WO2013092530A2

WO2013092530A2 - Contact pin for high-voltage circuit breakers and high-voltage circuit breaker with such a contact pin

Info

Publication number: WO2013092530A2
Application number: PCT/EP2012/075860
Authority: WO
Inventors: Dirk Moog; Willy Kretz
Original assignee: Doduco Gmbh; Alutec Metal Innovations Gmbh & Co. Kg
Priority date: 2011-12-21
Filing date: 2012-12-17
Publication date: 2013-06-27
Also published as: WO2013092530A3; CH707639B1; DE102012101222A1

Abstract

The invention relates to a contact pin for high-voltage circuit breakers, with a jacket (5b) made of copper, which is closed off at one end by an end wall (5a) made of copper, with a solid core (15) that extends from the end wall (5a) into the jacket (5b), supports it and consists of a material having a lower density than copper, and with a contact tip (12), which is mounted on the exterior on the end wall (5a) and consists of a composite material containing copper or silver, which is more resistant than copper to the effects of arcs that arise during switching of the high-voltage circuit breaker.

Description

Contact pin for high-voltage circuit breaker and high-voltage circuit breaker with such a contact pin

description

It is known to use in electric high-voltage circuit breakers electrical contact arrangements, which consist of a tubular contact piece and a contact pin, which makes contact with one end of the tubular contact piece when the switch is closed. In a high-voltage circuit breaker, it is important that the switching operations are carried out quickly, so that an arc that arises between the tubular contact piece and the contact pin breaks off as quickly as possible when opening the switch and when closing the switch as soon as possible by the impact of the contact pin the opposite contact piece is deleted. It is known to produce the contact pin from a pin made of copper and to provide this with a contact tip of a copper-tungsten composite material to minimize the occurring under arc burning of the contact tip.

The speed with which a high-voltage circuit breaker can be opened and closed is limited, on the one hand, by the inertial mass of the contact pin to be accelerated and, on the other hand, by the boundary condition that the high-voltage circuit breaker should switch over. The larger the inertial mass of the contact pin to be accelerated, the more complex the drive for the contact pin.

In order to achieve short switching times, it is known to reduce the mass of the contact pin by forming the copper pin hollow. Since copper is a relatively soft metal, the mass of the copper pin can not be reduced as much by a hollow design, as you would like, because the pin otherwise would not withstand the mechanical stresses that occur during the switching process. To remedy this disadvantage, it is known to produce a hollow copper pin made of a hardened copper alloy. However, this is a major disadvantage. Even small amounts of hardening alloy constituents in the copper lead namely to a drastic reduction of the electrical conductivity compared to the electrical conductivity of pure copper. Therefore, when using a hardened copper alloy, the cross-section of the contact pin must be increased to achieve the same current carrying capacity as a contact pin made of pure copper.

Furthermore, it is known to use as a carrier for the contact tip instead of a pin made of copper, a hollow contact pin made of steel. However, in this case too, there is the disadvantage that the electrical conductivity of steel is much smaller than that of copper. The present invention has for its object to provide a way in which high-voltage circuit breakers in the simplest possible way the cost of driving the movable contact pin can be reduced.

According to the invention this object is achieved by a contact pin having the features specified in claim 1. A method for producing a contact pin according to the invention is the subject of claim 17, Advantageous developments of the invention are the subject of the dependent claims. An inventive high-voltage circuit breaker is the subject of claim 25.

The contact pin for high-voltage circuit breaker has a sheath of copper, which is closed at one end by a copper end wall, a solid core, which, starting from the end wall in the jacket, supports it and consists of a material which has a lower density As a copper, and a contact tip, which is externally attached to the end wall and consists of a copper or silver-containing composite, which is more resistant to the action of arcs, which occur when switching the high-voltage circuit breaker, as copper.

This has significant advantages:

- The solid core, which fills the jacket starting from the end wall, gives the contact pin a strength which is similar to the strength of a corresponding contact pin, which, except for the contact tip, made of copper. Due to the lower density of the core, however, the mass of the contact pin, compared to a corresponding contact pin, which, apart from the contact tip, consists of pure copper, significantly reduced.

- Due to the lower mass of the movable contact pin, the performance of the drive required for him can be reduced. This is a reduction of the effort goes hand in hand, which must be driven for the realization of the drive. - The fact that the Kupiermantel is supported from the inside by the core, it may have a particularly small wall thickness, which is limited only by the required current carrying capacity. The required for a particular high-voltage circuit breaker mechanical strength of the contact pin is not critical for the design of the wall thickness of his existing copper shell.

By closing the copper sheath at one end by a copper end wall, the contact tip, regardless of the material chosen for the core, can be fully bonded to the copper end wall by welding or brazing.

- The contact pin according to the invention allows a simple and inexpensive way to shorten the duration of the switching operation of high-voltage circuit breakers.

Preferably, the end of the copper sheath facing away from the contact tip projects beyond the core and an overhanging section of the sheath is designed as a connection device for an electrical supply line. This ensures that the required electrical supply line ends directly at the protruding portion of the jacket made of copper, so that a low contact resistance is ensured.

According to a method according to claim 17, such a contact pin can be made simple and inexpensive, when the material for the core is filled in a blind hole, which is arranged coaxially in a straight cylinder made of copper. Thereafter, the cross-section of the cylinder is reduced by extrusion most of its length, especially by forward extrusion, and then a contact tip of a copper or silver-containing composite material that is more resistant to the action of switching arcs than copper, by welding or Brazing attached to the copper existing end wall of the extrusion-molded cylinder. At the end of the cylinder facing away from the contact tip, after or before attaching the cone iaktspitze preferably formed a connection device for an electrical supply line.

This too has significant advantages:

The fact that the cross-section of the copper cylinder is reduced over most of its length by extrusion, in particular by forward extrusion, creates a strong bond between the cylinder jacket and the filled material, which has a lower density than copper.

The material for the core can be introduced not only as a solid whose dimensions are adapted to the blind hole in the copper cylinder in the blind hole, but also as bulk material, because this can be compressed by extrusion, so that a solid bond between the Core material and the copper jacket results.

- The forming of the copper cylinder filled with the core material by extrusion does not produce copper waste. After the extrusion is at best still a little rework on the Formtei formed by the extrusion! required, eg. B. smoothing the surface and / or removing a passivating topcoat on the end wall made of copper, in order to prepare for the attachment of the contact tip, and optionally the formation of a connection device for an electrical supply line. The latter can be done simply by cutting an internal thread into an end of the copper sheath projecting beyond the core, into which an electrical supply line provided with an external thread or a coupling part of an electrical supply line can be turned.

Due to the fact that the copper cylinder filled with the core material is not formed by extrusion over a full length but only over a predominant part of its length, a section of the shell projecting beyond the core preferably remains at a greater wall thickness than at the end of the copper cylinder the extrusion formed section. In the a thicker-walled, preferably projecting portion of the shell can be easily cut an internal thread and from the outer periphery of the thicker wall portion, a portion of the copper can be milled to form two flat, mutually parallel surfaces, which provide a possibility of attack for a wrench.

- The extrusion can be carried out inexpensively at room temperature.

For the core, a material with a density less than 5 g / cm ³ is preferably selected. In this area fall the light metals, of which especially aluminum with a density of 2.7 g / cm ³ , titanium with a density of 4.51 g / cm ³ , magnesium with a density of 1, 74 g / cm ³ and their alloys are eligible. Particularly preferred are materials having a density of less than 3 g / cm ³ , that is not more than one third of the density of copper. This can be achieved for a solid contact pin according to the invention, a mass which is substantially smaller than when using a pin which consists of pure copper.

The use of a light metal or a light alloy for the core has the further advantage that it can contribute to the power line. Although light metals such as aluminum and titanium easily coat with an oxide skin, which impedes the passage of electricity from the copper to the light metal, however, when the core is reformed together with the surrounding copper sheath, as is the case with extrusion, the oxide skin may be on the core tear open and the core at least in places cold welded to the copper sheath, so that a current transition from the copper sheath into the core and vice versa from the core in the copper sheath is readily possible. This is an advantage of using extrusion molding to make the solid bond between the copper sheath and a light metal core.

The core does not have to consist of a metal, but can z. B. also consist of a metal oxide or a metalloid. As metal oxides are mainly alumina and magnesium oxide in question, as metalloid z. B. graphite. The metal oxides or metalloids can be introduced as a preformed body or as a powder in the blind hole of the copper cylinder. Becomes a metal oxide or metalloid introduced as a powder, this is compacted by extrusion of the filled copper cylinder and forms a composite body with the extruded copper cylinder.

Another possibility is to provide a ceramic core, in particular a core made of a ceramic foam. The latter has the advantage that it combines a particularly low density with a high strength.

Finally, it is also possible to provide a core made of a plastic. Preferably, it should be a cross-linked plastic handein, z. B. an epoxy resin or a silicone resin. The plastic is preferably only then filled into the initially hollow contact pin when the cavity has already its final shape. Conveniently, the components of the plastic are mixed together and then poured immediately into the cavity of the contact pin to then tie it in, d. H. to network.

In principle, a patent according to the contact pin could also be prepared so that first a copper tube with a core whose density is smaller than the density of copper, produced in appropriate length and formed by extrusion. This copper tube can then be closed at one end with a copper disc by being welded or brazed to the end of the copper tube. Preferably, the copper disc is formed as a stepped lid, which dips a little way into the copper tube until it abuts the edge of the copper tube. For this to be possible, an appropriate amount of the core material is previously removed from the copper tube. A contact tip made of a material which has a greater erosion resistance than copper can be welded onto the cover beforehand or subsequently, preferably subsequently. At the opposite end of the copper tube, a cap made of copper can be fixed by welding or soldering, which can be equipped with a connection device for an electrical supply line. It is more favorable, however, to apply the method according to claim 17.

The blind hole, in which, according to claim 17, the material for the core is to be filled, can be milled into the straight cylinder of copper. Preferably, the blind hole in the cylinder is already extruded, preferably se by backward extrusion. This has the advantage that no copper waste is produced during the manufacture of the blind hole. Also in this case, the extrusion molding is preferably carried out at room temperature. As a cylinder of copper, a straight circular cylinder is preferably used. But it is also possible to use a cylinder instead of a circular cylinder whose base is a polygon, in particular regular polygon, preferably with an even number of corners. Preferably, the polygon has at least six corners.

If a circular cylinder is selected as the cylinder, a cylindrical blind hole is expediently formed therein as well. If a cylinder is used, whose base is a regular polygon, then the blind hole has expediently a cross section in the form of a corresponding regular polygon, so that the cylinder has a substantially constant wall thickness in the circumferential direction.

The composite material from which the contact tip is formed is suitably selected from the group consisting of the materials copper-tungsten, silver-tungsten, silver-tungsten-carbide and silver-molybdenum, with copper-tungsten being preferred, for. B. a composite of copper with 60 wt .-% to 85 wt .-% tungsten.

In view of the fact that it is expedient to design a connection device for an electrical supply line at the rear end of the contact pin, it is preferred that the portion of the copper sheath lying on the core has a smaller wall thickness than the protruding section of the copper sheath. Preferably, the wall thickness of the lying on the core portion of the shell is only 1 mm to 2 mm, in particular only about 1 mm.

A preferred embodiment for the manufacture of a contact pin according to the invention is shown in the accompanying drawings.

Figure 1 shows an oblique view of a solid, circular cylindrical copper cylinder, from which starts the process for producing the contact pin. Figure 2 shows the forming of the copper cylinder by backward extrusion.

Figure 3 shows a cylindrical formed by the backward extrusion

Cup, in which a light metal cylinder is used.

Figure 4 shows the forming of the cup shown in Figure 3 by forward extrusion.

FIG. 5 shows in a side view that shown by the forward extrusion according to FIG

Figure 4 produced contact pin blank, at the front end wall of a contact tip is welded.

FIG. 6 shows a longitudinal section through the finished contact pin. FIG. 7 shows the finished contact pin in a side view.

A Kupferzyiinder 1 is inserted into a die 2 with a cylindrical cavity 3 and formed by a punch 4, which has a smaller diameter than the copper cylinder 1, by backward extrusion to form an elongated cylindrical cup 5, see Figure 2. In this cup 5 is a light metal cylinder 6 is inserted whose outer diameter substantially coincides with the inner diameter of the cup 5 and whose length is shorter than the inside measured length of the cup 5, so that the jacket 5b of the cup 5 projects slightly beyond the end 6a of the light metal cylinder 6, see FIG. 3.

The cup 5 prepared in this way is introduced into a pressing tool 7 which has a passage 8 with a reduced tool opening 9 through which a punch 10 presses the cup 5 containing the light metal cylinder 6 over part of its length, see FIG This forward extrusion creates a contact pin blank 1 1, which has retained its original diameter in its rear portion 1 1 a and in its front portion 1 1 b has a determined by the reduced cross-sectional tool opening 9 smaller diameter. Backward extrusion and the pre- Downstream extrusion presses are preferably cold, ie at room temperature.

The copper jacket 5 b of the blank 1 1 is open at the rear end and closed at the front end by an end wall 5 a, which is formed from the bottom of the cup 5.

At this contact pin blank 1 1 now a contact tip 12 is soldered, which preferably consists of a copper-tungsten composite material, see Figure 5, in which the soldering is symbolically indicated by a soldering tool 14.

In a final step, an internal thread 13 is cut into this contact pin blank 11 from the rear, if necessary, the rear end of the contact pin blank 1 1 has been drilled a bit far, see Figure 6. In the internal thread 13, one with corresponding external thread provided electrical connection line to be rotated.

reference numerals

1 copper cylinder

2 matrix

3 cylindrical cavity

4 stamps

5 bowls

5a end wall

5b copper jacket

6 light metal cylinder

7 pressing tool

8 passage

9 tool opening

10 stamps

1 1 contact pin blank

1 1 a rear section

1 1 b front section

12 contact point

13 internal thread

14 soldering tool

15 solid core

Claims

claims

1. Contact pin for high voltage circuit breaker with a Mante! (5b) of copper terminated at one end by a copper end wall (5a),

with a solid core (15) which, starting from the end wall (5a), is inserted in the shell (5b), supports it and consists of a material which has a lower density than copper,

and a contact tip (12) fixed externally to the end wall (5a) and made of a composite containing copper or silver, which is more resistant to the action of arcs occurring in switching of the high voltage circuit breaker than copper ,

2. Contact pin according to claim 1, characterized in that the core (15) has a density which is less than 5 g / cm ³ , in particular less than 3 g / cm ³ .

3. Contact pin according to claim 1 or 2, characterized in that the core (15) consists of a metal or an alloy, in particular of a light metal or of a light metal alloy.

4. Contact pin according to claim 3, characterized in that the core (5) in the casing (5b) pressed and / or at least in places with the jacket (5b) is cold welded.

5. Contact pin according to claim 1 or 2, characterized in that the core (15) consists of a metal oxide, in particular of aluminum oxide or magnesium oxide, or of a metalloid, in particular of graphite.

6. Contact pin according to claim 1 or 2, characterized in that the core (15) consists of a ceramic, in particular of a foamed ceramic.

7. Contact pin according to claim 1 or 2, characterized in that the core (5) consists of a plastic.

8. Contact pin according to one of the preceding claims, characterized in that the combination of jacket (5b) and end wall (5a) is integrally formed.

9. Contact pin according to one of the preceding claims, characterized in that the combination of jacket (5b), end wall (5a) and connecting device is integrally formed.

10. Contact pin according to one of the preceding claims, characterized in that the composite material of which the contact tip (12) is formed, is selected from the group of materials copper-tungsten, silver-tungsten, silver-tungsten carbide and silver-molybdenum with copper-tungsten being preferred.

11. Contact pin according to one of the preceding claims, characterized in that the contact tip (12) facing away from the end of the shell (5b) over the core (15) and a projecting portion of the jacket (5b) is formed as a connection device for an electrical supply line ,

12. Contact pin according to claim 11, characterized in that on the core (15) lying portion of the jacket (5b) has a smaller wall thickness than the protruding portion of the jacket (5b).

13. Contact pin according to one of the preceding claims, characterized in that on the core (15) lying portion of the jacket (5b) has a smaller wall thickness than the end wall (5a).

14. Contact pin according to claim 12 or 13, characterized in that the wall thickness of the on the core (15) lying portion of the jacket (5b) is 1 mm to 2 mm.

15. Contact pin according to one of claims 11 to 14, characterized in that the connection device for an electrical supply line an internal thread de (13) formed in the projecting portion of the shell (5b).

16. Contact pin according to one of claims 1 1 to 15, characterized in that the protruding portion of the jacket (5 b) on the outside has at least two mutually parallel surfaces.

17. A method for producing a contact pin according to one of the preceding claims

(a) filling the material for the core into a blind hole which is arranged coaxially in a straight cylinder made of copper,

(b) reducing the cross-section of the cylinder over a majority of its length by extrusion,

(c) attaching a contact tip to the end wall of the cylinder by welding or brazing.

18. The method according to claim 17, characterized in that the extrusion is carried out as a forward extrusion.

19. The method according to claim 17, characterized in that the blind hole in the cylinder is produced by extrusion, preferably by Rückwärtsfließpressen.

20. The method according to any one of claims 17 to 19, characterized in that the extrusion is carried out at room temperature.

21. The method according to any one of claims 17 to 20, characterized in that a circular cylinder or a cylinder is used as the cylinder whose base is a regular polygon with an even number of corners is used.

22. The method according to any one of claims 17 to 21, characterized in that the blind hole is cylindrical and has a circular cross section or a Has cross section in the shape of a regular polygon with an even number of corners.

23. The method according to any one of claims 17 to 22, characterized in that the material for the core is filled in the form of a fixed cylinder in the blind hole, whose cross section is closely adapted to the cross section of the blind hole.

24. The method according to any one of claims 17 to 23, characterized in that a connection device for an electrical supply line at the end remote from the contact tip of the cylinder between steps (b) and (c) or after step (c) is formed.

25. High-voltage circuit breaker with a contact arrangement, which has a tubular contact piece and a movable contact pin, and with a drive which brings the contact pin into contact with the contact piece for closing the circuit breaker and disconnects the contact pin for opening the circuit breaker from the contact piece,

characterized by a contact pin having the features according to one of claims 1 to 16.