Title of Invention

A DEVICE FOR DEIONIZING GASES NOTABLY BREAKING GASES AND AN ARC EXTINGUISHING CHAMBER EQUIPPED WITH SAID DEVICE

Abstract The invention relates to a gas deiornzation device and an arc extinguishing chamber notably for a multipole low voltage circuit breaker with a molded case. A porous shield comprising one or more superposed metallic wire cloths. Each cloth is formed by a criss-crossing of straight wire yams spaced apart from and parallel to one another with tight joined undulated wire yams that extend appreciably perpendicular to the straight wire yams, and pass alternately over and under at least one of the successive straight wire yams. At least three superposed wire cloths have progressive mesh openings.
Full Text

A DEVICE FOR DEIONIZING THE GASES NOTABLY THE BREAKING GASES IN AN ARC EXTINGUISHING CHAMBER OF A LOW VOLTAGE MOLDED CASE CIRCUIT BREAKER AND AN ARC EXTINGUISHING CHAMBER EQUIPPED WITH THIS DEVICE
BACKGROUND OF THE INVENTION
The present invention relates to a gas deionization device notably designed to be placed in the zone of the outlet orifice of an arc extinguishing chamber of a multipole low voltage circuit breaker with molded case, and an arc extinguishing chamber equipped with this device.
Devices are known comprising fine-mesh metallic grates or shields, notably made of steel, housed in the outlet orifices of circuit breaker arc extinguishing chambers. The breaking gases generated in the arc extinguishing chamber when breaking takes place are outlet to the outside environment after passing through the grates acting as flame protection shields. It has however been observed that these gases were still highly ionized when outlet from the chamber.
In order to improve deionization by cooling of the breaking gases, other deionization devices have already been proposed, notably a labyrinth formed by a plurality of shields with offset windows, a reflecting grate etc., but the large size of these devices does not enable them to be used in compact arc extinguishing chambers for molded case circuit breakers.
The European Patent EP 0,022,708 describes a deionization device comprising a porous shield formed from agglomerated balls made from a copper base. Gaps are arranged between the balls to enable the breaking gases to pass to the outside environment. This device of compact structure enables a relatively efficient cooling of the breaking gases ventilated from an arc extinguishing chamber with a high breaking capacity to be achieved.
SUMMARY OF THE INVENTION
The present invention proposes an improved deionization device of compact structure enabling an even more efficient cooling of the breaking gases outlet to the outside environment to be achieved, so as to reduce external manifestations.

This device is designed to be incorporated in an arc extinguishing chamber with a high breaking capacity and presents a structure adapted according to the arcing energy developed in said chamber.
For this purpose, the object of the present invention is to provide a gas deionization device comprising a porous shield designed notably to be arranged near to the outlet orifice of the arc extinguishing chamber of a low voltage circuit breaker to perform cooling of the breaking gases generated when separation of the contacts takes place after the circuit breaker has tripped, this device being characterized in that the above-mentioned porous shield comprises at least one cloth called reps comprising a crossed texture of straight wire yarns spaced apart from and parallel to one another with tight joined undulated wire yams, said undulated wire yarns extending appreciably perpendicularly to said straight wire yarns and passing alternately over and under at least one of the successive straight wire yarns.
According to a particular feature, the above-mentioned cloth(s) is (are) made of a corrosion-resistant metallic material such as stainless steel or nickel.
According to a particular embodiment, each cloth comprises meshes of appreciably triangular shape designed for passage of the gas and each defined by a straight wire yarn and two undulated wire yarns tangent to one another in the mid-plane of the cloth.
According to a particular embodiment, at least one of the above-mentioned cloths comprises undulated wire yarns passing alternately over and under one single straight wire yarn at a time, and arranged two by two so that when one passes over a straight wire yarn, the other one passes under this same straight wire yarn.
According to another particular embodiment, at least one of the above-mentioned cloths comprises undulated wire yarns passing alternately under and over two straight wire yarns at a time, each time with an offset of a straight wire yarn with respect to the previous undulated wire yarn, the undulated wire yarns being imbricated.
Advantageously, the undulated wire yams are the weft yarns.

According to another feature, the diameter of the undulated wire yarns is smaller than that of the straight wire yarns.
According to another feature, it comprises at least two superposed cloths having mesh openings of different size.
Advantageously, it comprises at least three superposed cloths having progressive mesh openings, the cloth presenting the largest mesh openings called the first cloth being passed through first by the gases.
Advantageously, the above-mentioned first cloth presents a diameter of undulated and straight yarns greater than 0.5 mm and a nominal opening greater than 400 µm, whereas the last doth presents a nominal opening smaller than 200 µm.
The object of the invention is also to achieve an arc extinguishing chamber notably for a multipole low voltage circuit breaker with an isolating molded case, comprising per pole : a pair of stationary and movable separable contacts, an actuating mechanism of the movable contact, metallic plates for cooling of the arc drawn between said contacts when the latter separate, an orifice for outlet of the breaking gases arranged in the case at the outlet of said chamber and a deionization device, comprising the previous features taken alone or in combination, arranged near to said outlet orifice to cool the breaking gases outlet to the outside environment.
According to a particular feature, this chamber comprises in addition at least one additional perforated shield made of insulating material placed between the ends of the above-mentioned cooling plates and the porous shield.
According to another feature, this chamber comprises in addition perforated plates or stiffeners placed on each side of the porous shield to increase its mechanical resistance to the pressure wave.
BRIEF DESCRIPTION OF THE DRAWINGS
But other advantages and features of the invention will become more cleariy apparent from the following detailed description which refers to the accompanying drawings given to serve as examples only and in which ;

- Figure 1 is a longitudinal sectional view of an arc extinguishing chamber according
to the invention belonging to a molded case circuit breaker represented partially torn
away.
' Figures 2, 2a and 2b illustrate respectively a top view, a cross sectional view and a side view of a cloth called weft reps according to a particular embodiment of the invention.
- Figures 3, 3a and 3b illustrate respectively a top view, a cross sectional view and a side view of a cloth called crossed weft reps according to another embodiment of the invention.
- Figures 4, 4a and 4b illustrate respectively a top view, a cross sectional view and a side view of a cloth called even wrap reps according to another embodiment of the invention.
- Figures 5, 5a and 5b illustrate respectively a top view, a cross sectional view and a side view of a cloth called crossed wrap reps according to another embodiment of the invention.
- Figure 6 is a partial perspective schematic view illustrating a straight weft yam and two adjacent undulated wrap yarns of an even reps cloth.
- Figures 7 and 8 illustrate schematically the path of the gas through respectively two superposed reps cloths and four superposed reps cloths,
- Figures 9, 10 and 11 are partial cross-sectional views illustrating two triangular
meshes associated respectively to an even wrap reps cloth, to a crossed wrap reps
cloth and to an even wrap reps cloth of high porosity.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In figure 1, a low voltage multipole circuit breaker Dr can be seen with a case made from molded insulating material and a manual operating handle. This circuit breaker Dr comprises per pole an arc extinguishing chamber 1 housed in a lower compartment of the case B.

Each arc extinguishing chamber 1 comprises a pair of separable contacts 2, 3 and a stack of cooling plates 4 with V-shaped notches extending transversely to the direction of extension of the arc drawn between the contacts 2, 3 when separation of the latter takes place after the circuit breaker has tripped. The stationary contact 2 is supported by a conductor 5 in the form of a U-shaped pin positioned on an intermediate wall 6 of the case B and in electrical connection with an external connection strip 7. A metallic shielding element 8 is inserted between the two branches of the pin of the conductor 5 and is provided with an extension 9 acting as end separator. The movable contact 3 is securedly united to a contact arm 10 associated to a pivoting bar of the actuating mechanism (not represented) common to all the poles. A braided connecting strap 11 connects the opposite end of the arm 10 to the thermal and electromagnetic tripping elements (not represented) of each pole. The transverse face of the lower compartment of the case B is provided with an orifice 12 for outlet of the breaking gases arranged at the outlet of each arc extinguishing chamber 1.
According to the invention, a gas deionization device, designated by the general reference R, is disposed in each outlet orifice 12 to reduce the external manifestations of the ionized gases by means of an efficient cooling of the hot gases at the outlet of the chamber 1. Each deionization device R cooperates with the plates 4 and comprises a porous shield E formed by juxtaposition of several metallic cloths called reps T,
These reps cloths T are constituted in general manner by a criss-crossing of straight wire yarns 15 spaced apart from and parallel to one another with tight joined undulated wire yarns 16 passing alternately over and under one or more of the successive straight wire yarns 15, and extending appreciably perpendicularly to said straight wire yarns 15.
These reps cloths T may have different structures i.e. for instance an even reps structure or a crossed reps structure. According to the even reps structure represented in figures 2, 4 and 6, the cloth T is formed by parallel straight wire yarns 15 and undulated wire yams 16 passing alternately over and under the successive straight wire yams 15, one at a time, and each time with staggering of a straight wire yarn 15 with respect to the previous undulated wire yarn, that is to say that two adjacent undulated wire yarns 16 pass respectively over and under the same straight wire yarn 15,

According to the crossed reps structure as illustrated in figures 3 and 5, each cloth T is formed by straight wire yams 15 and undulated wire yarns 16, each undulated wire yarn 16 passing alternately over and under two straight wire yams 15 at a time with staggering of a straight wire yam 15 with respect to the previous undulated wire yarn, the undulated wire yarns 16 being criss-crossed.
The parameters defining these structures are among others the diameters of the straight wire yarns 15 and undulated wire yams 16, the spacing apart (or pitch) of the straight wire yarns 15, the nominal opening or mesh gap which corresponds, as illustrated in figures 9. 10, 11 to the diameter of the sphere S tangent to the wire yams 16a, 16b forming the mesh. Advantageously, the diameter d of the undulated wire yams 16 is smaller than the diameter D of the straight wire yarns 15. This weaving enables mesh openings to be obtained which are considerably smaller than the diameter d, D of the wire yams 15, 16 forming the cloth.
Advantageously, the porous shield E is formed by several cloths T as previously described, stacked on one another (advantageously between 2 and 5 cloths). These juxtaposed cloths T have progressive mesh openings, the cloth T having the largest openings, i.e. the diameter of the wire yams is greater, being situated in such a way that the gases pass through it first. This first cloth thus presents a high thermo-mechanical strength necessary for the first element filtering the breaking gases, whereas the last element presents a minimum mesh opening necessary for maximum cooling of the breaking gases. For this purpose, the diameters d, D of the wire yarns (undulated and straight) associated to the first cloth are greater than 0.5 mm and the nominal opening greater than 400µm, whereas the nominal mesh opening associated to the last cloth is less than 200pm.
It should moreover be noted that the progressive decrease of the nominal openings procures a better mastery of the pressure rise in the arc extinguishing chamber.
Referring to figure 1, it can be seen that an additional shield 17 made of insulating material is advantageously placed in the outlet zone of the arc extinguishing chamber 1 in the gap arranged between the ends of the plates 4 and the porous shield E according to the invention.

This insulating shield 17 arranged facing the porous shield E presents a regular and perfectly defined perforation allowing flow of the gases. This shield 17 is designed to prevent the arc from looping back onto the metallic elements of the filter.
It should also be noted that perforated plates or stiffeners (not represented) could be added on each side of the porous shield E. These perforated plates will enable stirring of the gas to be achieved and will increase the mechanical strength of the assembly in order to resist the pressure wave associated with breaking of the short-circuit currents.
Thus, in operation, when breaking of the arc takes place in the extinguishing chamber 1, the breaking gases after they have passed through the insulating shield 17 are efficiently cooled through the porous shield E.
The ionized gases in fact pass through the meshes M formed in the different layers of cloth, each mesh M being defined as can be seen more particularly in figures 9 to 11, whatever the structure of the cloth, even reps or crossed reps texture, by a straight wire yarn 15 and two undulated wire yams 16 tangent to one another in the mid-plane p of the cloth. The ionized gas flows through these passages of minimum cross section and is greatly disturbed in terms of direction and velocity. Figures 7 and 8 should be referred to to observe the path of the gas respectively in an even reps texture cloth and a crossed reps texture cloth. The heat exchanges between the gases and the wire yarns 15, 16 constituting the shield E, and therefore their deionization by cooling, are thus enhanced. It should be noted that it is necessary for the cloth T to keep a certain porosity in order to enable an outflow of the gases thus limiting the overpressure occurring in the apparatus. It will therefore be necessary to find a compromise between the exhaust cross section and the heat exchange surface.
In comparison to traditional square-mesh metallic cloths, these cloths enable considerably finer mesh openings than the diameter of the wire yams of the cloth to be obtained. It is then possible to combine in the same filter a good thermo-mechanical strength and a large heat exchange surface necessary for cooling.
It should be noted that particular reps cloth structures can be envisaged such as for instance the high-porosity reps cloth as illustrated in figure 11, in which the finest

wire yarns 20 are of smaller diameter than the diameter of the sphere S tangent to the wire yarns forming the mesh M,
The material constituting the wire yarns may be any metallic material which is heat-conducting and corrosion-resistant such as stainless steel or nickel.
The number of superposed cloths is varied according to the arc energy developed in the arc extinguishing chamber, For example, for an energy of 200kJ, four thicknesses will be used.
Naturally the invention is not limited to the embodiments described and illustrated which have been given to serve as examples only.
On the contrary, the invention comprises all the technical equivalents of the means described and any combination thereof if the latter are performed within the spirit of the invention.



CLAIMS
1. A gas deionization device, comprising a porous shield designed notably to be
arranged near to the outlet orifice of the arc extinguishing chamber of a low voltage
circuit breaker to perform cooling of the breaking gases generated when separation
of the contacts takes place after the circuit breaker has tripped,
characterized in that the above-mentioned porous shield (E) comprises at least one cloth called reps (T) comprising a crossed texture of straight wire yarns (15) spaced apart from and parallel to one another with tight joined undulated wire yarns (16), said undulated wire yarns (16) extending appreciably perpendiculariy to said straight wire yarns (15) and passing alternately over and under at least one of the successive straight wire yarns (15).
2. The device according to claim 1, characterized in that the above-mentioned
cloth(s) (T) is (are) made of a corrosion-resistant metallic material such as stainless
steel or nickel.
3. The device according to claim 1 or 2, characterized in that each cloth (T) comprises meshes M of appreciably triangular shape designed for passage of the gas and each defined by a straight wire yam (15) and two undulated wire yarns (16) tangent to one another in the mid-plane p of the cloth (T).
4. The device according to any one of the foregoing claims, characterized in that at least one of the above-mentioned cloths (T) comprises undulated wire yarns (16) passing alternately over and under a single straight wire yarn (15) at a time, and arranged two by two so that when one passes over a straight wire yarn (15) , the other one passes under this same straight wire yam (15).
5. The device according to any one of the claims 1 to 3, characterized in that at least one of the above-mentioned cloths (T) comprises undulated wire yarns (16) passing alternately under and over two straight wire yarns (15) at a time, each time with an offset of a straight wire yarn (15) with respect to the previous undulated wire yarn (16), the undulated wire yarns (16) being imbricated.
6. The device according to any one of the foregoing claims, characterized in that the undulated wire yams (16) are the weft yams.

7. The device according to any one of the foregoing claims, characterized in that the diameter of the undulated wire yarns (16) is smaller than that of the straight wire yarns (15).
8. The device according to any one of the foregoing claims, characterized in that it comprises at least two superposed cloths (T) having mesh openings of different size.
9. The device according to any one of the foregoing claims, characterized in that it comprises at least three superposed cloths (T) having progressive mesh openings, the cloth (T) presenting the largest mesh openings, called the first cloth, being passed through first by the gases.

10. The device according to claim 9, characterized in that the above-mentioned first cloth (T) presents a diameter (d) of undulated yarns (16) and straight yarns (15) greater than 0.5 mm and a nominal opening greater than 400 µm, whereas the last cloth presents a nominal opening smaller than 200µm,
11. An arc extinguishing chamber notably for a multipole low voltage circuit breaker with isolating molded case, comprising per pole : a pair of stationary and movable separable contacts (2, 3), an actuating mechanism of the movable contact (2), metallic plates (4) for cooling of the arc drawn between said contacts (2, 3) when the latter separate, an orifice (12) for outlet of the breaking gases arranged in the case (B) at the outlet of said chamber (1) and a deionization device (R) according to any one of the foregoing claims arranged near to said outlet orifice (12) to cool the breaking gases outlet to the outside environment.
12. The arc extinguishing chamber according to claim 11, characterized in that it comprises in addition at least one additional perforated shield (17) made of insulating material placed between the ends of the above-mentioned cooling plates (4) and the porous shield (E),
13. The arc extinguishing chamber according to claim 11 or 12, characterized in that said chamber (1) comprises in addition perforated plates or stiffeners placed on each side of the porous shield (E) to increase its mechanical resistance to the pressure wave.

14. A gas deionization device, substantially as herein described with reference to the accompanying drawings.
15. An arc extinguishing chamber notably for a multipole low voltage circuit breaker with isolating molded case, substantially as herein described with reference to the accompanying drawings.


Documents:

1368-mas-1997-abstract.pdf

1368-mas-1997-claims filed.pdf

1368-mas-1997-claims granted.pdf

1368-mas-1997-correspondnece-others.pdf

1368-mas-1997-correspondnece-po.pdf

1368-mas-1997-description(complete)filed.pdf

1368-mas-1997-description(complete)granted.pdf

1368-mas-1997-drawings.pdf

1368-mas-1997-form 1.pdf

1368-mas-1997-form 26.pdf

1368-mas-1997-form 3.pdf

1368-mas-1997-other document.pdf


Patent Number 212423
Indian Patent Application Number 1368/MAS/1997
PG Journal Number 07/2008
Publication Date 15-Feb-2008
Grant Date 03-Dec-2007
Date of Filing 23-Jun-1997
Name of Patentee SCHNEIDER ELECTRIC SA
Applicant Address 40 AVENUE ANDRE MORIZET F, 92100 BOULOGINE BILLANCOURT,
Inventors:
# Inventor's Name Inventor's Address
1 RIVAL MARC F 38730 PANISSAGE,
2 KILINFJIAN CHRISTOPHE 5 ALLEEEDE LA PIAT- F 38240 MEYLAN,
3 CLERY YVES 22, RUE DE LAVOIR DE CRIEL, F 38500 VOIRON,
4 BONENTE SERGE 30, IMPASSE CHARLES NICOLLE, F 38920 CROLLES,
PCT International Classification Number H 01 H 9/34
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA