EP3025361B1 - Switching device with electromagnetic arc deflection - Google Patents

Description

The invention relates to a switching device with an electromagnetic arc drive, wherein the switching device has a switching chamber with a fixedly positioned switching piece and a movable contact piece arranged opposite thereto.

In switching devices of this kind, when electric currents are switched off, an arc occurs at the opening contact points. This arc causes wear at the contact points due to erosion of the contact material and delays the disconnection of the circuit since the current continues to flow across the arc until it extinguishes. To limit the damage caused by the arc, electrical switching or protective devices are equipped with an arc extinguishing device above a certain power.

Such arc extinguishing device often consists of an arc chamber with Lichtbogenleitblechen and various components, which fulfill, among other things, fluidic tasks.

The arc chamber is often designed as a package of U-shaped punched quenching plates, which are arranged in parallel and are kept at a distance. Around the quenching plates, a strip of insulating material, usually a Vulkanfieberstreifen folded, which keeps the quenching plates at a distance and summarized into an assembly. In the insulating strip openings are punched, which influence, among other things, the flow conditions in the arc chamber. The baffles are located at the top and bottom of the arc chamber. The upper arc guide plate together with a movable contact bridge forms a contact point.

In the arc extinguishing device, the arc migrates from the contact point into the arc chamber. When opening the contact point, an arc is formed between the contacts that are separated from each other. Electromagnetic forces move the arc towards the arc quenching chamber. The arc base points of the arc at the exit points of the arc guide plates thereby migrate away from the contact point along the arc guide plates electrically connected to the circuit.

The arc guide plates are shaped and arranged so that they lead the arc as quickly as possible to the arc chamber. Inside the arc chamber, the arc is then extinguished. During the described process, current or thermomechanical forces occur between the quenching plates and the arc guide plates. If the arc guide plate is not fixed stable enough, which often does not succeed due to the structural conditions often, they touch the outer quenching plates and weld with them. As a result, the efficiency of the arc chamber for further deletion processes is reduced.

In the case of particularly strong arcs - as they occur as a result of short circuit shutdowns - there is a risk that they will pass through the arc chamber and short circuit behind it. In this case, the extinguishing effect of the arc chamber is no longer present.

In order to avoid the shorting of the arc in the space behind the arc chamber, various solutions are known. For example, it is possible to keep the arc guide plates relatively short, that is, not to the end of the arc chamber, where the quenching plates end.

Another possibility is the complete abandonment of the lower arc guide plate. Usually, the very short held Lichtbogenleitbleche either not at all mechanically supported, or it is used to support an additional plastic part, which, however, associated with additional costs. The solution with short baffles has the significant disadvantage that under certain circumstances not the entire volume of the inner part of the arc chamber is optimally utilized during the deletion process.

The mechanism of action is accordingly that the flow of current across the arc creates a magnetic flux which is deflected by ferromagnetic parts near the contact point such that a force acts on the arc which drives it away from the contact point to an arc extinguishing system.

The WO 2013/130035 A1 . JP S63 126136 A , The US 2008/073327 A1 , the US Pat. No. 5,589,572 , the US 5 548 258 A and the EP 1 998 349 A1 each disclose a switching device with an electromagnetic arc drive, wherein the switching device has a switching chamber with a fixedly positioned switching piece with a movable contact piece arranged opposite thereto. In this case, the electromagnetic arc drive is designed in the form of a sheet which is positioned around the fixedly positioned switching piece around.

Accordingly, the object of the present invention is to provide a switching device with an electromagnetic arc drive, which allows optimization of the deflection and extinguishing of switching arcs.

This object is achieved by a switching device having the features of patent claim 1. Advantageous embodiments and developments, which can be used individually or in combination with each other, are the subject of the dependent claims.

This object is achieved by a switching device with an electromagnetic arc drive, wherein the Switching device having a switching chamber with a fixedly positioned switching piece and a movable contact piece arranged opposite thereto. The invention is characterized in that the electromagnetic arc drive is designed in the form of a sheet, which is positioned around the fixedly positioned switching piece around.

In this case, the sheet, in particular blower U-shaped with two legs, which are connected to each other via a connecting central part. The connecting central part of the sheet is parallel between the legs of the U-shaped curved fixedly positioned contact piece arranged in the area behind the contacts. Due to the current flow from the conductor connection to the contact, a magnetic flux is induced in the connecting central part of the U-shaped metal sheet, which interacts with the magnetic flux which is induced by the current flow in the arc and thus generates a force on the arc. This force drives the arc away from the contacts.

Also, a magnetic field is induced by the current flow through the movable contact piece. Since the lateral limbs of the U-shaped sheet are pulled only up to the contacts, essentially only the magnetic field of the arc and the magnetic flux in the blower to each other act. The peculiarity of this geometric arrangement is that no or only very small contact opening forces act on the movable contact piece, but also high forces on the arc.

The connecting middle part on the sheet metal is arranged in the area behind the contacts. If the connecting central part of the sheet were further offset in the direction of contacts, the current flow would reduce the induction of the magnetic flux in the sheet metal. The lateral legs of the U-shaped sheet are pulled only so far in the direction of the movable contact piece that they cover the area in which the contacts are located. In this way, the interaction of the magnetic fields is caused by the flow of current in the movable contact piece or minimized by the flowing in the fixed contact piece to the right current to the plate.

The advantages of the switching device according to the invention with electromagnetic arc drive are that a magnetic flux is already induced by the current flow in the fixed contact piece between terminal and contact point in the sheet, whereby the magnetic force on the arc is increased. Since no insulation material between the lateral legs on the plate and the contacts is present, the arc can also commutate to the plate and divide. This results in a faster arc voltage increase, which limits the flow of current over the arc faster.

In a particularly advantageous embodiment of the invention can be provided that the sheet is U-shaped with two legs which are connected to each other via a connecting central part is formed. The connecting central part of the U-shaped plate is arranged in parallel between the legs of the U-shaped bent fixedly positioned contact piece in the area behind the contacts. Due to the current flow from the conductor connection to the contact, a magnetic flux is induced in the connecting central part of the U-shaped metal sheet, which interacts with the magnetic flux induced by the current flow in the arc and thus generates a force on the arc. This force drives the arc away from the contacts.

In a special embodiment of the invention, another concept may be that the legs of the U-shaped plate are formed parallel to each other and congruent. The spacing of the two mutually parallel legs of the U-shaped sheet is determined essentially by the leg of the U-shaped sheet.

In a particularly preferred embodiment of the invention, a technical continuation of the inventive concept may consist in that the legs of the U-shaped sheet are guided obliquely from the connecting middle part to the rear. The connecting central part of the sheet is arranged in the area behind the contacts. If the connecting central part were further offset in the direction of contacts, then the current flow would reduce the induction of the magnetic flux in the metal sheet. The lateral legs on the plate are pulled only so far in the direction of moving contact piece that they cover the area in which the contacts are located. Thus, the interaction of the magnetic fields by the current flow in caused movable switching element, or minimized by the fixedly positioned switching piece to the right current flowing through the plate.

In a further particularly advantageous embodiment of the invention can be provided that the connecting central part of the U-shaped sheet is positioned between two legs of the U-shaped fixedly positioned switching piece. The connecting central part of the U-shaped sheet is arranged in parallel between the legs of the U-shaped fixed fixed contact piece in the area behind the contacts. Due to the current flow from the conductor connection to the contact, a magnetic flux is induced in the connecting central part of the sheet, which interacts with the magnetic flux which is induced by the current flow in the arc and thus generates a force on the arc.

In a further particularly advantageous embodiment of the invention can be provided that the connecting central part is positioned below quenching plates, which are arranged in the switching chamber. The immediate proximity to the extinguishing agents in the switching chamber allows a fast extinction of the switching arcs.

In a special continuation of this concept it can be provided that the contours of the limbs of the U-shaped sheet are adapted to the positioning of the quenching plates arranged above it. This particular geometric embodiment allows optimal use of space.

It can also be provided that the end portions of the legs of the U-shaped plate are positioned in the region of the contact points of the fixed and the movable contact piece. The lateral legs of the sheet are drawn only so far in the direction of movable contact piece that they cover the area in which the contacts are located. Thus, the interaction of the magnetic fields is caused by the current flow in the movable contact piece, or by the im firmly positioned switching piece to the right flowing current through the plate minimized.

In a particularly advantageous embodiment of the invention can be provided that between the connecting central part of the U-shaped plate and the legs of the U-shaped, fixedly positioned contact piece, an insulating body is positioned. The insulator essentially insulates the connecting central part of the sheet from the fixedly positioned contact piece. The insulator does not isolate the lateral legs on the sheet metal toward the arc or to the switching chamber interior. This allows the arc created between the contacts to commutate and divide on the lateral legs. Since there is an insulating body between the connecting central part of the sheet and the fixedly positioned contact piece, the commutation of the arc does not interfere with the sheet. That is, there can be no short circuit at any other point between the fixedly positioned contact piece on the plate to the movable contact point.

In a particularly advantageous embodiment of the invention can be provided that the connecting central part of the U-shaped sheet between two legs of the U-shaped insulating body, which shield the legs of the fixedly positioned contact piece is positioned. Due to the positioning of the insulator, the commutation of the arc on the sheet does not interfere. This leads to the result that there can be no short circuit at any other point between the fixedly positioned contact piece on the plate to the movable contact piece.

The feature combinations described above can be used in particular in a contactor. However, it is also possible that the present invention finds application in particular in its preferred embodiment as a circuit breaker. In a further use, the present invention may also be used in a compact engine feeder.

Further advantages and embodiments of the invention will be explained below with reference to embodiments and with reference to the drawing.

• Fig. 1 in einer perspektivischen Darstellung ein fest positioniertes und ein bewegliches Schaltstück mit einem elektromagnetischen Lichtbogenantrieb in Form eines Bleches;
• Fig. 2 in einer Schnittdarstellung die Darstellung nach Fig. 1;
• Fig. 3 in einer perspektivischen Darstellung die Darstellung nach Fig. 1 inklusive des Stromflusses und der induzierten Magnetfelder;
• Fig. 4 in einer perspektivischen Darstellung die Darstellung nach Fig. 1 inklusive Isolierkörper.

Here are shown schematically:

• Fig. 1 in a perspective view of a firmly positioned and a movable contact piece with an electromagnetic arc drive in the form of a sheet;
• Fig. 2 in a sectional view the representation after Fig. 1 ;
• Fig. 3 in a perspective view the representation after Fig. 1 including the current flow and the induced magnetic fields;
• Fig. 4 in a perspective view the representation after Fig. 1 including insulator.

Fig. 1 shows an arrangement of the components in a switching chamber of a switching device. These include a fixedly positioned contact piece 1 with a contact point 2, which is arranged opposite to a contact point 3 of a movable contact piece 4. The fixedly positioned contact piece 1 is preferably U-shaped with two legs 5, 6, which may be of different lengths and parallel to each other, and the two legs 5, 6 interconnecting connecting portion 7. Also shows Fig. 1 an electromagnetic arc drive in the form of a sheet 8, which is preferably U-shaped with two legs 9, 10, which are preferably formed parallel and congruent to each other, and a connecting central portion 11. The connecting central portion 11 of the sheet 8 is preferably between the legs 5, 6 of the fixedly positioned contact piece 1 is arranged. Above the region of the connecting central part 11 of the sheet 8 are preferably quenching plates 12 arranged. The legs 9, 10 of the sheet 8 are preferably drawn obliquely backwards in the direction of the contact points 2, 3. In the legs 9, 10 contours 13, 14 are incorporated, which take into account the positioning of the quenching plates 12.

Out Fig. 2 the arrangement goes out Fig. 1 shows, in addition, a conductor terminal 15 is shown on the leg 6 of the fixedly positioned contact piece 1. The current flow 16, in the form of arrows in Fig. 2 is shown, passes over the leg 6 of the fixedly positioned contact piece 1 and continues in the movable contact piece 4. It is also in Fig. 2 the positioning of the arc 17 shown in the case of triggering, which is to be expected between the contact points 2, 3 of the fixedly positioned contact piece 1 and the movable contact piece 4.

In Fig. 3 In addition to the current flow 16 and arc 17, the induced magnetic fields 18, 19, 20 and the magnetic flux 21 are shown. The induced magnetic field 18 is formed on the movable contact 4. The induced magnetic field 19 is located between the movable contact 4 and the fixedly positioned contact 1. The induced magnetic field 20 is formed at the connecting central portion 11 of the sheet 8. The superposition of the magnetic fields 19 and 20 causes a deflection of the arc to the outside. Due to the flow of current from the conductor terminal 15 to the contact points 2, 3, a magnetic flux is induced in the connecting central part 11 of the U-shaped plate 8, which cooperates with the magnetic flux, which is induced by the current flow in the arc 17 and thus a force on the Arc 17 is generated. This force drives the arc 17 away from the contact points 2, 3. Also, a magnetic field is induced by the flow of current through the movable contact 4. The arrangement with sheet 8 according to the invention makes it possible that no or only very small contact opening forces act on the movable contact 4, but high forces on the arc 17th

Fig. 4 shows the arrangement of the components in a switching chamber of a switching device including an insulating body 22 which is U-shaped with two legs 23, 24 and a connecting part 25 between the legs 23, 24. The legs 23, 24 are preferably parallel to each other and opposite each other aligned horizontally. The leg 23 surrounds the leg 5 of the fixedly positioned contact piece 1. The leg 24 of the insulating body 22 is formed in the form of a cover over the leg 6 of the fixedly positioned contact piece 1. Between the legs 23, 24 of the insulating body 22, the connecting central part 11 of the sheet 8 is placed. Fig. 4 also shows the formation of arcs 26.

The switching device according to the invention with electromagnetic arc drive in the form of a sheet is characterized in that a magnetic flux is already induced by the current flow in the fixed contact between terminal and pad in the sheet, so that the magnetic force on the arc is significantly increased. Since there is no insulating material between the lateral legs on the plate and on the contacts, the arc can also commutate to the plate and divide. This results in a faster arc voltage increase, which limits the flow of current through the arc faster. In addition, since there is an insulating body between the connecting central part of the sheet and the fixed contact piece, the commutation of the arc does not interfere with the sheet. This causes the formation of a short circuit is excluded.

LIST OF REFERENCE NUMBERS

1

firmly positioned contact piece

2

contact point

3

contact point

4

movable contact piece

5, 6

leg

7

connecting area

8th

sheet

9, 10

leg

11

connecting middle section

12

splitters

13, 14

contours

15

wire connection

16

current flow

17

Electric arc

18, 19, 20

induced magnetic fields

21

River

22

insulator

23, 24

leg

25

connecting part

26

electric arc

Claims (10)

1. Switching device comprising an electromagnetic arc driving mechanism, wherein the switching device has a switching chamber with a fixedly positioned switching piece (1) having a contact point (2) and, arranged opposite, a movable switching piece (4) having a contact point (3), wherein the electromagnetic arc driving mechanism takes the form of a metal sheet (8), which is positioned around the fixedly positioned switching piece (1), wherein an insulating body (22) is positioned between the connecting middle part (11) of the U-shaped metal sheet (8) and the legs (5, 6) of the fixedly positioned switching piece (1) formed in a U-shaped manner, characterized in that the insulating body is formed in a U-shaped manner, having two legs (23, 24) and a connecting part (25) between the legs (23, 24), and wherein the leg (23) encloses the leg (5) of the fixedly positioned switching piece (1).
2. Switching device according to Claim 1, characterized in that the metal sheet (8) is formed in a U-shaped manner, having two legs (9, 10), which are connected to one another by way of a connecting middle part (11).
3. Switching device according to Claim 2, characterized in that the legs (9, 10) of the U-shaped metal sheet (8) are formed parallel to one another and congruently.
4. Switching device according to Claim 3, characterized in that the legs (9, 10) of the U-shaped metal sheet (8) are made to extend from the connecting middle part (11) back at an angle in the direction of the contact points (2, 3).
5. Switching device according to one of Claims 1 to 4, characterized in that the connecting middle part (11) of the U-shaped metal sheet (8) is positioned between two legs (5, 6) of the U-shaped fixedly positioned switching piece (1).
6. Switching device according to one of Claims 1 to 5, characterized in that the end regions of the legs (9, 10) of the U-shaped metal sheet (8) are positioned in the region of the contact points (2, 3) of the fixedly positioned and movable switching pieces (1, 4).
7. Switching device according to Claim 1, characterized in that the connecting middle part (11) of the U-shaped metal sheet (8) is positioned between two legs (23, 24) of the U-shaped insulating body (22), which shield the legs (5, 6) of the fixedly positioned switching piece (1).
8. Switching device according to one of Claims 1 to 7, characterized in that the switching device is a contactor.
9. Switching device according to one of Claims 1 to 7, characterized in that the switching device is a power circuit-breaker.
10. Switching device according to one of Claims 1 to 7, characterized in that the switching device is a compact motor feeder.

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