A moving contact adapted for incorporation within a circuit breaker

Abstract

The invention relates to a movable contact adapted to be assembled in a circuit breaker in abutment against a fixed contact near a cut-off chamber, the movable contact being in the form of a number of fingers (2) aligned with one another and arranged substantially parallel to one another and connected by one of their ends (2a) to a common core, characterized in that the comb-like space separating the respective surfaces of the two juxtaposed fingers (2) of the movable contact has a separation width of less than or equal to 1.3 millimeters.

Description

[Technical field]

[0001] The present invention relates to the field of contact interfaces in interruption mechanisms inside circuit breakers, and more particularly to the field of the arrangement of these contact interfaces. [Background technology]

[0002] A circuit breaker incorporates a mechanism for activating an electrical interruption in the event of an overload or overvoltage along the circuit in which the circuit breaker is located. The mechanism involves a pair of contact elements arranged in a cut-off chamber that allow current to flow when in a connected position and stop any conduction between the two contact elements when in a disconnected position. Mechanically, the contact elements are in the form of a fixed contact that is provided on the support structure of the circuit breaker and a movable contact that moves relative to the fixed contact. The two contacts, the fixed contact and the movable contact, have respective surfaces that are adapted to abut against each other to ensure the flow of current. It is noted, however, that the surface of the movable contact that abuts against the surface of the fixed contact must be large enough to optimize the amount of current passing through the interrupting mechanism of the circuit breaker.

[0003] Generally, the connection of the movable contact to the fixed contact is made at the location of a structure made of conductive material with several fingers arranged parallel to one another, each finger having a surface arranged to abut on the surface of the fixed contact. In contrast to a movable contact with a single finger of similar width to the fixed contact, the realization of a movable contact in the form of several fingers arranged at a distance from one another allows the contact surface of each movable finger to be optimized with the plane of the fixed contact. There is a risk of a tilt occurring between the plane of the movable contact formed by a single finger and the plane of the fixed contact, which would result in a limited abutment surface compared to the surfaces of the fixed and movable contacts present, which would then result in a separation. However, if there is too many fingers, the abutment surface of each finger against the surface of the fixed contact becomes too narrow, and the ends of these fingers under the effect of the pressure exerted by the movable contact can deteriorate the quality of the surface of the fixed contact.

[0004] Furthermore, the movable contact incorporates separating elements at the comb-like spaces between its fingers. These separating elements are essential components for maintaining the parallel orientation of the various fingers of the movable contact, thereby optimizing the distribution of their abutment surfaces with respect to the surface of the fixed contact. In conjunction with this, the dimensions of the cut-off chamber, which defines the volume occupied by the movable contact, are likewise governed by various dimensional constraints. These constraints impose a maximum value on the length of the movable contact, and in particular on the width of the surface of the movable contact that abuts the fixed contact.

[0005] Taking into account the various constraints mentioned above, related on the one hand to the dimensioning imposed by the cut-off chamber and the external dimensions of the separating element, and on the other hand to the optimization of the amount of current moving through the abutment surface of the movable and fixed contacts, the interrupting mechanisms for the third circuit breakers developed to date are based on a technical compromise in which the movable contact comprises up to five fingers, each about 6 millimeters wide, arranged in parallel and held at a distance of a few millimeters from each other by the separating element. In these circumstances, the performance of existing circuit breakers used in industrial applications is such that they are capable of passing currents that can reach ICW values ​​(rated short-time withstand current) of up to 50 kA while withstanding heating widths of the order of 70 Kelvin. However, this level of technical performance of the electrical interrupting mechanism of the circuit breaker tends to be insufficient with respect to the needs and safety conditions required in the range of industrial applications. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention aims to overcome the above-mentioned inconveniences by proposing a solution which makes it possible to reduce the heating width of the contacts and at the same time improve the current strength that the circuit breaker can withstand, whilst addressing the constraints of the cut-off chamber dimensioning solved by existing devices. [Means for solving the problem]

[0007] The present invention therefore relates to a movable contact adapted to be assembled in a circuit breaker in abutment against a fixed contact near a cut-off chamber, the movable contact being in the form of a plurality of fingers aligned with one another and arranged in a substantially parallel juxtaposed manner and connected by one end to a common core, characterised in that the comb-like space separating the surfaces of the two juxtaposed fingers of the movable contact has a separation width of less than or equal to a value of 1.3 millimetres.

[0008] The invention will be better understood on reading the following description of preferred embodiments given as a non-limiting example and with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing an example of an arrangement of movable contacts according to the present invention. [Diagram 2] FIG. 2 is an exploded view showing an example of an arrangement of movable contacts according to the present invention. [Diagram 3] 2 is a schematic diagram of an example of a movable contact finger according to the present invention incorporating a separation element; [Figure 4] 2 is a schematic diagram showing an example of a separation element for a finger of a movable contact according to the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The invention relates to a movable contact 1 adapted to be assembled in a circuit breaker in abutment against a fixed contact near a cut-off chamber, said movable contact being in the form of a number of fingers 2 aligned with one another and arranged substantially parallel to one another and connected by one of their ends 2a to a common core 2b, characterized in that the comb-like space 3 separating the respective surfaces of the two juxtaposed fingers 2 of the movable contact 1 has a separation width of less than or equal to a value of 1.3 millimeters.

[0011] Such a structure of the movable contact 1 according to the invention integrates the arrangement of the various fingers 2, bringing their individual positions closer to one another and freeing up enough space within the width of the cut-off chamber for the presence of an additional finger 2 compared to existing prior art movable contacts. The presence of the additional finger 2 allows the movable contact 1 to optimize its abutment surface with the surface of the fixed contact. Thus, while the movable contact known from the prior art comprises five fingers 2 abutting the surface of the fixed contact, the presence of a sixth finger 2 in the movable contact according to the invention allows the total exchange cross section between the movable contact and the fixed contact to be increased. This solution makes it possible on the one hand to increase the ICW value of the circuit breaker and, on the other hand, to reduce the heating taken by the circuit breaker without affecting the dimensioning of the cut-off chamber of the circuit breaker.

[0012] According to a structural variant embodiment related to a particular embodiment of the movable contact according to the invention, the movable contact 1 comprises at least six contact fingers 2, each of which is associated with at least one separation element 4 located in a comb-like space 3 separating two juxtaposed fingers 2, the separation element 4 having a size of 70×10 -8 It has a resistivity of Ω·m (ohm meter) or more. According to one embodiment, the separating element 4 is made of stainless steel. This arrangement incorporating the separating element 4 provides a rigidity to the pair of fingers 2 arranged on either side of the comb-like space 3, reducing the risk of deformation of the fingers 2 and limiting the risk of contact between two juxtaposed fingers 2 if at least one of the fingers is deformed.

[0013] According to a specific construction example, each of the six fingers 2 of the movable contact 1 has a width of about 6 mm and is separated by a comb-like space 3 of about 1.2 mm. This construction therefore allows the movable contact 1 with six fingers 2 to be positioned inside a cut-off chamber with a width of about 46 mm. This specific arrangement of the movable contact 1 with six fingers 2 therefore corresponds to a preferred embodiment in which the number of contact fingers 2 with such dimensions allows optimizing the combination of resistance to the current strength taken by the circuit breaker and heating limit of the contacts in a cut-off chamber with a width of 46 mm, i.e. in a circuit breaker in which a volume of 70 mm is allocated for positioning a pair of contacts, a movable contact and a fixed contact.

[0014] According to another construction variant, which is related to another particular embodiment of the movable contact according to the invention and which can be combined with the variants mentioned above, the various juxtaposed fingers 2 of the movable contact 1 have at least approximately the same dimensions in cross section in a plane perpendicular to the main axis of these fingers 2. This uniformity of cross section allows a gain in the exchange area of ​​20% compared to the total exchange cross section between the fixed and movable contacts of the prior art consisting of five fingers 2. Such an arrangement allows an improved performance between the movable and fixed contacts, on the one hand allowing the ICW value of the circuit breaker to reach 55 kA and, on the other hand, a heating temperature of 5 K lower compared to the devices known from the prior art.

[0015] According to another structural variant, which is related to a particular embodiment of the movable contact 1 according to the invention and which can be combined with the variants mentioned above, the various juxtaposed fingers 2 of the movable contact 1 have at least approximately the same dimensions in cross section in a plane perpendicular to the main axis of these fingers 2. This mutual uniformity of the shape and structure of the fingers 2 allows the distribution of the current flowing in the movable contact 1 to be similar, if not identical, between the various fingers 2. The constraints assumed by each finger 2 are also the same, so that the performance of the movable contact 1 can be more easily optimized.

[0016] According to another constructional variant, which is related to a particular embodiment of the movable contact 1 according to the invention and which can be combined with the variants mentioned above, at the location of the comb-like space 3, the faces 2a of each of the two juxtaposed contact fingers are connected to a respective separating element 4. Such an arrangement, with a pair of separating elements 4 located in each comb-like space 3, allows one separating element 4 to move relative to the other due to mutual friction of the respective surfaces in this comb-like space 3. Moreover, by arranging a pair of separating elements 4 in the comb-like space 3, a double insulation, thermal and electrical, can be set up between the two juxtaposed fingers.

[0017] According to another structural variant relating to a particular example of the structural variant of the separating elements 4, each separating element 4 is fixedly attached to a respective finger 2 such that each of these separating elements 4 can rub against the surface of its corresponding separating element. According to this particular variant, the comb-like space 3 comprises a separating element 4 which is coupled to a respective finger 2 of the movable contact 1, and the movement of one finger of the movable contact 1 relative to the juxtaposed adjacent finger is performed by sliding the surfaces of the separating elements 4 which are respectively coupled to each finger 2 surrounding the comb-like space 3 over one another.

[0018] According to another specific embodiment of the structural variant of the separating element 4, which can be combined with the previous one, at least one separating element 4 made of stainless steel has a clevis-like arrangement, which is arranged to be inserted against the comb-tooth surface 2a of the finger 2 along a cross section in a plane perpendicular to the main axis of the finger 2, with its legs positioned on two opposite faces 2a of the finger 2 having a common edge with the comb-tooth surface 2a. This arrangement of the separating element 4 in the form of a clevis provides thermal and electrical insulation on several sides of the finger 2. Moreover, such a clevis-like arrangement of the separating element 4 allows simple mounting and assembly of the separating element 4 with the dedicated finger 2 of the movable contact 1 by inserting the finger 2 between the legs of the separating element 4. According to a specific embodiment, the separating element 4 is positioned on the finger 2 by a clip mechanism, which is operated in particular by clamping.

[0019] According to another specific embodiment of the structural variant of the separating element 4, which can be combined with the previous embodiment, at least one separating element 4 made of stainless steel has a clevis-like arrangement along a cross section in a plane perpendicular to the main axis of the finger 2, and its legs are arranged so as to cover at least a large part of the comb-tooth faces 2a located on both sides of the same finger 2. Such an arrangement of the separating element 4 allows it to cover a large part, or even a major part, of the side face 2a of the finger 2 located opposite the surface of a corresponding one finger. Furthermore, the separating element 4 characterized in this way makes it possible to provide thermal and electrical insulation between two fingers juxtaposed along a large part of the comb-tooth space 3.

[0020] According to another specific embodiment of the construction variant of the separating element 4, which can be combined with the previous embodiment, at least one edge of one leg of the clevis of the separating element 4 has a retaining means 41, which is positioned against one of the faces of the finger 2 having a common edge with the comb-tooth surface 2a covered by the leg of the separating element 4. According to one construction embodiment, this retaining means 41 is arranged in such a way that, in cooperation with one of the faces of the finger 2, it limits and even prevents the surface of one leg of the separating element 4 from sliding against the comb-tooth surface of the finger 2 against which it abuts. This retaining means 41 has the form of a tab formed by the material continuity with the leg of the separating element 4, which is bent so as to be located in a plane approximately parallel to the clevis part joining the two legs. According to a particular construction embodiment, the legs of the clevis are relatively flexible relative to the joint so that the clevis of the separation element 4 can be inserted into the finger 2 until the tab of the holding means 41 cooperates with a face of the finger 2 opposite to the face of the finger 2 which interacts with the part of the clevis joining the two legs of the separation element 4. When the clevis of the separation element 4 is inserted into the finger 2, the finger 2 is clamped by the legs of the separation element 4.

[0021] According to another specific embodiment of the structural variant of the separation element 4, which can be combined with the previous embodiment, at least the part of the separation element 4 positioned in contact with the comb tooth surface of one finger has a thickness of less than 0.7 millimeters, preferably about 0.6 millimeters.

[0022] According to another specific embodiment of the structural variant of the separating element 4, which can be combined with the previous one, at least one separating element 4 comprises a spring means arranged to separate two juxtaposed separating elements. According to a first structural embodiment of the spring means, the spring means is formed by at least one protrusion of the separating element 4, which is arranged on one of the surfaces of the separating element arranged to contact the comb surface of one finger or to be located in the comb space. This protrusion can take the form of a boss which moderately changes the flatness of the surface of the separating element 4 with respect to the plane of the comb surface, so that the curvature of the boss separates a part of the surface of the separating element 4 from the remaining surface of the separating element which abuts on the comb surface of the finger 2. Thanks to the elasticity of the material of the separating element 4, the curvature of the boss gives it a certain flexibility in its deformation, forming the spring means in a manner similar to a Belleville washer which is integrated into a part of the separating element 4. According to a second embodiment, the spring means is formed from a Belleville washer and is coupled to a part of the surface of the separation element 4 adapted to be located in the interdigital space.

[0023] According to another specific embodiment of the structural variant of the separation element 4, which can be combined with the previous one, the surface of at least one separation element 4 abutting against the comb-tooth surface of the finger 2 has substantially the same shape and dimensions as the majority of the surface of the comb-tooth surface of the finger 2 on which the separation element 4 is located. Such surface similarity allows an optimal abutment of the separation element 4 against the comb-tooth surface of the finger 2, and ensures that the finger 2 of the movable contact 1 maintains its axial orientation along its greatest portion.

[0024] According to another construction variant embodiment, which is related to a particular embodiment of the movable contact 1 according to the invention and which can be combined with the variants mentioned above, the movable contact 1 is coupled to a straight through pivot shaft 5, which is mounted through through holes 10, 14 provided in each finger 2 of the movable contact 1 and in the associated separating element 4. The straight pivot shaft 5 defines a pivot axis about which each finger 2 of the movable contact 1 pivots as part of the movement of the movable contact 1 away from the fixed contact in case of an overload or overvoltage along the circuit in which the circuit breaker in which the movable and fixed contacts are integrated is arranged. According to one arrangement example, when the finger of the movable contact 1 is coupled to a separating element 4 comprising one or more spring means, said through hole 14 is centered on these spring means. For example, when the spring means take the form of a curved boss, the through hole 14 is located in the center of the boss, so that the arrangement of the boss is similar to a Belleville washer integrated into part of the separating element 4, through which the straight pivot shaft 5 passes.

[0025] According to another structural variant of a specific embodiment of the movable contact 1 according to the invention, the movable contact 1 also comprises at least one separator 40 made of stainless steel, which is positioned at the end of the movable contact 1 against the opposing surface of the comb-tooth surface of the finger 2. This separator 40 is designed to be located at one of the lateral ends of the movable contact 1 and is in contact with the side of the finger 2 of the movable contact 1 that is located at the end and does not correspond to the comb-tooth surface. These separators 40 located at the end therefore perform a function similar to that of the comb-tooth-like separating element 4, by ensuring the separation between the side of the finger 2 of the movable contact 1 located at the end and the surface of the support structure of the interrupter in which the movable contact 1 according to the invention is integrated. It should be noted that this separator 40 located at the lateral end of the movable contact 1 can be formed from the leg of a U-link of the separating element 4 that is attached to the finger located at the end of the movable contact 1.

[0026] Naturally, the invention is not limited to the embodiments described and shown in the accompanying drawings: various modifications are still possible, particularly in terms of the configuration of the various elements or by the substitution of equivalent techniques, without departing from the scope of protection of the invention.

Claims

1. 1. A movable contact (1) adapted for assembly in a circuit breaker in abutment against a fixed contact near a cut-off chamber, said movable contact being in the form of a number of fingers (2) aligned in a substantially parallel juxtaposition with one another and connected by one of their ends (2a) to a common core (2b), characterized in that a comb-like space (3) separating the respective surfaces of two juxtaposed fingers (2) of said movable contact (1) has a separation width of a value of less than or equal to 1.3 mm, in which a face (2a) of each of the two juxtaposed contact fingers (2) within said comb-like space (3) is connected to a respective separation element (4), while each of said separation elements (4) is fixedly mounted on a respective finger (2) such that each of said separation elements (4) can rub against a surface of another separation element juxtaposed with said separation element (4).

2. The movable contact (1) includes at least six contact fingers (2), each of which is coupled to at least one separation element (4) located in a comb-like space (3) separating two juxtaposed fingers (2), the separation elements (4) being 70×10 －８ The movable contact (1) according to claim 1, characterized in that it has a resistivity of Ω·m (ohm meter) or more.

3. 2. A movable contact (1) according to claim 1, characterized in that the various juxtaposed fingers (2) of the movable contact (1) have at least approximately the same dimensions in cross section in a plane perpendicular to the main axis of the fingers (2).

4. 2. The movable contact (1) according to claim 1, characterized in that at least one separating element (4) made of stainless steel has a C-shaped arrangement configured to be inserted against one comb-tooth surface (2a) of one finger (2) along a cross section in a plane perpendicular to the main axis of the fingers (2), so that the legs of the separating element (4) are located on two opposing surfaces (2a) of the finger (2) that have a common edge with the comb-tooth surface (2a).

5. 2. The movable contact (1) according to claim 1, characterized in that at least one separating element (4) made of stainless steel has a C-shaped arrangement along a cross section in a plane perpendicular to the main axis of the finger (2) and its legs are arranged to cover at least a large part of the comb-tooth surfaces (2a) located on both sides of the same finger (2).

6. 6. A movable contact (1) according to claim 4 or 5, characterized in that at least one edge of one leg of the C-link of the separation element (4) has a retaining means (41) positioned against one of the faces of the finger (2) having a common edge with a comb-tooth surface (2a) covered by one leg of the separation element (4).

7. A movable contact (1) as described in claim 1, characterized in that the thickness of the portion of the separation element (4) positioned in contact with the comb tooth surface of one finger is 0.7 millimeters or less.

8. 2. The movable contact (1) according to claim 1, characterized in that at least one separation element (4) comprises spring means arranged to separate two juxtaposed separation elements (4).

9. 2. The movable contact (1) according to claim 1, characterized in that the surface of at least one separation element (4) abutting the comb-tooth surface of a finger (2) has approximately the same shape and dimensions as the majority of the surface of the comb-tooth surface of the finger (2) on which the separation element (4) is positioned.

10. 2. The movable contact (1) according to claim 1, characterized in that the movable contact (1) is connected to a straight through pivot shaft (5) mounted via a through hole (10, 14) supported by each finger (2) of the movable contact (1) and each associated separation element (4).

11. 2. The movable contact (1) according to claim 1, characterized in that the movable contact (1) also comprises at least one separator (40) made of stainless steel positioned at the end of the movable contact (1) against the opposing surface of the comb-tooth surface of the finger (2).

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