ELECTRIC ARC-BLAST NOZZLE WITH IMPROVED MECHANICAL STRENGTH AND A CIRCUIT BREAKER INCLUDING SUCH A NOZZLE

Abstract

Provided herein is an electric arc-blast nozzle for a circuit breaker comprising a median part internally defining an axial electric arc cut-off passage and formed with a first dielectric material, first and second end parts formed with the first dielectric material and extending on either side of the median part and being intended to receive first and second arc contacts being axially moveable in relation to each other. The nozzle further comprises a sheath that is disposed on the external surface of the first end part and on a portion of the external surface of the neck-forming median part, said portion having the same radial external section than the first end part, is formed with a second dielectric material different from the first dielectric material and is obtained from a second composition comprising a thermoplastic polymer chosen from either a polysulfone or a polyetherimide, but not comprising fibrous reinforcements.

Claims

1. An electric arc-blast nozzle (5,20) for a circuit breaker comprising: a neck-forming median part (7) internally defining an axial electric arc cut-off passage (13) and formed with a first dielectric material obtained from a first composition comprising a fluorocarbon polymer matrix, first and second end parts (9,11) also formed with the first dielectric material and extending on either side of the median part (7) which are respectively intended to receive first and second arc contacts (1,3), the first and second arc contacts (1,3) being axially moveable in relation to each other, between a circuit breaker opening position in which the first and second arc contacts (1,3) are separated from each other and a circuit breaker closing position in which the first and second arc contacts (1,3) are in contact with each other and in which the second arc contact (3) partially closes the axial passage (13) of the median part (7), an electric arc cut-off gas circulating in the axial passage (13) of the median part (7) to cut an electric arc that is likely to be formed during the movement of the first and second arc contacts (1,3) from the closing position to the opening position of the circuit breaker, and a sheath (19) that is only disposed on the external surface of the first end part (9) and on a portion of the external surface of the neck-forming median part, said portion having the same radial external section than the first end part, and that is formed with a second dielectric material being different from the first dielectric material and being obtained from a second composition comprising a polymer, characterized in that the polymer of the second composition is a thermoplastic polymer chosen from either a polysulfone (PSU) or a polyetherimide (PEI) and in that the second composition does not comprise fibrous reinforcements.

2. An electric arc-blast nozzle (5,20) according to claim 1, wherein the fluorocarbon polymer of the first composition is chosen from the group consisting of polytetrafluoroethylene (PTFE), a copolymer of ethylene and tetrafluoroethylene (ETFE) and a polyfluoride of vinylidene (PVDF) and is, preferably, polytetrafluoroethylene (PTFE).

3. An electric arc-blast nozzle (5,20) according to claim 1 , wherein the first composition further comprises at least one inorganic filler in percentage weight of less than or equal to 10 with respect to the total weight of the first composition.

4. An electric arc-blast nozzle (5,20) according to claim 3, wherein the at least one inorganic filler is chosen from the group consisting of: a sulfur, preferably MoS.sub.2, Sb.sub.2S.sub.5 or Sb.sub.2S.sub.3, a ceramic, preferably BN, an oxide chosen from among SiO.sub.2, TiO.sub.2, Al.sub.2CoO.sub.4, ZnO, BaTiO.sub.3 and P.sub.2O.sub.5, preferably SiO.sub.2 and Al.sub.2CoO.sub.4, a graphite, a mica, a glass, and a fluoride, preferably CaF.sub.2.

5. An electric arc-blast nozzle (5,20) according to claim 1 , wherein the first composition does not comprise inorganic filler.

6. An electric arc-blast nozzle (5,20) according to claim 1, wherein the thickness e′ of the sheath (7) is between 5% and 80% of the total thickness e of the first end part (9).

7. An electric arc-blast nozzle (20) according to claim 1, further comprising an insert (22) that defines a downstream area (22a) of the axial passage (13) of the median part (7) considering the direction of the flow of the electric arc cut-off gas and is formed with a third dielectric material, this third dielectric material being different from the first dielectric material and chosen from: (i) a composite material obtained from a third composition comprising a fluorocarbon polymer matrix and: at least one inorganic filler A chosen from among a sulfur, preferably MoS.sub.2, Sb.sub.2S.sub.5 or Sb.sub.2S.sub.3, a ceramic, preferably BN, and an oxide chosen from among SiO.sub.2, TiO.sub.2, Al.sub.2CoO.sub.4, ZnO, BaTiO.sub.3 and P.sub.2O.sub.5, preferably SiO.sub.2, in a percentage weight ranging between 0.1% and 10%, with respect to the total weight of the third composition, and/or at least one inorganic filler B chosen from among a graphite, a mica, a glass and a fluoride, preferably CaF.sub.2, in a percentage weight ranging between 5% and 50%, with respect to the total weight of the third composition; and (ii) a ceramic material obtained from a fourth composition comprising at least one compound chosen from among a carbide, a boride and an oxide.

8. A circuit breaker, preferably a high voltage circuit breaker, comprising the electric arc-blast nozzle (5,20) according to claim 1.

9. A circuit breaker according to claim 8, wherein the electric arc cutoff gas consists of carbon dioxide CO.sub.2 or sulfur hexafluoride SF.sub.6 or is a gaseous mixture comprising mainly of CO.sub.2.

10. A circuit breaker according to claim 9, wherein the gaseous mixture has the following composition, in mole percent and relative to the whole composition: from 65% mol to 99% mol of CO.sub.2, and up to 35% mol of O.sub.2, and/or up 30% mol of a fluoronitrile compound.

11. A circuit breaker according to claim 10, wherein the gaseous mixture has the following composition, in mole percent and relative to the whole composition: from 65% mol to 97% mol of CO.sub.2, up to 35% mol of O.sub.2, and/or from 3% mol to 30% mol of (CF.sub.3).sub.2CF-CN.

12. An electric arc-blast nozzle (5,20) according to claim 2, wherein the first composition further comprises at least one inorganic filler in percentage weight of less than or equal to 10 with respect to the total weight of the first composition.

13. An electric arc-blast nozzle (5,20) according to claim 2, wherein the first composition does not comprise inorganic filler.

14. An electric arc-blast nozzle (5,20) according to claim 2, wherein the thickness e′ of the sheath (7) is between 5% and 80% of the total thickness e of the first end part (9).

15. An electric arc-blast nozzle (5,20) according to claim 3, wherein the thickness e′ of the sheath (7) is between 5% and 80% of the total thickness e of the first end part (9).

16. An electric arc-blast nozzle (5,20) according to claim 4, wherein the thickness e′ of the sheath (7) is between 5% and 80% of the total thickness e of the first end part (9).

17. An electric arc-blast nozzle (5,20) according to claim 5, wherein the thickness e′ of the sheath (7) is between 5% and 80% of the total thickness e of the first end part (9).

18. An electric arc-blast nozzle (20) according to claim 2, further comprising an insert (22) that defines a downstream area (22a) of the axial passage (13) of the median part (7) considering the direction of the flow of the electric arc cut-off gas and is formed with a third dielectric material, this third dielectric material being different from the first dielectric material and chosen from: (i) a composite material obtained from a third composition comprising a fluorocarbon polymer matrix and: at least one inorganic filler A chosen from among a sulfur, preferably MoS.sub.2, Sb.sub.2S.sub.5 or Sb.sub.2S.sub.3, a ceramic, preferably BN, and an oxide chosen from among SiO.sub.2, TiO.sub.2, Al.sub.2CoO.sub.4, ZnO, BaTiO.sub.3 and P.sub.2O.sub.5, preferably SiO.sub.2, in a percentage weight ranging between 0.1% and 10%, with respect to the total weight of the third composition, and/or at least one inorganic filler B chosen from among a graphite, a mica, a glass and a fluoride, preferably CaF.sub.2, in a percentage weight ranging between 5% and 50%, with respect to the total weight of the third composition; and (ii) a ceramic material obtained from a fourth composition comprising at least one compound chosen from among a carbide, a boride and an oxide.

19. An electric arc-blast nozzle (20) according to claim 3, further comprising an insert (22) that defines a downstream area (22a) of the axial passage (13) of the median part (7) considering the direction of the flow of the electric arc cut-off gas and is formed with a third dielectric material, this third dielectric material being different from the first dielectric material and chosen from: (i) a composite material obtained from a third composition comprising a fluorocarbon polymer matrix and: at least one inorganic filler A chosen from among a sulfur, preferably MoS.sub.2, Sb.sub.2S.sub.5 or Sb.sub.2S.sub.3, a ceramic, preferably BN, and an oxide chosen from among SiO.sub.2, TiO.sub.2, Al2CoO.sub.4, ZnO, BaTiO.sub.3 and P.sub.2O.sub.5, preferably SiO.sub.2, in a percentage weight ranging between 0.1% and 10%, with respect to the total weight of the third composition, and/or at least one inorganic filler B chosen from among a graphite, a mica, a glass and a fluoride, preferably CaF.sub.2, in a percentage weight ranging between 5% and 50%, with respect to the total weight of the third composition; and (ii) a ceramic material obtained from a fourth composition comprising at least one compound chosen from among a carbide, a boride and an oxide.

20. An electric arc-blast nozzle (20) according to claim 4, further comprising an insert (22) that defines a downstream area (22a) of the axial passage (13) of the median part (7) considering the direction of the flow of the electric arc cut-off gas and is formed with a third dielectric material, this third dielectric material being different from the first dielectric material and chosen from: (i) a composite material obtained from a third composition comprising a fluorocarbon polymer matrix and: at least one inorganic filler A chosen from among a sulfur, preferably MoS.sub.2, Sb.sub.2S.sub.5 or Sb.sub.2S.sub.3, a ceramic, preferably BN, and an oxide chosen from among SiO.sub.2, TiO.sub.2, Al.sub.2CoO.sub.4, ZnO, BaTiO.sub.3 and P.sub.2O.sub.5, preferably SiO.sub.2, in a percentage weight ranging between 0.1% and 10%, with respect to the total weight of the third composition, and/or at least one inorganic filler B chosen from among a graphite, a mica, a glass and a fluoride, preferably CaF.sub.2, in a percentage weight ranging between 5% and 50%, with respect to the total weight of the third composition; and (ii) a ceramic material obtained from a fourth composition comprising at least one compound chosen from among a carbide, a boride and an oxide.

21. An electric arc-blast nozzle (20) according to claim 5, further comprising an insert (22) that defines a downstream area (22a) of the axial passage (13) of the median part (7) considering the direction of the flow of the electric arc cut-off gas and is formed with a third dielectric material, this third dielectric material being different from the first dielectric material and chosen from: (i) a composite material obtained from a third composition comprising a fluorocarbon polymer matrix and: at least one inorganic filler A chosen from among a sulfur, preferably MoS.sub.2, Sb.sub.2S.sub.5 or Sb.sub.2S.sub.3, a ceramic, preferably BN, and an oxide chosen from among SiO.sub.2, TiO.sub.2, Al.sub.2CoO.sub.4, ZnO, BaTiO.sub.3 and P.sub.2O.sub.5, preferably SiO.sub.2, in a percentage weight ranging between 0.1% and 10%, with respect to the total weight of the third composition, and/or at least one inorganic filler B chosen from among a graphite, a mica, a glass and a fluoride, preferably CaF.sub.2, in a percentage weight ranging between 5% and 50%, with respect to the total weight of the third composition; and (ii) a ceramic material obtained from a fourth composition comprising at least one compound chosen from among a carbide, a boride and an oxide.

22. An electric arc-blast nozzle (20) according to claim 6, further comprising an insert (22) that defines a downstream area (22a) of the axial passage (13) of the median part (7) considering the direction of the flow of the electric arc cut-off gas and is formed with a third dielectric material, this third dielectric material being different from the first dielectric material and chosen from: (i) a composite material obtained from a third composition comprising a fluorocarbon polymer matrix and: at least one inorganic filler A chosen from among a sulfur, preferably MoS.sub.2, Sb.sub.2S.sub.5 or Sb.sub.2S.sub.3, a ceramic, preferably BN, and an oxide chosen from among SiO.sub.2, TiO.sub.2, Al.sub.2CoO.sub.4, ZnO, BaTiO.sub.3 and P.sub.2O.sub.5, preferably SiO.sub.2, in a percentage weight ranging between 0.1% and 10%, with respect to the total weight of the third composition, and/or at least one inorganic filler B chosen from among a graphite, a mica, a glass and a fluoride, preferably CaF.sub.2, in a percentage weight ranging between 5% and 50%, with respect to the total weight of the third composition; and (ii) a ceramic material obtained from a fourth composition comprising at least one compound chosen from among a carbide, a boride and an oxide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0101] FIG. 1 is a fragmentary and diagrammatic view in longitudinal section of a circuit breaker including an electric arc-blast nozzle of the invention.

[0102] FIG. 2 is a fragmentary and diagrammatic view in longitudinal section of a circuit breaker including an electric arc-blast nozzle of the invention, the nozzle being further equipped with an insert.

[0103] It is stated that the elements shared in FIGS. 1 and 2 are identified by the same reference numbers.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

[0104] FIG. 1 shows a circuit breaker portion.

[0105] This circuit breaker includes: [0106] at least two arc contacts 1 and 3 that are movable axially relative to each other, along an axis A, between an open position of the circuit breaker in which the arcing contacts 1 and 3 are separated from each other and a closed position of the circuit breaker in which the arcing contacts 1 and 3 are in contact with each other, and [0107] an electric arc-blast nozzle 5 according to the present invention.

[0108] This nozzle 5 comprises a neck-forming median part 7, a first end part 9 disposed upstream and a second end part 11 disposed downstream, the upstream and downstream disposition of the first and second end parts 9 and 11 being considered in the direction of the flow of the electric arc cut-off gas. These first and second end parts 9 and 11 extend on either side of the median part 7. These parts 7, 9 and 11 have a symmetrical revolution around axis A.

[0109] The median part 7 internally defines an axial passage 13 of the electric arc cut-off, this axial passage 13 comprising an inlet 13a and an outlet 13b. This median part 7 is called the neck-forming median part 7, due to the internal section of this axial passage 13, which is smaller than the internal section of each of the first and second end parts 9 and 11.

[0110] The first and second end parts 9 and 11 respectively receive and surround the arc contacts 1 and 3.

[0111] The first end part 9 disposed upstream channels the cut-off gas situated upstream and intended to blast the electric arc, whereas the second end part 11 disposed downstream evacuates and circulates the blast gas situated downstream, upstream and downstream being defined with reference to the direction of the flow of the electric arc cut-off gas.

[0112] The first end part 9 may have a cover 10 that surrounds arc contact 1.

[0113] In FIG. 1, the arc contacts 1 and 3 are separated from each other and therefore correspond to the opening position of the circuit breaker.

[0114] When the arc contacts 1 and 3 are in contact with each other, in the closing position of the circuit breaker, the arc contact 3 closes the axial passage 13 of the median part 7 partially.

[0115] There is an electric arc cut-off gas routing channel 15 between the arc contact 1 and the wall of the first end part 9, which allows the circulation of this gas in the axial passage 13 of the median part 7, from its inlet 13a to its outlet 13b, to cut an electric arc that is likely to be formed during the movement of arc contacts 1 and 3 from the closing position to the opening position of the circuit breaker.

[0116] The second end part 11 has a truncated cone shaped part 11a disposed in the extension of the median part 7 situated with respect to the outlet 13b of the axial passage 13, this truncated cone shaped part 11a being followed by a cylindrical part 11b.

[0117] The neck-forming median part 7 as well as the cover 10 and the first and second end parts 9 and 11 are made from a first dielectric material, which has good mechanical properties and thermal resistance. Typically, this first dielectric material is obtained from a first composition comprising a fluorocarbon polymer matrix, classically a PTFE matrix.

[0118] This first composition may comprise one or more inorganic fillers. When they are present, the inorganic fillers classically represent a percentage weight that may represent less than or equal to 10% of the total weight of the first composition, this percentage weight ranging advantageously between 0.01% and 5% and, preferably, between 0.1% and 2%, with respect to the total weight of the first composition.

[0119] Reference may be made to the summary of the invention for further details about the different inorganic fillers of this first composition suitable for being envisaged in order to obtain the first dielectric material constituting the cover 10, the middle part 7 and the first and second end parts 9 and 11 of the nozzle 5.

[0120] The electric arc-blast nozzle 5 further comprises a sheath 19 only disposed on the external surface of the first end part 9 and on a portion of the external surface of the neck-forming median part 7, said portion having the same radial external section than the first end part 9. The portion of the external surface of the neck-forming median part 7 is a portion that extends towards the first end part 9.

[0121] With regard to a nozzle comprising a sheath disposed on the external surfaces of the first end part 9, of the median part 7 and of the second end part 11, the localization of the sheath 19 only on the external surface of the first end part 9 and on a portion of the external surface of the neck-forming median part 7 has the advantage of avoiding a radial deformation of the nozzle part subject to the highest pressures while limiting material and process costs.

[0122] The sheath 19 is formed with a second dielectric material being different from the first dielectric material and being obtained from a second composition comprising a thermoplastic polymer that is chosen from either a polysulfone (PSU) or a polyetherimide (PEI), said second composition being devoid of fibrous reinforcements.

[0123] The second dielectric material obtained from such a thermoplastic polymer presents good mechanical properties and good high-temperature behavior.

[0124] In an advantageous embodiment, this second composition consists of PSU or PEI.

[0125] Such a sheath 19 can, for example, be produced by machining, molding or even by overmolding on the first end part 9 of the nozzle 5.

[0126] In one embodiment, the thickness, noted e′, of the sheath 19 is between 5% and 90%, advantageously between 10% and 60% and, preferably, between 30% and 50% of the total thickness, noted e, of the first end part 9.

[0127] Since PSU and PEI have a lower density than PTFE, replacing part of the PTFE forming the first end part 9 with PSU and/or PEI reduces the overall mass of the electric arc-blast nozzle, thereby also reducing the operating energy of the circuit breaker provided with such an electric arc-blast nozzle, while promoting PTFE depletion.

[0128] In one embodiment, the length of the sheath 19 represents between 10% and 80% and, preferably, between 20% and 60% of the total length of the nozzle 5.

[0129] Like FIG. 1, FIG. 2 shows a nozzle 20 of the invention, which is of the type shown in FIG. 1 and which further comprises an insert 22 defining a downstream area 22a of the axial passage 13 of the median part 7 considering the direction of the flow of the cut-off gas, direction that is established at the inlet 13a towards the outlet 13b of the axial passage 13, which is in the form of a ring.

[0130] The insert 22 of the nozzle 20 according to the invention is formed with a second dielectric material, separate from the first dielectric material forming the median part 7 (insert 22 not included) and the first and second end parts 9 and 11.

[0131] In FIG. 2, the insert 22 is in a form of a ring but nothing prevents the consideration of other conformations for this insert, in particular the conformations shown in FIGS. 2 and 4 to 7 of WO 2018/001798 A1.

[0132] The insert 22 is made from a third dielectric material that provides an excellent resistance to radiation from the electric arc. Typically, this third dielectric material is obtained is chosen from: [0133] (i) a composite material obtained from a third composition comprising a fluorocarbon polymer matrix and: [0134] at least one inorganic filler A chosen from among a sulfur, a ceramic and an oxide chosen from among SiO.sub.2, TiO.sub.2, Al.sub.2CoO.sub.4, ZnO, BaTiO.sub.3 and P.sub.2O.sub.5, in a percentage weight ranging between 0.1% and 10%, with respect to the total weight of the third composition, and/or [0135] at least one inorganic filler B chosen from among a graphite, a mica, a glass and a fluoride, in a percentage weight ranging between 5 % and 50%, with respect to the total weight of the third composition, and [0136] (ii) a ceramic material obtained from a fourth composition comprising at least one compound chosen from among a carbide, a boride and an oxide.

[0137] Reference may be made to the summary of the invention for further details about the different variants of the third and fourth compositions that are likely to be possible for obtaining these composite and ceramic materials constituting the third dielectric material suitable for the insert 22.