CN103681037B - The switchgear of electric mechanical - Google Patents

Abstract

The electromechanical switching device according to the invention has a switching contact for interrupting an electrical line, and an arc quenching device for extinguishing an arc which occurs when the energized switching contact opens. The arc quenching device has a first permanent magnet and a second permanent magnet, which are arranged opposite each other on both sides of the switching contact and are magnetized oppositely to each other in that they push away from each other. A magnetic field is generated by the first permanent magnet and the second permanent magnet, which overlaps the magnetic field of the arc generated when the energized switching contacts are opened. The resulting magnetic field exerts an electromagnetic force on the arc, the force vector of which depends on the polarity of the current. Regardless of the polarity of the arc, this force vector always has a directional component which pushes the arc away from the switching contacts. The arc quenching device and the switching device designed with the arc quenching device can be used not only for direct current but also for alternating current.

Description

Electromechanical switchgear

technical field

The invention relates to an electromechanical switching device having a switching contact for interrupting an electrical line and an arc extinguishing device for extinguishing an arc which occurs when the energized switching contact opens. The term switching device is to be understood here not only as a protective switching device, such as a power switch, a circuit breaker or a fault current switch, but also as a switching device without its own protective function, such as a load switch, disconnector or load disconnector.

Background technique

Different types of protective switching devices are known from the prior art: Power switches are specially designed for high currents. A line breaker (so-called LS switch) is an overcurrent protection device used in electrical installations and in particular in the field of low-voltage networks. The power switch and the line protection switch ensure reliable disconnection in the event of a short circuit and protect consumers and the electrical system against overloading, for example against damage to the line due to excessive heating caused by excessive currents. They are designed to automatically disconnect the circuit to be monitored in the event of a short circuit or in the event of an overload and thus separate it from the rest of the line network. Power switches and circuit breakers are therefore used in particular as switches and safety elements for monitoring and protecting circuits in electrical energy supply networks.

Protection against persons, property or fire can also be achieved with the aid of a fault current circuit breaker. Thus, it is a switching device which, in the event of a fault in electrical installations and systems, cuts them off in the shortest possible time and when the current is "on the wrong path", for example through a person's body towards earth When flowing, separate said equipment and systems from the rest of the grid. For this purpose, the fault current circuit breaker compares the amperage of the current flowing towards the electrical consumer with the amperage of the current flowing back from said consumer. A corresponding fault current circuit breaker is known, for example, from publication EP 0 957 558 A2.

Furthermore, switching devices are known from the prior art which do not have their own protective function. Falling below this are, for example, so-called switch-disconnectors, switch disconnectors or switch disconnectors. A load switch disconnector is understood to be a switching device which, with regard to its functionality, not only fulfills the requirements for a load switch, ie a switch under electrical load, but also fulfills the requirements for a switch disconnector, ie an approximately power-free isolation of electrical currents. system components. Load isolation switches are suitable for cutting off large currents, although their switching capacity is usually smaller than that of power switches. In low-voltage networks, load disconnectors are used, for example, to interrupt the main circuit in the main distribution area, wherein the switching power usually lies in the range of 40 and 63 kA. According to DIN EN 60947-3, not only switch disconnectors, but also switch disconnectors and switch disconnectors are classified according to their respective power capabilities into so-called consumption categories, in which different consumption categories are defined depending on the application Require.

In general, switching devices are usually electrically conductively connected via two terminals to the electrical lines of the circuit to be monitored, in order to interrupt the current in the individual lines when necessary. For this purpose, the switching device has a switching contact with a fixed contact element, the so-called fixed contact, and a contact element movable relative to the fixed contact, the so-called moving contact. point. To conduct a current, the moving contact contacts the fixed contact. In order to isolate the current, the moving contact is moved away from the fixed contact. In this case, the moving contact can be actuated, for example, via a switching mechanism of the switching device, so that the switching contacts can be opened and closed. In the case of a protective switching device, the switching contacts can be opened in this way in the event of a predefined state, such as a short circuit or overload, in order to separate the monitored circuit from the electrical line network. Switching devices of this type are also known in the field of low-voltage technology as series-mounted devices.

The current flow is interrupted by opening the switching contact, in which case a voltage breakdown between the fixed contact element and the moving contact element is caused at least briefly because the separation of the contact elements The distances used for insulation during the process are not sufficient. If there is gas between the two switching contacts, it is ionized by the breakdown at a correspondingly high voltage difference between the contact elements, a gas discharge forming a arc. In order to extinguish the arc, conventional switching devices have an arc quenching device, for example a so-called quenching chamber, which has a plurality of arc quenching plates arranged next to each other and spaced apart from one another. Alternatively, the arc extinguishing device can also consist only of a plurality of arc quenching plates or cooling plates aligned parallel to one another. If the arc is driven towards the arc quenching device, it is divided into a plurality of partial arcs when it encounters the quenching plates, which then burn in series between the individual quenching plates. The plurality of partial arcs electrically connected in series in series leads overall to a higher arc voltage, which in turn leads to a faster extinguishing of the arcs.

In order to exert a Lorentz force on the arc and extinguish it as quickly as possible, additional permanent magnets are often used in switching devices for direct current (DC) applications. Through the use of permanent magnets, relatively high magnetic field strengths can be achieved, but the magnetic field generated by the permanent magnets is constant in time in terms of its direction, so when installing the permanent magnets, attention should be paid to the correct magnetic poles towards the respective current directions, so that Obtain an arc along the desired direction. In the case of alternating current (AC-) applications, permanent magnets are generally not used in switching devices to influence the arc due to the continuously alternating polarity of the arc current.

Switching devices provided for AC power systems therefore often have so-called blower circuits in order to remove the arc from the switching contacts as quickly as possible. A blower circuit is an electrical coil which is arranged in the region of the switching contacts and which is additionally energized in the event of an electric arc which occurs by opening the switching contacts. As an alternative thereto, the blown circuit can also be permanently energized. The electromagnetic field caused by the energized blowing circuit is in this case oriented in such a way that a Lorentz force is exerted on the arc, which moves the arc away from the switching contacts and towards The arc extinguishing device is squeezed. Corresponding switching devices are known from publication DE 2 841 004 B1 or from publication DE 3333 792 A1. However, the blown circuit has the disadvantage that only a small electromagnetic field is generated at low currents, so that the resulting electromagnetic force acting on the arc is comparatively low. It can therefore exert its full effect only at high currents, for example in the event of a short circuit.

Contents of the invention

It is therefore the object of the present invention to provide an electromechanical switchgear with an arc extinguishing device, which is characterized in that an arc that occurs when the energized switch contacts are opened is quickly and reliably extinguished, and in that it is possible High variability in usage.

This object is solved by an electromechanical switching device according to the invention according to the independent claim 1 . Advantageous refinements are the subject matter of the subclaims.

The electromechanical switching device according to the invention has a switching contact for interrupting an electrical line, and an arc quenching device for extinguishing an arc which occurs when the energized switching contact opens. In this case, the arc quenching device has a first permanent magnet and a second permanent magnet, which are arranged opposite each other on both sides of the switching contact and are magnetized opposite to each other by pushing them away from each other.

The term switching device is to be understood here not only as a protective switching device, but also as a switching device without its own protective function. Examples of protective switching devices include power switches, line circuit breakers or fault current circuit breakers. Examples of switching devices that do not have their own protective function are load switches, disconnectors or load disconnectors. The term “switching contact” is used to designate a mechanically actuatable pair of electrical contact elements which have a fixed contact and a movable contact which is movable relative to the fixed contact. The fixed contacts and the moving contacts are arranged in the housing in the region of the so-called switching chamber. By mechanically actuating the moving contact, a closed switching contact can be opened, thereby interrupting the current flow through the switching contact.

The first permanent magnet and the second permanent magnet are arranged opposite each other on both sides of the switching contact, that is to say on the left and right of the switching chamber. In this case, they are mutually magnetized in opposite directions in that the field vectors of the first permanent magnet and the field vectors of the second permanent magnet are oriented opposite to each other. For example, the magnetic south pole of the first permanent magnet and the magnetic south pole of the second permanent magnet are respectively directed towards the switch chamber; instead, the magnetic north pole of the first permanent magnet and the magnetic south pole of the second permanent magnet The magnetic north poles are each directed towards the switching chamber. In both cases, the two permanent magnets push away from each other.

A magnetic field is generated by the first permanent magnet and the second permanent magnet, which overlaps the magnetic field of the arc that occurs when the energized switching contacts open. The resulting magnetic field in turn exerts an electromagnetic force, the so-called Lorentz force, on the arc. The Lorentz force in this case denotes a force which is exerted by a magnetic field on a moving charge, here the arc. The force vector of the Lorentz force in this case depends primarily on the polarity of the current, that is to say on the direction of the current through the arc. But regardless of the polarity of the current, and therefore regardless of whether direct current or alternating current flows in either direction through the switch contacts, the force vector always has a directional component due to the superimposedly generated magnetic fields, which component squeezes the arc away from the switch contacts. This results in a lengthening of the arc, which in turn results in a higher arc voltage. If the arc voltage is too high, the arc is extinguished and disappears.

In this way, a rapid and reliable extinguishing of the arc that occurs when the energized switching contacts are opened is achieved. The extinguishing power of the arc extinguishing device and thus the switching power of the switchgear is thereby significantly increased. In particular in the case of load disconnectors, a classification into a higher consumption category which would otherwise only be possible with the same system design can thus be achieved. Furthermore, the arc extinguishing device and the switchgear designed with the arc extinguishing device can be used not only for direct current (DC) but also for alternating current (DC-) applications. In this way, for example, a switch disconnector provided for AC use and thus classified into the AC consumption class also fulfills the requirements of the possibly lower DC consumption class and can therefore also be classified for this class. Due to the resulting high variability in the possible usage of the switching devices involved, the switching devices and thus the logistical costs are significantly reduced.

In an advantageous development of the electromechanical switchgear, the arc quenching device has a plurality of arc quenching plates for extinguishing the arc. In this case, the magnetic fields generated by the first permanent magnet and the second permanent magnet overlap with a magnetic field generated by the arc in such a way that an electromagnetic force acts on the arc. The force vector of the electromagnetic force in this case has a directional component which, independently of the polarity of the current, presses the arc towards the quenching plate.

The arc quenching device is arranged in the vicinity of the switching contacts and has a plurality of cooling plates or quenching plates arranged parallel to one another and spaced apart from one another. When the electric arc encounters the arc extinguishing plates, the electric arc is divided into a large number of partial arcs, which are each burnt between two arc extinguishing plates. The large number of partial arcs electrically connected in series increases the arc voltage considerably, which leads to rapid extinguishing of the arcs.

A magnetic field is generated by the first permanent magnet and the second permanent magnet, which overlaps the magnetic field of the arc that occurs when the energized switching contacts open. An electromagnetic force, the so-called Lorentz force, acts on the arc from the resulting magnetic field. Its force vector in this case depends primarily on the polarity of the current. Regardless of the polarity of the current flowing through the arc, however, the force vector always has a directional component that pushes the arc away from the switching contact and towards the arc quenching device. Due to the corresponding positioning of the arc quenching device in the housing of the switchgear, the extinguishing performance of the arc quenching device and thus the switching performance of the switchgear is further improved.

In a further advantageous development of the electromechanical switchgear, the arc quenching device can be used not only for extinguishing a DC arc but also for extinguishing an AC arc. As a result, the electromechanical switching device can be used not only for switching alternating current but also for switching direct current. The variety of variants of the arc quenching device and of the switchgear can thus be significantly reduced.

In another advantageous development, the electromechanical switching device has a housing which itself has a front side and a fastening side opposite the front side, and the front side A narrow side and a wide side connected to the fixed side. In this case, the switching contact is arranged in the housing, wherein the first permanent magnet and the second permanent magnet are arranged in the region of the broad sides. In this case, the permanent magnet is planar and is magnetized towards its normal vector. The normal vector of each permanent magnet is in this case aligned parallel to the normal vector assigned to the broad side of the permanent magnet. The permanent magnets are installed in the housing in such a way that they are pushed away from each other, ie either the two north poles or the two south poles are respectively oriented toward or away from each other. In this way, a space-saving arrangement can be achieved, in which the magnetic flux density is substantially concentrated in the region of the switching chamber.

In a further advantageous refinement, the electromechanical switching device is designed as a series-mounted device, the housing having a width of one graduation unit. Due to the space-saving arrangement of the two permanent magnets laterally beside the switching chamber, parallel to the wide sides of the housing, the arc extinguishing device can even be integrated with only one indexing unit (TE ) in series-mounted devices with a width of about 18 mm, the indexing unit corresponds to a housing width of approximately 18 mm. The small housing width of only one dividing unit presents a clear competitive advantage if the installation space for arranging a large number of such series-mounted devices in an electrical installation distributor is limited.

Description of drawings

Exemplary embodiments of the switchgear are explained in more detail below with reference to the drawings. in:

Figure 1 shows a schematic diagram of an open switchgear in side view;

FIG. 2 shows a schematic sectional view of the switchgear in a top view;

3A and 3B show schematic diagrams of the generated magnetic field in said top view.

Identical components are always provided with the same reference numerals in the different figures. This description applies to all figures in which the corresponding parts are likewise visible.

Detailed ways

FIG. 1 shows a schematic diagram of a switching device 1 in a side view. The switching device 1 has a housing 2 which is essentially formed from two housing half-shells which are connected to form the housing 2 by means of a plurality of riveted connections 14 . In this case, the open switching device 1 is shown in FIG. 1 , that is to say the front housing half-shell of the housing 2 has been removed in this illustration. The housing 2 has a front side 3 on which an operating element 8 is arranged for manually operating the switching device 1 . A fastening side 4 of the housing 2 is formed opposite the front side 3 and serves to fasten the switching device on a carrier rail (not shown), for example a top rail. For this purpose, a manually actuatable slide 15 is arranged on the housing 2 for engaging behind the carrier rail. In this way, the switchgear 1 can be quickly and easily fastened to the carrier rail or released again from the carrier rail. The operating surface 3 and the operating surface 4 are connected via a narrow side 5 and a wide side 6 to form the housing 2 .

Inside the housing 2 , in the region of the narrow side 5 is arranged a terminal 13 by means of which the switching device 1 can be connected to an electrical line. Furthermore, a switching contact 10 is arranged in the housing 2 and is designed to interrupt the current flow through the switching contact 10 . For this purpose, the switching contact 10 has a fixed contact 11 and a movable contact 12 which is movable relative to the fixed contact. The fixed contact 11 is electrically connected to a connection terminal 13 shown on the left. The moving contact 12 is mechanically fastened to a moving contact carrier 16 and is electrically conductively connected via a litz wire 17 to a connection terminal 13 shown on the right.

The moving contact carrier 16 is mechanically coupled to the operating element 8 via a clip 9 . When the switching device 1 is switched on, that is to say when the operating element 8 is actuated in a clockwise direction from the off position shown in FIG. 1 to the on position (not shown) , the moving contact 12 moves toward the fixed contact 11 via the bow clip 9 coupled with the moving contact carrier 16 . In the case of switching off the switching device 1 , that is to say in the case of actuating the operating element 8 in the counterclockwise direction from the on position to the off position shown in FIG. 1 , the moving contact 12 moves away from the fixed contact 11 via the bow clip 9 coupled to the moving contact carrier 16 .

When the energized switching contact 10 is opened, an electric arc is formed between the fixed contact 11 and the movable contact 12 (see FIG. 2 ). In order to achieve a quick opening of the switching contacts and thus a quick extinguishing of the arc, it is necessary to open the switching contacts 10 as quickly as possible, that is to say that the moving contacts 12 are disconnected from the fixed contacts. 11 to leave as quickly as possible. The opening movement is thus mechanically assisted by a spring 18 which is mechanically coupled to the moving contact carrier 16 and supported in the housing 2 . The spring force exerted on the moving contact carrier 16 by the pretensioned spring 18 thus facilitates the quick opening of the switching contact 10 . In this way, a rapid disconnection of the switching device 1 is achieved. Furthermore, the wear of the switching contacts 10 , so-called contact erosion, is significantly reduced.

FIG. 2 schematically shows a sectional view of the switching device 1 in a plan view. The first permanent magnet 21 of the arc quenching device 20 of the switchgear 1 is arranged on the broad side 6 of the housing 2 shown on the left. The second permanent magnet 22 of the arc quenching device 20 is arranged on the wide side 6 shown on the right. In this case, the permanent magnets 21 and 22 are arranged opposite each other in the region of the so-called switching chamber, that is to say in the region of the switching contact 10 , and are magnetized in such a way that they push away from each other. . In this case it is irrelevant whether the two north poles or the two south poles of the two permanent magnets 21 and 22 point towards each other.

FIG. 2 shows the switching device 1 at a point in time at which the switching contact 10 has just been opened so that a contact between the fixed contact 11 and the moving contact 12 is formed. arc7. In the plan view shown in FIG. 2 , the arc 7 is shown only as a point, the direction of its current flow is oriented either into the plane of the drawing or out of the plane of the drawing. The arc extinguishing device 23 also has a plurality of so-called cooling plates or quenching plates 20 , which are arranged in the housing 2 of the switchgear 1 at a distance from one another and parallel to one another between the spring 18 and the arc 7 . between. However, only the uppermost quenching plate 23 is visible in the plan view shown in FIG. 2 .

In order to bring the arc 7 into extinguishment, the arc is driven into the arc extinguishing device 20 and there it is divided into a large number of individual partial arcs upon encountering the quenching plate 23 , The partial arcs are electrically connected in series with one another. In this case, the arc voltage is increased until the arc 7 is finally extinguished and the current disappears. In order to drive the arc 7 in a targeted manner towards the arc quenching device 20 or towards the quenching plate 23, the two permanent magnets 21 and 22 are arranged as described above in the region of the switching chamber. middle. In this case, a magnetic field is generated by the first permanent magnet 21 and the second permanent magnet 22 , which overlaps the magnetic field of the arc 7 that occurs when the energized switching contact 10 opens. The resulting magnetic field in turn exerts an electromagnetic force, the so-called Lorentz force, on the arc 7, the force vector _FL of which in this case depends primarily on the polarity of the current, that is to say, The direction of current passing through the arc 7 .

The resulting magnetic field is shown in Figures 3A and 3B. The perspective view selected for this illustration corresponds in this case to the perspective view selected in FIG. 2 . The generated magnetic field is represented in this case by means of field lines 25 resulting from the superposition of the individual magnetic fields of both first permanent magnet 21 , second permanent magnet 22 and arc 7 .

The diagrams in FIGS. 3A and 3B differ in this case only in the direction of the current flow through the arc 7 . In both figures, force vector _FL represents the Lorentz force acting on said arc 7 . The force vector _FL can in this case be resolved into a force component Fx acting in the x direction and a force component Fy acting in the y direction. In this case it should be clear that the force vector _FL has a directional component Fx in both cases, that is to say both in the positive current direction and in the negative current direction through the arc 7 , which squeezes the arc 7 towards the arc extinguishing plate 23 . This effect is not only independent of the polarity of the current flowing through the arc 7 but also regardless of whether direct or alternating current flows in either direction through the switch contacts. In each case, the Lorentz force _FL has a directional component Fx which draws the arc 7 towards the quenching plate 23 .

List of reference signs

1 switchgear

2 housing

3 front side

4 Fixed sides

5 narrow sides

6 wide sides

7 arc

8 Operating elements

9 bow clips

10 switch contacts

11 Fixed contacts

12 moving contacts

13 terminal block

14 Riveted connections

15 sliders

16 Moving contact carrier

17 twisted wire

18 springs

19

20 Arc extinguishing device

21 The first permanent magnet

22 Second permanent magnet

23 Arc chute

twenty four

25 magnetic field lines

F _L Lorentz force

Fx, Fy direction components

x, y direction

Claims (5)

1. Electromechanical switchgear (1), with switching contacts (10) for interrupting electrical lines, having an arc extinguishing device (20) for extinguishing the arc (7) generated when the energized switch contacts (10) are opened, It is characterized in that, The arc extinguishing device (20) has a first permanent magnet (21) and a second permanent magnet (22), and the first permanent magnet and the second permanent magnet are on both sides of the switch contact (10) are arranged opposite each other and are magnetized oppositely to each other in such a way that they push away from each other, wherein the magnetic field generated by the first permanent magnet (21) and the second permanent magnet (22) overlaps with the magnetic field generated by the arc (7) in such a way that a an electromagnetic force, the force vector (F _L ) of which has a directional component (Fx) which directs the arc (7) towards the arc extinguishing device (20) independently of the current polarity The arc chute (23) squeezes. 2. The switchgear (1) as claimed in claim 1, It is characterized in that, The arc extinguishing device (20) has a plurality of arc extinguishing plates (23) for extinguishing the arc (7). 3. Switching device (1) according to one of claims 1 or 2, In this case, the arc extinguishing device ( 29 ) can be used not only for extinguishing a DC arc but also for extinguishing an AC arc. 4. The switching device (1) as claimed in one of the preceding claims, The housing (2) has a front side (3) and a fixed side (4) opposite the front side (3), and the front side and the fixed side (3, 4 ) connected narrow side and wide side (5, 6), wherein the switch contact (10) is arranged in the housing (2), and the first permanent magnet and the second permanent magnet ( 21 , 22 ) are arranged in the region of the broad side ( 6 ). 5. The switching device (1) as claimed in claim 4, It is configured as a series installation device, wherein the housing ( 2 ) has a width of one indexing unit.