FR2950471A1 - Unipolar cutoff unit useful in cutoff device for circuit-breaker, comprises rotating contact bridge, pair of fixed contacts connected with bridge, rotating rod having transverse opening, sealing shields, and arc extinction chambers - Google Patents

Abstract

The unipolar cutoff unit comprises a rotating contact bridge (22), pair of fixed contacts (41, 51) connected with the contact bridge and to a conductor (4, 5) of current lead, a rotating rod (26) having a transverse opening of housing (21) with clearance from the contact bridge, which extends out from the bar, sealing shields respectively placed between the radial faces of the rotating bar and sides to ensure a seal between inside and outside the phase unit, and two arc extinction chambers opening on a volume of opening of the contact bridge. The unipolar cutoff unit comprises a rotating contact bridge (22), pair of fixed contacts (41, 51) connected with the contact bridge and to a conductor (4, 5) of current lead, a rotating rod (26) having a transverse opening of housing (21) with clearance from the contact bridge, which extends out from the bar, sealing shields respectively placed between the radial faces of the rotating bar and sides to ensure a seal between inside and outside the phase unit, and two arc extinction chambers opening on a volume of opening of the contact bridge. The rotating bar is interposed between two sides of the phase unit, and comprises parallel side faces and two channels of direct link between the transverse opening of housing and a radial face so that the cut gas flows directly through the channel towards the sealing shield to push against the side faces to ensure the sealing. The opening channel comprises a longitudinal axis parallel to a longitudinal axis of the rotating bar so that the cutoff gas exerts a force aligned with the longitudinal axis of the bar and spread evenly over the sealing shields. The sealing shields comprise side flanges partially covering the longitudinal surface of the rotary bar. The side flanges are partially close to the transverse opening of the housing of the rotary bar. The sealing shields further comprise a hole for the passage of linking bar for mechanically fixing the rotating bars, where the linking bars are controlled by a mechanism common to all unipolar units. Each cutoff chamber is connected to an exhaust channel of the cutoff gas. The exhaust channels are opened on upstream face of the casing of the cutoff phase, which is positioned opposite to another downstream face intended to be placed contacting with a triggering unit. The exhaust channels of cutoff gas respectively of first and second cutoff chamber have different lengths, where the cutoff gas flowing in an exhaust channel is intended to draw the gas flowing through a second exhaust channel by Venturi effect. The gas exhaust channel of arc cutoff chamber crosses a decompression chamber comprising an internal wall covered by a metal sheet.

Description

1 UNIPOLAR CUT-OFF BLOCK COMPRISING A ROTARY CONTACTING BRIDGE, CUTTING DEVICE COMPRISING SUCH A BLOCK AND CIRCUIT BREAKER COMPRISING SUCH A DEVICE TECHNICAL FIELD OF THE INVENTION The invention relates to a unipolar break block comprising a rotary contact bridge, at the less a fixed contact cooperating with said contact bridge and connected to a current supply conductor, a rotary bar having a transverse housing hole with play of said contact bridge, which protrudes from the bar, said rotary bar being interposed between two lateral faces of the cutoff block, said lateral faces being substantially parallel. Said rotary contact bridge also comprises two sealing flanges placed respectively between the radial faces of the rotary bar and the side faces to ensure a seal between the inside and outside of the cutoff block. At least one arc extinction chamber opens on an opening volume of the contact bridge.

The invention also relates to a cut-off device comprising such a cutoff device breaking device. The invention also relates to a circuit breaker comprising a cut-off device. STATE OF THE ART The use of contact bridges in cut-off devices is described in numerous patents, in particular patents of the applicant EP0538149 and EP0560697. In known manner, as shown in FIGS. 1A, 1B, the molded-case cut-off device comprises a box 12, made of insulating plastic material containing cut-off elements of a pole, in this case a pair of fixed contacts 41 , 51 and a movable contact bridge 22, as well as two cutoff chambers 24. The box 12 of parallelepipedal general shape consists of two large side faces. The movable contact bridge 22 is carried by. a rotatable bar 26, interposed between the two large lateral faces. The rotating bar 26 has a transverse housing orifice 21 which extends along a diameter in a direction parallel to the large lateral faces. The movable contact bridge 22 passes through this hole with clearance projecting from both sides of the bar 26. The contact bridge 22 is mounted floating on the bar 26. Two current leads 4, 5 are connected to the fixed contacts 41, 51. In order to guarantee an efficient electrical cut, it is necessary to avoid gas leaks at the driving axes of the bar 26. These gas leaks have the effect of creating a retroflux and hindering the insertion of the arc in the Io chambers of cutoff. A seal between the rotating bar and the molded housing is necessary. This sealing can be achieved using two flanges placed respectively on the faces of the bar between said bar and the inner wall of the two large side faces. The effectiveness of these solutions however remains perfectible. The flanges are mounted around the drive shaft with an axial operating clearance that can be responsible for the passage of gas related to the cut. SUMMARY OF THE INVENTION The invention therefore aims to overcome the drawbacks of the state of the art, so as to propose a rotary bar cutoff block having effective sealing means. The rotary bar of the breaking block according to the invention comprises at least one channel in direct connection between the transverse housing orifice and a radial face so that the cutoff gases can flow directly via said channel 25 to at least one sealing flange to push against one of the side faces to ensure a seal. According to a particular embodiment of the invention, the rotary bar comprises two channels respectively connected between the transverse housing orifice and a radial face so that the cutoff gases can flow directly via said channels to the puddles. sealing to push them against the side faces to ensure a seal. According to another particular embodiment of the invention, the rotary bar comprises a channel opening and running on either side of the rotary bar from a first to a second radial face.

Advantageously, the opening channel has a longitudinal axis parallel to a longitudinal axis of the rotary bar. Advantageously, the opening channel comprises a longitudinal axis aligned with a longitudinal axis of the rotary bar so that the cutting gases can exert a thrust force substantially aligned with the longitudinal axis of said bar and evenly distributed on the sealing flanges. . Preferably, the sealing flanges comprise lateral cheeks covering at least partially the longitudinal surface of the rotary bar. Preferably, the lateral cheeks partially close the transverse housing housing of the bar.

Preferably, the lateral cheeks are positioned on the entire cylindrical periphery of the sealing flange. According to one embodiment of the invention, the sealing flanges comprise at least one eccentric through hole for the passage of a connecting bar for mechanically securing a plurality of bars, the connecting bar being controlled by a mechanism common to the set of several unipolar blocks. Advantageously, the breaking block comprises a pair of fixed contacts, each fixed contact cooperating with the rotating contact bridge and a current supply conductor. The block comprises two arc extinguishing chambers respectively opening on an opening volume of the contact bridge. Each interrupting chamber is connected to at least one exhaust channel of the cutoff gases, said exhaust channels being opening on an upstream face of the case of the cutoff block, said upstream face being positioned opposite to another downstream face intended to be placed in contact with triggering means. Advantageously, said exhaust channels of the cutoff gases meet in a common duct leading to the upstream face of the casing of the cutoff block.

Preferably, the exhaust channels of the cutoff gases, respectively of a first and second breaking chambers are of different length, the cutoff gases flowing in a first exhaust channel being intended to suck by Venturi effect the gases flowing in a second exhaust channel. According to a development mode of the invention, said at least one gas escape channel of an arc cutting chamber passes through at least one decompression chamber comprising at least one wall covered with at least one metal sheet. The breaking device according to the invention comprises at least one breaking block as defined above. Said device comprises a mechanism for actuating the contacts, said at least one breaking block being intended to be connected on the one hand to the trigger 7 at the downstream range 5 and on the other hand to a current line to be protected at level of an upstream range 4. The circuit breaker according to the invention comprises a cut-off device as defined above. Said circuit breaker comprises a trigger connected to the downstream beaches 20 of the cut-off device. BRIEF DESCRIPTION. Other advantages and features will emerge more clearly from the following description of a particular embodiment of the invention, given by way of non-limiting example, and represented in the accompanying drawings, in which: FIG. 1A shows a sectional side view of a known unipolar break block; Fig. 1B shows a perspective detail view of a rotary bar of a break block in Fig. 1A; FIG. 2 represents an overall perspective view of a circuit breaker comprising a breaking device according to one embodiment of the invention; FIG. 3A represents an exploded perspective view of a circuit breaker comprising a cut-off device according to one embodiment of the invention; Figure 3B shows a perspective view of a cut-off device during assembly according to one embodiment of the invention; Figures 4 to 8 show perspective views of a unipolar cutoff block and a portion of its housing according to a preferred embodiment of the invention; Figures 9A and 9B show detailed sectional views of a gas exhaust channel of a cutoff unit according to the invention. DETAILED DESCRIPTION OF AN EMBODIMENT According to one embodiment of the invention, the circuit breaker 100 comprises a trigger 7 associated with a cut-off device 600.

The breaking device 600 according to the invention comprises at least one unipolar breaking block 10. The unipolar breaking block according to the invention is intended to be connected on the one hand to the trigger 7 at the downstream range 5 and to on the other hand, to a current line to be protected at an upstream range 4. The unipolar cutoff block 10 is also called a light bulb.

According to one embodiment of the invention as shown in FIGS. 3A, 3B, the cut-off device 600 comprises three unipolar breaking blocks. The switching device 100 is then a three-pole circuit breaker. According to other embodiments not shown, the switchgear could be a uni circuit breaker, bi or four-pole.

For the sake of simplification of the presentation of a preferred embodiment of the invention, the elements making up the switching apparatus 100, and in particular the unipolar breaking blocks 10 forming the breaking device 600, will be described in relation to the use position in which the circuit breaker 100 is placed in a table, with the nose 9 comprising a vertical handle and parallel to the mounting wall, the upstream connection pads 4 on the power line located at the top and forming the face upper 74 of the cut-off device 100 and the trigger 7 at the bottom. The use of relative positional terms, such as "lateral", "superior", "background", etc., should not be construed as a limiting factor. The handle is intended to control an actuating mechanism 8 of the electrical contacts. Each unipolar break block 10 allows the breaking of a single pole. Said block is advantageously in the form of a flat housing 12 of molded plastic, with two large parallel faces 14 distant of a thickness e. In particular, in the illustrated embodiment, the thickness e is of the order of 23 mm for a 160 A caliber. The housing 12 is formed of two parts, preferably mirror-symmetrical, secured to one another. on their large surface 14 by any suitable means. As illustrated in an embodiment in FIG. 4, a complementary tenon / mortise type system allows the fitting of the housing portions 12 to one another, one of the two parts (not shown) comprising adapted lugs to penetrate recesses of the other. Arrangements 18 are also made to allow the juxtaposition of the housings 12 of unipolar block 10 and their connection to a multipole circuit breaker 100. The unipolar breaking unit comprises a cut-off mechanism 20 housed in the housing 12. The cut-off mechanism 20 comprises a movable contact bridge 22 rotatable around a Y axis of rotation. The movable contact bridge 22 comprises at least one end having a contact pad. Said contact pad of the movable contact bridge 22 is intended to cooperate with a fixed contact. Said bridge is pivotally mounted between an open position in which the contact area is spaced apart from a fixed contact 41 and a current flow position in which it is in contact with the fixed contact 41. The movable contact bridge 22 is mounted floating in a rotary bar 26 having a transverse housing hole 21 of said contact bridge. The movable contact bridge 22 passing through the transverse housing orifice 21 projects from the bar 26. Said rotary bar 26 is interposed between two lateral faces 14 of the housing 12 cutoff block 10. According to a development mode of the invention shown in Figures 5, 7 and 8, two sealing flanges 27 are preferably placed respectively between the radial faces of the rotary bar 26 and the side faces 14 to ensure a seal between the inside and outside of the block By way of example, taking into account the shape of the rotary bar, the sealing flanges 27 are of cylindrical shape and may take the form of a washer. ~ o The rotating bar 26 comprises at least one channel 29 in direct connection between the transverse housing orifice 21 and a side face 14 so that the cutoff gases can flow directly via said channel to at least one flange of sealing 27 to push against one of the side faces 14 to ensure a seal. According to a first alternative embodiment, the rotary bar 26 preferably comprises two channels 29 respectively connected between the transverse housing orifice 21 and a radial face so that the cutoff gases can flow directly via said channels to the sealing flanges 27 to push them against the side faces 14 to ensure a seal. According to a second alternative embodiment, the channel 29 of the rotary bar 26 is preferably opening and passes on either side of the rotary bar 26 from a first to a second radial face. Said opening channel 29 preferably comprises a longitudinal axis parallel to a longitudinal axis of the rotary bar 26. In addition, the opening channel 29 preferably comprises a longitudinal axis 25 aligned with a longitudinal axis of the rotary bar 26 so that the gases cutoff can exert a force to push substantially aligned with the longitudinal axis of the bar and evenly distributed on the sealing flanges. According to a particular embodiment of the sealing flanges 27, said flanges comprise lateral cheeks at least partially covering the longitudinal surface of the rotary bar 26 to partially close the transverse housing orifice 21. The lateral cheeks are preferably positioned on all cylindrical periphery of the sealing flange 27. According to a preferred embodiment illustrated in Figures 5 to 8, the cutoff mechanism 20 is double rotary cut. In fact, the switching device 100 according to the invention is particularly intended for applications up to 630 A and in some applications up to 800 A, for which the simple cut may not be sufficient. The movable contact bridge 22 then comprises at each end a contact pad. The contact pads of the contact bridge 22 are preferably placed symmetrically with respect to the axis of rotation Y. The rotatable movable contact bridge 1 o through the transverse housing orifice 21 protrudes from both sides. Another of the bar 26. The breaking block comprises a pair of fixed contacts 41, 51 intended to cooperate with a contact pad of the movable contact bridge 22. Said bridge is pivotally mounted between an open position in which the contact pads are spaced apart from the fixed contacts 41, 51 and a current passage position in which they are in contact with the fixed contacts 41, 51. A first fixed contact 41 is intended to be connected to the current line by an upstream range 4. A second fixed contact 51 is intended to be connected to the trigger 7 by a downstream range 5. The unipolar breaking block 10 comprises two arc-breaking chambers 24 for extinguishing the electric arcs. Each interrupting chamber 24 opens on an opening volume between a contact pad of the contact bridge 22 and a fixed contact 41, 51. Each breaking chamber 24 is delimited by two side walls 24A, a rear wall 24B remote. the opening volume, a bottom wall 24C close to the fixed contact and a top wall 24D. As shown in FIG. 5, each interrupting chamber 24 comprises a stack of at least two deionization vanes 25 separated from each other by a gap of exchange of the cutoff gases. As, according to a particular embodiment of the invention, such as in particular described in the French patent application filed today in the name of the Applicant and entitled: "Cutoff device having at least one unipolar cutoff block having a bridge of contacts and circuit breaker comprising such a device ", the housing 12 of the cutoff unit 10 further comprises arrangements for optimizing the flow of gases. Each interrupting chamber 24 comprises at least one output connected to at least one exhaust channel 38, 42 of the cutoff gases. Said exhaust channels 38, 42 are intended to evacuate the gases through at least one opening orifice 40 positioned on an upstream face of the housing 12 positioned opposite another downstream face. The downstream face of the housing 12 is intended to be placed in contact with the trigger 7. Each arc cutting chamber 24 has less than an exchange space between two fins 25 connected to a gas exhaust channel 38, 42. Preferably, all the exchange spaces are connected to the gas exhaust ducts 38, 42 at a zone remote from the opening volume towards the rear wall and at the side walls of the cutoff chamber. arc 24. According to this embodiment, the mounting of the contact bridge 22 and the rotary bar 26 in a unipolar breaking block 10 is "inverted": it is desired that the lever 9 of the mechanism 8 for actuating the contacts (see FIG. Figures 2 and 3A) is centered on the cut-off device 600 of the circuit breaker 100 in operation, the protective cover of the protective devices of the power line can then be symmetrical. To this end, a reversal of the direction of rotation of the bar 26 has been chosen, that is to say that the connection area 5 to the trigger 7 is located towards the rear of the circuit breaker 100 and the upstream connection range 4 is forward, above. Thus, the movable contact bridge 22 is rotatable between an open position and a closed position of the contacts in a clockwise direction. Thus, in this preferred embodiment in which the direction of rotation of the rotating contact bridge is reversed, the escape of the gas from the contact connected to the downstream range 5 which would have traditionally been downwardly directed and rear of the device is brought up and the front of the cutoff unit 10. The area placed at the back and bottom of the device corresponds to an area in which are placed the trigger 7 and possible supports fixing such as in particular a DIN rail. In particular, the substantially parallelepipedal shape of the casing of the casing 12 of the cut-off block 20 is extended on the front side by a first gas exhaust channel 38. Said first channel makes it possible to direct the cutoff gases of the range 10 downstream 5 coupled to the trigger 7 to the upper part of the switchgear 100. The cutoff gases are discharged outside the housing through a through hole 40. The positioning of the opening port 40 in the upper part of the cutting device and especially above the upstream range 4 also reduces the risk of rebooting the arc. Furthermore, advantageously, the escape of the gases from the contact 41 connected to the upstream range 4 are also directed upwards and forward of the breaking block 10 via at least a second exhaust channel 42. at least one exhaust channel 42 is positioned at least partly in the large parallel faces 14 of the housing 12 of the cut-off block 10. As shown in FIG. 6, in a development mode, two lateral escape channels 42 are arranged in part outside the housing 12 of the cut-off block 10. These two channels are connected to one and the same cutoff chamber 24. Each lateral exhaust channel 42 is connected inside the housing 12 by two orifices 44A, 44B. The portion of the external lateral flow channel 42 may preferably be hollowed out in the wall of the housing 12. According to a development mode of the invention shown in FIGS. 5 and 6, all the gas exhaust channels 38, 42 they meet in a common conduit opening on the upstream face of the housing 12 of the cut-off block 10. The cutoff gases are then discharged via a single opening orifice 40. Thus, the gases generated at the time of the cut in the breaking chambers 24 are advantageously directed away from the trigger 7 and any mounting brackets such as including a DIN rail. According to a first variant embodiment, the exhaust channels of the gases 38 and 42 respectively of a first and second breaking chambers 24 are of different lengths, the cutoff gases flowing in a first exhaust gas channel being intended to to suck by the Venturi effect the gases flowing in a second channel. Advantageously, each part of the housing 12 is molded with internal arrangements allowing a relatively stable positioning of the various elements making up the breaking mechanism 20, in particular two symmetrical housings for each of the breaking chambers 24, and a circular central housing allowing the implementation of the bar 26. As, according to a particular embodiment of the invention, such as in particular described in the French patent application filed today in the name of the Applicant and entitled: "Functional spacer separation of the ampoules in a device multipole breaking circuit breaker and circuit breaker ", the unipolar blocks 10 are assembled through spacers 46 to form a double jacket 48. It is advantageous to take advantage of this architecture to integrate each lateral flow channel 42 in part to 46. In particular, as illustrated in FIG. 4, the spacers 46 are molded plastic and mainly comprise a central partition 52, intended to be parallel to the large faces 14 of the cutoff blocks 10. The juxtaposition of two spacers 46 and defines a cavity 56 in which is housed a unipolar break block 10; advantageously, two opposing bottom flanges 54 of each spacer 46 close the cavity 56 on its rear in a substantially watertight manner when the spacers 46 are tightened one on the other. Each spacer 46 includes arrangements to define in part the second lateral channels 42 of gas evacuation. Advantageously, each lateral flow channel 42 is partially etched in the large outer face 14 of the housing 12 of the bulb 10, between the two through-holes 44A, 44B, and a corresponding element 68, etching and / or protruding contour on the central partition 52. At the time of the juxtaposition and the clamping of the spacer 46 on the bulb 10, it is then possible to direct the gas from the discharge orifice 44A to the upper orifice 44B along from the partition 52.

The unipolar cutoff blocks 10 are intended to be driven simultaneously, and are coupled for this purpose by at least one rod 30, in particular at the bar 26, and for example by orifices 32 forming the limit stops of the movable contact bridge. 22. According to a preferred embodiment, a single drive rod 30 is used and each housing portion 12 comprises an orifice 34 in the shape of a circular arc allowing at least the mobilization of the rod 30 passing through it between the position of current flow and the open position. As, according to a particular embodiment of the invention, such as in particular described in the French patent application filed today in the name of the Applicant and entitled: "Cutoff device comprising effective means for evacuation of cutoff gases" said at least second gas exhaust channel 42 passes through at least one decompression chamber 43 having at least one wall covered by a metal foil 85. Said decompression chamber is preferably positioned as close as possible to the exit of the chamber arc cutting. According to a particular embodiment, the decompression chamber is placed under the bottom wall of the arc extension chamber 24. As shown in FIGS. 9A, 9B, the inner wall covered by the metal sheet 85 is in a plane forming an angle α between 45 ° and 180 ° with respect to the direction of gas flow. The inner wall covered by the metal foil is preferably in a plane perpendicular to the flow direction of the gases (a = 90 °).

According to a second variant of the embodiments, a gas exhaust channel 38 comprises a rotary valve 45 intended to be rotated by the passage of the cutoff gases. The rotation of the valve from a first position to a second position is intended to actuate triggering means of the cutoff device to cause the opening of the contacts.

The circuit breaker 100 according to the invention thus obtained makes it possible to best meet the following antinomic industrial constraints: the same architecture can be used for the entire range up to 800 A thanks to the use of a double bridge break. mobile contact 22; the reliability of the cutoff mechanisms and their optimization is proven by the use of proven solutions; the trigger 7 can be connected from below to the downstream range of the cutoff device 600, which gives the best accessibility to the connection screws by reversing the direction of rotation of the rotary cutoff bridge 22; The interchangeability of the triggers 7 is complete and allows a very delayed differentiation of the switching devices 100; the nose 9 of the cut-off device 600 is centered, in particular at 42.5 mm, thanks to the reversal of the direction of rotation in the cut-off blocks 10, which makes it possible to use symmetrical plastrons in the cabinets; the cutoff gases are not evacuated next to the trigger 7, which limits the pollution on this element which can be sensitive, especially in its electronic version, and releases volume; the exhaust gas cutoff is also not carried out under the connections 4, 5 of the circuit breaker 100, which limits the risks of ignition in cutoff;

Claims (2)

REVENDICATIONS1. Unipolar breaking block comprising: - a rotary contact bridge (22), - at least one fixed contact (41, 51) cooperating with said contact bridge and connected to a current supply conductor (4, 5), - a rotary bar (26) having a transverse housing orifice (21) with play of said contact bridge, which protrudes from the bar (20), said rotary bar (20) being interposed between two lateral faces (14) of the block cutoff, said lateral faces being substantially parallel - two sealing flanges (27) respectively placed between the radial faces of the rotary bar (26) and the lateral faces (14) to ensure a seal between the inside and the outside the breaking block, - at least one arc extinguishing chamber (24) opening on an opening volume of the contact bridge (22), characterized in that the rotary bar (26) comprises at least a channel (29) in direct connection between the transverse housing orifice (21) and a this radial so that the cutoff gases can flow directly via said channel to at least one sealing flange (27) to push against one of the side faces (14) to provide a seal. 2. Cutoff unit according to claim 1, characterized in that the rotary bar (26) comprises two channels (29) respectively connected between the transverse housing orifice (21) and a radial face so that the gases cutoff can flow directly via said channels to the sealing flats (27) to push them against the side faces (14) to provide a seal. Cutoff block according to claim 1, characterized in that the rotary bar (26) comprises a channel (29) opening and through on both sides the rotary bar (26) from a first to a second radial face. 1415. Cutoff block according to claim 3, characterized in that the channel (29) opening comprises a longitudinal axis parallel to a longitudinal axis of the rotary bar (26). 5. Cutoff unit according to claim 4, characterized in that the channel (29) opening comprises a longitudinal axis aligned with a longitudinal axis of the rotary bar (26) so that the cutoff gases can exert a thrust force substantially aligned with the longitudinal axis of said bar and distributed evenly over the sealing flanges (27). 6. Cutoff unit according to any one of the preceding claims, characterized in that the sealing flanges (27) comprise lateral cheeks at least partially covering the longitudinal surface of the rotary bar (26). 7. Cutoff unit according to claim 6, characterized in that the side flanges partially close the transverse housing hole (21) of the rotary bar (26). 8. Cutoff unit according to claim 6 or 7, characterized in that the lateral cheeks are positioned over the entire cylindrical periphery of the sealing flange (27). 9. Cutoff unit according to one of the preceding claims, characterized in that the sealing flanges (27) comprise at least one eccentric passage hole (32) for the connecting bar passage (30) for mechanically fastening several rotary bars (26), the connecting bars (30) being controlled by a mechanism common to the set of several unipolar blocks. 10. Cutoff block according to one of the preceding claims, characterized in that it comprises a pair of fixed contacts (41, 51), each fixed contact cooperating with the rotating contact bridge (22) and a conductor (4). 5), two arcing chambers (24) respectively opening on an opening volume of the contact bridge (22), each interrupting chamber (24) being connected to least one exhaust gas channel (38, 42), said exhaust channels being opening on an upstream face of the housing (12) of the cut-off block (10), said upstream face being positioned opposite the another downstream face intended to be placed in contact with triggering means (7). 11. Cutoff unit according to claim 10, characterized in that said 10 exhaust channels cutoff gases (38, 42) meet in a common conduit opening on the upstream face of the housing (12) of the cutoff block ( 10). 12. Cutoff unit according to claim 11, characterized in that the exhaust gas channels (38, 42) respectively of a first and second breaking chambers (24) are of different length, the cutoff gases circulating in an exhaust channel being intended to suck by Venturi effect the gases flowing in a second exhaust channel. 13. Cutoff block according to one of claims 10 to 12, characterized in that said at least one gas exhaust channel (42) of an arc cutting chamber (24) passes through at least one chamber decompression device (43) having at least one inner wall covered by a metal sheet (85). 14. Cutoff device (600) comprising at least one cutoff block (10) according to the preceding claims, characterized in that it comprises a mechanism (8) for actuating the contacts, said at least one cutoff block being intended to be connected on the one hand to the trigger 7 at the downstream range 5 and on the other hand to a current line to be protected at an upstream range 4. 15. Circuit breaker (100) comprising a cut-off device (600) according to claim 14, characterized in that it comprises a trigger (7) connected to the downstream ranges (5) of the cut-off device (600).