ELECTRICAL CONNECTION ASSEMBLY IN AN ELECTRICAL SWITCHGEAR

Abstract

An electrical connection assembly in an electrical switchgear comprising a circuit breaker movable between a disconnected, withdrawn, position and a connected, service, position, wherein said circuit breaker comprises, for each phase, a first connection terminal couplable to/uncouplable from a corresponding second, stationary, connection terminal of said switchgear, characterized in that said electrical connection assembly comprises a first contact element electrically and mechanically connected to said first connection terminal of said circuit breaker, a second contact element electrically and mechanically connected to said second, stationary, connection terminal of said switchgear, and a third, intermediate, contact element that is electrically and mechanically connected with one of said first and second contact elements and that is electrically and mechanically couplable to/uncouplable from the other of said first and second contact elements, and further characterized in that said first and second contact elements respectively forms a first and a second contact pair with a portion of said third intermediate contact element, each of said first and second contact pair having a male contact element and a female contact element having a hollow cavity into which said male element is instertable with sliding contacts positioned at the interface between said male and female contact elements, the external surface of said female contact element having linear and curved portions devoid of any sharp edge and being symmetrical with respect to a central longitudinal axis.

Claims

1. An electrical connection assembly in an electrical switchgear comprising: a circuit breaker movable between a disconnected, withdrawn, position and a connected, service, position, wherein said circuit breaker comprises, for each phase, a first connection terminal couplable to/uncouplable from a corresponding second, stationary, connection terminal of said switchgear; a first contact element electrically and mechanically connected to said first connection terminal of said circuit breaker, a second contact element electrically and mechanically connected to said second, stationary, connection terminal of said switchgear, and a third, intermediate, contact element that is electrically and mechanically connected with one of said first and second contact elements and that is electrically and mechanically couplable to/uncouplable from the other of said first and second contact elements; wherein said first and second contact elements respectively forms a first and a second contact pair with a portion of said third, intermediate, contact element, each of said first and second contact pairs having a male contact element and a female contact element having a hollow cavity into which said male element is insertable, and having sliding contacts positioned at the interface between said male and female contact elements, the external surface of said female contact element having linear and curved portions devoid of any sharp edge and being symmetrical with respect to a central longitudinal axis.

2. The electrical connection assembly, according to claim 1, wherein said male contact element comprises a cylindrical body and said female contact element comprises a cylindrical hollow cavity into which said cylindrical body is insertable.

3. The electrical connection assembly, according to claim 1, wherein said hollow cavity of said female contact element comprises one or more slots on its internal surface into which said sliding contacts are positioned.

4. The electrical connection assembly, according to claim 1, wherein said male contact element comprises one or more slots on its external surface into which said sliding contacts are positioned.

5. The electrical connection assembly, according to claim 3, characterized in that, wherein for each contact pair said male contact element and/or said female contact element comprises a plurality of slots into which a corresponding plurality of sliding contacts are positioned.

6. The electrical connection assembly, according to claim 1, wherein said third, intermediate, contact element comprises a single-piece elongated body.

7. The electrical connection assembly, according to claim 1, wherein said third, intermediate, contact element comprises a single-piece elongated sleeve made of conductive material having a cylindrical hollow cavity, and in that each of said first and second contact elements comprises a cylindrical body insertable in said cylindrical cavity, said first contact pair being formed by said third, intermediate, contact element and the cylindrical body of said first contact element at a first end of said single-piece elongated sleeve, said second contact pair being formed by said third, intermediate, contact element and the cylindrical body of said second contact element at a second end of said single-piece elongated sleeve.

8. The electrical connection assembly, according to claim 1, wherein said third, intermediate, contact element comprises a single-piece elongated cylindrical body, and in that each of said first and second contact elements comprises a female contact element having a hollow cavity into which a portion of said single-piece elongated cylindrical body, said first contact pair being formed by said third, intermediate, contact element and the female contact element of said first contact element at a first end of single-piece elongated cylindrical body, said second contact pair being formed by said third, intermediate, contact element and the female contact element of said second contact element at a second end of said single-piece elongated cylindrical body.

9. The electrical connection assembly, according to claim 1, wherein said third, intermediate, contact element is electrically and mechanically connected with said first contact element and is electrically and mechanically couplable to/uncouplable from said second contact element.

10. The electrical connection assembly, according to claim 1, wherein said third, intermediate, contact element is adapted to slightly bend with respect to said longitudinal axis to compensate possible misalignment between said first and second contact elements.

11. The electrical connection assembly, according to claim 1, wherein said sliding contacts are compressible in a direction perpendicular to said longitudinal axis to compensate possible misalignment between said first and second contact elements.

12. The electrical connection assembly, according to claim 1, wherein said sliding contacts are Baumann contact springs or Multi-Contact bands.

13. The electrical connection assembly, according to claim 1, wherein the external surface of said female element is coated with an insulated coating.

14. An electrical switchgear comprising an electrical connection assembly according to claim 1.

15. The electrical connection assembly according to claim 2, wherein said hollow cavity of said female contact element comprises one or more slots on its internal surface into which said sliding contacts are positioned.

16. The electrical connection assembly according to claim 15, wherein said male contact element comprises one or more slots on its external surface into which said sliding contacts are positioned.

17. The electrical connection assembly according to claim 4, wherein for each contact pair said male contact element and/or said female contact element comprises a plurality of slots into which a corresponding plurality of sliding contacts are positioned.

18. The electrical connection assembly according to claim 3, wherein said male contact element comprises one or more slots on its external surface into which said sliding contacts are positioned; wherein said third, intermediate, contact element comprises a single-piece elongated body; and wherein said third, intermediate, contact element comprises a single-piece elongated cylindrical body, and in that each of said first and second contact elements comprises a female contact element having a hollow cavity into which a portion of said single-piece elongated cylindrical body, said first contact pair being formed by said third, intermediate, contact element and the female contact element of said first contact element at a first end of single-piece elongated cylindrical body, said second contact pair being formed by said third, intermediate, contact element and the female contact element of said second contact element at a second end of said single-piece elongated cylindrical body.

19. The electrical connection assembly according to claim 2, wherein said male contact element comprises one or more slots on its external surface into which said sliding contacts are positioned.

20. The electrical switchgear according to claim 14, wherein said male contact element comprises a cylindrical body and said female contact element comprises a cylindrical hollow cavity into which said cylindrical body is insertable; and wherein said hollow cavity of said female contact element comprises one or more slots on its internal surface into which said sliding contacts are positioned.

Description

[0039] Further features and advantages of the present invention will be more clear from the description of preferred but not exclusive embodiments of an electrical connection assembly in an electrical switchgear according to the present invention, shown by way of examples in the accompanying drawings, wherein:

[0040] FIG. 1 is a side view of an electrical switchgear with a circuit breaker in a disconnected, withdrawn, position;

[0041] FIG. 2 is a side view of an electrical switchgear with a circuit breaker in a connected, service, position;

[0042] FIG. 3 is a schematic view of a first exemplary embodiment of an electrical connection assembly, according to the invention, in a first position;

[0043] FIG. 4 is a schematic view of a first exemplary embodiment of an electrical connection assembly, according to the invention, in a second position;

[0044] FIG. 5 is a schematic view of a first exemplary embodiment of an electrical connection assembly, according to the invention, in a third position;

[0045] FIG. 6 is a view of a component of a first exemplary embodiment of an electrical connection assembly, according to the invention;

[0046] FIG. 7 is a schematic view of a second exemplary embodiment of an electrical connection assembly, according to the invention, in a first position;

[0047] FIG. 8 is a schematic view of a third exemplary embodiment of an electrical connection assembly, according to the invention, in a first position.

[0048] With reference to the attached FIGS. 1 and 2, an electrical switchgear 100 normally comprises a circuit breaker 101 which is movable between a disconnected, withdrawn, positionshown in FIG. 1and a connected, service, positionshown in FIG. 2according to well-known embodiments that will not be described in further details.

[0049] In order to achieve the electrical connection with the switchgear 100, said circuit breaker 101 normally comprises, for each phase, a first connection terminal 102 (circuit breaker contact arm), which is couplable to and uncouplable from a corresponding second, stationary, connection terminal 103 (switchgear contact pin) of said switchgear 100, typically on both line and load side. With reference to the attached FIGS. 3-8, one of the distinguishing features of the switchgear 100 of the present invention is given by the fact that the electrical connection assembly, designated by the reference numerals 1, 10, 20, in its more general definition comprises a first contact element 11, 21 which is electrically and mechanically connectedfor exampleto the first connection terminal 102 of said circuit breaker 101, and a second contact element 12, 22 which in turn is electrically and mechanically connected to the second, stationary, connection terminal 103 of said switchgear 100. The electrical connection assembly 1, 10, 20 then comprises a third, intermediate, contact element 13, 23, 33 that is electrically and mechanically connected with one of said first 11, 21 and second 12, 22 contact elements and that is electrically and mechanically couplable to/uncouplable from the other of said first 11, 21 and second 12, 22 contact elements

[0050] In practice, in the switchgear 100 according to the invention, the third, intermediate, contact element 13, 23, 33 that carries out the electrical connection of the insertion points, can be fixed on either the moving connection terminals 102 of the circuit breaker 101 or on the stationary connection terminals 103 of the switchgear 100.

[0051] Thus, the electrical connection assembly 1, 10, 20 of the switchgear 100 of the present invention, can be considered as formed by two contact pairs 41, 42. The first contact element 11, 21 forms a first contact pair 41 with a first portion of said third, intermediate, contact element 13, 23, 33 and similarly the second contact element 12, 22 forms a second contact pair 42 with a second portion of said third, intermediate, contact element 13, 23, 33.

[0052] The mechanical and electrical connection in each contact pair 41, and 42 is conveniently achieved with a male/female coupling. In practice, each of said first 41 and second 42 contact pair has a male contact element 411, 421 and a female contact element 412, 422 having a hollow cavity into which said male element 411, 421 is instertable, according to exemplary embodiments better disclosed hereinafter.

[0053] A further distinguishing features of the switchgear 100 of the present invention is given by the fact that a number of sliding contacts 51, 52, 53, 5 are positioned at the interface between the male 411, 421 and female 412, 422 contact elements, thereby providing a contact interface having a higher number of sliding contact points with respect to the conventional tulip contact systems.

[0054] Furthermore, the external surface 400 of said female contact element 412, 422, is conveniently symmetrical with respect to a central longitudinal axis and is suitably shaped so as to have linear and curved portions which are devoid of any sharp edge. The presence of sharp hotspots and the consequent problem of field concentration around said sharp hotspots are therefore greatly reduced.

[0055] Typically, the male contact element 411, 421 of the first and second contact pairs 41, 42 can be conveniently made as a cylindrical body (therefore very easy to manufacture) and the corresponding female contact element 412, 422 can be conveniently made as a cylindrical hollow cavity into which said cylindrical body is insertable (and therefore likewise very easy to manufacture).

[0056] In the embodiment of an electrical connection assembly 1, 10 shown in FIG. 3-7, the hollow cavity of said female contact element 412, 422 conveniently comprises one or more slots 450 which are formed on its internal surface 451. The sliding contacts 51, 52, 53, 54 are then positioned in said slots 450 and kept in place during the sliding connection/disconnection movement of male contact element 411, 421 inside the hollow cavity.

[0057] Alternatively, as shown in FIG. 8, the sliding contacts 51, 52, 53, 54 can be positioned on the male contact side of the connection pairs 41 and 42. In such a case, the male contact element 411, 421 conveniently comprises one or more slots 461 which are formed on its external surface 460, said sliding contacts 51, 52, 53, 54 being the positioned and kept in place into said slots 461.

[0058] As shown in the embodiment of FIG. 7, if it is desired to increase the contact density at the contact interface between the various contact elements, it is possible, for each contact pair 41, 42, to provide said male contact element 411, 421 and/or said female contact element 412, 422 with a plurality of slots 450 into which a corresponding plurality of sliding contacts 51, 52, 53, 54 are conveniently positioned.

[0059] In a largely preferred embodiment of an electrical connection assembly 1, 10, 20, as disclosed herein, shown in FIGS. 3-8, said third, intermediate, contact element 13, 23, 33 comprises a single-piece elongated body.

[0060] In particular, with reference to FIGS. 3-8, the third, intermediate, contact element 13, 23, 33 conveniently comprises a single-piece elongated sleeve 130, 230, 330 which is made of a conductive material having a cylindrical hollow cavity 131, 231, 331. In turn, each of said first 11, 21 and second 12, 22 contact elements conveniently comprises a cylindrical body which is insertable in said cylindrical cavity 130, 230, 330.

[0061] Thus, the first contact pair 41 is formed by said third, intermediate, contact element 13, 23, 33 and by the cylindrical body of said first contact element 11, 21 at a first end of said single-piece elongated sleeve 130, 230, 330, while said second contact pair 42 is formed by said third, intermediate, contact element 13, 23, 33 and the cylindrical body of said second contact element 12, 22 at a second end of said single-piece elongated sleeve 130, 230, 330, on the opposite side of said single-piece elongated sleeve 130, 230, 330.

[0062] In an alternative embodiment of an electrical connection assembly 1, 10, 100, not illustrated in details, said third, intermediate, contact element comprises a single-piece elongated cylindrical body, while each of said first and second contact elements comprises a female contact element having a hollow cavity into which a portion of said single-piece elongated cylindrical body, thereby realizing a contact configuration which is opposite with respect to the one previously described.

[0063] In practice, in this embodiment the first contact pair is therefore formed by said third, intermediate, contact element and the female contact element of said first contact element at a first end of said single-piece elongated cylindrical body, while said second contact pair is likewise formed by said third, intermediate, contact element and the female contact element of said second contact element at a second end of said single-piece elongated cylindrical body, on the opposite side said single-piece elongated cylindrical body.

[0064] In a typical embodiment of an electrical connection assembly 1, 10, 20 in an electrical switchgear 100, according to the present disclosure, the third, intermediate, contact element 13, 23, 33 is electrically and mechanically connected with said first contact element 11, 21, in turn connected to the circuit breaker 101, and is electrically and mechanically couplable to/uncouplable from said second contact element 12, 22, in turn connected to the second, stationary, connection terminal 103 of said switchgear 100.

[0065] In other words, the third, intermediate, contact element 13, 23, 33, i.e. the single-piece elongated sleeve 130, 230, 330 that carries out the electrical connection of the insertion points, in the embodiments illustrated is fixed on the moving connection terminals 102 of the circuit breaker 101, thereby following it during the rack-in and rack-out operation. The opposite configuration, in which the sleeve 130, 230, 330 is fixed on the second, stationary, connection terminal 103 of the switchgear 100 is however also possible.

[0066] As shown in FIG. 5, the structure of the electrical connection assembly 1, 10, 20 presently disclosed allows compensating possible misalignments between the circuit breaker terminals 102 and the switchgear terminals 103.

[0067] In practice, the third, intermediate, contact element 13, 23, 33 is adapted to slightly bend with respect to its longitudinal axis thereby assuming an inclined orientation with respect to the insertion/extraction direction an making possible a compensation of any misalignment between said first 11, 21 and second 12, 22 contact elements.

[0068] Such compensation is also possible by using sliding contacts 51, 52, 53, 54 with elastic characteristics and which are compressible in a direction perpendicular to said longitudinal axis, for instance Baumann contact springs

[0069] Alternatively the sliding contacts 51, 52, 53, 54 Multi-Contact bands or any other kind of sliding contact system which is able to guarantee the required performance.

[0070] As previously said, when desired, it is possible to increase the dielectric and thermal performances of the electrical connection assembly 1, 10, 20 by applying an insulating painting or coating on the external surface 452 of the female element 412, 422, thereby improvement the insulation level and enhancing the heat exchange capability of the electrical connection assembly 1, 10, 20.

[0071] It is clear from the above that the presently disclosed electrical connection assembly 1, 10, 20 in an electrical switchgear 100 fully solves the technical problems underlined above.

[0072] Indeed, despite the extreme compactness of the design compared to traditional tulip contact, the high contact point density of the sliding contact elements ensures a good current carrying capability and low contact resistance. Moreover, the particular design of the various contact elements, allows minimizing the electric field stress compared to tulip contact solution allowing a better design/product robustness.

[0073] Moreover, in high rating circuit breakers (like >3000 A rated current) or high short circuit current (like >50 kA), the presently disclosed solution increasing current carrying performances, keeping at the same time low overall dimensions and therefore low phase-to-phase dielectric stress.

[0074] Also, in particular case, where a traditional tulip design would require a complex shielding of the insulating bushing in order to eliminate dielectric hotspots on sharp edges, the dielectric robustness of this solution can allow a lower bushing shielding complexity and good current carrying capability in a compact design.

[0075] Several variations can be made to the electrical connection assembly in an electrical switchgear 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.