EP0047696A2 - Miniature circuit breaker with arcing-contacts - Google Patents

Abstract

1. Miniature circuit-breaker with a narrow insulating housing (10) comprising connection terminals (16, 18) arranged on the narrow lateral sides of the housing, an operation device (14) located on the front side (12) and a fastening device of the housing located on the rear side (34), said insulating housing comprising separable contacts (20, 22) arranged in an arcing chamber, an arc extinction chamber (30) towards which the arc drawn during the contact separation is guided by arcing horns (46, 48) associated to said contacts (20, 22), a control mechanism (25) for the manual opening and closing of said contacts and an electromagnetic (28) or thermal (26) tripping device for an automatic opening control when a fault occurs, characterized in that the movable contact (42) is constituted by a monoblock piece made principally of copper, comprising two contact surfaces (20, 50) without pellet, a main contact surface (20) and an arcing contact surface (50) inserted between the main contact surface and the arcing horn (48) and that the stationary contact comprises a piece made principally of copper comprising a main contact surface (22), without pellet, and an elastic blade or piece (54, 56, 62) associated with the copper piece, which comprises an arcing contact surface (52), without pellet, and inserted between the main contact surface (22) and the arcing horn (46), the elastic blade or piece (54, 56, 62) being able to make a limited movement to accompany the movable contact (42) during its opening movement, in order to open the arcing contacts (50, 52) after the separation of the main contacts (20, 22).

Description

The invention relates to a power cut device: for a low voltage electrical installation with low currents, comprising a molded plastic housing housing one or more poles, a pair of separable contact parts for each of the poles and a control mechanism for separating said contact parts.

The contacts are delicate points in the electrical equipment and their quality generally determines the reliability and the resistance over time of the device. The heating of the contact parts is directly linked to the contact resistance and in low-voltage devices with low currents, the contacts are almost exclusively made of an alloy with a high silver content, in particular in silver pellets of low resistivity, fixed on copper contact parts. The pads are of sufficient thickness to resist wear by friction during successive operations and they withstand without too much damage, in this case without welding or excessive erosion, the action of arcs or sparks appearing at the opening. . The contacts with silver pellets are nevertheless complex and expensive to manufacture and their price constitutes a non-negligible part of that of the device.

It has already been proposed to remove the silver pellets and to ensure contact directly with the copper. The devices, in this case miniature circuit breakers, equipped with such contacts, have a correct contact resistance and they resist well to high current cuts, but contact welds which can destroy the device, are frequent.

It is also known, essentially in medium and high voltage devices, to make the contacts so that the breaking or separation does not take place on the parts ensuring the passage of the permanent current, when the device is closed, but these devices are complicated and their size and manufacturing cost preclude their use in low voltage devices such as miniature circuit breakers, small switches or contactors.

The object of the present invention is to remedy these drawbacks and to allow the production of a device for breaking low low voltage currents having contact parts devoid of silver or silver alloy contact pads.

The apparatus according to the invention is characterized in that one of said contact pieces has two spatially distinct contact areas, a main contact area and an arcing contact area, which the associated contact piece has a first part cooperating with said main contact zone of said one contact part to constitute main contacts and a second semi-mobile part capable of effecting a limited relative movement and of cooperating with said arc contact zone to constitute arcing contacts, the assembly being arranged. so that in the device closed position, said main contacts and arcing contacts connected in parallel are both closed and said relative movement delays the separation of the arcing contacts with respect to the separation of the main contacts during an opening movement, said main contacts being devoid of contact pads and being made of a material ensuring good electrical contact, in particular coated with an antioxidant material and said arcing contacts being made of a material resistant to action of an arc or spark, generated when the device is opened or closed.

The semi-mobile part provided on one of the contact parts allows the conservation of the device opening kinematics and the opening or closing in two phases, the arcing contact carried by the semi-mobile part accompanying in a first step the associated contact in its course and opening with delay. It is clear that the only modification of the mechanism of the device, in this case a small elongation of the stroke of the movable contact, does not present any difficulty and that the overall size is easily respected. These modifications can be made on existing series of devices.

The semi-mobile part is advantageously constituted by a one-piece elastic blade or attached to the associated contact part, or a part resiliently mounted on this contact. It is preferably provided on the fixed contact of the device to cooperate with an arcing contact area of the movable contact adjacent to the main contact area, but an arrangement on the movable contact is conceivable without significant complication as will become clear of an example of implementation described below.

The invention is applicable to any low-voltage device using contact pieces with silver discs, in particular to switches, contactors, circuit breakers, remote control switches, whether these devices are single cut or double cut. In devices fitted with arc extinguishing chambers, in particular in miniature circuit breakers, electrodes or guide horns; from the arc to the extinguishing chamber can be easily modified to constitute the arcing contacts without requiring additional parts. A particularly simple embodiment comprises a flexible blade incorporated or integral part of the electrode connecting the fixed contact to the extinguishing chamber, the end of the blade constituting the fixed arcing contact. The flexible blade is advantageously shaped as a blowing loop from the arc to the extinguishing chamber. An articulated or sliding piece can obviously replace the elastic blade.

The contact parts, made of copper or copper alloy or possibly aluminum, can wear an antioxidant coating, for example silver or tin in the main contact area to reduce the contact resistance and the arcing contacts can be a tellurium copper alloy or any other material resistant to the action of the arc, for example steel.

• la figure est une vue schématique en élévation d'un disjoncteur miniature selon l'invention, représenté en position fermée, la paroi latérale étant supposée enlevée;
• la figure 2 est une vue partielle de la figure 1, montrant les contacts en cours de séparation, les contacts principaux étant ouverts et les contacts d'arc encore fermés;
• la figure 3 est une vue analogue à celle de la figure 2, montrant les contacts en position ouvert;
• les figures 4 et 5 sont des vues partielles analogues à celle de la figure 1, illustrant deux variantes de réalisation;
• la figure 6 est une vue analogue à celle de la figure 1, montrant un autre mode de mise en oeuvre de l'invention, comportant un contact mobile portant un contact d'arc semi-mobile;
• la figure 7 est une vue schématique d'un disjoncteur à double coupure selon l'invention, seules les pièces constitutives étant représentées.

Other advantages and characteristics will emerge more clearly from the description which follows of different embodiments of the invention, given by way of nonlimiting examples and represented in the appended drawings, in which:

• the figure is a schematic elevation view of a circuit breaker miniature according to the invention, shown in the closed position, the side wall being assumed to be removed;
• Figure 2 is a partial view of Figure 1 showing the contacts being separated, the main contacts being open and the arcing contacts still closed;
• Figure 3 is a view similar to that of Figure 2, showing the contacts in the open position;
• Figures 4 and 5 are partial views similar to that of Figure 1, illustrating two alternative embodiments;
• Figure 6 is a view similar to that of Figure 1, showing another embodiment of the invention, comprising a movable contact carrying a semi-movable arcing contact;
• Figure 7 is a schematic view of a double break circuit breaker according to the invention, only the component parts being shown.

The invention is described below in its preferred application to a miniature circuit breaker of the type commercially known as C 32. Figure 1 shows such a miniature circuit breaker and corresponds to Figure 1 of patent application No. 79 25859, filed by plaintiff on October 16, 1979, to which one will advantageously refer for further details on the constructive characteristics of this circuit breaker. We recognize in Figure 1 the molded housing 10 having on the front face 12 an operating handle 14 and on the two narrow lateral faces of the connection terminals 16, 18. In the housing 10 are housed a movable contact 20 and a fixed contact 22, the latter being connected by a loop conductor 24 to terminal 16. Le _; movable contact 20 is controlled by a control mechanism, designated by the general reference 25. The housing 10 also contains a thermal trip device formed by a bimetallic strip 26 and an electromagnetic trip device 28 capable of causing an opening in the event of overload or short-circuit automatic contact 20, 22. In the lower part of the housing 10 is arranged a breaking chamber 30 constituted by a stack of sheets 32, which extend parallel to the rear face 34 of the housing 10. Clamps 36 carried by the rear face 34 cooperate with a symmetrical DIN rail for support in a manner well known to specialists. The breaking chamber 30 is delimited by end plates or plates 38, 40 parallel to the rear face 34, the plate 38 being attached to this rear face 34. The movable contact 20 is carried by a contact piece 42, mounted with limited rotation on an axis 43 carried by a contact arm 44, pivotally mounted on an axis 45. During a pivoting in the open position of the movable contact piece 42, the movable contact 20 moves in a direction substantially parallel to that of the sheets 32, the arc drawn between the separate contacts moving along an electrode of guide 46 connecting the conductor 24 to the end plate 38 to spread at the entrance to the breaking chamber 30. Such a circuit breaker and its operation are well known to specialists.

According to the present invention, the movable contact 20 and the fixed contact 22 are devoid of silver pellets. The contact piece 42 in copper, possibly silver or tinned, comes directly into contact with the conductor 24 also in copper, possibly silver or tinned. The silver or tin coating is weak thickness and has the sole purpose of opposing the oxidation of the contact surface. The movable contact piece 42 extends beyond the movable contact 20 into a curved horn 48 for guiding the arc towards the breaking chamber 30, this curved horn 48 having movable an arc contact area / 50 capable of cooperate with a semi-fixed arcing contact 52. The semi-fixed arcing contact 52 is carried by an elastic blade 54, formed by an extension of the end plate 38. The elastic blade 54 passes through an orifice formed in the electrode 46 and protrudes from the latter at a point close to the fixed contact 22, interposed between this last contact 22 and the breaking chamber 30. The elastic blade 54 and the semi-fixed contact 52 can be made of a copper alloy - tellurium or any other suitable material resistant to the action of an arc. In the closed position of the circuit breaker, shown in FIG. 1, the pair of contacts 20, 22 and the pair of contacts 50, 52 are both closed, the current passing in its quasi-totality the path of least. resistance, constituted by the contacts 20, 22, forming main contacts. During a pivoting of the movable contact piece 42 clockwise in FIG. 1 towards the open position; the semi-fixed contact 52 accompanies in a first phase the movable contact piece 42 in its movement thanks to the elasticity of the elastic blade 54 allowing separation of the main contacts 20; 22 without arc, the current being switched to the arc circuit comprising the arcing contacts 50, 52 remaining in contact (fig. 2). During a continued movement of the movable contact piece 42, the elastic blade 54 is retained in abutment, so as to cause the separation of the arcing contacts 50, 52 with the formation of an arc. The arc quickly switches over the guide electrode 46 to direct itself towards the breaking chamber 30 in the usual manner. Similarly, during a pivoting of the movable contact piece 42 in the closed position, the arcing contacts 50, 52 close first, the main contacts 20, 22 being closed after deformation of the elastic blade 54 pushed back by the movable contact piece 42. It is easy to see that the main contacts 20, 22 open and close without an arc and are thereby freed from any risk of welding or erosion due to a closing or opening arc or spark. The main contacts 20, 22 can therefore be made without contact pads. The arcing contacts 50, 52 do not participate in the conduction of the permanent current and can be made of a material chosen for its properties of resistance to the action of the arc. The mechanism of the circuit breaker can be fully preserved, the only modification consisting in a slight increase in the pivoting stroke of the movable contact piece 42, corresponding to the deflection of the elastic blade 54. It is obvious that the elastic blade 54 can be a piece independent of the end plate 38 of the same material or of a material different from the latter. In the example illustrated in Figure 1, the elastic blade 54 extends at the rear of the electrode 46 forming with the latter a closed loop. In the closed position of the circuit breaker, the current flows directly through the main contacts 20, 22, but as soon as the latter is separated, the current coming from the terminal 16 flows through the conductor 24, the electrode 46, the blade 54, the contacts of arc 50, 52 following a loop path generating a magnetic field - blowing of the arc drawn during the separation of the arc contacts 50, 52. As soon as the arc is formed, the latter switches over to the electrode 46 again switching off the loop formed by the elastic blade 54. This magnetic blowing present during the formation of the arc promotes rapid migration to the cutting chamber 30. L ₂ inventive device takes advantage of the one hand presence of an arc horn 48 on the movable contact piece 42 to create an arc contact zone, and on the other hand, the presence of the electrode 46 for guiding the arc towards the breaking chamber 30 to insert a semi-fixed contact 52 acting as an arcing contact. The structure and the arrangement of the arcing contacts according to the invention allow conservation of the size of the circuit breaker. It is obvious that the arcing contact system according to the invention can be applied with the same advantages to miniature circuit breakers of another type or that the arcing contacts can be produced in a different way, some variants being described below by way of examples, with reference to FIGS. 4 to 6, in which the same reference numerals designate parts similar or identical to that of FIG. 1.

In FIG. 4, the semi-fixed arcing contact 52 is carried by a rigid part 56 mounted with pivoting limited by its end 58 opposite the arcing contact 52 on the plate 38. The rigid part 56 extends forward of electrode 46. and is biased towards the projection of electrode 46 in contact with the contact movable arc 50 by a compression spring 60 bearing on the housing 10. The movement of the part 56 is limited by stops (not shown). A braid 61 connects the rigid part 56 to the conductor 24 to ensure a good electrical connection. It is understood that the operation of the circuit breaker according to Figure 4 is identical to that described with reference to Figures 1 to 3. The material of the rigid part 56 may be different from that of the end plate 38, and the articulation of the the end 58 on the plate 38 can be of any type.

The rigid part 56 can be arranged as an arc guiding electrode and in this case replace the electrode 46.

FIG. 5 illustrates another variant, in which the semi-fixed arcing contact 52 is carried by an extension 62 of the end plate 38, the extension 62-plate 38 assembly being mounted with neck. smoothing parallel to the rear face 34 to bring the semi-fixed arcing contact 52 closer or further apart from the movable contact 50. A spring 64 biases the extension 62-plate 38 assembly in the projecting position from the semi-fixed arcing contact 52 The extension 62 can extend into a slot made in the electrode 46, but it is clear that this extension 62 can be arranged as an arc guide electrode and replace the electrode 46. The braid 61 electrically connects the conductor 24 at the free end of the extension 62 to ensure a good electrical connection. The operation of the circuit breaker according to FIG. 5 is the same as that described above.

It can be noted that the semi-fixed or semi-mobile arcing contact part is not necessarily associated with the fixed part of the circuit breaker contact, and FIG. 6 illustrates a variant in which the movable contact part 42 carries a semi-mobile arcing contact 66. The conductor 24 has on the one hand a main contact zone 22, which cooperates with the main mobile contact 20 carried by the mobile contact piece 42 and on the other hand offset in the direction of the guiding electrode 46, an arcing contact zone 68 cooperating with the semi-movable arcing contact 66. This latter semi-movable contact 66 is carried by an elastic blade 70 secured to the moving contact piece 42, so as to urge the semi-movable arcing contact 66 in the direction of the associated fixed contact 68. It is understood that during a pivoting from the movable contact piece 42 to the open position, the main contacts 20, 22 separate before the arcing contacts 66, 68, the semi-movable arcing contact 68 being driven in rotation after coming into abutment of the end of the movable main contact 20 against the elastic blade 70. The semi-movable arcing contact 66 can obviously be articulated or mounted with limited sliding on the movable contact piece 42.

In the aforementioned examples, the arcing contacts are offset with respect to the main contacts in the direction of travel of the arc towards the breaking chamber 30 to avoid any action of the arcing on the main contacts 20, 22. It is not would not depart from the scope of the invention by juxtaposing or incorporating the arcing contacts in the main contacts, the risk of arcing on the main contacts being eliminated by any appropriate means.

The invention is applicable to other types of circuit breakers or switches, in particular double break, and FIG. 7 illustrates such an application to a circuit breaker described in the applicant's patent application N ° 79 00827 of 11-1-1979 . In Figure 7 _; which corresponds to Figure 1 of the aforementioned patent, we recognize the moving element 72 in the form of a slide capable of being locked in the closed position by an attachment 74. The attachment 74 is controlled by a bimetallic strip 76 or an electromagnetic trip device 78 to release the slider 72 in the event of an overload or a fault, and to authorize its displacement towards an open position. The slider 72 carries a movable contact piece 80 in the form of a contact bridge carrying at its ends movable main contacts 82, 84, capable of cooperating with main fixed contacts 86, 88, formed by contact zones formed on parts fixed contact 90, 92. The displacement in the open position of the slide 72 causes separation of the contacts 82, 86; 84, 88 by drawing two arcs at the entry of extinguishing chambers 94, 96. A detailed description of the circuit breaker and of its operation is given in the aforementioned patent, to which reference will be made advantageously. According to the present invention, .on associating with the movable contact piece 80 an elastic blade 98 extending at its two ends the piece 80 and carrying semi-movable arcing contacts 100, 102 cooperating with arcing contact zones 104, 106 formed on the fixed contact parts 90, 92. The elastic mounting of the semi-movable contacts 100, 102 is arranged to delay the opening of the arcing contacts 100 , 104; 102, 106, as described above with reference to FIG. 6, and allow an opening without arc of the main contacts 82, 86; 84, 88. It can be noted that again the arcing contacts 100, 104; 102, 106 are interposed between the main contacts 82, 86; 84, 88 and the associated arc extinguishing chambers 94, 96, preventing any migration of the arcs to the main contacts 82, 86; 84, 88. The device is particularly simple and allows the use of contacts without silver pellets. The semi-fixed or semi-mobile arcing contacts can be associated with the fixed contact parts 90, 92 in a manner similar to that illustrated in FIGS. 1 to 5.

The embodiments described above clearly show that the invention is in no way limited to a particular type of contact or device. It applies to a circuit breaker, a switch or a contactor with single or double break, as well as to medium intensity devices with the effect of eliminating 'or only reducing the amount of money necessary for manufacturing contacts.

Claims (10)

1.Current-breaking device for a low-voltage electrical installation with low currents, comprising a casing (10) of molded plastic material housing one or more poles, a pair of contact parts (42, 24, 80 , 90, 92) separable for each of the poles and a control mechanism (25) for separating said contact parts, characterized in that one (42; 90, 92) of said contact parts has two contact zones ( 22, 50; 86, 104; 88, 106) spatially distinct, a main contact area (20; 86, 88) and an arc contact area (50; 104, 106), as the associated contact piece ( 24,80) has a first part (22; 82, 84) cooperating with said main contact area (20; 86, 88) of said one contact part to constitute main contacts, and a second semi-mobile part (52 ; 100, 102) capable of effecting a limited relative movement and of cooperating with said arc contact zone (50, 104, 106) to constitute arcing contacts, the assembly being arranged so that in the device's closed position, said main contacts (20, 22; 82, 86; 84, 88) and arcing contacts (50, 52; 100, 104; 102, 106) connected in parallel are both closed and that said relative movement delays the separation of the arcing contacts from the separation of the main contacts during movement, opening, said main contacts (20, 22; 82, 86; 84, 88) being devoid of contact pads and being made of a material ensuring good electrical contact, in particular coated with a material antioxidant and said arcing contacts (50, 52; 100, 104; 102, 106) being of a material resistant to the action of an arc or a spark, generated during the opening or the closing the device. 2. Apparatus according to claim 1, characterized in that said second part (52; 100, 102) of the associated contact piece (24; 80) is constituted by an elastic blade (54;, 88) or a piece (56 , 62) pivotally or slidingly mounted and resiliently biased towards said one contact piece (42; 90.92 3. Apparatus according to claim 1 or 2, characterized in that said associated contact piece (24) is a fixed part, cooperating with said one movable mounted contact piece (42). 4. Apparatus according to claim 1, 2 or 3, characterized in that said a contact piece (42; 90, 92) is a single piece of copper or a copper alloy provided with an anti-oxidant coating in silver , made of tin or a tin-lead alloy in the main contact area (20; 86, 88). 5. Apparatus according to claim 4, characterized in that said semi-mobile part (52; 100, 102) is made of a copper-tellurium alloy. 6. Cutting device according to any one of the preceding claims, characterized in that it further comprises a - chamber (30; 94,96) of arc extinction and electrodes (46; 104,106) for guiding the arc towards the arc extinguishing chamber, said arcing contacts (50.52; 100.104; 102.106) being interposed between the main contacts (20.22; 82.86; 84.88), and the chamber extinction on said guide electrodes. 7. Modular step circuit breaker according to claim 6, with a flat miniature shoemaker (10) comprising a fixed contact (22) extended by a fixed electrode (46) extending towards the arc extinguishing chamber (30) and a movable contact (42) extended by an arcing horn (48) in the direction of the extinguishing chamber, characterized in that said semi _- movable part (52) is mechanically and electrically connected to said fixed electrode (46), so as to constitute an arcing contact (52) adjacent to the fixed main contact (22) and cooperating with said arcing horn of the movable contact. 8. Circuit breaker according to claim 7, characterized in that said semi-mobile part (52) is constituted by an elastic tongue (54) stamped in said fixed electrode (46). 9. Circuit breaker according to claim 7, characterized in that said semi-mobile part (52) is connected to said fixed electrode (46) along a loop path forming a blowing loop from the arc towards the extinguishing chamber. 10. Circuit breaker according to claim 6, with flat miniature housing (10) comprising a movable contact (42) cooperating with a fixed contact (22) extended by a fixed electrode (46) for guiding the arc towards the extinguishing chamber. , characterized in that said semi-mobile part (66) is fixed in extension of the mobile contact (42) to cooperate with an arcing contact zone (68) formed on said fixed electrode (46) between the main contact zone (22) and the extinguishing chamber (30). (fig. 6).

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