact arm 52 ', which extends parallel to the fixed conductor 44 in the limiter block 16 and whose opposite end is rotatably mounted on a axis 54 'and is connected by a braid 66 to the end of the fixed conductor 44. A stop 68 limits the movement of the arm 52' in the closing direction of the contacts 62, 26 to allow normal opening or tripping of the circuit breaker 10. In the event of a short circuit, the contacts 62, 26 quickly separate as described above. The structure of the limiter block 16 is notably simplified by the absence of the contacts and of the associated breaking chamber.

Other arrangements and connections of conductors subjected to or generating electrodynamic forces can of course be devised.

Claims (10)

1. Current limiting and cutting device comprising: - a block (16) current limiter with rapid opening of contacts (48, 50; 62, 26) by electrodynamic effect, - a block (10) standard protection circuit breaker, in particular a molded case circuit breaker, having contacts (24, 26) and an automatic contact opening mechanism (24, 26) on default, said blocks (10, 16) being electrically connected in series and mechanically secured by back-to-back joining (14), - A first movable conductor (52) carrying a movable contact (50; 62) and extending inside said limiter block (16) parallel to said backs in the closed position of said contacts (48, 50; 62, 26) at quick opening, - a second fixed conductor (44) extending inside said limiter block (16) parallel to said first conductor (52) in the closed position, said first (52) and second (44) conductors being electrically connected in series for being traversed by currents generating an electrodynamic displacement force of said first conductor (52) movable in the open position of said contacts (48, 50; 62, 26) with rapid opening, a third conductor (28) extending inside said circuit breaker block (10) being electrically connected in series with said first (52) and second (44) conductors,
characterized in that said third conductor (28) extends in the closed position of the contacts (24, 26; 62, 26) of the circuit breaker (10) near said backs (14) joined together, parallel to said first (52) and second (44) conductors of the limiter block (16),
and in that said first (52) and third (28) conductors are electrically connected in series to be traversed by currents generating an additional electrodynamic force of displacement of the first conduc teur ( ₅ 2) movable in the open position of said contacts (48, 50; 62, 26) quick opening. 2. Device according to l, in which the third conductor (28) is movable and carries a movable contact (26) of the circuit breaker block (10) and is subjected to an electrodynamic displacement force in the open position of the contacts (24,26 ) of the circuit breaker (10) generated by the currents flowing through the third conductor (28) and a conductor (44) of the limiter block (16). 3. Device according to 2, in which said conductors (28, 44, 52) constitute an f-shaped circuit, the central branch of which is constituted by the second fixed conductor (44) framed by the first (52) and third (28) conductors. 4. Device according to 2 or 3, in which the second (44) and third (28) conductors are traversed by currents of the same direction generating an electrodynamic force of attraction of the third conductor (28) movable in the open position of the contacts (24, 26) of the circuit breaker (10) and in which the first movable conductor (52) is traversed by a current of opposite direction to that of the currents traversing the second (44) and third (28) conductors, the currents of opposite directions generating an electrodynamic repulsion force of the first conductor (52) in an open position of the contacts (48, 50; 62, 26) with rapid opening. 5. Device according to 1, 2, 3 or 4, in which said conductors (28, 44, 52) extend in the same plane corresponding to the plane of movement of the first (52) and third (28) movable conductors. 6. Device according to any one of the preceding claims, in which ferromagnetic yokes (36, 36 '; 60, 60') are arranged in the circuit breaker block (10) and / or the limiter block (16) to increase the electrodynamic forces acting on the first (52) and third (28) movable conductors . 7. Device according to 6, in which yokes (60, 60 ') frame the second conductor (44) and have an air gap in which the first conductor (52) penetrates in the closed position of the contacts (48, 50; 62, 26 ) quick opening. 8. Device according to any one of the preceding claims, in which the second conductor (44) is attached to the backs (14) of the blocks (10, 16) and ends in a connection terminal (46) and in which the contact fixed (24) of the circuit breaker block (10) is electrically connected to the first conductor (52) of the limiter block (16), the third conductor (28) being connected to a connection terminal (40) of the circuit breaker block (10) arranged on the opposite side of the terminal (46) of the limiter block (16). 9. Device according to any one of the preceding claims, in which the first conductor (52) carries the movable contact (50) of the contacts (48, 50) of the limiter block (16) and an appendage (64) passing through said backs ( 14) joined and carrying a movable contact (62) cooperating with the movable contact (26) carried by the third conductor (28). 10. Device according to any one of claims 1 to 8, in which the first conductor (52 ') is extended by a curved part (64) passing through the backs (14) placed side by side and carrying a movable contact (62) cooperating with the movable contact (26) carried by the third conductor (28), the limiter block (16) being devoid of contacts.

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