Low voltage switch pole

Abstract

A low voltage switch pole which comprises an insulating casing having lateral walls and a front and a rear wall and defining an internal space with a contact area and an arc extinguishing area, a fixed contact assembly and a movable contact assembly being positioned in said contact area, said movable contact assembly being movable between a closed position in which it is into contact with said fixed contact assembly and an open position in which it is spaced apart from said fixed contact assembly, an arc chamber comprising a plurality of substantially parallel metallic plates inserted into an enclosure made of insulating material being positioned in said arc extinguishing area; the switch pole further comprises an insulating wall which is positioned in said internal space between said contact area and said arc extinguishing area and partially separates said contact area from said arc extinguishing area, a channel connecting said contact area to said arc extinguishing area being provided in said insulating wall.

Claims

1. A low voltage switch pole comprising an insulating casing having lateral walls and a front and a rear wall and defining an internal space with a contact area and an arc extinguishing area, a fixed contact assembly and a movable contact assembly being positioned in said contact area, said movable contact assembly being movable between a closed position in which it is into contact with said fixed contact assembly and an open position in which it is spaced apart from said fixed contact assembly, an arc chamber comprising a plurality of substantially parallel metallic plates inserted into an enclosure made of insulating material being positioned in said arc extinguishing area, characterized in that an insulating wall is positioned in said internal space between said contact area and said arc extinguishing area and partially separates said contact area from said arc extinguishing area, and in that a channel connecting said contact area to said arc extinguishing area is provided in said insulating wall.

2. The low voltage switch pole according to claim 1, wherein said insulating casing comprises a first half shell and a second half shell.

3. The low voltage switch pole according to claim 1, wherein said channel connects a middle portion of said contact area with a terminal portion of said arc extinguishing area.

4. The low voltage switch pole according to claim 1, wherein said insulating wall is positioned in said internal space opposite to said fixed contact assembly.

5. The low voltage switch pole according to claim 1, wherein said insulating wall is positioned in said internal space in correspondence of the open position of said movable contact assembly.

6. The low voltage switch pole according to claim 1, wherein said insulating wall is integral with said front wall and said lateral walls of said insulating casing and extends in said internal space from said front wall towards said fixed contact assembly and said rear wall.

7. The low voltage switch pole according to claim 1, wherein said metallic plates are inserted into said enclosure of said arc chamber at a distance from said contact area and said movable and fixed contact assemblies.

8. The low voltage switch pole according to claim 1, wherein said arc chamber comprises a terminal metallic plate positioned at said insulating wall.

9. The low voltage switch pole according to claim 8, wherein said channel opens into said arc extinguishing area between said terminal metallic plate and said front wall.

10. A low voltage switch which comprises a low voltage switch pole according to claim 1.

11. The low voltage switch pole according to claim 2, wherein said channel connects a middle portion of said contact area with a terminal portion of said arc extinguishing area.

12. The low voltage switch pole according to claim 2, wherein said insulating wall is positioned in said internal space opposite to said fixed contact assembly.

13. The low voltage switch pole according to claim 3, wherein said insulating wall is positioned in said internal space opposite to said fixed contact assembly.

14. The low voltage switch pole according to claim 2, wherein said insulating wall is positioned in said internal space in correspondence of the open position of said movable contact assembly.

15. The low voltage switch pole according to claim 3, wherein said insulating wall is positioned in said internal space in correspondence of the open position of said movable contact assembly.

16. The low voltage switch pole according to claim 4, wherein said insulating wall is positioned in said internal space in correspondence of the open position of said movable contact assembly.

17. The low voltage switch pole according claim 2, wherein said insulating wall is integral with said front wall and said lateral walls of said insulating casing and extends in said internal space from said front wall towards said fixed contact assembly and said rear wall.

18. The low voltage switch pole according claim 3, wherein said insulating wall is integral with said front wall and said lateral walls of said insulating casing and extends in said internal space from said front wall towards said fixed contact assembly and said rear wall.

19. The low voltage switch pole according claim 4, wherein said insulating wall is integral with said front wall and said lateral walls of said insulating casing and extends in said internal space from said front wall towards said fixed contact assembly and said rear wall.

20. The low voltage switch pole according to claim 6, A low voltage switch pole comprising an insulating casing having lateral walls and a front and a rear wall and defining an internal space with a contact area and an arc extinguishing area, a fixed contact assembly and a movable contact assembly being positioned in said contact area, said movable contact assembly being movable between a closed position in which it is into contact with said fixed contact assembly and an open position in which it is spaced apart from said fixed contact assembly, an arc chamber comprising a plurality of substantially parallel metallic plates inserted into an enclosure made of insulating material being positioned in said arc extinguishing area, characterized in that an insulating wall is positioned in said internal space between said contact area and said arc extinguishing area and partially separates said contact area from said arc extinguishing area, and in that a channel connecting said contact area to said arc extinguishing area is provided in said insulating wall: wherein said insulating wall is integral with said front wall and said lateral walls of said insulating casing and extends in said internal space from said front wall towards said fixed contact assembly and said rear wall; wherein said insulating wall has a terminal edge in correspondence of a middle portion of said contact area and in that said channel has a first opening communicating with said contact area proximate to said terminal edge and a second opening communicating with said arc extinguishing area proximate to said front wall.

21. A low voltage switch pole comprising: an insulating casing having lateral walls and a front and a rear wall and defining an internal space with a contact area and an arc extinguishing area, a fixed contact assembly and a movable contact assembly being positioned in said contact area, said movable contact assembly being movable between a closed position in which it is into contact with said fixed contact assembly and an open position in which it is spaced apart from said fixed contact assembly, an arc chamber comprising a plurality of substantially parallel metallic plates inserted into an enclosure made of insulating material being positioned in said arc extinguishing area; wherein an insulating wall is positioned in said internal space between said contact area and said arc extinguishing area and partially separates said contact area from said arc extinguishing area; wherein said contact area and said arc extinguishing area are in direct communication with each other in a region near the front wall of said insulating casing, opposite to said fixed assembly; wherein said contact area and said arc extinguishing area are isolated one from each other by said insulating wall in the region near said fixed assembly; and wherein a channel connects said contact area to said arc extinguishing area is provided in said insulating wall to allow passage of hot gases formed during arc formation.

Description

(1) Further features and advantages of the present invention will be more clear from the description of preferred but not exclusive embodiments of a low voltage switch pole according to the invention, shown by way of examples in the accompanying drawings, wherein:

(2) FIG. 1 is a perspective view of a low voltage switch comprising a low voltage switch pole according to the invention;

(3) FIG. 2 is a perspective view showing the poles arrangement of the low voltage switch of FIG. 1;

(4) FIG. 3 is an exploded view of an embodiment of a low voltage switch pole according to the invention;

(5) FIG. 4 is a perspective view of the low voltage switch pole of FIG. 3 at the initial movement of the movable contact assembly from the closed position;

(6) FIG. 5 is a perspective view of the low voltage switch pole of FIG. 3 in a first intermediate position of the movable contact assembly;

(7) FIG. 6 is a perspective view of the low voltage switch pole of FIG. 3 in a second intermediate position of the movable contact assembly;

(8) FIG. 7 is a perspective view of the low voltage switch pole of FIG. 3 in the open position of the movable contact assembly;

(9) FIG. 8 is a plan view of the low voltage switch pole of FIG. 3 at the initial movement of the movable contact assembly from the closed position;

(10) FIG. 9 is a plan view of the low voltage switch pole of FIG. 3 in a first intermediate position of the movable contact assembly;

(11) FIG. 10 is a plan view of the low voltage switch pole of FIG. 3 in a second intermediate position of the movable contact assembly;

(12) FIG. 11 is a plan view of the low voltage switch pole of FIG. 3 in the open position of the movable contact assembly.

(13) With reference to the attached figures, in particular to FIG. 3, a low voltage switch pole according to the invention, generally designated with the reference numeral 1, comprises in its more general definition an insulating casing 2 having a first 21 and a second 22 lateral wall, a front wall 23 and a rear wall 24. As represented in the attached figures, the insulating casing 2 preferably comprises a first half shell 10 and a second half shell 20 that are coupled to each other so as to form the insulating casing 2. In practice, the first half shell 10 comprises the first lateral wall 21, at least a portion of the front wall 23 and at least a portion of the rear wall 24, while the second half shell 20 comprises the second lateral wall 22, at least a portion of the front wall 23 and at least a portion of the rear wall 24.

(14) The internal space defined by the insulating casing 2 comprises a contact area 3 and an arc extinguishing area 4 which is positioned at an upper level with respect to said contact area 3.

(15) A fixed contact assembly 31, comprising electrical contacts 311, 312 is positioned inside the contact area 3 in correspondence of the rear wall 24 of the insulating casing 2. Likewise, a movable contact assembly 32 is also positioned in said contact area 3, said movable contact assembly 32 being movable between a closed position in which it is into contact with the fixed contact assembly 31 and an open position in which it is spaced apart from said fixed contact assembly 31.

(16) In the embodiment shown in the figures, the movable contact assembly 32 generally comprises electrical contacts 321, 322, and a supporting structure 323 for supporting the contacts 321, 322 which is rotatably mounted on an axis 325 so as to allow engagement/disengagement of the contacts 321, 322 to/from the contacts 311, 312 of the fixed contact assembly 31. The supporting structure 323 also comprises a connecting element 324 which protrudes outside the insulating casing 2 from a window in the front wall 23 for connection with a driving mechanism (not shown) operating the opening/closing of the movable contact assembly 32. Different structures of the movable contact assembly 32 are however possible.

(17) The low voltage switch pole 1 according to the invention also comprises an arc chamber 41 which in turn comprises a plurality of substantially parallel metallic plates 42 inserted into an enclosure 43 made of insulating material. Said arc chamber 41 is inserted into said arc extinguishing area 4 so as to be positioned above said contact area 3.

(18) One of the characterizing features of the low voltage switch pole 1 according to the invention is that an insulating wall 5 is positioned in said internal space between said contact area 3 and said arc extinguishing area 4 and partially separates said contact area 3 from said arc extinguishing area 4. In this way, the contact area 3 and the arc extinguishing area 4 are in direct communication with each other in the region near the fixed contact assembly 31 (i.e. near the rear wall 24 of the insulating casing 2), thereby allowing arc formation in the arc chamber 41. Conversely, in the region near the front wall 23 of the insulating casing 2 (i.e. opposite to the fixed contact assembly 31), the contact area 3 and the arc extinguishing area 4 are isolated from each other by the insulating wall 5, thereby avoiding a jump of the arc directly on the terminal plates of the arc chamber 41, bypassing some of the intermediate metallic plates 42.

(19) In practice, as shown in the attached figures, the insulating wall 5 can be conveniently positioned in said internal space opposite to said fixed contact assembly 31, i.e. in correspondence of the front wall 23 of the insulating casing 2.

(20) A further characterizing features of the low voltage switch pole 1 according to the invention is that a channel 6 is provided in the insulating wall 5. The channel 6 put the contact area 3 into communication with the arc extinguishing area 4, allowing a passage of the hot gas developed during arc formation from the contact area 3 to the arc extinguishing area 4.

(21) As previously explained, the hot gas flows into the terminal portion of the arc chamber 41 and greatly improves the fluid dynamics inside the arc chamber 41, helping (urging) the arc to develop throughout the whole arc chamber 41 and involving all metal plates 42. In particular, the channel 6 connects a middle portion of said contact area 3 with a terminal portion of said arc extinguishing area 4, i.e. the hot gases start passing through the channel 6 from the contact area 3 to the arc extinguishing area 4 when the movable contact assembly 32 is in an intermediate position between the closed position and the open position.

(22) In practice, with reference to FIGS. 4 and 8, when the movable contacts assembly 32 starts separating from the fixed contact assembly 31, an electrical arc (schematically illustrated as solid arrows between plates) is formed in the initial portion of the arc chamber 41 involving the first metallic plates 42 (i.e. those on the right hand side which are closer to the fixed contact assembly 31).

(23) Then, while the movable contacts assembly 32 is travelling in the intermediate positions of FIGS. 5, 9 and 6, 10, the arc (schematically illustrated as solid arrows between plates) continues developing also in the middle portion of the arc chamber 41 involving also the metal plates 42 present in said middle portion; at the same time, the hot gases (schematically illustrated as dotted arrows) flow due to pressure build up from the contact area 3 into the channel 6 and then into the terminal portion of the arc chamber 41.

(24) Finally, when the movable contacts 32 is substantially in the open position of FIGS. 7, 11, the arc has developed throughout the whole arc chamber 41 involving substantially all metallic plates 42. As clearly shown in this latter figures, the insulating wall 5 is conveniently positioned in the internal space of the insulating casing 2 in correspondence of the open position of said movable contact assembly 32, thereby guaranteeing a perfect electrical insulation and avoiding any risk of arc striking/current leakage toward the external.

(25) From a construction standpoint, in the low voltage switch pole 1 according to the present invention the insulating wall 5 is preferably made integral with the front wall 23 and the lateral walls 21 and 22 of the half shells 10 and 20 of the insulating casing 2. The insulating wall 5 extends in the internal space of the insulating casing 2 from said front wall 23 in the direction of the fixed contact assembly 31 and of the rear wall 24, so as to partially separate the contact area 3 from the arc extinguishing area 4.

(26) In practice, in the embodiment illustrated in the figures, the insulating wall 5 has a terminal edge 51 in correspondence of a middle portion of said contact area 3. The channel 6 has therefore a first opening 61 which communicates with said contact area 3 proximate to said terminal edge 51 and a second opening 62 which communicates with said arc extinguishing area 4 proximate to the front wall 23 of the insulating casing 2. As previously said, in this way it is possible to convey the hot gases from the middle portion of the contact area 3 to the terminal portion of the arc chamber 41.

(27) The metallic plates 42 of the arc chamber 41 can have different dimensions and shapes according to the needs. The metallic plates 42 are generally inserted into the enclosure 43 of said arc chamber 41 so that in the operating position a certain gap is left between their lower edge and said contact area 3, as well as between their lower edge and said movable 32 and fixed 31 contact assemblies.

(28) In a largely preferred embodiment of the low voltage switch pole 1 according to the present invention, said arc chamber 41 comprises a terminal metallic plate 45 acting as a roof for said arc chamber 41, i.e. acting so as to close the arc chamber 41 in the terminal portion thereof.

(29) In practice, the terminal metallic plate 45 is inserted into the insulating enclosure 43 of said arc chamber 41 at a lower level with respect to the other metallic plates 42, so as to be located, when in the operating position, substantially in contact with, or very close to, the insulating wall 5.

(30) In such a case, the channel 6 has a first opening 61 which communicates with said contact area 3 in correspondence of a middle portion thereof and a second opening 62 which communicates with said arc extinguishing area 3 at a point between said terminal metallic plate 45 and said front wall 23. In other words, according to this largely preferred embodiment the hot gases are vented from the contact area 3 to a position in the arc chamber 41 which is beyond the roof formed by the terminal metallic plate 45.

(31) As is clear from the above description, the technical solutions adopted for the low voltage switch pole according to the present invention allow the proposed aims and the objects to be fully achieved.

(32) In particular, substantially all metal plates 42 are involved during the arc quenching thereby allowing a more uniform utilization of the arc chamber 41. Less mechanical and thermal stresses are therefore generated into the arc chamber 41 with a consequent prolonged lifetime of it and of the associated switch pole.

(33) Thanks to the insulating wall 5, the possibility for the arc to bypass some of the intermediate metal plates 42 is substantially avoided and is also avoided or considerably reduced any risk of arc strikes toward the external of the pole 1. At the same time, thanks to the channel 6 provided in the insulating wall 5, the fluid dynamics of the hot gases is greatly improved, contributing to stripping the arc throughout the arc chamber 41 so as to involve all metal plates 42. The improved flow of hot gases from the contact area 3 to the arc extinguishing area 4 also helps cooling the movable contacts.

(34) A low voltage switch 100 comprising at least one low voltage switch pole 1 as previously described is also part of the present invention.

(35) With reference to FIGS. 1 and 2, a three pole low voltage circuit breaker 100 comprising three low voltage switch poles 1 (i.e. circuit breaker poles) is shown. In this embodiment, the insulating casing 2 of each pole 1 is made of two half shells 10 and 20, and the poles 1 are positioned side by side in a supporting a containing structure having rigid flanks 101 and 102, as well as a cover 103. From windows in the front side 23 of the insulating casings 2, connecting elements 324 protrude outside for connection with a driving mechanism (not shown). The general structure of such low voltage circuit breaker is well known in the art and therefore will be not described in more details.

(36) Several variations can be made to the low voltage switch pole thus conceived, all falling within the scope of the attached claims. In practice, the materials used and the contingent dimensions and shapes can be any, according to requirements and to the state of the art.