EP1090404B1 - Multi-pole low voltage circuit breaker with high electrodynamic strength, whereby the shaft of the poles is arranged within the pole container compartment - Google Patents

Abstract

The invention concerns a low voltage multipole circuit breaker (10) with high electrodynamic resistance comprising a box made of insulating material, subdivided into a front compartment (12) housing a control mechanism (24) for opening and closing the circuit breaker and a rear compartment (14) separated from the front compartment by an intermediate wall (20). The rear compartment (14) is itself subdivided into elementary compartments (36) by separating partitions (38), each elementary compartment (36) housing one of the circuit breaker poles (56). The control mechanism (24) is linked to a pole shaft (78) common to the whole set of poles (56). The pole shaft (78) is located in the rear compartment (14) and is supported by bearings passing through the partition walls.

Description

The invention relates to a high-current, high-current low-voltage multipole circuit breaker electrodynamic resistance. In the past, high current circuit breakers (for information between 630 A and 6300 A) serving as basic devices for arrivals and departures in important installations, consisted of composite elements assembled on a metal chassis, hence their designation of “open” power circuit breakers. But gradually the devices of this range have inherited part of the technology of lower power circuit breakers; called "molded case" because characterized by a protective insulating jacket, generally molded in reinforced polyester, enclosing the poles with their interrupting chambers, as well as a control mechanism and triggers. The protective envelope, helping to ensure containment of the cut and a limitation of these external effects, complete partitioning between poles and better insulation between the power circuit and the auxiliaries, in turn allowed to decrease considerably the size of the equipment.

Document EP-A-0 322 321 describes a circuit breaker of this type, the housing of which is made up by assembling an intermediate box, the cover constituting the front face of the circuit breaker, and a rear base. The front side of the intermediate case divides the case in a front compartment delimited by this face and by the cover, and a rear compartment intended to house the poles and electrically isolated from the anterior compartment. The front compartment contains a control mechanism acting on a transverse switching shaft common to all the poles, known as the poles. This shaft is supported by bearings reported on the front side of the housing intermediate. The rear compartment is further divided into compartments elementary pole housing, by insulating partitions. Wall front of the intermediate box further comprises, for each pole, a light of access to the corresponding elementary compartment. Each pole has a pair of separable contacts with a fixed contact and a movable contact, and an extinguishing chamber arc. Each movable contact is mechanically linked to the transverse shaft via of a connecting rod crossing the anterior wall of the intermediate housing by the access lumen corresponding.

Each connecting rod connecting one of the movable contacts to the transverse shaft, is arranged in such a way so that in the closed position of the contacts, and in a cross section plane perpendicular to the pivot axis of the pole shaft, the distance between a straight line passing through the axes of rotation of the connecting rod and the axis of pivoting of the shaft, is low. In in other words, the lever arm of the result of the forces exerted by the contacts on the pole shaft is weak, which guarantees that the connecting rod, when it transmits forces significant electrodynamics, generates only a low torque at the shaft. AT the static balance in the closed position of the contacts, the control mechanism acts on the shaft a torque opposite to the electrodynamic forces transmitted by the connecting rods. This couple" only generate reduced forces at the control mechanism. In addition, the resulting from the reaction forces at the level of the shaft guide bearings is important and opposes the forces transmitted by the connecting rod and by the control mechanism.

This architecture is characteristic of circuit breakers with high electrodynamic resistance. Through definition indeed, these circuit breakers must, to ensure time discrimination in the electrical installation, be able to withstand the passage of established fault currents which generate significant electrodynamic forces tending to separate the contacts. The relative arrangement of the pole shaft, connecting rods with the movable contacts and of the connecting rod to the control mechanism must therefore be such that these efforts do not not result in separation of the contacts or opening of the ordered. In this case, the arrangement chosen allows these forces to be transmitted to the housing through the shaft bearings, so that the control mechanism is not subjected to excessive forces or torques.

However, the guidance of the pole shaft and the transmission of forces to the housing of the circuit breaker are not entirely satisfactory. Indeed, the transverse tree must be dimensioned, arranged and supported in such a way that its deformation is limited and does not interfere with its operation. In addition, the bearings of the pole shaft require a efficient anchoring in the case because the significant efforts transmitted to them have tendency to tear them from the front face of the intermediate box to which they are fixed. The stiffening of the assembly requires the use of expensive fasteners and bearings and bulky as well as additional provisions on the housing. The assembly of circuit breaker requires a large number of parts, resulting in a high cost price and a tedious assembly. Furthermore, this architecture limits the miniaturization of the circuit breaker.

Furthermore, the numerous openings for passage of the connecting rods between the shaft of the poles and each of the poles, affect the sealing of the breaking chambers. Gold bow electric and the endothermic vaporizations it generates at the level of certain elements partitions of the breaking chambers, are at the origin of an overpressure and a flow gas which must be piped to exhaust outlets fitted with suitable filters. For do not obstruct the entry of the arc into the breaking chamber, it is wise to place these discharge ports at the bottom of the switching chambers. The presence of the openings of passage of connecting rods, located just above the contacts at the entrance to the chambers, hinders therefore considerably the circulation of gases towards the evacuation orifices. It allows a uncontrolled gas flow through the anterior compartment and the face openings front, directly outwards, without protective filter.

The invention therefore aims to remedy the drawbacks of the state of the prior art and in particular to increase the rigidity of the mechanism of a high-resistance circuit breaker electrodynamics, at low cost.

According to the invention, this problem is solved by means of a low-voltage withstand circuit breaker high electrodynamics with an insulating material housing, comprising a control linked to a pole shaft supported by bearings integral with the housing, a plurality of blades, each pole comprising at least one pair of contact members separable, at least one of the contact members of each pair, called the contact member mobile, being mechanically linked to the pole shaft, the pole shaft, the control and the movable contact member being movable between an open position corresponding to the separation of the contact members of each pair, and a closed position corresponding to the contact between the contact members of each pair, the housing of the circuit breaker comprising a front compartment for housing the control mechanism and a rear compartment separated from the front compartment by an intermediate wall and subdivided into elementary compartments by partition walls, each elementary compartment housing one of the poles of the circuit breaker, circuit breaker whose axis of rotation of the pole shaft is located in the posterior compartment.

In the devices of the state of the art whose pole shaft was located in the front compartment, it was necessary to provide a minimum distance between the shaft of the poles and the movable contact members in the open position. Indeed, the link between movable contact members and the shaft was made through the intermediate wall between the anterior compartment and the posterior compartment. The configuration according to the invention allows this distance to be reduced considerably until canceled, since no element no longer comes between the shaft and the contact members. The size of the device can thus be decreased.

This arrangement also makes it possible to ensure that the electrodynamic forces acting on the contacts are taken up by the housing, without causing deformations important intermediate parts. Indeed, it becomes possible to place the bearings of support in the rear compartment. If we plan to join these bearings at least partially at the intermediate wall, it is then easy to ensure that the organs of joining together, in response to the electrodynamic forces exerted on the contact members mobile, work in compression instead of working in pullout.

Furthermore, this arrangement eliminates the passage holes of the connecting rods between the pole shaft and each movable contact member. Pollution of the compartment ' anterior is reduced and the circulation of cut gases to the orifices evacuation of the bottom of the improved breaking chamber.

The assembly is facilitated by the fact that it is no longer necessary to set up the connection between the pole shaft and each connecting rod through holes in the intermediate partition.

Preferably, each of the partition walls supports one of said bearings and the pole shaft crosses each partition at one of said bearings. This provision enables the bearings to be multiplied and distributed regularly along the pole tree, without increasing the overall size. Alternatively, it is also possible to provide that the bearings are arranged between the partition walls of the rooms, on stand-alone supports. Advantageously, each of the partition walls comprises a partition element molded with the intermediate wall, in a rim of which is formed a semi-cylindrical sector constituting part of the corresponding level. We thus obtain a multifunctional part which facilitates assembly and reduces costs.

Advantageously, the intermediate wall includes a window for the passage of a mechanical connection between the pole shaft and the control mechanism.

Preferably, the outer surface of the pole shaft is made of electrically material insulating, in particular in thermosetting polyester plastic. This provision allows obtain both electrical insulation between the poles and with the control mechanism. The thermoset offers the advantage of good dielectric strength after switching off. In practice, the tree can be made of solid thermoset. Alternatively, the tree can have a soul metal covered with insulating material.

Advantageously, the circuit breaker comprises at least one connecting rod between the shaft of the poles and each movable contact member, linked to the pole shaft by a pivot in such a way that in a certain relative position of the shaft and the connecting rod, called the mounting position, the connecting rod can be freely moved parallel to the pivot axis, and once the connecting rod mounted and moved out of its mounting position, a positive connection is made prohibiting translative movement of the connecting rod parallel to the axis of the pivot, the position of mounting being such that in operating condition, the pole shaft and the connecting rod do not never by this position.

• la figure 1 représente une vue en perspective d'un disjoncteur selon l'invention, coupé au niveau d'un pôle.
• la figure 2 représente une vue éclatée d'un arbre des pôles et d'une partie d'un boítier du disjoncteur selon l'invention.
• la figure 3 représente une coupe du disjoncteur de la figure 1, en position fermée
• la figure 4 représente une coupe du disjoncteur de la figure 1, en position ouverte
• la figure 5 représente une vue en perspective de l'arbre des pôles et d'une bielle de liaison à l'un des pôle dans une position précédent leur montage
• la figure 6 représente une vue en perspective de l'arbre des pôles et d'une bielle de liaison à l'un des pôle dans une respective dite de montage
• la figure 7 représente une vue en perspective de l'arbre des pôles sur lequel est monté la bielle de liaison, dans leur positionnement l'un par rapport à l'autre lorsque le disjoncteur est ouvert
• la figure 8 représente une vue en perspective de l'arbre des pôles sur lequel est monté la bielle de liaison, dans leur positionnement l'un par rapport à l'autre lorsque le disjoncteur est fermé.

Other advantages and characteristics of the invention will emerge from the description which follows of an embodiment of the invention, given by way of nonlimiting example and represented in the appended drawings in which:

• Figure 1 shows a perspective view of a circuit breaker according to the invention, cut at a pole.
• 2 shows an exploded view of a pole shaft and part of a case of the circuit breaker according to the invention.
• Figure 3 shows a section of the circuit breaker of Figure 1, in the closed position
• Figure 4 shows a section of the circuit breaker of Figure 1, in the open position
• Figure 5 shows a perspective view of the pole shaft and a connecting rod to one of the pole in a position preceding their mounting
• Figure 6 shows a perspective view of the pole shaft and a connecting rod to one of the pole in a respective so-called mounting
• Figure 7 shows a perspective view of the pole shaft on which the connecting rod is mounted, in their positioning relative to each other when the circuit breaker is open
• 8 shows a perspective view of the pole shaft on which is mounted the connecting rod, in their positioning relative to each other when the circuit breaker is closed.

With reference to FIGS. 1 to 3, a non-limiting low-voltage circuit breaker 10 withstand high electrodynamics is arranged in a molded housing with a compartment front 12 and a rear compartment 14. The front compartment 12 is limited by a front face 16, side faces 18 integrally formed with the front face, and a wall intermediate 20 separating it from the posterior compartment. It has openings in front front, for the passage of a pivoting lever 22 ensuring the resetting of a mechanism for controlling the circuit breaker 24, an opening push button and a push button closing. The control mechanism 24 is housed in the front compartment 12.

The rear compartment 14 is limited by the intermediate wall 20, by a base 26 constituting a rear face, and by lateral faces 28, part of which came from material with the base and another is molded with the intermediate wall. The base 26 supports connection pads 30 of the circuit breaker 10 to an external electrical circuit. The base 26 and the intermediate wall 20 are fixed to each other by means of screws fixing 32 dimensioned so as to be able to withstand significant stresses removal. A window 34, visible in particular in FIG. 2, is made in the wall intermediate 20 and allows communication between the front compartment 12 and the rear compartment 14. The rear compartment 14 is subdivided into compartments elementary 36 by partition walls 38. Each partition 38 has two parts side arranged on either side of a central part. Each side part has a partition element 40 molded with the base and a partition element 42 molded with the intermediate wall, the partition elements 40, 42 being contiguous on the mounted device. The central part comprises a partition element 44 molded with the height base more important than the adjacent side elements 40. This partition element 44 includes ribs 46 which cooperate during assembly with complementary grooves 48 of the side partition elements 42 integral with the intermediate wall 20. The partition element central 44 of the base has a smooth semi-cylindrical surface 50. The intermediate wall 20 comprises a complementary central partition element 52 of reduced height, which also has a smooth semi-cylindrical sector 54 opposite that of the element secured to the base.

In each elementary compartment 36 is housed a pole 56 of the circuit breaker. Each pole 56 includes an arc extinguishing chamber 58 and a contact device separable. The latter comprises a fixed contact member 60 electrically connected to a connection pad 30 of the circuit breaker passing through the base 26 of the insulating housing, and a movable contact member 61. This has a plurality of contact fingers 62 in parallel pivotally mounted on a first transverse axis 64 supported by a cage support 66. The heel of each finger is connected by a flexible conductor 68 constituted by a metallic braid, to a second connection pad 30 of the circuit breaker. Each finger 62 comprises a contact pad 70 cooperating with a pad 72 of the member fixed contact 60, in the closed position of FIG. 3. The cage 66 is shaped like a U (see fig. 5). Its end located near the second connection pad is equipped with a pin 74 housed in a bearing integral with the insulating housing, so as to authorize the pivoting of the cage 66 between a closed position of the pole 56, shown in FIG. 3, and an open position, shown in Figure 4. A spring pressure device contact 76 is disposed in a notch in the cage 66 and urges the contact fingers 62 into pivoting around the first axis 64 anticlockwise.

Arc extinguishing chamber 58 comprises a stack of arc deionization sheets electric drawn during the separation of the poles, as well as the gas exhaust ports cutoff. Further details on the structure of the poles 56 can be found in document FR-A-2 650 434, the description of which is incorporated here by reference.

A pole tree 78 is placed between the semi-cylindrical sectors 50, 54 which form, once mounted, sealed bearings for supporting the shaft 78 rotating around of its axis 79. The shaft 78 is molded from thermosetting polyester. Each of the cages 66 is coupled to the pole shaft 78 by a pair of parallel connecting rods 80 which rotate around a geometric axis coincident with the axis 64. Each connecting rod 80 is linked to the pole shaft 78 by a pivot 81.

The control mechanism 24 includes a storage closure device of energy and an opening device. This mechanism is known per se and we will refer for more details in document FR-A-2 589 626 which is incorporated here by reference on this point. We will simply recall here that the opening device includes a device to knee brace which comprises two links 82, 84 articulated to each other by an axis of pivot 86, the lower transmission link 82 being mechanically coupled to the pole shaft 78 by a pivot axis 88 cooperating with a bearing made in a crank 90 secured to the shaft 78. An opening spring 92 is anchored between the axis 88 and a fixed retaining cleat. Figure 3 shows that in the closed position, the window 34 made in the intermediate wall 20 is used for the passage of the lower transmission link 82 and of the opening spring 92. In the closed position, the lever arm of the connecting rods 80 on the shaft poles 78 is significantly weaker than that of the rod 82. In other words, the distance between the axis 79 of the pole tree 78 and the plane which contains the axes 64, 81 of the pivots of the connecting rods 80 is less than the distance between the axis 79 of the pole shaft 78 and the plane which contains the axes 86, 88 of the pivots of the lower link 82. In practice, the ratio of the two distances is less than 0.3.

In the closed position shown in Figure 3, we observe for each pole 56 that the contact pads 70 of the contact fingers 62 are in contact with the pad 72 of the fixed contact member 60. The contact pressure is ensured by the spring device 76 which makes it possible to make up for any play in the mechanism and the wear of the pads 70, 72. The electrodynamic forces exerted on the contact fingers 62 are taken up at the cage 66 by the bearing surfaces of the springs 76 and by the axis 64, and generate a moment around the pivot axis 74 of the cage 66, tending to rotate the cage 66 in the sense of contact separation. This moment is compensated by an opposite moment exerted by the connecting rods 80 on the cage 66 at their relative pivot axis 64. At equilibrium dynamic, the connecting rods 80 are therefore subjected at the level of their connecting pivot 64 to the cage 66, to a force directed towards their connecting pivot 81 with the pole shaft 78. This force, transmitted to the pivot 81, generates a moment around the axis 79 of the pole shaft 78. The same phenomenon occurs for each of the poles. At the sum of the moments of the forces exerted by all the connecting rods 80 and by the opening spring 92 on the shaft 78, opposes a moment generated by the lower link 82 of the toggle joint of the opening device. Of made of the relative position of the connecting rods 80, of the connecting rod 82 and of the pole shaft 78, that is to say the weakness of the lever arm of the connecting rods 80 compared to that of the connecting rod 82, the resulting at the link 82 remains moderate. So here we find the characteristics of a circuit breaker with high electrodynamic resistance, since the forces. electrodynamics on the contact members generate only limited stresses on the control mechanism so that the latter can oppose it. At balance, the tree poles 78 exerts pressure levels at the support bearings, the resulting is a reaction force opposing the sum of the forces exerted by the connecting rods 80 and the link 82. These relatively large pressure forces are exerted mainly on the semi-cylindrical sector 54 formed in the intermediate wall 20.

When the circuit breaker opens, the rod 82 ceases to oppose the rotation of the shaft poles counterclockwise. This rotation, generated jointly by the opening spring 92 and the result of the electrodynamic forces brought back to the pivots 81 connecting the connecting rods 80 and the shaft 78, drives all the cages 66 towards the open position shown in FIG. 4. In this position, the crank 90 of the pole shaft 78 slightly emerges from the window 34.

Figures 5 to 8 describe the mounting mode of the pivot connection between the shaft of poles 78 and the connecting rods 80 for connection with each cage 66. The shaft of the poles 78 comprises, for each pole, an arm 94 carrying two coaxial pivots 81, eccentric relative to the axis pivot 79 of the pole shaft 78. These pivots 81 are each located on a offset 98 from the lateral face 100 of the arm. A tongue 102 overhanging the offset 98 materializes a groove 104.

Each connecting rod 80 has, on the side intended to cooperate with the shaft 78, a bore cylindrical 108 intended to form a bearing for one of the pivots 81, and a flat 110. When of the assembly, the connecting rod 80 is presented so that the flat 110 is parallel with the lower edge of the tongue 100, in the relative mounting position shown on Figure 6. It is then possible to introduce the pivots 81 in the bores 108. Once assembled, the assembly constituted by the connecting rods 80 and the pole shaft 78 is placed in the case, where it oscillates between two extreme positions: a position corresponding to the opening of the contacts and represented in FIG. 7 and a position corresponding to the contact closure and shown in Figure 8. In either of these two positions, as well as in all the intermediate positions, the connecting rods 80 cooperate with the corresponding grooves 104 of the pole shaft 78, which constitute a guide preventing any movement of the connecting rods 80 parallel to the pivot axis 81. This produces a simple positive connection which avoids the use of any intermediate piece additional.

Claims (6)

1. A low-voltage, high electrodynamic strength circuit breaker (10) with a case made of insulating material, comprising an operating mechanism (24) linked to a pole shaft (78) supported by bearings securedly affixed to the case, a plurality of poles (56), each pole (56) comprising at least one pair of separable contact parts (60, 61), one at least of the contact parts of each pair, called the movable contact part (61), being mechanically linked to the pole shaft (78), the pole shaft (78), operating mechanism (24) and movable contact part (61) being movable between an open position corresponding to separation of the contact parts (60, 61) of each pair, and a closed position corresponding to contact between the contact parts (60, 61) of each pair, the case of the circuit breaker comprising a front compartment (12) housing the operating mechanism (24) and a rear compartment (14) separated from the front compartment (12) by an intermediate wall (20) and sub-divided into individual compartments (36) by separating partitions (38), each individual compartment (36) housing one of the poles (56) of the circuit breaker (10), characterized in that the rotation axis (79) of the pole shaft (78) is located in the rear compartment (14).
2. The circuit breaker according to claim 1, characterized in that each of said separating partitions (38) supports one of said bearings and that the pole shaft (78) passes through each partition (38) at the level of one of said bearings.
3. The circuit breaker according to claim 2, characterized in that each of said separating partitions (38) comprises a partition element (52) moulded with the intermediate wall (20), in an edge of which wall there is formed a semi-cylindrical sector (54) forming a part of the corresponding bearing.
4. The circuit breaker according to any one of the foregoing claims, characterized in that the intermediate wall (20) comprises an aperture (34) for passage of a mechanical link part (82) between the pole shaft (78) and the operating mechanism (24).
5. The circuit breaker according to any one of the foregoing claims, characterized in that the external surface of the pole shaft (78) is made of electrically insulating material, in particular of thermosetting polyester plastic.
6. The circuit breaker according to any one of the foregoing claims, characterized in that it comprises at least one connecting rod (80) between the pole shaft (78) and each movable contact part (61), this rod (80) being linked to the pole shaft (78) by a pivot (81) in such a way that in a certain relative position of the shaft (78) and of the rod (80), called the assembly position, the connecting rod (80) can be moved freely in a direction parallel to the axis of the pivot (81), and that once the connecting rod (80) has been fitted and moved from its fitting position, a positive link is achieved preventing translational movement of the rod (80) in a direction parallel to the axis of the pivot (81), the assembly position being such that in the operating state, the pole shaft (78) and rod (80) never take this position.

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