EP2124238A1 - Contact device for a contactor with high resistive power - Google Patents

Abstract

The device (30) has two pieces (30-1-30-2) made of folded conductor metal i.e. folded copper, and respectively with conductors and identical connection parts. The connection parts include thicknesses lower than a plane connection pad such that superposition of the connection parts forms the connection pad. The pad is connected to power bars (46) of an electric contactor (1), and the conductors longitudinally extend from an end integrated to the pads to a support of a fixed contact, where the fixed contact cooperates with a mobile contact of the contactor. An independent claim is also included for an electric contactor comprising a casing.

Description

TECHNICAL AREA

The invention relates to contact systems of electrical switching and switching devices, in particular contactors. The invention relates more particularly to the contact device extending between the connection range and the fixed contact area of such devices, particularly in the case of use for high power resistive loads.

STATE OF THE ART

A contactor is an electrically or pneumatically controlled switching device whose function is similar to that of an electromechanical relay, namely to establish or interrupt the current flow. This electrotechnical apparatus with high breaking capacity is used in particular to power industrial motors with power exceeding 0.5 kW, and supports a current greater than the relay. Standardized job categories, depending on the nature of the receiver and the conditions under which the closures and openings are made, set the current values that the contactor must withstand. For example, the AC3 category concerns high power consumers, including elevator-type cage motors, whose cut is engine launched. In particular, commercial contactors establish a starting current of five to seven times the rated current of the motor and cut at the opening the rated current absorbed by the motor; at this time, the voltage across the poles of the contactor is of the order of 20% of the network voltage and the cut remains easy.

Other devices have a different regime, less jerky, with for example higher opening / closing cycles, as for heating. In particular, the AC equipment whose power factor, or cos φ, is at least 0.95 are applied to the category called AC1. The constraints on the contactors for these uses Resistives are different: especially for high power, thermal heating can become important. In fact, the AC1 contactors beyond 1500 A are typically derived from the so-called "contactor on bar" technology, very bulky and made to measure, so expensive.

The document DE 100 28 076 describes such a contact device for an electrical contactor.

The development of certain fields, in particular the production of wind energy or the output of inverters, however, requires AC1 contactors of increasingly high power, and smaller size and cost, type "molded housing". However, certain factors can not be ignored: the section and therefore the mass of the contacts thus depend directly on the current that must circulate there; Furthermore, the connection areas to the power system must have a minimum size to meet the standards on the temperature they reach following the resistive heating.

SUMMARY OF THE INVENTION

Among other advantages, the invention aims to overcome the disadvantages of existing fixed contact devices, in particular for high power applications with resistive loads. In particular, contacts whose geometry is optimized to reduce overheating and costs have been developed, to offer a range of contactors whose operating range is increased while maintaining an acceptable size. The invention finds a particularly advantageous application for contactors with a current greater than 1000 A or 1500 A in category AC1, particularly concerning resistive heating, lighting, wind turbine generators, etc.

In one aspect, the invention thus relates to a contact device comprising a substantially flat, preferably rectangular and pierced connection pad for the connection of power supply bars, said strip being extended by several conductors, preferably U-shaped, which have fixed contact areas. Thus, the final architecture of the contactor facilitates the visualization of the connections of the phases, which are each associated with a single input device, respectively output, and therefore only include a connection pad at the input, respectively at the output: branching errors are avoided.

Preferably, the contact device according to the invention is made of copper, which can be unprotected, tinned or silvered, and the contact areas comprise supports on which silver alloy pellets are brazed. The thickness of the conductors is in particular given by the intensity of the current to which the contact device will be subjected, in particular more than 1000 A or 1300 A, in particular more than 1700 A, 2100 A, or even 2300 A; the orientation with respect to the contact areas and the size of the connection area are optimized to minimize thermal heating, and also to facilitate the connection of the bars. Advantageously, the connecting surface of the bars is thus identical to that of the connection pads, in order to maximize the assembled copper masses and thus better dissipate the heat; for example, for the powers such as 2100 A, the standards impose four power bars of determined section, and the connection pads are adapted there, four holes including being pierced for the coupling.

According to the invention, the contact device comprises a superposition of a number of pieces equal to the number of conductors. Each piece of the contact device is derived from a sheet of metal which is then folded to its final shape, and comprises one of the conductors secured to a connection portion whose shape is substantially equal to the connection range of the device ; in fact, the connecting parts of each part of the contact device are superimposed in their main plane, directly or with a conductive interface product filling any surface imperfections, to form the connection area, which makes more than 8 mm thick.

According to a preferred embodiment of the invention, the connecting device comprises two symmetrical parts, preferably from the same metal blank and / or having undergone the same folds. In particular, each piece of the device is made of copper of substantially constant thickness, and comprises a rectangular connecting portion, one side of which is extended by a flat branch of a conductor, offset orthogonally with respect to the rectangular portion of half of its thickness, then by a folded portion to a second parallel conductor branch and comprising a contact support arrangement on its surface opposite to the first branch.

The first branch of each conductor may comprise orifices for securing the parts of the contact device in a housing, the conductors then being advantageously parallel to one another. The connecting portions of each piece also comprise orifices which are superimposed during the assembly of the devices according to the invention, so that the connection of the supply bars ensures the tightening of the connection parts one on the other and optimizes the electrical conduction; for the contact to be homogeneous, it is advantageous to have four bolts on the connecting surface.

In another aspect, the invention relates to a switchgear device comprising a pair of similar contact devices whose contact areas are arranged facing each other in a housing, the connection pads being located on the outside of said housing. A movable contact bridge associated with an actuator may take a closed position in which it provides electrical conduction between the two connection pads, and an open position in which it is remote from the contact devices. In a preferred embodiment, the switchgear is a three-phase contactor comprising three pairs of contact devices, juxtaposed in the plane of the connection pads, associated with a mobile contact bridge device simultaneously ensuring the opening and closing between the three phases.

BRIEF DESCRIPTION OF THE FIGURES

• La figure 1 illustre une coupe d'un contacteur sur lequel le dispositif de contact selon l'invention peut être monté.
• Les figures 2A et 2B représentent un mode de réalisation d'un dispositif de contact selon l'invention.
• Les figures 3A, 3B, 3C montrent une pièce et un dispositif de contacts selon un mode de réalisation préféré selon l'invention, ainsi que son raccordement.

Other advantages and features will emerge more clearly from the following description of particular embodiments of the invention, given by way of illustration and in no way limiting, represented in the appended figures.

• The figure 1 illustrates a section of a contactor on which the contact device according to the invention can be mounted.
• The Figures 2A and 2B represent an embodiment of a contact device according to the invention.
• The FIGS. 3A, 3B, 3C show a part and a contact device according to a preferred embodiment according to the invention, as well as its connection.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The invention finds a particular and preferred application in a contactor 1 with a molded case 2 used in three-phase supply: for each of the phases, the contactor 1 comprises a conduction circuit as schematically illustrated in FIG. figure 1 , the circuits being juxtaposed normally to the drawn plane (of the sheet), for example within the same housing 2 arranged.

In particular, according to a conventional construction, for each supply phase, two connection pads 4 protrude from the housing 2 of the contactor 1 and are intended to be connected to a power supply busbar 6. The connection pads 4 are extended inside the housing 2 by conductors 8 comprising two fixed contact areas 10 separated from each other; the contact areas 10 may, depending on the use, either be manufactured unitarily with the conductor 8 itself, or be reported, with for example a brazing of pellets on a support arranged in the conductor 8. Two contacts 12 coupled by a conductor 14 are located facing the fixed contacts 10 and form a movable contact bridge 16. The movable contact bridge 16 is moved by an actuating device 18 between a closed position in which it provides the electrical connection between the fixed contacts 10, and an open position in which the current does not flow between the connection pads 4.

For electrodynamic reasons, it is more usual for the conductor 8 forms a U at the fixed contact 10, as illustrated: a first branch _8a of the lead 8 carrying the contact 10 is substantially parallel to a second branch _8b located at the bottom of the housing 2; the second branch _8b extends towards the pad 4 which is here parallel with the first branch _8a, but other orientations of the connecting strip 4 may also be provided. The fixed contact device 20 comprising the connection pad 4 and the conductor 8 is usually made of copper, which leads from about 4.5 to 5 A / mm ² ; the copper may especially be crude, tinned or silver.

In addition to the juxtaposition of the contact devices 20 within the housing 2 for the contactors 1 operating in multi-phase power supply, for high power applications, it is conventional that the conduction is provided simultaneously on a plurality of fixed contacts 10, to optimization purposes. Indeed, the contact resistance is reduced by the same amount, and thus the limited heating. It is then possible to multiply the number of connection areas 4 which would thus each extend one of the conductors 8, to the detriment of the ease of implementation by the operator, the bars 6 of each phase must therefore be connected to several ranges 4; according to the invention, each phase is associated only two connection pads 4 to which are coupled the different conductors 8 of the conduction circuit.

Thus, in particular for contactors 1 of high caliber, especially greater than 1000 A, and as illustrated in FIG. Figure 2A , the fixed contact device 20 comprises a plurality of conductors 8 _i , here three, which are provided with as many contact zones 10. Unlike the illustration, the conductors 8 are advantageously of identical section and similar shape in order to optimize the costs of industrialization. Each of the conductors 8, whose section is determined by the current flowing therethrough, is connected to the connection area 4, the size of which also meets certain criteria. In particular, the orientation, the dimensions, and in particular the volume of the connection pad 4 are limited by the ease of connection of a busbar 6, but especially by thermal stresses. In fact, for the contactors 1 for resistive load, the heating of the contact devices 20 can become important with the power; as the temperature of the connection pads 4, directly accessible to the public since external to the housing 2, is limited by the standards, the range 4 is of consistent size.

The contact device 20 thus comprises a bulky connection area 4, usually made of copper, extended by a plurality of conductors 8 spaced apart from one another, also made of copper, each of the conductors 8 forming a U with a branch _8b extending the range 4 and a parallel branch _8a having a support area of the contact 10; conventionally, the contact carrier is an arrangement in the branch 8 _has a chip, such as silver alloy, the size is optimized for the contactor life 1. To fabricate a device of this type, all forging machining, or molding, a unitary unit block is removed, for reasons of industrialization cost in particular. One of the conventional manufacturing options is the screw / bolt connection of the conductors 8 to the connection pad 4 as described in the document US 3,402,274 . This solution, in addition to the multiplication of assembly steps, has the disadvantage of a heating at each bolting by creating a contact resistance, and thus the loss of electrical conduction.

According to the invention, the folded technology is preferred: inexpensive, it is optimized industrially and is commonly applied for the manufacture of contact conductors switching devices and / or switching. It appears however that the industrial limit of this manufacture is a thickness of 7 mm of copper: beyond, the reliability and the realization of the drivers 8 can not be guaranteed. Thus, a direct application of this folded technology to the high power ranges can not be envisaged: an unacceptable congestion would then be generated for the connection pads 4, whose thickness would be limited by that of the conductors 8 while its volume is determined by normative constraints.

According to the invention and as schematized in Figures 2A and 2B , the connecting pad 4 is made in several parts 24 _i , each of the parts 24 _i having a thickness less than the folding limit (for example: 7 mm for Cu) and being extended by one of the conductors 8 _i of contact. Preferably, the contact surface between the different parts 24 _i of the connection pad 4 is maximum, with superposition between them, so that the electrical resistance generated by their connection is minimized and the heating of the range 4, the dissipated heat being maximum. In particular, in the embodiment of the figures 2 , three folded copper single pieces 20 _i constitute the contact device 20, each of the parts comprising a conductor 8 _i contact support 10 _i and a connecting portion 24 _i corresponding to a wafer of the connection pad 4. Preferably, each of the connecting portions 24 _i is of the same thickness, identical to that of the conductors 8, although, as illustrated in Figure 2A other options are possible.

The contact device 20 is obtained by superposition of the different parts 20 _i ; the contacts 10 are advantageously located on the same plane, and bends 26 on the conductors 8 _i make it possible to "catch up" with the offset generated by the superposition of the connecting portions 24 ₁ , 24 ₂ , 24 ₃ . The fastening of the parts 20 _i of the contact device 20 for a maximum contact surface can be obtained by any suitable clamping means. To eliminate the negative effects of any deformation of the connecting portions 24 _i during their tightening, it is possible to have a conductive product at the interface: during coupling, the viscous product, for example a paste, fills the interstices that would form on the surfaces in contact to fill the cavities and thus reduce the contact resistance between two connecting portions 24 _i , 24 _{i + 1} and improve the thermal conductivity. This option can also prevent internal oxidation of the connection range 4.

Preferably, to couple the connecting portions 24 _i , a screw is set up at their level, with formation of at least one orifice 28 _i ; advantageously, the power bars 6 on the connection pad 4 will be coupled by the same means 28. The size of the orifice 28 is determined by the necessary clamping force, which depends directly on the size of the bolt that will be used; it is also possible to increase the number of orifices 28.

According to a particularly advantageous embodiment, the contact device 30 according to the invention comprises two symmetrical parts 30 ₁ , 30 ₂ , made by the same means in order to optimize the industrial investment. Illustrated in figures 3 , it is particularly suitable for contactors 1 to three phases of 1700 or 2100 A AC1, range for which the dimensions will be given for information only - the person skilled in the art will adapt the criteria according to the envisaged use, for example 1000 or 1300 or 2500 A, according to the operating constraints, according to the available space, ...

In particular, the contact device 30 comprises two conductors 32 ₁ , 32 ₂ , in particular made of copper and having a cross section of 25 to 35 mm (for example 30 mm) over 5 to 7 mm; the conductors 32 _i extend on one side the connection pad 34 which is parallelepipedal in shape, in particular rectangle, with sides of 70 to 85 or 100 mm and twice the thickness of the conductors 32. The connection pad 34 is divided into the direction of its thickness in two parts 34 ₁ , 34 ₂ equal; the two pieces 30 ₁ , 30 ₂ base, from the cut, are stackable one on the other: see Figures 3A and 3B . Preferably, the two conductors 32 _i are in the extension of two opposite sides of said range 34, so that the side cut of the copper is straight over the entire length and optimized.

A machining 36 _i can be performed at the end of the conductor 32 _i opposite to the connecting portion 34 _i , to prepare the surface for the contact. Orifices 38 _i are arranged in the connecting portions 34 _i to ensure their clamping one on the other; four orifices 38 with a diameter of 10 to 20 mm, in particular 14 mm, are preferred, this choice optimizing the clamping force to ensure good contact which reduces heating.

Each piece 30 _i is then folded to obtain its final shape: according to the preferred embodiment, two folds are made. One of the bends 40 relates to the U-shape of the conductor 32 _i : the first branch 32 _{has the} end of the conductor 32 supporting the contact is folded to be parallel to the second branch 32 _b of the conductor 32 integral with the connection pad 34. To further obtain two contact supports 36 _i located in the same plane parallel to the connection pad 34 despite the different starting point generated by the superposition of the connecting portions 34 _i , another folding 42 is made in order to shift orthogonally to the plane of the track 34 the second part 32 _b of each conductor 32 of the half of its thickness, preferably at the connecting portion 34 _i. The two offsets are opposite each other for the two parts 30 ₁ , 30 ₂ of the contact device.

According to the embodiment of figures 3 , the contact device is thus made with a cutting tool and two folding tools. Other options (not shown) are possible, with for example a part comprising only the fold 40 in U, and the other part comprising the fold 40 in U associated with a deflection 42 to make up the difference in thickness; in this case, two different cuts are necessary for the devices 30 of consequent size because of the range of the contactor 1.

The parts 30 _i of the contact device 30 are provided with suitable pads 44, in particular by brazing, and then placed one on the other in the housing 2 of the contactor 1. It is advantageous to keep the orifices 38 connection 34 free to easily join the power bars 46. To maintain the contact device 30 in position in the switch 1, any suitable means can be used; in particular, second legs 32 _b of the conductors can be drilled to couple the parts 30 _1, 30 ₂ of 30 individually contact device to the housing 2 through the holes 48. The device 30 itself is finalized once the contactor 1 mounted: the clamping between the connection parts 30 _i will, in most cases, be completed only when the contactor 1 is mounted in the electrical distribution system by the connection of the bars 46.

The busbars 46 are connected directly to the connection pads 34. In particular, in the case of a contactor at 2100 A, the standard requires four copper bars 100 × 5 mm: each of the bars 46 can be secured to a or several orifices 38 in the range 34. Depending on the options, it is possible to place bars 46 at each surface of the connection area ( figure 3C ), but also between its two connecting pieces 34 ₁ , 34 ₂ , "in sandwich": this variant not illustrated can improve the thermal and / or electrical conductivity and further reduce the temperature rise of the connection pads 34. The dimensions of the The preferred embodiment according to the invention is furthermore such that the busbar assembly 46 / contact device 30 rests on a maximum surface, and therefore a mass, which further improves the heat dissipation; in particular the copper surface of the busbar 46 is thus substantially equal to the double surface of the connection pad 34.

The design according to the invention thus makes it possible to reduce the heating of the connection pads 4, 34, of a fixed contact device 20, 30, in particular for use in resistive load of a switch 1. It is then possible to to reduce the size of the contactor 1, which is even more significant in the case where three devices 20, 30 are juxtaposed for a three-phase use. Despite the compactness, at least two contacts 10, 44 per phase are made, obeying neither the reliability of the contactor 1 nor the thermal resistance at the contact pads 44; moreover, the combination of the ranges 4, 34 of the plurality of contacts 10, 44 in parallel of the same phase avoids wiring errors on the busbars 6, 46 and makes mounting easier. The removal of the bolted connections further reduces the internal heating of the housing 2. Finally, the parts 20 _i , 30 _i are designed to limit the industrial investment, and thus reduce costs. Proper cutting of the parts 30 _i of the device can also allow minimization of raw material losses, and thus a decrease in copper uses.

Although the invention has been described with reference to a three-phase contactor with high power double contacts for resistive load, it is not limited thereto and can be used on devices intended for AC3 or other uses. Similarly, if the design of the fixed contact devices according to the invention finds main advantages for contactors of more than 1000 or 1300 A, in particular 1700, 2100 or 2500 A, in particular downstream of wind generators, the solution according to the invention. invention can be adopted for lower powers. Finally, the characteristics of the various embodiments described can be combined with each other in different ways.

Claims (11)

Contact device (20, 30) for an electric contactor (1) comprising: - a substantially planar connection area (4, 34) having a range thickness and for connecting contactor bars (6, 46) of the contactor (1); - at least two conductors (8, 32) extending longitudinally from an end secured to the connection pad (4, 34) to a fixed contact support (10, 36) for cooperating with a movable contact (12) of the contactor (1); characterized in that the contact device (20, 30) is composed of at least two parts (20 ₁ , 20 ₂ , 30 ₁ , 30 ₂ ) and wherein: each piece (20 _i , 30 _i ) is unitary, made of folded conductive metal; each piece (20 _i , 30 _i ) comprises one of the conductors (8 _i , 32 _i ) and a connecting part (24 _i , 34 _i ); each connecting part (24 _i , 34 _i ) is identical in shape and of a thickness smaller than the connection area (4, 34) of the device (20, 30), so that the superposition of said parts (24 _i , 34 _i ) forms the connection area (4, 34). Device according to claim 1, wherein the thickness of the connection pad (4, 34) is greater than 8 mm. Device according to one of claims 1 or 2 wherein the contact supports (10 _i , 36 _i ) of each of the conductors (8 _i , 32 _i ) are located in the same plane parallel to the connection pad (4, 34 ) and offset from it. Device according to one of claims 1 to 3 consisting of two parts (30 ₁ , 30 ₂ ) and wherein the connection pad (34) is rectangular, one of its sides being extended on both edges by the two conductors (32 ). Apparatus according to claim 4 wherein the two pieces (30 ₁ , 30 ₂ ) are from the same metal blank which is folded to form each of said pieces. Device according to one of claims 4 or 5 wherein each of the conductors (32 _i ) is U-shaped with two parallel branches (32 _a , 32 _b ), the first legs (32 _a ) comprising the contact supports (36). ) being situated in the same plane parallel to the connecting strip (34), the second branches (32 _b) being parallel to the first branches ₍₃₂₎ and offset relative to their connecting portion (34 _i) respectively. Device according to claim 6 wherein the bending of the two parts (30 ₁ , 30 ₂ ) to form the conductors (32 ₁ , 32 ₂ ) are identical. Device according to one of claims 1 to 7 wherein the connection pad (34) comprises four orifices (38) for clamping the connecting portions (34 _i ) one on the other. Device according to one of claims 1 to 8 further comprising a silver alloy contact pad (44) brazed to the contact support (36 _i ) of each conductor (32 _i ). Electric contactor (1) comprising a housing (2) in which is partially positioned at least one pair of contact devices (20, 30) according to one of claims 1 to 9 and in which is located a movable contact bridge (16 ) capable of establishing the connection between the fixed contacts (10, 44) of each pair of contact devices (20, 30). Contactor according to claim 10 comprising three pairs of contact devices (30) similar to each other, the contact devices (30) being juxtaposed according to the plane of their connection pads (34).

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