EP0064906B1 - Multi-pole circuit breaker with an interchangeable thermal-magnetic trip unit - Google Patents

Description

The invention relates to a low-voltage multipolar electrical circuit breaker formed by the modular assembly of a cut-off block with molded insulating housing subdivided into a plurality of juxtaposed poles, and of an interchangeable magneto-thermal trip unit according to the chosen rating , each pole of the breaking block comprising a pair of separable contacts whose fixed contact is in connection with an upstream terminal for connection of the circuit breaker and whose movable contact is electrically connected to a connection pad capable of coming into contact by superposition with a connection block of the trip unit, the housing of which rests in a position mounted on the box of the cut-off unit, said trip unit comprising a thermal trip device and an electromagnetic trip device controlled by the current flowing in a conductor aligned with the pair of contacts in the direction longitudinal of the pole, said connection pad being arranged at one end of the conductor, the opposite end of which is integral with the downstream connection terminal of the circuit breaker, electrical continuity by pole between the conductor of the trip unit and the pair of contacts of the breaking unit being ensured by a connection screw ensuring the tightening of the pair intermediate connecting and connecting pads in the superimposed position.

It is conventional to have a range of magnetothermal tripping blocks with different tripping characteristics which can be selectively associated with the same standard breaking block to constitute circuit breakers of different ratings. Failure to tighten the connection screw when installing the trip unit can cause excessive heating, which is detrimental to the proper operation of the circuit breaker.

According to a known device of the kind mentioned, the connection area of each pole of the cut-off block is supported on a fixed stud secured to the base, said stud comprises a threaded orifice cooperating with the connection screw when connecting the pair of pads. connection and connection, in superimposed position. It is noted that defects in positioning in height of the housings of the cut-off block and of the trigger block most often resulting from plastic molding imperfections can be the cause of insufficient tightening of a connection screw at the level d 'a determined pole, since all the threaded orifices of the fixed studs are arranged in the same plane.

To overcome these imperfections, it has already been proposed to use flexible deformable pads for connection and / or connection provided with a flexibility suitable for good clamping of the pads when the trigger block is put in place. This type of deformable pads by superimposition of thin conductive sheets nevertheless has a high manufacturing cost, and is not suitable for circuit breakers of high ratings.

The aim of the present invention is to remedy these drawbacks and to allow the production of a circuit breaker with an interchangeable trip unit whose electrical connection is reliable independently of any differences in level between the housings of the switching unit and the trip unit.

The circuit breaker according to the invention is characterized in that a flexible shunt of the mobile contact arm is secured directly to the connection pad of each pole, comprising a contact face cooperating with the associated connection pad, and an opposite face provided with a nut, and that each connection pad is positioned with vertical clearance in a transverse groove of the box of the cut-off block, the tightening of the connection screw introduced in the nut in the position mounted by the trigger block on the box requesting said floating connection area in the direction of said clearance to ensure good electrical contact with the corresponding connection area of the trip unit, independently of the positioning faults of the two housings.

According to a particular embodiment of the invention, the interchangeable magnetothermal trip unit comprises a device for adjusting the thermal and / or electromagnetic trip thresholds of said trip devices, said electromagnetic trip device is formed by a fixed U-shaped magnetic circuit crossed by said conductor and cooperating with a movable ferromagnetic pallet. The latter is biased in the separated position by a traction return spring anchored by its end opposite to an air gap adjustment bar. The variation in the air gap occurs via a spacer rod coupled between the adjustment bar and the pallet, and extending parallel to the return spring and at a short distance from the latter.

The presence of the spacer rod allows factory adjustment of the air gap and cancels the forces exerted by the return spring on the adjustment bar. It follows from this relative position of the spacer rod and the spring that any modification of the air gap of the electromagnetic trip device keeps the tensile force of the return spring constant.

• la figure 1 est une vue schématique partiellement arrachée du bloc de coupure du disjoncteur selon l'invention, représenté en position de fermeture ;
• la figure 2 est une vue du bloc déclencheur représenté en coupe suivant la ligne II-II de la figure 6 ;
• les figures 3 et 4 sont des vues de dessous et en élévation d'un bras de contact mobile associé à une plage de liaison selon l'invention ;
• la figure 5 montre une vue de profil du bloc de coupure, les demi-vues de gauche et de droite représentant respectivement le bloc sans et avec le socle ;
• la figure 6 est une vue de profil du bloc déclencheur ;
• la figure 7 est une vue en plan de la figure 6 ;
• la figure 8 est une vue partielle d'un élément déclencheur électromagnétique représenté en coupe selon la ligne VIII-VIII de la figure 2.

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

• Figure 1 is a schematic partially cutaway view of the circuit breaker cutoff block according to the invention, shown in the closed position;
• Figure 2 is a view of the trigger block shown in section along line II-II of Figure 6;
• Figures 3 and 4 are bottom views and in elevation of a movable contact arm associated with a connection pad according to the invention;
• FIG. 5 shows a profile view of the cut-off block, the left and right half-views respectively representing the block without and with the base;
• Figure 6 is a side view of the trip unit;
• Figure 7 is a plan view of Figure 6;
• FIG. 8 is a partial view of an electromagnetic trip element shown in section along the line VIII-VIII in FIG. 2.

In FIG. 1, a cut-off block 10 of a low-voltage multipole electric circuit breaker, in particular a four-pole for the protection of a three-phase network with neutral, is housed in a housing 12 of molded insulating material constituted by the assembly of an intermediate case 14 with open bottoms, a cover 16 for closing the upper bottom and a base plate 18 or base for closing the lower bottom. The intermediate casing 14 comprises a central partition 20 parallel to the bottoms, and dividing the internal space of the housing 12 into two superimposed compartments, one upper 22 and the other lower 24, isolated from each other. The cover 16, the casing 14 and the base 18 are fixed to each other by assembly means (not shown). An opening is provided in the upper face of the cover 16 to allow the passage of an operating lever 26 associated with the control mechanism (not shown) disposed in the upper compartment 22. The four identical poles of the cut-off block 10 are juxtaposed in the lower compartment 24 along planes parallel to that of FIG. 1. The control mechanism common to all the poles is advantageously associated with an intermediate pole, so as to transmit the movement to the poles juxtaposed by means of a bar 28 actuation integral with the contact arm 30 of each pole. The transverse bar 28 is housed in the lower compartment 24 and extends perpendicular to the different contact arms 30, which are actuated simultaneously during the movement of movement of the bar 28 between the open and closed positions of the circuit breaker.

In each pole of the switching block 10, the movable contact arm 30 carries a contact 32 cooperating in the closed position with a fixed contact 34 secured to a loop-shaped conductor 36 in electrical connection with a connection terminal 38. A each pair of fixed 34 and movable 32 contacts is associated with an arc extinguishing chamber 40 with deionization plates arranged in the lower compartment 24 between the conductor 36 supporting the fixed contact 34 and the base plate 18. A spring of compression 42 interposed between the bar 28 and the contact arm 30 ensures an appropriate contact pressure in the closed position of the contacts 32, 34.

The circuit breaker is opened in a conventional manner by rotation of the bar 28 anticlockwise under the action of the control mechanism controlled manually by the lever 26 and automatically by a magnetothermal trip unit. 44. Each pole of the circuit breaker is associated with a thermal element and an electromagnetic element housed in the trip unit 44, so as to cause the tripping of the circuit breaker respectively during an overload or short-circuit current.

The thermomagnetic trip unit 44 (FIGS. 2 and 6 to 8) is interchangeable according to the chosen rating of the circuit breaker, and is arranged in a housing (46) made of molded insulating material, the bottom bottom 48 of which is open. The number of poles of the tripping block 44 corresponds to that of the breaking block 10, and a range of removable tripping blocks 44 of identical structures, but having different tripping characteristics, is associated with the same breaking block 10 to constitute circuit breakers of different calibers. Each circuit breaker is thus formed by a modular assembly of the standard cut-off block 10 and a predetermined trip block 44.

The trigger block 44 is introduced through its open bottom 48 into a housing 49 of the base 18 of the cut-off block 10, and comprises connection pads 50R, 50S, 50T, 50N coming into contact by superposition with bonding pads 52R, 52S , 52T, 52N of the corresponding poles of the cut-off block 10. The electrical continuity of the blocks 10 and 44 in the assembled position occurs by means of a connection screw 54, which passes through aligned holes 55, 53, formed respectively in each pair of superimposed areas 50R, 52R; 50S, 52S; 50T, 52T; 50N, 52N. The head of each screw 54 is carried by a transverse flange 56 of the housing 46, the opposite face of which serves to support the fixed connection pads 50R to 50N of the trigger block 44. A nut 58 cooperating with the screw 54 during tightening is secured to the lower face 60 of each range 52R, 52S, 52T, 52N of the cut-off block 10, opposite the face 62 of contact with the range 50R, 50S, 50T, 50N conjugate of the block 44. Two connection braids or shunts 64, 66 (FIGS. 3 to 5) are welded to the underside 60 of each pad 52R to 52N and to the movable contact arm 30 of the corresponding pole. The connection range 52R to 52N of each pole is positioned with play in a transverse groove 68 of the intermediate casing 14 (see half-view on the left, fig. 5). The groove 68 is delimited at its upper part by a stop formed by two flanges 70, 72, arranged in projections 74 of the casing 14 at the level of the partition partitions of two adjacent poles. The upper shoulders 76 of the projections 74 of the casing 14 are shaped in front of the bearing of the trip unit 44, the housing 44 of which rests on the other hand on the opposite side walls of the base 18.

When the intermediate casing 14 is put in place on the base 18, each connection pad 52R, 52S, 52T, 52N is supported on the edge of a transverse wall 78 separating the housing 49 (see right half-view, fig. 5). A predetermined interval d remains in the height direction between the contact face 62 of each pad 52R to 52N and the flanges 70, 72 of the corresponding stop of the casing 14. This results in a floating mounting of the pads 52R to 52N of connection of the cut-off block 10 during the casing of the housings of the base 18 and of the intermediate casing 14.

In contrast to the connection pads 50R to 50N, the trip unit 44 includes connection pads 80R, 80S, 80T, 80N cooperating with fixed pads 82 housed in the base 18 to form the downstream connection terminals of the circuit breaker, the terminals upstream 38 being directly connected to the fixed contacts 34 of the corresponding poles of the cut-off block 10. When inserting the trigger block 44 into the housing 49, the shoulders 76 of the intermediate casing 14, the opposite side walls of the base 18 and the studs 82 position the block 44 in height with a precision which depends on the unevenness and possible deformations of the plastic. The floating mounting of each connection pad 52R to 52N in the interval d makes it possible to overcome the inaccuracies of molding of the housing 46 of the trigger block 44 and that 12 of the cut-off block 10, and ensures a reliable electrical connection at the level of each pole. When tightening the connection screws 54, each floating area 52R to 52N of the cut-off block 10 is urged in the direction of the height to apply its contact face 62 against the corresponding fixed connection area 50R to 50N of the trip unit 44.

The triggering elements (fig. 2 and 6 to 8) of the poles of the triggering block 44 are identical and thereafter, only one of them will be described, in this case that associated with phase T. The connection area 50T and the connection area 80T are interconnected by a conductor 84 passing longitudinally through the trip unit 44 and extending in alignment with the pair of contacts 32, 34 of the corresponding pole of the cutout unit 10. The conductor 84 is traversed by the pole current and is inserted between the legs 86, 88 of a U-shaped magnetic circuit 90 cooperating with a movable pallet 92 of ferromagnetic material to form the electromagnetic tripping element sensitive to a short current -circuit. The conductor 84 has a U-shaped curved structure, the middle part of which is pressed against the base 93 of the magnetic circuit 90 by means of an assembly bolt 94. An insulating washer 96 is interposed between the base 93 and the conductor 84 , and the head of the bolt 94 is supported on a protuberance 98 of the housing 46. The middle part of the conductor 84 is thus trapped between the magnetic circuit 90 and the housing 46.

The thermal trip element comprises a long bimetallic strip 100 fixed by riveting to the conductor 84. The bimetallic strip 100 extends substantially in the vertical median plane arranged between the ranges 50T and 80T and is heated indirectly by conduction during the passage of current through the conductor 84. The free end of the bimetallic strip 100 cooperates during sufficient deflection with a finger 102 carried by a common trigger bar 104 main. The latter is mounted with limited rotation on an axis 106 positioned transversely in the housing 46 in the direction of the bar 28.

The pivoting pallet 92 of the electromagnetic tripping element is provided with two lateral wings 108, 110 fitted between the two legs 86, 88 of the magnetic circuit 90 in a U shape. The end of each wing 108, 110 comprises a notch 112 semi open housed on a fixed lug 114 projecting towards the inside of the leg 86, 88 associated to constitute the articulation of the pallet 92. A control tab 116 secured to the pallet 92 is capable of cooperating with an extension 118 of the main trigger bar 104 when the magnetic field generated by a short-circuit current passing through the conductor 84 causes the pallet 92 to be attracted against the polar pole surface 120 of the end faces of the legs 86, 88 of the magnetic circuit 90.

An adjustment bar 122 for the electromagnetic trip threshold extends parallel to the trip bar 104 above the pallet 92, and is rotatably mounted in bearings of the housing 46 to cause a variation in the air gap formed between the pallet 92 and the corresponding polar surface 120. A spacer rod 124 (FIGS. 2 and 8) is coupled unidirectionally between the adjustment bar 122 and the movable pallet 92 to transmit the adjustment movement from the bar 122 to the pallet 92 without hampering the electromagnetic attraction of the latter against the pole surface 120 when a short-circuit current appears.

A tension spring 126, anchored between the adjustment bar 122 and each movable pallet 92, extends parallel and at a short distance from the associated spacer rod 124, and biases the movable pallet 92 towards the inactive position for spacing the surface polar 120. One end of the spacer rod 124 is mechanically secured to the movable pallet 92, and its opposite end comprises an end piece 128 bearing on a seat 130 of the adjustment bar 122. The end piece 128 is extended by a threaded rod 132 projecting from the bar 122 and cooperating with a nut 134 to form a device for adjusting the length of the spacer rod 124 constituting a factory setting for the air gap.

The pivoting of the adjustment bar 122 of the gap of the magnetic circuits 90 is controlled by a button 136 for customer adjustment of the electromagnetic trip threshold. A torsion spring 138 (fig. 2) acts clockwise and urges the bar 122 to bear against the button 136.

The main trigger bar 104 receives the pulses from the bimetallic strip 100 and the paddle 92 respectively when an overload or short-circuit current appears, and cooperates with the lock 139 of an energy storage device 140, the striker 142 of which causes the automatic control of the control mechanism of the cut-off block 10 causing the opening of the contacts of the circuit breaker.

• Le réglage usine du seuil intervient en position écartée de la palette 92 par variation de la longueur de la tige entretoise 124 au moyen de l'embout 134 réglable. La présence de la tige entretoise 124 annule d'autre part les efforts exercés par le ressort 126 de rappel sur le barreau de réglage 122.

The operation of an electromagnetic trip unit pole and the factory and customer setting of the electromagnetic trip threshold are carried out as follows:

• The factory setting of the threshold takes place in the separated position of the pallet 92 by variation of the length of the spacer rod 124 by means of the adjustable end piece 134. The presence of the spacer rod 124 also cancels the forces exerted by the return spring 126 on the adjustment bar 122.

The length of the spacer rod 124 being fixed, the customer adjustment of the threshold is effected by rotation of the adjustment knob 136 causing the pivoting of the adjustment bar 122. The latter drives the end piece 128 of the spacer rod 124 in a direction of approach or spacing of the pallet 92 relative to the pole surface 120 depending on whether one wishes to decrease or increase the air gap. During this air gap variation, the tension spring 126 is clamped to the spacer rod 124 of predetermined length, and the pallet 92 is then subjected to a constant intensity return force for the desired triggering threshold.

The appearance of a short-circuit current in the pole causes, after exceeding the threshold fixed by the air gap, the electromagnetic attraction of the pallet 92 against the pole surface 120 of the magnetic circuit 90. This results in pivoting in the trigonometric direction (fig. 2) of the main trigger bar 104 actuated towards the triggered position via the control tab 116 of the movable pallet 92. During the attraction stroke, the pallet 92 drives the spacer rod 124 downwards by virtue of the vertical displacement of the end piece 128 in the orifice delimited by the seat 130 of the adjustment bar 122. The latter remains practically stationary when the end piece 128 leaves the seat 130 in the attracted position of the pallet 92.

The main tripping bar 104 and the setting rod 122 for the electromagnetic tripping threshold are located on either side of the vertical median plane in which the bimetallic strips 100 extend, the latter not being affected by heating to level of connection of ranges 50R to 50N; 80R to 80N of trip unit 44.

The invention is of course in no way limited to the mode of implementation more particularly described and represented in the drawing, but it extends quite the contrary to any variant remaining within the framework of electro-technical equivalences, in particular that in which each connection area 50R, 50S, 50T, 50N of the trip unit 44, instead of being fixed (according to FIGS. 1 to 8) would be mounted floating in the housing 46 to cooperate with the connection area 52R, 52S, 52T, 52N floating or fixed from the corresponding pole of the cut-off block 10.

Claims (10)

1. Low voltage multipole electric circuit breaker formed by the modular assembly of a interrupting unit (10) having a molded insulating casing (12) subdivided into several poles placed side by side, and of a magnetothermal release unit (44) interchangeable in terms of the chosen rating, each pole of the interrupting unit (10) comprising a pair of separable contacts (32, 34), the fixed contact (34) of which is connected to a connection supply-side terminal (38) of the circuit breaker, and the moving contact (32) of which is electrically connected to a binding lug (52R, 52S, 52T, 52N) likely to be brought into contact by superimposition with a connection lug (50R, 50S, 50T, 50N) of the release unit (44), the casing (46) of which takes support in fastened position on the casing (12) of the interrupting unit (10), said release unit (44) comprising a thermal release and an electromagnetic release driven by the current flowing in the conductor (84) aligned with the pair of contacts in the longitudinal direction of the pole, said connection lug (50R, 50S, 50T, 50N) being disposed at one of the conductor (84) ends, the opposite end of which is linked together onto the connection load-side terminal (80) of the circuit breaker, the electric continuity by pole between the conductor (84) of the release unit (44), and the pair of contacts (32, 34) of the interrupting unit (10) being ensured by a connection screw (54) assuring the tightening of the pair of the intermediate binding and connection lugs (52R, 50R; 52S, 50S; 52T, 50T; 52N, 50N) in superimposed position, characterized in that a flexible shunt (64, 66) of the moving contact arm (30) is directly secured to the binding lug (52R, 52S, 52T, 52N) of each pole, comprising a contact face (62) cooperating with the associated connection lug (50R, 50S, 50T, 50N), and an opposite face (60) equipped with a nut (58), and that each binding lug (52R, 52S, 52T, 52N) is positioned in vertical play in a cross-groove (68) of the casing (12) of the interrupting unit (10), the tightening of the connection screw (54) introduced in the nut (58) in fastened position of the release unit (44) on the casing (12) biasing said floating binding lug (52R, 52S, 52T, 52N) in the direction of said play to ensure a good electric contact with the corresponding connection lug (50R, 50S, 50T, 50N) of the release unit (44), independently of the positioning faults of both casings (12, 46).

2. Multipole electric circuit breaker according to claim 1, characterized in that the housing groove (68) of each floating binding lug (52R, 52S, 52T, 52N) is delimited at its upper part by a stop, the opposite face of which is used as support to the casing (46) of the release unit (44) in fastened position.

3. Multipole electric circuit breaker according to claim 2, in which the casing (12) of the interrupting unit (10) is made by the assembly of an intermediate enclosure (14) with opened bottoms, a lid (16) to seal the upper bottom and a base (18) to close the lower bottom, said enclosure (14) comprising a median partition (20) parallel to said bottoms and defining an upper compartment (22) to put the control mechanism and a lower compartment (24) including the poles, the release unit (44) being inserted in an auxiliary compartment (49) of the base (18), separated from the lower compartment (24) of the poles by a cross-wall (78), characterized in that each binding lug (52R, 52S, 52T, 52N) takes support on the upper edge of said cross-wall (78), previously to the tightening of the connection screw (54), and that a gap (d) exists in the height direction between the contact face (62) and said stop secured to the intermediate enclosure (14).

4. Multipole electric circuit breaker according to claim 3, characterized in that said stop is formed by two edges (70, 72) disposed in projections (74) of the enclosure (14).

5. Multipole electric circuit breaker according to any of the claims 1 to 4, characterized in that each connection lug (50R, 50S, 50T, 50N) of the release unit (44) is fixed being fastened to the casing (46) of the release unit (44).

6. Multipole electric circuit breaker according to claim 1, characterized in that said interchangeable magnetothermal release unit (44) comprises a device to adjust the thermal and/or electromagnetic trip thresholds of said releases, said electromagnetic release is formed by a U-shaped fixed magnetic circuit (90) crossed by said conductor (84), and cooperating with a ferromagnetic moving plate (92) associated with a tension restoring spring (126) tied by its opposite end to a bar (122) of the air-gap adjustment accommodated between the polar surface (120) of the magnetic circuit (90) and the plate (92) in separate position, the air-gap variation occurring through a spacer rod (124) extending slightly parallel to the restoring spring (126), and coupled between the adjustment bar (122) and the moving plate (92).

7. Multipole electric circuit breaker according to claim 6, characterized in that the spacer rod (124) to adjust the air-gap is secured to the moving plate (92) by being located at short range from the tension spring (126) and comprises at its opposite end a tip (128) taking support in separate position from the plate (92) on the adjustment bar (122) so as to cancel the tractive forces exerted by the restoring spring (126) on the adjustment bar (122), said tip (128) being automatically unpaired from the bar (122) when the electromagnetic attraction of the plate (92) against the polar surface (120) occurs after running past the electromagnetic trip threshold determined by the airgap.

8. Multipole electric circuit breaker according to claim 6 or 7, characterized in that the rotating plate (92) of the electromagnetic release is equipped with two side wings (108, 110) fitted together between the vertical legs (86, 88) of the U-shaped magnetic circuit (90), the end of each wing opposite to the plate (92) comprising a half- opened notch (112) cooperating with a projecting pin (114) of the associated leg to build the plate (92) hinge.

9. Multipole electric circuit breaker according to claim 6, 7 or 8, in which the thermal release of each pole comprises a bimetal strip (100) being indirectly heated by conduction, characterized in that the bimetal strip (100) is secured to the conductor (84) and vertically extends inside the U-shaped magnetic circuit (90) in a plane perpendicular to the legs (86, 88), in particular the median plane of the release unit (44).

10. Multipole electric circuit breaker according to claim 6, 7, 8 or 9, characterized in that for each pole the electromagnetic release and the thermal release are fastened to the casing (46) of the release unit (44) by a single assembling bolt (94), which confines on the other hand the conductor (84) between the base (93) of the magnetic circuit (90) and a knob (98) of the casing (46).

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