Movable contact configured to be integrated into a circuit breaker

Abstract

The subject of the present invention relates to a movable contact configured to be integrated into a circuit breaker and bearing against a fixed contact in the vicinity of an arc extinguishing chamber, the movable contact having the form of a plurality of fingers (2) juxtaposed in a substantially parallel manner and aligned with one another and joined by one of their ends (2a) to a common trunk, characterized in that the inter-digital spaces separating the respective surfaces of two juxtaposed fingers (2) of the movable contact have a spacing width with a value equal to or less than 1.3 millimetres.

Description

[0001] The present invention relates to the field of contact interfaces in breaking mechanisms inside circuit breakers and more particularly to the field of arrangements of these contact interfaces.

[0002] A circuit breaker incorporates a mechanism for activating electrical interruption in the event of an overload or overvoltage along the circuit on which the breaker is located. This mechanism involves a pair of contact elements arranged in a breaking chamber. When connected to each other, these elements allow the flow of electrical current, and when separated, they interrupt all electrical continuity between the two contact elements. Mechanically, these contact elements consist of, on the one hand, a fixed contact with the breaker's support structure and, on the other hand, a movable contact that can be positioned relative to the fixed contact. Both the fixed and movable contacts have surfaces designed to bear against each other to ensure the passage of electrical current.However, it should be noted that the surface area of ​​the moving contact in contact with the surface of the fixed contact must be large enough to ensure optimization of the electrical flow through the breaking mechanism of the circuit breaker.

[0003] Traditionally, the connection between the moving contact and the fixed contact is made via a conductive material structure with multiple parallel fingers, such that the surface of each finger bears against the surface of the fixed contact. Publication EP 1298692 provides an example of a moving contact made with multiple fingers. Unlike a moving contact with a single finger of similar width to the fixed contact, a moving contact made with several spaced fingers ensures optimal contact area between the plane of each moving finger and the flat surface of the fixed contact.The risk of an inclination between, on the one hand, the plane of a moving contact formed by a single finger and, on the other hand, the plane of the fixed contact, resulting in a bearing surface that is small compared to the surfaces of the fixed and moving contacts, is thus eliminated. However, too many fingers would lead to bearing surfaces for each finger against the surface of the fixed contact being particularly small, such that under the pressure exerted by the moving contact, the tips of these fingers could degrade the quality of the surface of the fixed contact.

[0004] Furthermore, the moving contact incorporates separating elements at its inter-finger spaces. These elements are essential components for maintaining the individual fingers of the moving contact in parallel orientations, thus ensuring optimal distribution of the contact surfaces against the surface of the fixed contact. Simultaneously, the dimensions of the switching chamber, which forms the volume occupied by the moving contact, are also subject to space constraints. These constraints impose maximum values ​​on the lengths of the moving contact and, in particular, on the width of the contact surface against the fixed contact.

[0005] In light of these various constraints, related on the one hand to the dimensions imposed by the breaking chamber and the size of the separating elements, and on the other hand to the optimization of the electrical current flowing through the contact surface between the moving and fixed contacts, the breaking mechanisms for tertiary circuit breakers developed to date rely on a technical compromise. In this compromise, the moving contacts comprise, at most, five fingers, each approximately 6 millimeters wide, arranged parallel to each other and separated by several millimeters by separating elements. Under these conditions, existing circuit breakers used in industrial applications can withstand an electrical current reaching an ICW value of up to 50 kA while withstanding a temperature rise of approximately 70 Kelvin.However, this level of technical performance of circuit breaker electrical breaking mechanisms tends to become insufficient with regard to the needs and safety conditions required in industrial applications.

[0006] The present invention aims to overcome these various drawbacks by proposing a solution that allows an improvement in the electrical intensity that can be supported by a circuit breaker together with a reduction in the heating amplitude of its contacts, while meeting the sizing constraints of the breaking chamber solved by existing devices.

[0007] The invention thus relates to a movable contact as detailed in the statement of main claim 1.

[0008] The invention will be better understood from the following description, which relates to various preferred embodiments, given by way of non-limiting example, and explained with reference to the accompanying schematic drawings, in which: [ Fig. 1 ] represents a schematic illustration of an example of an arrangement of a movable contact according to the invention, [ Fig. 2 ] represents a schematic illustration according to an exploded view of an example of the arrangement of a movable contact according to the invention, [ Fig. 3 ] represents a schematic illustration of an example of a finger of a movable contact according to the invention incorporating a separating element, [ Fig. 4 ] represents a schematic illustration of an example of a finger separation element for a movable contact according to the invention.

[0009] The invention relates to a movable contact 1 configured to be integrated into a circuit breaker in support against a fixed contact near a breaking chamber, the movable contact having the form of several fingers 2 juxtaposed in a substantially parallel and aligned manner and joined by one of their ends 2a to a common trunk 2b, characterized in that the interdigital spaces 3 separating the respective surfaces of two juxtaposed fingers 2 of the movable contact 1 have a spacing width whose value is equal to or less than 1.3 millimeters.

[0010] The construction of such a movable contact 1 according to the invention incorporates an arrangement of its various fingers 2 such that their close relative positioning allows for sufficient space in the width of the switching chamber to accommodate an additional finger 2 compared to the movable contacts of the existing prior art. The presence of an additional finger 2 allows the movable contact 1 to optimize its bearing surface against the surface of the fixed contact. Thus, while known movable contacts of the prior art have five fingers 2 bearing against the surface of the fixed contact, the presence of a sixth finger 2 in the movable contact of the invention allows for an increase in the total exchange area between the movable and fixed contacts.This solution makes it possible to obtain, on the one hand, an increase in the ICW value of the circuit breaker and, on the other hand, a reduction in the heating borne by the circuit breaker without impacting the sizing of the circuit breaker's breaking chamber.

[0011] According to one embodiment relating to a particular example of the moving contact according to the invention, the moving contact 1 comprises at least six contact fingers 2, each associated with at least one separating element 4 positioned at the interdigital spaces 3 separating two adjacent fingers 2. The separating element 4 has a resistivity greater than or equal to 70 × 10⁻⁸ Ω·m (Ohm meters). In one embodiment, the separating element 4 is made of stainless steel. This arrangement, incorporating a separating element 4, provides rigidity to the pair of fingers 2 positioned on either side of an interdigital space 3, so as to limit the risk of deformation of the fingers 2 and to restrict the risk of two adjacent fingers 2 coming into contact in the event of deformation of at least one of them.

[0012] According to a particular construction example, each of the six fingers 2 of the moving contact 1 has a width of approximately 6 millimeters, separated by inter-finger gaps 3 of approximately 1.2 millimeters. This construction thus allows the positioning of a moving contact 1 comprising six fingers 2 within a breaking chamber with a width of approximately 46 millimeters. Such a particular arrangement of a moving contact 1 with six fingers 2 therefore corresponds to a preferred embodiment where the number of contact fingers 2 with such dimensions optimizes the combination between, on the one hand, the resistance to the electrical current carried by the circuit breaker and, on the other hand, the limitation of the heating of its contacts, in a breaking chamber 46 millimeters wide, i.e., in a circuit breaker allocating a volume of 70 millimeters for the positioning of a pair of contacts, one moving and one fixed.

[0013] According to another construction variant relating to another particular example of the moving contact according to the invention and capable of being combined with the variants previously mentioned, the various juxtaposed fingers 2 of the moving contact 1 have substantially identical dimensions, at least in cross-section, in a plane perpendicular to the main axis of the fingers 2. This identical cross-section makes it possible to obtain a 20% gain in exchange surface area compared to the total exchange area between the fixed contact and the moving contact of the prior art, which consists of five fingers 2. Such an arrangement makes it possible to obtain an increase in performance between the moving contact and the fixed contact, so that, on the one hand, the ICW value of the circuit breaker is able to reach 55 kA and, on the other hand, the heating temperature is likely to be reduced by 5K compared to known devices of the prior art.

[0014] According to another construction variant relating to a particular example of the moving contact 1 according to the invention and capable of being combined with the variants previously mentioned, the various juxtaposed fingers 2 of the moving contact 1 have substantially identical dimensions, at least in cross-section, in a plane perpendicular to the principal axis of the fingers 2. This homogeneity of form and construction of the various fingers 2 makes it possible to obtain a similar, if not identical, distribution of the electric current moving in the moving contact 1 between the various fingers 2. The stresses borne at the level of each of the fingers 2 are also identical, so that an optimization of the performance of the moving contact 1 can be achieved more easily.

[0015] In the construction of the movable contact 1 according to the invention, at the level of the interdigital spaces 3, the faces 2a of each of the two juxtaposed contact fingers 2 are associated with a respective separating element 4. This arrangement, positioning a pair of separating elements 4 at each interdigital space 3, allows the movement of one separating element 4 relative to another by friction of their respective surfaces against each other in this interdigital space 3. Furthermore, the positioning of a pair of separating elements 4 in an interdigital space 3 allows for double insulation between two juxtaposed fingers, both thermally and electrically.

[0016] According to another construction variant relating to a specific example of the construction variant of the separating element 4, each of the separating elements 4 is fixedly mounted with a respective finger 2 such that each of the separating elements 4 is capable of rubbing against the surface of its counterpart. According to this specific variant, the interdigital space 3 comprises a separating element 4 associated with a respective finger 2 of the movable contact 1 such that the displacement of one of the fingers of the movable contact 1 relative to its adjacent neighbor is achieved by the sliding of the surfaces of the separating elements 4 respectively associated with each of the fingers 2 that surround the interdigital space 3.

[0017] According to another construction variant relating to a further specific example of the construction variant of the separating element 4 and capable of being combined with the previous example, at least one stainless steel separating element 4 has, in a cross-sectional plane perpendicular to the principal axis of the fingers 2, a rider-like arrangement configured to be inserted against an interdigital face 2a of a finger 2 such that the legs are positioned at two opposite faces 2a of the finger 2 which share a common edge with the interdigital face 2a. This rider-like arrangement of the separating element 4 provides thermal and electrical insulation of the finger 2 at several of its faces.Furthermore, such a rider arrangement of the separating element 4 allows for easy mounting and assembly of the separating element 4 with a dedicated finger 2 of the mobile contact 1 by inserting the finger 2 between the legs of the separating element 4. According to a specific embodiment variant, the separating element 4 is positioned on the finger 2 by a clipping mechanism which is operated in particular by pinching.

[0018] According to another construction variant relating to a further specific example of the construction variant of the separating element 4 and capable of being combined with the preceding example, at least one stainless steel separating element 4 has, in a cross-sectional plane perpendicular to the principal axis of the fingers 2, a saddle-like arrangement whose legs are arranged to cover at least most of the interdigital faces 2a positioned on either side of the same finger 2. Such an arrangement of the separating element 4 allows for the covering of a significant, even essential, portion of the lateral surfaces 2a of the fingers 2 positioned opposite a surface of a corresponding finger. Therefore, the separating element 4 as characterized allows for thermal and electrical insulation between two juxtaposed fingers along a significant portion of the interdigital space 3.

[0019] According to another construction variant relating to another specific example of the construction variant of the separating element 4 and capable of being combined with the previous example, at least one edge of one of the legs of the rider of the separating element 4 has a retaining means 41 positioned against one of the faces of the finger 2 which have a common edge with an interdigital face 2a covered by a leg of the separating element 4. According to one construction example, this retaining means 41 is arranged to cooperate with one of the faces of the finger 2 so as to restrict, or even block, a sliding of the surface of a leg of the separating element 4 against the interdigital surface of the finger 2 against which it is in contact.This retaining means 41 may take the form of a tab formed by a continuous material with the leg of the separating element 4 and curved to be positioned in a plane substantially parallel to the portion of the rider that connects the two legs. According to a specific construction example, the relative flexibility of the rider's legs with respect to the connecting portion allows the rider of the separating element 4 to be inserted onto the finger 2 until the tab of the retaining means 41 cooperates with a surface of the finger 2 opposite to the surface of the finger 2 intended to interact with the portion of the rider that connects the two legs of the separating element 4. The insertion of the rider of the separating element 4 onto the finger 2 then pinches the finger 2 with the legs of the separating element 4.

[0020] According to another construction variant relating to another specific example of the construction variant of the separating element 4 and capable of being combined with the previous example, at least the portion of the separating element 4 positioned against the interdigital surface of a finger has a thickness equal to or less than 0.7 millimeters, preferably a value of the order of 0.6 millimeters.

[0021] According to another construction variant relating to a further specific example of the construction variant of the separating element 4 and capable of being combined with the previous example, at least one separating element 4 comprises a spring means configured to separate two juxtaposed separating elements. According to a first construction example of this spring means, it is formed by at least one relief of the separating element 4 at one of its surfaces intended to be positioned against an interdigital surface of a finger or in an interdigital space.This relief is likely to take the form of a boss, providing a moderate variation in the flatness of the surface of the separating element 4 relative to the plane of the interdigital surface, such that the curvature of the boss creates a separation of a portion of the surface of the separating element 4 from the rest of the surface of the separating element bearing against the interdigital surface of the finger 2. Thanks to the elasticity of the material of the separating element 4, the curvature of the boss allows a certain flexibility in its deformation, thus creating a spring mechanism similar to that of a Belleville washer integrated into a portion of the separating element 4. According to a second embodiment, the spring mechanism is formed by a Belleville washer associated with a portion of the surface of the separating element 4 intended to be positioned in an interdigital space.

[0022] According to another construction variant relating to a further specific example of the construction variant of the separating element 4 and capable of being combined with the preceding examples, the surface of at least one separating element 4 bearing against the interdigital surface of a finger 2 has a shape and dimensions substantially identical to a major portion of the surface of the interdigital surface of the finger 2 against which the separating element 4 is positioned. Such surface similarity allows for optimized contact between the separating element 4 and the interdigital surface of a finger 2, so as to ensure that the finger 2 remains in contact with the mobile contact 1 along the orientation of its axis along the largest portion.

[0023] According to another construction variant relating to a particular example of the moving contact 1 according to the invention and capable of being combined with the variants mentioned above, the moving contact 1 is associated with a straight pivot axis 5 mounted through through holes 10, 14 carried by each of the fingers 2 of the moving contact 1 and the associated separating elements 4. This straight pivot axis 5 defines the pivot axis of each of the fingers 2 of the moving contact 1 as part of its operation to separate the moving contact 1 from the fixed contact in the event of an overload or electrical overvoltage along the circuit on which the circuit breaker, which incorporates the moving and fixed contacts, is located. According to one example of the arrangement, when the fingers of the moving contact 1 are associated with separating elements 4 comprising one or more spring means, these through holes 14 are centered on these spring means.For example, when the spring means take the form of a curved boss, the through hole 14 is centered on the boss so that the arrangement of the boss appears similar to a Belleville washer integrated into a portion of the separating element 4 and traversed by the straight pivot axis 5.

[0024] According to another embodiment relating to a particular example of the moving contact 1 of the invention, the moving contact 1 also comprises at least one stainless steel separator 40 positioned against the face opposite the interdigital face of a finger 2 at the end of the moving contact 1. This separator 40 is intended to be positioned at one of the lateral ends of the moving contact 1, against the lateral surfaces of the fingers 2 of the moving contact 1 positioned at the ends and which do not correspond to interdigital surfaces. These separators 40 positioned at the ends thus fulfill a function similar to that of the interdigital separating elements 4 by ensuring separation between, on the one hand, a lateral surface of a finger 2 of the moving contact 1 positioned at the end and, on the other hand, a surface of a support structure for the switching mechanism that incorporates the moving contact 1 of the invention.It should be noted that this separator 40 positioned at the lateral end of the mobile contact 1 is likely to be formed by the leg of the rider of a separating element 4 mounted on a finger positioned at the end of the mobile contact 1.

[0025] Of course, the invention is not limited to the embodiments described and shown in the accompanying drawings. Modifications remain possible, particularly with regard to the composition of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention described in the claims.

Claims

1. Movable contact (1) configured to be built into a circuit breaker bearing against a static contact close to an arcing chamber, the movable contact having the form of several substantially parallel juxtaposed fingers (2) aligned with one another and joined at one of the ends (2a) thereof to a common trunk (2b), the inter-digital spaces (3) separating the respective surfaces of two juxtaposed fingers (2) of the movable contact (1) have a gap width equal to or less than 1.3 mm, characterized in that, on one hand, in the inter-digital spaces (3), the faces (2a) of each of the two juxtaposed contact fingers (2) are associated with a respective separating element (4) and, on the other hand, each of the separating elements (4) is mounted fixedly with a respective finger (2) such that each of the separating elements (4) is able to rub against the surface of its counterpart.

2. Movable contact (1) according to Claim 1, characterized in that the movable contact (1) comprises at least six contact fingers (2) respectively associated with at least one separating element (4) positioned in the inter-digital spaces (3) separating two juxtaposed fingers (2), the separating element (4) having a resistivity equal to or greater than 70×10-8 Ω·m (ohm-metre).

3. Movable contact (1) according to either of the preceding claims, characterized in that the different juxtaposed fingers (2) of the movable contact (1) have substantially identical dimensions at least in section in a plane perpendicular to the main axis of the fingers (2).

4. Movable contact (1) according to one of the preceding claims, characterized in that at least one separating element (4) made of stainless steel has, in a plane in section in a plane perpendicular to the main axis of the fingers (2), a rider arrangement designed to be inserted against an inter-digital face (2a) of a finger (2) so that the legs are positioned on two opposing faces (2a) of the finger (2) that have a common edge with the inter-digital face (2a).

5. Movable contact (1) according to one of the preceding claims, characterized in that at least one separating element (4) made of stainless steel has, in a plane in section in a plane perpendicular to the main axis of the fingers (2), a rider arrangement in which the legs are arranged to cover at least the majority of the inter-digital faces (2a) positioned on both sides of a given finger (2).

6. Movable contact (1) according to either of Claims 4 and 5, characterized in that at least one edge of one of the legs of the rider of the separating element (4) has a retaining means (41) positioned against one of the faces of the finger (2) that has a common edge with an inter-digital face (2a) covered by a leg of the separating element (4).

7. Movable contact (1) according to one of the preceding claims, characterized in that at least the portion of the separating element (4) positioned against the inter-digital surface of a finger has a thickness equal to or less than 0.7 mm.

8. Movable contact (1) according to one of the preceding claims, characterized in that at least one separating element (4) comprises a spring means designed to separate two juxtaposed separating elements (4).

9. Movable contact (1) according to one of the preceding claims, characterized in that the surface of at least one separating element (4) bearing against the inter-digital face of a finger (2) has a shape and dimensions substantially identical to a majority portion of the surface of the inter-digital face of the finger (2) against which the separating element (4) is positioned.

10. Movable contact (1) according to one of the preceding claims, characterized in that the movable contact (1) is associated with a rectilinear pivot through-pin (5) mounted in through-holes (10, 14) in each of the fingers (2) of the movable contact (1) and the related separating elements (4).

11. Movable contact (1) according to one of the preceding claims, characterized in that the movable contact (1) further comprises at least one separator (40) made of stainless steel positioned against the face opposite the inter-digital face of a finger at an end of the movable contact (1).

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