HK1137848A - Switch device - Google Patents

Description

Switching device

Technical Field

The invention relates to a switching device according to the preamble of claim 1.

Background

Switching devices are known which, in the event of excessive currents in the line network (which last for a predeterminable period of time), disconnect the line network from the supply network in order to prevent further current supply. Thereby avoiding possible damage such as cable burning due to excessive current flowing through the conductor increasing the temperature of the conductor. Such a switching device therefore has a so-called overcurrent tripping device, which for example comprises a bimetallic element, which heats up in the line network under the effect of the current flow, thereby bending the bimetallic element. At a predeterminable degree of bending of the bimetallic element, which is proportional to a predeterminable temperature rise of the network, the bimetallic element triggers a mechanical tripping device, which separates the switching contacts of the switching device and prevents further current flow.

A disadvantage of the known switching device is that the accuracy of the triggering of the switching device and the repeatability of the triggering of the switching device are very low, mainly in the case of only very low overcurrents. A problem that often occurs in the known switching devices is that-mainly in case of low overcurrent, in which the triggering of the switching device can be performed after a longer time-the switching device is triggered too late. This constitutes a danger for personnel and equipment.

Disclosure of Invention

The object of the present invention is therefore to provide a switching device of the type mentioned at the outset, with which the disadvantages mentioned can be avoided and with which the accuracy and reproducibility of the triggering of the switching device and the adjustment of the overcurrent triggering device can be improved.

This object is achieved according to the invention by the features of claim 1.

This reduces the heat dissipation or cooling of the bimetal element via its fastening. The heat dissipation or cooling of the bimetal element by its fixing causes the bending of the bimetal element to be dependent not only on the magnitude or height of the current in the current path through the switching device, but also on other magnitudes (which do not necessarily relate to the current height), with the consequence that the triggering of the known switching device may be inaccurate and less repeatable. By the features of claim 1, the accuracy and repeatability of the triggering of the switching device can be increased by the bimetal element. The adjustment of the bimetallic element or the overcurrent tripping device can thereby be improved.

The dependent claims, which form part of the description together with claim 1, relate to further advantageous configurations of the invention.

Drawings

The invention will now be described in detail in the accompanying drawings which show by way of example only preferred embodiments. Here:

fig. 1 shows a preferred embodiment of a switching device according to the invention in an exploded view by axonometry;

fig. 2 shows a preferred embodiment of the arrangement of bimetallic element and first switching contact in a partially cut-away isometric view;

fig. 3 shows an undivided arrangement according to fig. 2 in an isometric view;

fig. 4 shows a detail of the arrangement according to fig. 2 in a side view with a sectional view;

FIG. 5 shows a view according to FIG. 2 with additional components; and

fig. 6 shows a view according to fig. 3 with additional components.

Detailed Description

Fig. 1 shows a switching device 1, preferably a circuit breaker, having at least one input 2 and at least one output 3 for connecting electrical conductors, and having a first 4 and a second 4 switching contact, wherein the switching contacts 4 close a current path between the input 2 and the output 3 in a closed position, wherein an overcurrent tripping device 6 is provided for separating the first 4 and the second switching contact, and wherein the overcurrent tripping device 6 comprises at least one bimetallic element 7 heated by a current flow, wherein at least one thermal insulator 9 for reducing the heat dissipation of the bimetallic element 7 is provided in the region of a fastening 8 of the bimetallic element 7.

This reduces the heat dissipation or cooling of the bimetallic element 7 by its fastening 8. The heat dissipation or cooling of the bimetal element 7 by its fixing 8 causes the bending of the bimetal element 7 to be dependent not only on the magnitude or height of the current in the current path through the switching device 1, but also on other magnitudes (which do not necessarily relate to the current height), with the consequence that the triggering of the known switching device 1 may be inaccurate and less repeatable. By virtue of the features according to the invention, the precision and reproducibility of the triggering of the switching device 1 can be increased by the bimetallic element 7. This improves the setting of the bimetallic element 7 or the overcurrent tripping device 6.

Fig. 1 shows a series of components of a preferred embodiment of a switching device 1 according to the invention in an exploded isometric view. The illustrated configuration of the switching device 1 has three interruptions or current paths, wherein a presettable number of interruptions or connectable current paths can be provided. The switching device 1 according to the invention is preferably provided with one, two, three or four current paths. Corresponding to the number of current paths, the same number of inputs 2 or outputs 3 are provided. Fig. 1 to 4 show only the housing-fixing part of the input 2 or output 3, respectively. The respective input 2 or output 3 usually comprises, in addition to the illustrated parts, at least one clamping screw and preferably at least one clamping frame which is movable by means of the clamping screw.

The switchgear 1 comprises in the shown preferred embodiment an insulating material housing, which in this preferred embodiment comprises a lower housing shell 15 and an upper housing shell 16. In the closed position, the at least one first switching contact 4 is located on at least one second switching contact, which in the embodiment shown is arranged invisibly inside the assembly of the arc chute 14.

According to the invention, the bimetallic element 7 is fixed in a predetermined position within the switching device 1. The bimetallic element 7 is preferably fastened to a first conductor 10 of the current path, which is preferably assigned to the input 2 and/or the output 3, as shown in the drawing. In the preferred embodiment shown, the bimetallic element 7 is passed directly by the current, i.e. is itself part of the current path, and can be heated directly by the current. However, it is also possible to provide that the bimetallic element is heated completely or additionally indirectly by means of, for example, a conductor arranged on the bimetallic element 7 through which the current flows. By fixing the bimetallic element 7 to the first conductor 10, this preferred embodiment is advantageously supported, since this results in a construction which can be produced particularly simply and inexpensively.

As the bimetal element 7 increases in temperature due to the passage of current, it bends more and more. At a predeterminable degree of bending of the bimetallic element 7, which is proportional to a predeterminable temperature rise of the grid, the bimetallic element 7 triggers the overcurrent tripping device 6, which either directly or via a further mechanical tripping device co-operates with or is controlled by the overcurrent tripping device 6, separates the switching contact 4 of the switching device 1 and prevents further current flow. The preferred embodiment shown for the switching device 1 has a pivoting lever 18 for this purpose. The pivot lever 18 can be controlled directly by the bimetallic element 7. Preferably, the bimetallic element 7, as shown in fig. 5 and 6, has an adjusting screw 23, and the adjusting screw 23 actuates the trigger shaft 13 in a predeterminable bending of the bimetallic element 7. The bending of the bimetallic element 7 required for operating the triggering shaft 13 can also be preset or adjusted by means of the adjusting screw 23. Furthermore, it is preferably provided that the tripping shaft 13 is also assigned a short-circuit trip unit 19 which is preferably additionally arranged on the switching device 1, and that the short-circuit trip unit 19 is designed to operate the tripping shaft 13 by means of the pivot lever 18. At a predeterminable degree of bending of the bimetal element 7, it moves the trigger shaft 13 with the adjusting screw 23, which operates the latching mechanism 5. The latching mechanism 5 serves for manually opening and closing the switching contact 4 by means of the operating lever 17 and for separating the switching contact 4 in the event of triggering of the overcurrent tripping device 6 or of the short-circuit trip 19.

Fig. 2 to 6 show different views of a preferred embodiment of the arrangement of the bimetallic element 7 and the first switching contact 4, wherein at least one thermal insulator 9 for reducing the heat dissipation of the bimetallic element 7 is arranged in the region of the fastening portion 8 of the bimetallic element 7. The bimetallic element 7 is fastened with the first end 21 to the first conductor 10, wherein, in addition to the illustrated fastening by means of the connecting rivet 12, a fastening by means of screws, clips, welding or soldering can also be provided. A flexible conductor 20 is arranged at a second end 22 of the bimetal element 7 opposite the first end 21, which connects the bimetal element 7 to the first switching contact 4.

To reduce the heat dissipation of the bimetal element 7, any type of thermal insulator 9 can be designed. As in the case of use with an indirectly heated bimetallic element 7, an insulator comprising glass and/or ceramic may be designed. In the illustrated preferred embodiment of the bimetallic element 7 in which the current flows in the direct current path, the thermal insulator 9 is preferably designed as a metallic electrical conductor, wherein the thermal insulator 9 is further preferably designed to increase the electrical resistance in the region of the fastening 8. In addition to reducing the heat dissipation or cooling of the bimetallic element 7 via the first conductor 10 or the input 2 or the output 3, an additional temperature rise of the bimetallic element 7 via the thermal insulator 9 can thereby additionally be achieved. Since this additional temperature increase takes place at the first end 21 and therefore in particular away from the second end 22, the mechanical action of this additional temperature increase in the manner of a double bending and a torque increase of the bimetallic element 7 is particularly high. This not only increases the mechanical properties of the bimetallic element 7, but also improves the triggering accuracy by further reducing the influence of external physical influences on the temperature rise of the bimetallic element 7.

Particularly preferably and as shown in fig. 1 to 4, the thermal insulator 9 comprises a plate 11 arranged between the first conductor 10 and the bimetallic element 7. Both a high degree of mechanical stability and a high degree of thermal insulation can be achieved by means of such a plate 11 or such a sheet. Preferably, the plate 11 has a thermal conductivity of less than 350W/(m × K), in particular less than 200W/(m × K), preferably less than 85W/(m × K). "W" herein refers to power in watts, "m" refers to linear expansion in meters, "K" refers to absolute temperature in Kelvin, andand ". sup" refers to the operator of the multiplication. Whereby the heat dissipation through the plate is smaller than that in direct contact with the first conductor 10, which is usually made of copper. In connection with this, it can be provided that the plate 11 can comprise any material having a thermal conductivity that is less than that of copper, wherein it can be provided according to a further preferred embodiment that the plate 11 is furthermore technically a metallic electrical conductor, thus having a conductivity of less than 0.5 Ω mm²M, preferably less than 0.2 Ω mm²A unit electrical impedance of/m, but greater than copper (about 0.01724 Ω mm)²Per m) unit electrical impedance. In a preferred embodiment of the switching unit 1 according to the invention, it can therefore be provided that the plate 11 is formed from at least one material selected from the group consisting of: aluminum, brass, zinc, steel, preferably stainless steel, nickel, iron, platinum, tin, tantalum, lead and/or titanium. In this case, particular preference is given to an embodiment of the plate 11 comprising steel, preferably stainless steel, whereby a particularly advantageous balance of electrical conductivity, resistance and thermal insulation can be achieved. In addition, the steel has good mechanical workability and low cost.

As already described, any type of fixing of the bimetallic element 7 to the first conductor 10 can be envisaged. Particularly preferably and as shown in fig. 1 to 4, the bimetallic element 7 is connected to the first conductor 10 by means of at least one connecting rivet 12. For the purpose of additionally increasing the action of the thermal insulator 9, the thermal insulator 9 preferably comprises a connecting rivet 12. However, it is also possible to provide that the thermal insulator 9 comprises only the at least one connecting rivet 12, without the plate 11 between the bimetallic element 7 and the first conductor 10.

In a preferred embodiment of the connecting rivet 12, it is preferably provided that it has a thermal conductivity of less than 350W/(m × K), in particular less than 250W/(m × K), preferably less than 150W/(m × K). "W" herein refers to power in watts, "m" refers to linear expansion in meters, "K" refers to absolute temperature in Kelvin, and "x" refers to the operator of the multiplication. The heat dissipation through the connecting rivet 12 thus formed is thus less than the heat dissipation through the connecting rivet 12 formed from copper. In connection with this, it can be provided that the connecting rivet 12 can comprise a heat guideAny material with a rate of less than copper, wherein it is possible to design according to another preferred embodiment already described, furthermore the connecting rivet 12 is technically a metallic electrical conductor, thus having a rate of less than 0.5 Ω mm²Unit impedance of/m. In addition to the technical parameters relating to the electrical and thermal conductivity, the mechanical deformability of the ductility is also important for the material used for the connecting rivet 12. In a preferred embodiment of the switching unit 1 according to the invention, it can therefore be provided that the connecting rivet 12 is formed from at least one material selected from the group consisting of: aluminum, brass, zinc, steel, preferably stainless steel, nickel, iron, platinum, tin, tantalum, lead and/or titanium. It is particularly preferably provided that the connecting rivet 12 comprises brass, wherein any type of brass alloy comprising copper and zinc can be provided in this case.

Other embodiments according to the invention have only some of the features mentioned, wherein in particular any combination of the features of the different embodiments can also be provided.

Claims (12)

1. Switching device (1) having at least one input (2) and at least one output (3) for connecting electrical conductors and having a first switching contact (4) and a second switching contact, wherein the switching contact (4) closes a current path between the input (2) and the output (3) in the closed position, wherein an overcurrent triggering device (6) for separating the first switch contact (4) and the second switch contact is provided, and wherein the over-current triggering device (6) comprises at least one bimetal element (7), the bimetal element (7) being heated by the flow of current, characterized in that at least one thermal insulator (9) for reducing the heat dissipation of the bimetallic element (7) is provided in the region of the fastening section (8) of the bimetallic element (7).

2. The switching device (1) as claimed in claim 1, characterized in that the bimetallic element (7) is fastened to a first conductor (10) of the current path, which is preferably assigned to the input (2) and/or the output (3).

3. The switching device (1) as claimed in claim 1, wherein the thermal insulator (9) is designed as a metallic electrical conductor.

4. The switching device (1) as claimed in claim 1, wherein the thermal insulator (9) is designed to increase the electrical resistance in the region of the fastening (8).

5. The switching device (1) according to claim 2, wherein said thermal insulator (9) comprises a plate (11), said plate (11) being arranged between said first conductor (10) and said bimetal element (7).

6. The switching device (1) according to claim 5, wherein said plate (11) has a thermal conductivity of less than 350W/(mK), in particular less than 200W/(mK), preferably less than 85W/(mK).

7. Switching device (1) according to claim 5 or 6, characterized in that said plate (11) is formed comprising at least one material selected from the group consisting of: aluminum, brass, zinc, steel, preferably stainless steel, nickel, iron, platinum, tin, tantalum, lead and/or titanium.

8. The switching device (1) as claimed in claim 2, wherein the bimetallic element (7) is connected to the first conductor (10) by means of at least one connecting rivet (12).

9. The switching device (1) according to claim 8, wherein said thermal insulator (9) comprises said connecting rivet (12).

10. The switching device (1) according to claim 9, wherein the connecting rivet (12) has a thermal conductivity of less than 350W/(m x K), in particular less than 250W/(m x K), preferably less than 150W/(m x K).

11. Switching device (1) according to one of the claims 8 to 10, characterized in that the connecting rivet (12) is constructed comprising at least one material selected from the group: aluminum, brass, zinc, steel, preferably stainless steel, nickel, iron, platinum, tin, tantalum, lead and/or titanium.

12. The switching device according to claim 1, wherein said device is configured as a circuit breaker.