EP1655749A1 - Contact pastille for a movable electrical contact of a circuit breaker, movable electrical contact with such a pastille and circuit breaker with such a contact - Google Patents
Contact pastille for a movable electrical contact of a circuit breaker, movable electrical contact with such a pastille and circuit breaker with such a contact Download PDFInfo
- Publication number
- EP1655749A1 EP1655749A1 EP05354035A EP05354035A EP1655749A1 EP 1655749 A1 EP1655749 A1 EP 1655749A1 EP 05354035 A EP05354035 A EP 05354035A EP 05354035 A EP05354035 A EP 05354035A EP 1655749 A1 EP1655749 A1 EP 1655749A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- contact
- circuit breaker
- carbon fibers
- silver
- pastille
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 235000010603 pastilles Nutrition 0.000 title abstract description 7
- 229920000049 Carbon (fiber) Polymers 0.000 claims abstract description 28
- 239000004917 carbon fiber Substances 0.000 claims abstract description 28
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 19
- 239000004332 silver Substances 0.000 claims abstract description 17
- 229910052709 silver Inorganic materials 0.000 claims abstract description 16
- 239000000835 fiber Substances 0.000 claims abstract description 13
- 239000004020 conductor Substances 0.000 claims abstract description 10
- 239000002245 particle Substances 0.000 claims abstract description 10
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 9
- 239000000956 alloy Substances 0.000 claims abstract description 9
- 239000010949 copper Substances 0.000 claims abstract description 9
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 claims abstract description 8
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052802 copper Inorganic materials 0.000 claims abstract description 6
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052721 tungsten Inorganic materials 0.000 claims abstract description 6
- 239000010937 tungsten Substances 0.000 claims abstract description 6
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 claims abstract description 4
- 239000000463 material Substances 0.000 claims description 17
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 13
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 5
- 238000001914 filtration Methods 0.000 claims description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 3
- 239000007789 gas Substances 0.000 claims description 3
- 239000001257 hydrogen Substances 0.000 claims description 3
- 229910052739 hydrogen Inorganic materials 0.000 claims description 3
- 230000007246 mechanism Effects 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 239000001301 oxygen Substances 0.000 claims description 3
- 229910052760 oxygen Inorganic materials 0.000 claims description 3
- 239000008188 pellet Substances 0.000 description 12
- 230000003628 erosive effect Effects 0.000 description 9
- 229910002804 graphite Inorganic materials 0.000 description 7
- 239000010439 graphite Substances 0.000 description 7
- 239000000843 powder Substances 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 238000003466 welding Methods 0.000 description 5
- 230000006399 behavior Effects 0.000 description 4
- 239000011159 matrix material Substances 0.000 description 4
- 229910001316 Ag alloy Inorganic materials 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 230000004075 alteration Effects 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 229910000881 Cu alloy Inorganic materials 0.000 description 1
- 238000002679 ablation Methods 0.000 description 1
- 230000008033 biological extinction Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010891 electric arc Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000008240 homogeneous mixture Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910001338 liquidmetal Inorganic materials 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 229910000679 solder Inorganic materials 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000009987 spinning Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 239000000080 wetting agent Substances 0.000 description 1
Images
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H1/00—Contacts
- H01H1/02—Contacts characterised by the material thereof
- H01H1/021—Composite material
- H01H1/027—Composite material containing carbon particles or fibres
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H1/00—Contacts
- H01H1/02—Contacts characterised by the material thereof
- H01H1/021—Composite material
- H01H1/023—Composite material having a noble metal as the basic material
- H01H1/0233—Composite material having a noble metal as the basic material and containing carbides
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H1/00—Contacts
- H01H1/02—Contacts characterised by the material thereof
- H01H1/021—Composite material
- H01H1/025—Composite material having copper as the basic material
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H3/00—Mechanisms for operating contacts
- H01H3/22—Power arrangements internal to the switch for operating the driving mechanism
- H01H3/30—Power arrangements internal to the switch for operating the driving mechanism using spring motor
Definitions
- the invention relates to a contact pad intended to be fixed on a low voltage circuit breaker movable contact intended to withstand short-circuit peak currents of between 200 and 600 amperes per square millimeter of pellet.
- the pellet consists of an alloy of conducting material based on silver or copper, a fraction of refractory particles such as tungsten carbide, tungsten or titanium nitride and a fraction of carbon fibers.
- Solutions include adding at the surface or contact area composite materials in the form of pellets of different thicknesses and different materials.
- the pellets are usually made of silver or copper alloy. They are made in the usual manner by sintering a powder composed of a silver-based alloy, in particular silver and tungsten or silver and nickel. These contact materials have a high electrical conductivity, a high sufficient resistance to oxidation and good properties with regard to contact resistance.
- the known silver-based contact materials show an undesirable tendency to weld. In addition, they tend to cause adhesion of the contact surfaces and / or migration of material between the contact elements. Finally, their use is generally associated with excessive wear of the contacts.
- Carbon, in the form of fibers may also be provided to the alloy powder (US4699763).
- the resistance to erosion is then improved, but this improvement is achieved at the cost of an alteration of the behavior of the contact at the weld.
- the carbon fibers are mixed with the metal powder with a wetting agent, lubricant and wet solvent, followed by drying, compression and sintering.
- the disadvantage of such a method is that it involves complications inherent to a wet process.
- EP0171339 is described a method of manufacturing electrical contacts by impregnating a carbon fiber substrate with a liquid metal under pressure, then by hot spinning the mixture thus obtained. It can be seen that the resulting contacts show an excessive propensity for welding.
- EP0729162 is described a method of manufacturing powder-based electrical contacts of a good electrically conductive metal such as silver and crushed carbon fibers of average length less than 20 .mu.m.
- a good electrically conductive metal such as silver and crushed carbon fibers of average length less than 20 .mu.m.
- the contact surface keeps, after cutting under a short-circuit current, its fine, homogeneous and isotropic structure of fiber residues of variable length and any orientation in the matrix of money.
- the weight proportions of crushed carbon fiber residues are between 2 and 5% with the silver powder.
- the material thus obtained shows a low post contact resistance, good anti-weld qualities and acceptable erosion resistance.
- the invention therefore aims to overcome the disadvantages of the state of the art, so as to provide a contact pad having a low contact resistance post cut, high erosion resistance and good anti-welding properties.
- a contact pad according to the invention comprises a weight percentage of carbon fibers in the pellet strictly less than 2% of the total mass of said contact patch.
- the weight percentage of carbon fibers in the contact pad is between 0.5% and 1.9% of the total mass of said contact pad.
- the carbon fibers are crushed fibers with a length of less than 20 ⁇ m.
- the carbon fibers consist of carbonized fibers containing at least 90% carbon, less than 10% nitrogen, substantially 1% oxygen and less than 1% hydrogen.
- the contact patch is composed of 79% of the silver alloy, 20% of tungsten carbide (CW) and 1% of carbon fiber.
- a mobile circuit breaker contact according to a development mode of the invention comprises a movable contact finger connected to a contact pad as defined above, the chip being connected to the movable contact finger via a thin layer of conductive material based on silver alloy.
- the contact pad 3 is intended to be fixed on a moving contact 2 low-voltage circuit breaker 1 for supporting short-circuit currents of several kilo amperes.
- a contact pad 3 according to the invention is intended to withstand short-circuit peak currents of between 200 and 600 amperes per square millimeter of pellet.
- the contact pad 3 is composed of a conductive material such as silver (Ag) or copper (Cu) in which is inserted a fraction of carbon fibers and a fraction of refractory particles such as for example carbide tungsten (WC), tungsten (W), titanium nitride (TiN). These refractory particles have an average diameter of 1 to 10 microns.
- a conductive material such as silver (Ag) or copper (Cu) in which is inserted a fraction of carbon fibers and a fraction of refractory particles such as for example carbide tungsten (WC), tungsten (W), titanium nitride (TiN). These refractory particles have an average diameter of 1 to 10 microns.
- the carbon fibers consist of carbonized fibers containing at least 90% carbon, less than 10% nitrogen, substantially 1% oxygen and less than 1% hydrogen.
- carbon fibers with an average length L1 of between approximately 100 ⁇ m and 800 ⁇ m and a diameter of between 4 and 20 ⁇ m are chosen. These fibers undergo a cold and dry mechanical treatment in a mechanical grinder. The conditions of intensity and duration of grinding make it possible to obtain fibers the length of which is statistically distributed around a mean value which is much lower than the initial average value. From the initial fibers, crushed fiber residues having an average length of less than 20 ⁇ m are thus obtained. The crushed fibers are then added to the conductive material containing the refractory fractions. The powder mixture of conductive material and the crushed carbon fibers is carried out dry in a mechanical mixer until a homogeneous mixture is obtained. Said mixture then undergoes a unitary compression and a sintering so as to obtain an isotropic material structure
- the weight percentage of carbon fibers in the pellet is strictly less than 2%. It is preferably between 0.5% and 1.9% of the total mass of the pellet.
- an ideal compromise in the choice of the proportions of materials for this type of application consists in using a pellet comprising 79% silver (Ag), 20% tungsten carbide (CW) and 1% of crushed carbon fibers.
- this material having an appropriate homogeneous structure shows a low and stable post-cut contact resistance as well as a good resistance to erosion under a short circuit of several tens of kiloamperes.
- this material develops anti-welding characteristics with respect to the steel balls present in the environment during the cut especially in the electric arc column.
- An explosive phenomenon due to the degradation of the carbon fiber explains the anti-adhesion characteristics of this material with respect to molten steel balls.
- a movable contact 2 circuit breaker 1 comprising a movable contact finger moving relative to a fixed contact 4 of the circuit breaker, has a contact pad 3 as defined above.
- Said contact pad is connected to the movable contact finger by means of a thin layer of conductive material based on silver or a mixture of copper and silver. This intermediate layer makes it possible to block the propagation of cracks in the interface zone between the contact pad 3 and the finger.
- a circuit breaker 1 comprising an opening mechanism 6 acting on at least one electric moving contact 2 as defined above.
- Said at least one moving contact 2 is placed opposite a fixed contact 4.
- Said fixed contact is made of an alloy, generally comprising a silver metal matrix in which a fraction of particles of graphite powder is inserted. Said fraction of particles constitutes 3 to 5% of the mass of the alloy.
- the alloy may also comprise a certain amount of refractory elements (W, WC, Ni) of between 2 and 30% of the total mass.
- the circuit breaker 1 according to a particular embodiment, is intended to accept nominal currents of 1600 amps and short-term currents of 42000 amps for one second.
- the breaking chambers 10 comprise, by pole, five movable contacts 2 associated with a fixed contact area 4.
- Filtering means 5 placed on the walls of the breaking chambers 10 are intended to strongly attenuate external manifestations of the gases present in said rooms at the time of opening contacts.
- the filtering means 5 comprise filters having characteristics specific techniques as described in the patents of the Applicant (EP-A-1115132, EP-A-1251533).
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Composite Materials (AREA)
- Materials Engineering (AREA)
- Contacts (AREA)
Abstract
Description
L'invention est relative à une pastille de contact destinée à être fixée sur un contact mobile de disjoncteur basse tension destiné à supporter des courants crêtes de court-circuit compris entre 200 et 600 ampères par millimètre carré de pastille. La pastille est constituée d'un alliage de matériau conducteur à base d'argent ou de cuivre, d'une fraction de particules réfractaires telles que du carbure de tungstène, du tungstène ou du nitrure de titane et d'une fraction de fibres de carboneThe invention relates to a contact pad intended to be fixed on a low voltage circuit breaker movable contact intended to withstand short-circuit peak currents of between 200 and 600 amperes per square millimeter of pellet. The pellet consists of an alloy of conducting material based on silver or copper, a fraction of refractory particles such as tungsten carbide, tungsten or titanium nitride and a fraction of carbon fibers.
La présence de défauts électriques à l'intérieur de dispositifs de coupure tel que des disjoncteurs électriques provoque une brusque ouverture de leurs contacts électriques. Cette ouverture rapide est généralement accompagnée d'arcs électriques donnant naissance à des contraintes importantes au niveau desdits contacts, plus particulièrement au niveau de leurs surfaces ou zones de contact.The presence of electrical faults within cut-off devices such as electrical circuit breakers causes their electrical contacts to open abruptly. This rapid opening is generally accompanied by electric arcs giving rise to significant stresses at said contacts, more particularly at their surfaces or contact areas.
Afin d'augmenter la longévité des contacts électriques utilisés dans de tels dispositifs, il est connu de modifier la structure de la surface ou zone de contact des contacts électriques. Des solutions consistent à ajouter au niveau de la surface ou zone de contact des matériaux composites sous la forme de pastilles de différentes épaisseurs et de différents matériaux.In order to increase the life of the electrical contacts used in such devices, it is known to modify the structure of the surface or contact area of the electrical contacts. Solutions include adding at the surface or contact area composite materials in the form of pellets of different thicknesses and different materials.
Les pastilles sont généralement en alliage d'argent ou de cuivre. Elles sont réalisées de manière usuelle par frittage d'une poudre composée d'un alliage à base d'argent, notamment argent et tungstène ou argent et nickel. Ces matériaux de contact présentent une conductibilité électrique élevée, une résistance suffisante à l'oxydation et de bonnes propriétés en ce qui concerne la résistance de contact.The pellets are usually made of silver or copper alloy. They are made in the usual manner by sintering a powder composed of a silver-based alloy, in particular silver and tungsten or silver and nickel. These contact materials have a high electrical conductivity, a high sufficient resistance to oxidation and good properties with regard to contact resistance.
Cependant, les matériaux de contact connus à base d'argent montrent une tendance indésirable à la soudure. En outre, ils ont tendance à provoquer l'adhérence des surfaces de contact ou/et une migration de matière entre les éléments de contact. Enfin, leur utilisation est généralement associée à une usure trop important des contacts.However, the known silver-based contact materials show an undesirable tendency to weld. In addition, they tend to cause adhesion of the contact surfaces and / or migration of material between the contact elements. Finally, their use is generally associated with excessive wear of the contacts.
De nombreuses solutions consistent à ajouter à la poudre d'alliage un matériau conducteur tel que du graphite. De tels matériaux sont couramment utilisés pour réaliser les pastilles de contact des disjoncteurs. Le graphite présent dans la matrice métallique permet de réduire le risque de soudure des contacts. Toutefois, la présence du graphite entraîne une érosion mécanique accrue de la pastille.Many solutions consist in adding to the alloy powder a conductive material such as graphite. Such materials are commonly used to make the contact pads of the circuit breakers. The graphite present in the metal matrix makes it possible to reduce the risk of welding of the contacts. However, the presence of graphite causes increased mechanical erosion of the pellet.
Du carbone, sous forme de fibres peut être aussi apporté à la poudre d'alliage (document US4699763). La résistance à l'érosion est alors améliorée, mais cette amélioration est acquise au prix d'une altération du comportement du contact à la soudure. Les fibres de carbone sont mélangées à la poudre métallique avec un apport d'agent mouillant, lubrifiant et solvant par voie humide, puis on effectue un séchage, une compression et un frittage. L'inconvénient d'un tel procédé est qu'il implique des complications inhérentes à un processus conduit en voie humide.Carbon, in the form of fibers may also be provided to the alloy powder (US4699763). The resistance to erosion is then improved, but this improvement is achieved at the cost of an alteration of the behavior of the contact at the weld. The carbon fibers are mixed with the metal powder with a wetting agent, lubricant and wet solvent, followed by drying, compression and sintering. The disadvantage of such a method is that it involves complications inherent to a wet process.
Pour trouver un compromis acceptable entre le comportement du matériau à l'érosion et son comportement anti-soudure, il est proposé d'après le document DE4111683 de mélanger des particules de graphite à des fibres de carbone, ce mélange étant incorporé à la poudre métallique. Cet apport hybride de carbone dans la matrice métallique, permet d'obtenir des comportements du matériau à l'érosion et à la soudure intermédiaires entre ceux qu'il aurait montrés avec un apport de particules de graphite seules ou avec un apport de fibres de carbone seules. Mais il s'avère que, sous de fortes sollicitations et en particulier sous de forts courants de court-circuit, les particules de graphite, de part leur parfaite structure cristalline, montrent une tendance à être expulsées de la surface du matériau. Cette expulsion détériore la surface du matériau d'une manière telle que les fibres de carbone en sont également expulsées à leur tour. Il en résulte un enrichissement de la surface en argent et donc une altération des qualités initialement recherchées par l'apport de graphite.In order to find an acceptable compromise between the behavior of the material with erosion and its anti-welding behavior, it is proposed from DE4111683 to mix graphite particles with carbon fibers, this mixture being incorporated into the metal powder. . This hybrid carbon contribution in the metal matrix makes it possible to obtain intermediate erosion and solder behaviors between those which it would have shown with a contribution of graphite particles alone or with a contribution of carbon fibers. alone. But it turns out that, under heavy loads and in particular under strong short-circuit currents, the graphite particles, because of their perfect crystalline structure, show a tendency to be expelled from the surface. of the material. This expulsion deteriorates the surface of the material in such a way that the carbon fibers are also expelled in turn. This results in an enrichment of the silver surface and thus an alteration of the qualities initially sought by the contribution of graphite.
Dans le document EP0171339 est décrit un procédé de fabrication de contacts électriques par imprégnation d'un substrat de fibres de carbone par un métal liquide sous pression, puis par filage à chaud du mélange ainsi obtenu. On constate que les contacts résultants montrent une trop forte propension au soudage.In EP0171339 is described a method of manufacturing electrical contacts by impregnating a carbon fiber substrate with a liquid metal under pressure, then by hot spinning the mixture thus obtained. It can be seen that the resulting contacts show an excessive propensity for welding.
Dans le document EP0729162 est décrit un procédé de fabrication de contacts électriques à base de poudre d'un métal bon conducteur électrique tel que l'argent et de fibres de carbone broyées de longueur moyenne inférieure à 20µm. Dans des applications courantes de coupure, on constate que la surface de contact garde, après coupure sous un courant de court-circuit, sa structure fine, homogène et isotrope de résidus de fibres de longueur variable et d'orientation quelconque dans la matrice d'argent. Les proportions pondérales de résidus de fibre de carbone broyées sont comprises entre 2 à 5% avec la poudre d'argent. Pour des disjoncteurs limiteurs utilisés pour des applications dans lesquelles l'arc stagne peu sur les contacts, le matériau ainsi obtenu montre une résistance de contact après coupure faible, de bonnes qualités d'anti-soudure et une résistance à l'érosion acceptable. Cependant, l'utilisation de ce matériau trouve ses limites dans des applications pour lesquelles on est présence de disjoncteurs sélectifs où le courant de défaut apparaissant sur les pastilles, a la valeur du courant présumé de court-circuit ; soit plusieurs dizaines de kilo ampères. La robustesse à l'érosion des pastilles de contact décrites ci-dessus n'est plus suffisante et des micro-soudures sont observées lors de passage de courant de plusieurs dizaines de kilo ampères pendant 1 seconde sans ouverture de l'appareil.In EP0729162 is described a method of manufacturing powder-based electrical contacts of a good electrically conductive metal such as silver and crushed carbon fibers of average length less than 20 .mu.m. In common breaking applications, it is found that the contact surface keeps, after cutting under a short-circuit current, its fine, homogeneous and isotropic structure of fiber residues of variable length and any orientation in the matrix of money. The weight proportions of crushed carbon fiber residues are between 2 and 5% with the silver powder. For limiting circuit breakers used for applications in which the arc stagnates little on the contacts, the material thus obtained shows a low post contact resistance, good anti-weld qualities and acceptable erosion resistance. However, the use of this material finds its limits in applications for which there is presence of selective circuit breakers where the fault current appearing on the chips, has the value of the presumed short-circuit current; that's several tens of kilo amps. The erosion resistance of the contact pads described above is no longer sufficient and micro-welds are observed when current passes several tens of kilo amperes for 1 second without opening the device.
Par ailleurs, lorsque la taille de ce type de disjoncteur est miniaturisée et lorsque l'adjonction d'éléments filtrants réduit de manière drastique les manifestations extérieures, le choix optimum de matériau de contact est encore plus draconien. En effet, l'énergie de coupure similaire à celle dégagée dans les disjoncteurs classiques doit être absorbée dans un volume miniaturisé et quasiment clos. Il s'ensuit un dépôt important de polluants sur les contacts. Ce dépôt est constitué en particulier d'acier fondu issu de l'ablation des ailettes de la chambre d'extinction d'arc.Moreover, when the size of this type of circuit breaker is miniaturized and when the addition of filter elements drastically reduces the external manifestations, the optimum choice of contact material is even more draconian. Indeed, the cutoff energy similar to that released in conventional circuit breakers must be absorbed in a miniaturized volume and almost closed. This results in a large deposit of pollutants on the contacts. This deposit consists in particular of molten steel resulting from the ablation of the fins of the arc extinction chamber.
L'invention vise donc à remédier aux inconvénients de l'état de la technique, de manière à proposer une pastille de contact ayant une faible résistance de contact post coupure, une forte résistance à l'érosion et de bonnes propriétés anti-soudure.The invention therefore aims to overcome the disadvantages of the state of the art, so as to provide a contact pad having a low contact resistance post cut, high erosion resistance and good anti-welding properties.
Une pastille de contact selon l'invention comprend un pourcentage pondéral de fibres de carbone dans la pastille strictement inférieur à 2% de la masse totale de ladite pastille de contactA contact pad according to the invention comprises a weight percentage of carbon fibers in the pellet strictly less than 2% of the total mass of said contact patch.
Le pourcentage pondéral de fibres de carbone dans la pastille de contact est compris entre 0,5% et 1.9% de la masse totale de ladite pastille de contact.The weight percentage of carbon fibers in the contact pad is between 0.5% and 1.9% of the total mass of said contact pad.
Avantageusement, les fibres de carbone sont des fibres broyées de longueur inférieure à 20 µm.Advantageously, the carbon fibers are crushed fibers with a length of less than 20 μm.
De préférence, les fibres de carbones sont constituées de fibres carbonisées contenant au moins 90% de carbone, moins de 10% d'azote, sensiblement 1 % d'oxygène et moins de 1 % d'hydrogène.Preferably, the carbon fibers consist of carbonized fibers containing at least 90% carbon, less than 10% nitrogen, substantially 1% oxygen and less than 1% hydrogen.
Selon un mode de développement de l'invention, la pastille de contact est composée de 79% de l'alliage d'argent, de 20% de carbure de tungstène (CW) et de 1 % de fibre de carbone.According to one embodiment of the invention, the contact patch is composed of 79% of the silver alloy, 20% of tungsten carbide (CW) and 1% of carbon fiber.
Un contact mobile de disjoncteur selon un mode développement de l'invention, comprend un doigt de contact mobile relié à une pastille de contact telle que définie ci-dessus, la pastille étant reliée au doigt de contact mobile par l'intermédiaire d'une fine couche de matériau conducteur à base d'alliage d'argent.A mobile circuit breaker contact according to a development mode of the invention comprises a movable contact finger connected to a contact pad as defined above, the chip being connected to the movable contact finger via a thin layer of conductive material based on silver alloy.
Un disjoncteur selon un mode développement de l'invention comprend une chambre de coupure comportant des moyens de filtrage destinés à atténuer des manifestations extérieures des gaz présents dans la chambre de coupure au moment des ouvertures, et comprend un mécanisme d'ouverture agissant sur au moins un contact mobile tel que défini ci-dessus et placé en vis à vis d'un contact fixe, lesdits contacts étant placés dans la chambre de coupure.A circuit breaker according to a development mode of the invention comprises an interrupting chamber comprising filtering means intended to attenuate external manifestations of the gases present in the breaking chamber at the time of the openings, and comprises an opening mechanism acting on at least a movable contact as defined above and placed opposite a fixed contact, said contacts being placed in the interrupting chamber.
D'autres avantages et caractéristiques ressortiront plus clairement de la description qui va suivre d'un mode particulier de réalisation de l'invention, donné à titre d'exemple non limitatif, et représenté au dessin annexé sur lequel :
- la figure 1 représente une vue en coupe d'un disjoncteur comportant un contact mobile possédant une pastille de contact selon un mode de réalisation de l'invention.
- Figure 1 shows a sectional view of a circuit breaker having a movable contact having a contact pad according to one embodiment of the invention.
Selon le mode de réalisation préféré de l'invention, la pastille de contact 3 est destinée à être fixée sur un contact mobile 2 de disjoncteur basse-tension 1 destiné à supporter des courants de court-circuit de plusieurs kilo ampères. En exprimant la densité de courant électrique en ampères par unité de surface de pastille, une pastille de contact 3 selon l'invention est destinée à supporter des courants crêtes de court-circuit compris entre 200 et 600 ampères par millimètre carré de pastille.According to the preferred embodiment of the invention, the
Les effets engendrés par le passage de ces forts courants de court-circuit se font encore plus ressentir lorsque l'énergie de coupure est absorbée dans une chambre de coupure 10 ayant un volume interne miniaturisé et quasiment clos ou étanche.The effects generated by the passage of these strong short-circuit currents are even more felt when the cut-off energy is absorbed in a
La pastille de contact 3 est composée d'un matériau conducteur tel que l'argent (Ag) ou le cuivre (Cu) dans lequel est insérée une fraction de fibres de carbone et une fraction de particules réfractaires telle que par exemple du carbure de tungstène (WC), du tungstène (W), du nitrure de titane (TiN). Ces particules réfractaires possèdent un diamètre moyen de 1 à 10 microns.The
Les fibres de carbone sont constituées de fibres carbonisées contenant au moins 90% de carbone, moins de 10% d'azote, sensiblement 1% d'oxygène et moins de 1 % d'hydrogène.The carbon fibers consist of carbonized fibers containing at least 90% carbon, less than 10% nitrogen, substantially 1% oxygen and less than 1% hydrogen.
Dans le mode de réalisation présenté, on choisit des fibres de carbone de longueur moyenne L1 comprise entre environ 100µm et 800µm et de diamètre compris entre 4 et 20µm. Ces fibres subissent un traitement mécanique à froid et à sec dans un broyeur mécanique. Les conditions d'intensité et de durée du broyage permettent d'obtenir des fibres dont la longueur est répartie statistiquement autour d'une valeur moyenne très inférieure à la valeur moyenne initiale. On obtient ainsi à partir des fibres initiales des résidus de fibres broyées ayant une longueur moyenne inférieure à 20µm. Les fibres broyées sont ensuite ajoutées au matériau conducteur contenant les fractions réfractaires. Le mélange de poudre de matériau conducteur aux fibres de carbone broyées s'effectue par voie sèche dans un mélangeur mécanique jusqu'à obtenir un mélange homogène. Ledit mélange subit ensuite une compression unitaire et un frittage de manière à obtenir une structure de matériau isotropeIn the embodiment shown, carbon fibers with an average length L1 of between approximately 100 μm and 800 μm and a diameter of between 4 and 20 μm are chosen. These fibers undergo a cold and dry mechanical treatment in a mechanical grinder. The conditions of intensity and duration of grinding make it possible to obtain fibers the length of which is statistically distributed around a mean value which is much lower than the initial average value. From the initial fibers, crushed fiber residues having an average length of less than 20 μm are thus obtained. The crushed fibers are then added to the conductive material containing the refractory fractions. The powder mixture of conductive material and the crushed carbon fibers is carried out dry in a mechanical mixer until a homogeneous mixture is obtained. Said mixture then undergoes a unitary compression and a sintering so as to obtain an isotropic material structure
Un tel procédé de fabrication est décrit en détail dans le document EP-B-0729162, dont la description est sur ces points incorporée ici par référence.Such a manufacturing method is described in detail in EP-B-0729162, the description of which is incorporated herein by reference.
Dans le but de résister aux contraintes spécifiques observées dans les disjoncteurs sélectifs capables de supporter des courants dans les conditions décrites ci-dessus, il est nécessaire d'augmenter la résistance à l'érosion de la pastille ainsi obtenue. Pour ce faire, le pourcentage pondéral de fibres de carbone dans la pastille est strictement inférieur à 2%. Il est compris de préférence entre 0,5% et 1,9% de la masse totale de la pastille.In order to resist the specific stresses observed in selective circuit breakers capable of withstanding currents under the conditions described above, it is necessary to increase the erosion resistance of the pellet thus obtained. To do this, the weight percentage of carbon fibers in the pellet is strictly less than 2%. It is preferably between 0.5% and 1.9% of the total mass of the pellet.
Dans un exemple d'application de l'invention, un compromis idéal dans le choix des proportions des matériaux pour ce type d'application, consiste à utiliser une pastille comprenant 79% d'argent (Ag), 20% de carbure de tungstène (CW) et 1 % de fibres broyées de carbone.In an exemplary application of the invention, an ideal compromise in the choice of the proportions of materials for this type of application consists in using a pellet comprising 79% silver (Ag), 20% tungsten carbide ( CW) and 1% of crushed carbon fibers.
Finalement, ce matériau ayant structure homogène appropriée, montre une résistance de contact post coupure faible et stable ainsi qu'une bonne résistance à l'érosion sous court-circuit de plusieurs dizaines de kilo ampères. En outre, ce matériau développe des caractéristiques anti-soudure vis à vis des billes en acier présentes dans l'environnement lors de la coupure notamment dans la colonne d'arc électrique. Un phénomène explosif du à la dégradation de la fibre de carbone explique les caractéristiques anti-adhésion de ce matériau vis à vis des billes d'acier en fusion.Finally, this material having an appropriate homogeneous structure shows a low and stable post-cut contact resistance as well as a good resistance to erosion under a short circuit of several tens of kiloamperes. In addition, this material develops anti-welding characteristics with respect to the steel balls present in the environment during the cut especially in the electric arc column. An explosive phenomenon due to the degradation of the carbon fiber explains the anti-adhesion characteristics of this material with respect to molten steel balls.
Un contact mobile 2 de disjoncteur 1 comprenant un doigt de contact mobile se déplaçant par rapport à un contact fixe 4 du disjoncteur, possède une pastille de contact 3 tel que défini ci-dessus. Ladite pastille de contact est reliée au doigt de contact mobile par l'intermédiaire d'une fine couche de matériau conducteur à base d'argent ou d'un mélange de cuivre et d'argent. Cette couche intermédiaire permet de bloquer la propagation des fissures dans la zone d'interface entre la pastille de contact 3 et le doigt.A
Un disjoncteur 1 comprenant un mécanisme d'ouverture 6 agissant sur au moins un contact mobile électrique 2 tel que défini ci-dessus. Ledit au moins un contact mobile 2 est placé en vis à vis d'un contact fixe 4. Ledit contact fixe est constitué d'un alliage, comportant généralement une matrice métallique d'argent où est insérée une fraction de particules de poudre de graphite. Ladite fraction de particules constitue 3 à 5 % de la masse de l'alliage. L'alliage peut également comprendre une certaine quantité d'éléments réfractaires (W ,WC, Ni) comprise entre 2 et 30% de la masse totale. Le disjoncteur 1 selon un mode particulier de réalisation, est destiné à accepter des courants nominaux de 1600 ampères et des courants de courte durée de 42000 ampères pendant une seconde. Les chambres de coupures 10 comportent, par pole, cinq contacts mobiles 2 associés à une plage de contacts fixes 4. Des moyens de filtrage 5 placés sur les parois des chambres de coupure 10 sont destinés à atténuer fortement des manifestations extérieures des gaz présents dans lesdites chambres au moment des ouvertures des contacts. A titre d'exemple non limitatif, les moyens de filtrage 5 comprennent des filtres possédant des caractéristiques techniques spécifiques telles que décrites dans les brevets de la demanderesse (EP-A-1115132, EP-A-1251533).A
Claims (6)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR0411869A FR2877763B1 (en) | 2004-11-08 | 2004-11-08 | CONTACT BAG FOR A MOBILE ELECTRIC CONTACT OF A CIRCUIT BREAKER, MOBILE ELECTRICAL CONTACT HAVING SUCH A PASTILLE AND CIRCUIT BREAKER COMPRISING SUCH A CONTACT |
Publications (2)
Publication Number | Publication Date |
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EP1655749A1 true EP1655749A1 (en) | 2006-05-10 |
EP1655749B1 EP1655749B1 (en) | 2007-11-28 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP05354035A Active EP1655749B1 (en) | 2004-11-08 | 2005-10-11 | Contact pastille for a movable electrical contact of a circuit breaker, movable electrical contact with such a pastille and circuit breaker with such a contact |
Country Status (6)
Country | Link |
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US (1) | US7598832B2 (en) |
EP (1) | EP1655749B1 (en) |
CN (1) | CN1773647B (en) |
DE (1) | DE602005003537T2 (en) |
ES (1) | ES2297652T3 (en) |
FR (1) | FR2877763B1 (en) |
Cited By (1)
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CN104532050A (en) * | 2015-01-15 | 2015-04-22 | 潍坊学院 | Titanium nitride reinforced sliver base contact material and preparation method thereof |
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DE102009018035A1 (en) * | 2009-04-18 | 2010-10-28 | Moeller Gmbh | Contact arrangement for low-voltage applications |
IN2013CH05861A (en) * | 2013-12-16 | 2015-06-19 | Gen Electric | |
FR3036841B1 (en) * | 2015-05-28 | 2017-06-23 | Schneider Electric Ind Sas | MOBILE POLE AND CUTTING APPARATUS |
US11798751B2 (en) * | 2021-06-30 | 2023-10-24 | Siemens Industry, Inc. | Metal contact of a residential circuit breaker including ordered ceramic microparticles |
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US4699763A (en) | 1986-06-25 | 1987-10-13 | Westinghouse Electric Corp. | Circuit breaker contact containing silver and graphite fibers |
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EP0729162A1 (en) | 1995-02-27 | 1996-08-28 | Schneider Electric Sa | Process for the fabrication of a material for electric contact composite |
EP1115132A1 (en) | 2000-01-07 | 2001-07-11 | Schneider Electric Industries SA | Pole for electrical circuit breaker with arc extinguishing chamber provided with dielectric shields |
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US20050153160A1 (en) | 2004-01-12 | 2005-07-14 | Yourong Liu | Durable thermal barrier coating having low thermal conductivity |
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2004
- 2004-11-08 FR FR0411869A patent/FR2877763B1/en active Active
-
2005
- 2005-10-11 EP EP05354035A patent/EP1655749B1/en active Active
- 2005-10-11 ES ES05354035T patent/ES2297652T3/en active Active
- 2005-10-11 DE DE602005003537T patent/DE602005003537T2/en active Active
- 2005-11-01 US US11/262,984 patent/US7598832B2/en active Active
- 2005-11-04 CN CN2005101201210A patent/CN1773647B/en active Active
Patent Citations (10)
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FR2115865A5 (en) * | 1970-11-24 | 1972-07-07 | Duerrwaechter E Dr Doduco | Carbon fibres - satd with copper or silver to form solid soln contact material |
EP0171339A1 (en) | 1984-07-25 | 1986-02-12 | Le Carbone Lorraine | Method of making electrical contacts |
US4689196A (en) * | 1985-06-24 | 1987-08-25 | Gte Products Corporation | Silver-tungsten carbide-graphite electrical contact |
US4699763A (en) | 1986-06-25 | 1987-10-13 | Westinghouse Electric Corp. | Circuit breaker contact containing silver and graphite fibers |
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DE4111683A1 (en) | 1991-04-10 | 1992-10-22 | Duerrwaechter E Dr Doduco | MATERIAL FOR ELECTRICAL CONTACTS MADE OF SILVER WITH CARBON |
EP0729162A1 (en) | 1995-02-27 | 1996-08-28 | Schneider Electric Sa | Process for the fabrication of a material for electric contact composite |
EP0729162B1 (en) | 1995-02-27 | 1999-07-28 | Schneider Electric Sa | Process for the fabrication of a material for electric contact composite |
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CN104532050A (en) * | 2015-01-15 | 2015-04-22 | 潍坊学院 | Titanium nitride reinforced sliver base contact material and preparation method thereof |
Also Published As
Publication number | Publication date |
---|---|
CN1773647B (en) | 2011-09-21 |
US7598832B2 (en) | 2009-10-06 |
EP1655749B1 (en) | 2007-11-28 |
CN1773647A (en) | 2006-05-17 |
DE602005003537D1 (en) | 2008-01-10 |
FR2877763B1 (en) | 2007-03-16 |
DE602005003537T2 (en) | 2008-10-23 |
US20060096846A1 (en) | 2006-05-11 |
FR2877763A1 (en) | 2006-05-12 |
ES2297652T3 (en) | 2008-05-01 |
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