EP2819137B1 - Arc chamber for an electric protection device and electric protection device including such an arc chamber - Google Patents

Description

TECHNICAL AREA

The present invention relates to electrical protection devices intended to achieve the interruption of the electric current by separation of the contacts so as to protect the goods and the people from the effects of short-circuit currents, and more particularly the field of protection circuit breakers. ultra terminal type.

The invention relates more particularly to the exhaust volume located downstream of the breaking chamber of such an apparatus.

This interrupting chamber comprises an arc forming chamber enclosing a fixed contact and a movable contact which, at the moment of their separation, form an arc between them, said arc forming chamber communicating with the input of a second so-called arc extinction chamber, at least one partition wall placed in a volume located downstream of said arc extinction chamber, said wall extending in the direction of the gas flow so as to achieve a partitioning of the above-mentioned volume in the direction of this flow of gases, and at least one discharge orifice for evacuation of the cutoff gases to the outside of the apparatus.

STATE OF THE PRIOR ART

In known manner, as soon as the contacts separate due to the occurrence of a short circuit in an electrical circuit, an electric arc occurs between the contacts, which arc will establish an arc voltage.

Then, the arc moves to an arc extinguishing chamber usually having separators for cooling the gases, after which the gases due to the arc exit the arc extinction chamber and pass through slots arranged in a bottom grid located downstream of the separators.

These gases are then collected in a volume which is located under the arc extinction chamber.

This volume may consist of one or more channels intended to allow the flow of gas to the outlet ports provided in the housing of the apparatus through which these gases escape to the outside.

For example, patents are known WO 02/075760 and FR 2575861 describing a cutoff chamber equipped with a wall forming a partitioning of the aforementioned volume in the direction of the gas flow.

The patent FR 2575861 further describes the use of baffles downstream of the arc extinguishing chamber, the purpose of which is to slow down the gas flow.

These known architectures of the exhaust zone are not entirely satisfactory. In fact, gaseous plugs are formed at the outlet of the interrupting chamber, which plugs are due to a conflictual interaction between the flows occurring between the separators. Indeed, the gas flows out of the breaking chamber in a direction perpendicular to the direction they must follow to go to the discharge ports at the end of the gas collection volume.

This problem related to the flow of gas may be at the origin of a partial melting of the aforementioned bottom grid. This problem is all the more important as it reduces the step of the circuit breaker, this reduction of the step resulting in a reduction of the collection volume.

The electrical protection device of the document is also known. FR2977066 gathering the features of the preamble of claim 1.

SUMMARY OF THE INVENTION

The present invention solves these problems and proposes a breaking chamber for a electrical protection apparatus, of simple design, for removing these gaseous plugs so as to increase and stabilize the voltage of the short-circuit arc, in particular in the prechambre, and thus allow a faster and more frank cut, as well as an electrical protection device comprising such a chamber.

For this purpose, the subject of the present invention is an interrupting chamber for an electrical protection device according to claim 1.

Thanks to this total separation of the gas flows, it is avoided that the main flow has a negative influence on the secondary flow.

By means of this flow separation, this particular embodiment of the interrupting chamber avoids the gaseous plugs occurring at the outlet of the interrupting chamber, because of the conflicts that may occur between the flows between the separators.

According to another characteristic, the electrical protection apparatus comprising an electromagnetic protection device, and the arc extinguishing device being located between this electromagnetic protection device and the fixing face of the device to a device. fixing bracket, the first main flow is issued on the side of the fixing support while the second secondary flow is issued on the side of the electromagnetic protection device.
Due to this structure of the apparatus, the main flow occurs on the side of the fixing support, for example a fixing rail, while the secondary flow occurs on the side of the electromagnetic protection device and is more low.

According to another characteristic, the section of the aforementioned ducts gradually decreases when approaching the discharge orifices.

According to another characteristic, this breaking chamber comprises an insulating bottom grid placed downstream of the arc extinguishing chamber and having orifices intended to allow the passage of the gases generated during the breaking.
The dissociation of the flows improves the gas crossover effects between the different outlets of the chamber bottom grid.

According to another characteristic, this chamber further comprises means for balancing the lengths of the paths of the gas flows in the two ducts. As a result, the length of the main flow path is closer to that of the secondary flow path. This feature allows the arc to return in a direction perpendicular to the alignment axis of the separators of the arc extinguishing chamber.

According to another characteristic, these means comprise means for separating the gas flows according to the thickness of the apparatus. The realization of this partitioning in three dimensions thus makes it possible to have an adapted length of these ducts in spite of the asymmetrical architecture of these ducts due to the location of the exhaust orifices on the fixing face of the apparatus.

According to another characteristic, the aforementioned separation means according to the thickness of the apparatus comprise two partitions substantially perpendicular to each other and forming a step, said step being arranged in the said first conduit so as to form a volume protruding into this duct, and at the same time to increase the length of the path of the gaseous flow in this conduit, and in return, to form a hollow volume in the conduit said second, the gas flow flowing in the first conduit above this step while the gas stream flows in the second conduit below this walk.

According to another feature, the discharge port associated with the second conduit is located under the aforementioned step, while the discharge port associated with the first conduit is located at the foot of the step.

According to another characteristic, the aforementioned discharge orifices are located at the same height, the latter being defined parallel to the rear face of the apparatus and perpendicular to the longitudinal direction of the fixing support.

According to a particular embodiment, the aforementioned ducts are integrally molded with the casing of the apparatus.

In another embodiment, the aforementioned conduits are housed in a modular cassette.

The present invention further relates to an electrical protection apparatus comprising a breaking chamber having the above-mentioned features taken alone or in combination.

According to a particular characteristic, this apparatus is a low-voltage circuit breaker.

BRIEF DESCRIPTION OF THE DRAWINGS

• La figure 1 est une vue en plan d'un disjoncteur selon l'art antérieur, illustrant la partie intérieure de l'appareil,
• La figure 2 est une vue en plan partielle de la figure précédente, illustrant la chambre de coupure seule,
• La figure 3 est une vue similaire à la figure précédente, mais illustrant une chambre de coupure selon une réalisation particulière de l'invention,
• La figure 3a est une vue en coupe selon m-m de la figure 3,
• La figure 3b est une vue de gauche de la figure 3,
• Les figures 4 et 4a sont des vues en perspective, respectivement selon deux orientations différentes, illustrant la chambre de coupure selon la réalisation particulière illustrée sur les figures 3,3a et 3b, et
• La figure 5 est une représentation graphique illustrant le courant et la tension d'arc en fonction du temps, dans une chambre de coupure selon l'art antérieur, et dans une chambre de coupure selon l'invention,

But other advantages and features of the invention will become more apparent in the detailed description which follows and refers to the accompanying drawings given solely by way of example and in which:

• The figure 1 is a plan view of a circuit breaker according to the prior art, illustrating the inner part of the apparatus,
• The figure 2 is a partial plan view of the previous figure, illustrating the cutoff chamber alone,
• The figure 3 is a view similar to the previous figure, but illustrating a breaking chamber according to a particular embodiment of the invention,
• The figure 3a is a sectional view according to mm of the figure 3 ,
• The figure 3b is a left view of the figure 3 ,
• The Figures 4 and 4a are views in perspective, respectively in two different orientations, illustrating the breaking chamber according to the particular embodiment illustrated on the Figures 3,3a and 3b , and
• The figure 5 is a graphical representation illustrating the current and the arc voltage as a function of time, in a breaking chamber according to the prior art, and in a breaking chamber according to the invention,

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

On the figure 1 , we see a miniature circuit breaker pole p comprising an insulating housing B having on its front face a maneuvering handle M and on its two narrow side faces, connection terminals 1,2. Inside the housing are housed, as is known per se, a movable contact 3 and a fixed contact 4.
The movable contact 3 is controlled by a control mechanism C connecting the aforesaid lever M to the movable contact for closing or opening the contacts.

In this housing are also housed a thermal trip unit 5 and an electromagnetic release 6 may cause, in case of overload or short circuit, an automatic opening of the contacts 3,4.
The lower part of the housing B encloses a breaking chamber 7 constituted by a first so-called arc-forming chamber 8, communicating with the inlet of a second chamber 9, said arc extinction, the latter comprising fins 10.
The movable contact 3 extends substantially perpendicular to the plane in which the plates extend, so as to stretch an arc between the contacts during their separation, whose initial direction is substantially parallel to the plates. The aforementioned breaking chamber 7 is delimited laterally by arc horns 11, 12 respectively electrically connected to the two aforementioned terminals. These arc horns are arranged to capture the arc drawn between the contacts during their separation.
This circuit breaker comprises, downstream of the arc extinguishing chamber, a volume v for exhausting the cut-off gases and, at the outlet of this volume, orifices for evacuating gases towards the outside of the apparatus.
As such a circuit breaker is well known to specialists, it will be useless to describe in more detail its arrangement or its operation.
The arc extinguishing chamber 9 of the circuit breaker advantageously comprises, in a known manner at its downstream part, a gate 13 made of a plastic material, which may be molded with the housing or the cover of the apparatus, but may also be to be independent. The function of this grid is to prevent the arc from reforming behind the fins downstream of the arc extinction chamber.
On the figure 2 has been shown a breaking chamber 14 according to the prior art having downstream of the arc extinguishing chamber 15, a partition 16 for separating the gas flow in the flow direction.
On the Figures 3 to 4a , we see a breaking chamber 17 according to a preferred embodiment of the invention, wherein the volume 18 for collecting the gas stream is partitioned firstly in the direction of the gas flow, and secondly, according to the invention. thickness of the apparatus.

The partitioning according to the direction of the flow is carried out by a partition wall 19 starting from the separators 20, at a position situated between one quarter and three quarters of the length of the set of separators, then, after a curvature, extending up to to the plane of the rear face 21, or fixing face, of the apparatus. This partition wall 19 is thus formed of two portions 19a, 19b extending at an angle of between 90 ° and 160 ° relative to one another, one extending in a plane substantially parallel to the plane of the fins 20, while the other extends in a plane extending substantially perpendicularly to the face 21 of fixing the device. Note that the angle between the two partitions will vary depending on the position of the partition. This partition 19 thus forms two exhaust ducts 22, 23 of the gas stream, respectively a first duct 22 located opposite the fins 24 situated as close as possible to the exhaust orifices 25, 26 of the outward gas ducts, and a second duct 23 located opposite the fins 27 located away from these orifices, each duct 22, 23 being associated with a discharge orifice 25, 26.

This partitioning according to the thickness of the apparatus is achieved by means of a step 28 formed projecting inside the first conduit 22 and hollow inside the second conduit 28, this step formed of two walls 28a, 28b substantially perpendicular to each other creating an additional volume of substantially parallelepiped shape in the first duct 22 and at the same time decreasing the volume of the second duct 23 by the same volume. It will be noted that other shapes than the parallelepipedal shape are possible for this wall.
This partitioning according to the thickness of the apparatus makes it possible to carry out the two aforesaid evacuation conduits 22, 23 associated respectively with two discharge outlets 25, 26 of the outward gas, these being situated at the same height. , this height being defined perpendicular to the longitudinal direction of the fixing rail.
Note that these openings or discharge orifices may be of different positions, size and shape, for example one above the other, one next to the other, staggered according to lock position and shape partitions. In addition, as explained above, these openings may open elsewhere than towards the rear of the circuit breaker.

Thus, in operation, thanks to the dissociation of the flows carried out by the partitioning according to the flow direction, which partitioning is carried out along the entire path of the gases, the gaseous flows furthest from the exhaust ports 25, 26 are collected separately from each other. those emitted near the gas outlet orifices, said orifices being on the side of the fixing rail R.
This dissociation of the flows improves the flows by limiting the effects of gas crossing between the different outlet orifices of the chamber bottom grid 13. By limiting these crossing effects, it also limits the flow disturbances likely to create the aforementioned plugs.
This partitioning according to the thickness of the apparatus makes it possible to rearrange the volume v of gas collection by a redistribution of the volume used by the second duct 23. This remodeling makes it possible on the one hand to lengthen the length of the path of the gases in the first conduit, which allows the gases to be emitted at a lower temperature than usual in the apparatus according to the prior art.
This rearrangement of the collection volume v also makes it possible to obtain in the two ducts 22, 23 a progressive decrease in the section of the exhaust ducts as one approaches the exhaust outlet in order to keep account of the decrease of the temperature and therefore of the volume of the gases.
The realization of this partitioning according to the three dimensions thus makes it possible to have an adapted length of these ducts in spite of the asymmetric architecture of the exhaust ducts due to the location of the exhaust orifices on the face 21 for fastening the appliances.
The realization of these arrangements can be made advantageously during the molding of the casings of the circuit breaker.
This volume v of cut gas collection can also be performed in a modular cassette in the form of a cassette dissociated envelopes. One of the advantages of this realization of the collection volume in a cassette dissociated is to be able to develop the different compartments according to the constraints related to the flow of gases and to offer flexibility in the material of this cassette, regardless of the device.
In addition, this solution has the advantage of enabling specialized cassettes to be optimized for a particular type of product depending on its performance (high breaking capacity, low breaking capacity), its cost, the fact that it is associated with a Vigi or not, etc ...
Referring to the figure 5 , it is possible to compare the breaking behavior of an apparatus according to the prior art compared to that of an apparatus according to the invention performing a separation of the flows at 6kA.
The graphical representation of the figure 5 illustrates the current in ampere (left scale) and the arc voltage (right scale) as a function of time in seconds. It is observed that in the case of an apparatus according to the invention, the rise in arc voltage (curve a) is performed 400 μs faster than in the case of an apparatus according to the prior art (curve b). This gives a better limitation of the current in a breaking chamber according to the invention (curve c) with respect to that obtained in the breaking chamber according to the prior art (curve d).

It will be noted that this dissociation of the gas flows can be carried out by means of one or more flow separation partitions, this or these partitions being arranged in such a way that the partitioning is carried out as far as the outlet orifices, so as to obtain this dissociation. This separation of the streams makes it possible to obtain a good cooling of the gases before they are ejected from the product.

Thus, according to the invention, an interruption chamber and an electrical protection device comprising it have been realized, in which the gaseous flows are dissociated so as to eliminate the influence of one of the flows on the other of the flows and on the other hand, in which the main gas flow is disturbed so as to disadvantage it with respect to the secondary flow, and thus favor a homogeneous arc insertion.

Thus, the invention for removing gaseous plugs, which currently go up even at the mechanism of the device, this increases and stabilize the short-circuit arc voltage, particularly in the prechamber. This also allows to obtain a faster and more frank cut to obtain better protection of property and people. The invention also makes it possible to better manage the gaseous flow at the outlet of the chamber, thus to better evacuate the cut-off residues from the chamber and thus to make the product more robust.
The invention also makes it possible to ensure, in addition, the maintenance and positioning of the chamber, to be able to choose a material different from that of the housings in the case of the choice of using a cassette, this possibility being more difficult in the case of partitions. molded directly into the envelopes.
Of course, the invention is not limited to the embodiments described and illustrated which have been given by way of example.
For example, the number of partition walls can be increased so as to further increase the dissociation of the gas flows.
Similarly, the main claim also covers the case where the discharge ports are lateral to the ducts formed by the wall and close to the rear face of the apparatus. Thus, these orifices can be oriented upwards, downwards, or laterally. Similarly, these openings may lead into the terminal compartment or to the differential protection device, etc .....

Claims (13)

1. Switching chamber for an electrical protection device comprising an arc-forming chamber enclosing a fixed contact and a mobile contact which, at the moment of their separation, form an arc between them, said arc-forming chamber communicating with the input of a second, so-called arc extinguishing chamber, and at least one discharge orifice making it possible to discharge extinguishing gases to the outside of the device, the at least one discharge orifice (25, 26) and the arc-extinguishing chamber (9) being arranged relative to one another in such a way that the gas flows leave the arc-extinguishing chamber (9) in a direction substantially at right angles to the direction in which the gas flows leave the device through the at least one discharge orifice (25, 26), and in that the abovementioned at least one discharge orifice (25, 26) is situated on the rear face (21) of the device intended for its fixing onto a fixing support R,
   characterized in that
   the switching chamber also comprises at least one separation wall placed in a volume situated downstream of said arc-extinguishing chamber, said wall extending in the direction of the gas flow so as to produce a partitioning of the abovementioned volume in the direction of this gas flow,
   and in that
   the abovementioned separation wall(s) (19) extends (extend) in such a way as to produce a substantially complete partitioning in the direction of the flow as far as these orifices and thus form at least one first discharge duct (22) and one second discharge duct (23), said ducts being each associated with a discharge orifice (25, 26), and making it possible to produce a substantially complete separation between a so-called first flow and a so-called secondary second flow, said flows being emitted at the output of the arc-extinguishing chamber (9) and circulating respectively in the first (22) and in the second (23) ducts.
2. Switching chamber according to Claim 1, characterized in that, the electrical protection device comprising an electromagnetic protection device (6), and the arc-extinguishing device (9) being situated between this electromagnetic protection device (6) and the face (21) for fixing the device to a fixing support R, the first so-called main flow is emitted on the side of the fixing support R whereas the second so-called secondary flow is emitted on the side of the electromagnetic protection device (6).
3. Switching chamber according to Claim 1 or 2, characterized in that the section of the exhaust ducts (22, 23) decreases progressively approaching the discharge orifices (25, 26).
4. Switching chamber according to any one of the preceding claims, characterized in that it comprises an insulating base grating (13) placed downstream of the arc-extinguishing chamber (9) and comprising orifices intended to allow the passage of the gases generated during the switching.
5. Switching chamber according to any one of Claims 1 to 4, characterized in that it further comprises means for equalizing the lengths of the paths of the gas flows in the two ducts (22, 23).
6. Switching chamber according to Claim 5, characterized in that these means comprise means for separating the gas flows in the thickness of the device.
7. Switching chamber according to Claim 6, characterized in that the abovementioned separation means in the thickness of the device comprise two partitions (28a, 28b) substantially at right angles to one another and forming a tread (28), said tread being arranged in the so-called first duct (22) so as to form a volume protruding into this duct and, at the same time, to increase the length of the path of the gas flow in this duct, and on the other hand, to form a hollow volume in the so-called second duct (23), the gas flow circulating in the first duct (22) above this tread (28) whereas the gas flow in the second duct (23) circulates below this tread (28).
8. Switching chamber according to Claim 7, characterized in that the discharge orifice (26) associated with the second duct (23) is situated under the abovementioned tread (28), whereas the discharge orifice (25) associated with the first duct (22) is situated at the foot of the tread (28).
9. Switching chamber according to any one of Claims 3 to 8, characterized in that the abovementioned discharge orifices (25, 26) are situated at a same height, the latter being defined parallel to the rear face (21) of the device and at right angles to the longitudinal direction of the fixing support R.
10. Switching chamber according to any one of the preceding claims, characterized in that the abovementioned ducts (22, 23) are produced by moulding with the enclosure of the device.
11. Switching chamber according to any one of Claims 1 to 9, characterized in that the abovementioned ducts (22, 23) are housed in a modular cassette.
12. Electrical protection device comprising a switching chamber according to any one of the preceding claims.
13. Electrical protection device according to Claim 12, characterized in that it is a low-voltage circuit breaker.

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