EP1884969B1 - Switch for direct and alternating current operation - Google Patents

Description

The invention relates to a contactor for DC and AC operation according to the preamble of the independent claim 1.

Contactors are known from the prior art, with at least two contact points with a fixed contact and a movable contact, wherein the movable contacts are arranged on a contact bridge and adjacent to each contact point at least one permanent magnet is arranged to produce a permanent magnetic blowing field and at least one adjacent Each contact point arranged coil for generating an electromagnetic blowing field, for blowing an arc resulting from the opening of the contact points in at least one extinguishing device.

Such contactors are used for example in railway operation for switching loads and for interrupting circuits with high currents or high voltages. In the switching operation, i. When opening the contact points, an arc is created between the fixed contact and the movable contact. This arc maintains the flow of current between the contacts. In addition, the arc releases a large amount of heat, which leads to the burning of the contacts and thus reduces the life of the contactor. In addition, the entire area affected by the influence of the arc is subject to very high thermal loads. It is therefore a quick extinction of the arc required.

Depending on the application, various methods for arc quenching are known: A contactor for use in DC operation with a constant current direction usually has permanent magnetic blast fields, which are arranged so that their field direction is perpendicular to the arc. The Blasfelder practice a force on the arc, the Lorenzkraft, through which the arc is driven in the direction of a quenching device.

For bidirectional DC operation, as it is known, for example, in the recuperation from the tram area or ICEs with multiple, alternately active pantographs, and for AC operation can be used due to the alternating current direction of the arcs no purely permanent magnetic fields. In these areas, therefore, the use of so-called bubble coils is common, which generate an electromagnetic blow field whose field direction is determined by the current direction. Regardless of the current direction, a correctly directed force effect on the arc is achieved in each case.

However, the use of coils involves a number of disadvantages. If the coil is permanently flowed through by high currents, as they are common in the railway sector, then a strong warming occurs. It is therefore known to activate the coil only at Abschaltmoment. However, the coil builds up the electromagnetic blowing field with a time delay (e-function), which increases the residence time of the arc in the contact zone of the contactor.

For small currents, on the other hand, only a small blown field is created by the coil. It may therefore happen that the blower field is not sufficient to drive the arc into the extinguishing device and bring about a deletion (critical current range).

From the DE 298 23 717 U1 For example, a circuit breaker is known in which a permanent magnet and a coil for generating a blowing field are combined. The contact or interruption point of the circuit breaker comprises a fixed contact which is connected to a first supply line and a movable contact which is connected via a stranded wire to a second supply line. In the region of the contact point, a permanent magnet and a blow coil are arranged, wherein the blow coil is connected to the same supply line as the movable contact. When opening the contact point, the movable contact is moved into a catching shoe, which is electrically connected to the coil. The resulting arc is blown over the blowing field generated by the permanent magnet in the direction of the catching shoe and jumps over to this. Since the fishing boot is electrically connected to the coil, this activates the coil. The coil then builds up an electromagnetic blowing field that blows the arc into an arc quenching device.

A disadvantage of this circuit breaker is that the movable contact with a flexible strand must be connected to the supply line and has a large opening stroke. In addition, the fishing boot has a complex geometry and must surround the movable contact on at least two opposite sides.

In the DE 1 962 559 is an arc quenching device for switching devices with double break described. The arc quenching device is used for DC switching devices, which comprise a contact bridge with movable contacts arranged thereon. The movable contacts interact with fixed contacts and form two contact points out. The contact bridge is surrounded on its end faces, on which the contact points are arranged by U-shaped parts of arc guide plates. The arc guide plates are isolated from the contact bridge and fixed in the extinguishing device. Between the arc guide is a blow coil, which is electrically connected to the arc guide. At least one permanent magnet is arranged on the end faces of the contact bridge and generates a permanent magnetic blowing field. When switching, ie when opening the contact points, arcing occurs at the two contact points, which are blown by the permanent magnetic blower field on the legs of the U-shaped parts of the arc guide. Since the permanent magnetic blow field is polarized in both directions in the same direction, the arcs are driven to the arranged on opposite sides of the contact bridge leg of the U-shaped parts of the arc guide. When the arcs have jumped over the arc guide plates, the blow coil is activated, which generates an electromagnetic blow field, which drives the arcs in a Löschkeilanordnung into it. In order to be able to use the switching device in AC operation, the arc quenching device must be replaced.

It is therefore an object of the present invention to provide a contactor, which can be used for DC operation, bidirectional DC and AC operation and causes a rapid arc extinction, excluding a critical current range. Here, a structurally simple structure and thus an economical production must be considered.

The object is solved by the features of independent claim 1.

The permanent magnets generate permanent magnetic blowing fields in the region of the two contact points which are polarized in opposite directions. On the two resulting when opening the contact points arcs so immediately act permanent magnetic blowing fields. Since the current direction of the arc at the first contact point is opposite to the current direction of the arc at the second contact point, the two arcs are driven by the two permanent magnetic Blasfeldern in the same direction. It is thus achieved that, irrespective of the current direction, one of the arcs is always blown through the permanent magnetic blowing fields in the direction of the electromagnetic blowing regions and the arc extinguishing device.

Since two movable contacts are provided, only half an opening stroke is required compared to a single break. An elaborate and space-consuming mechanism to increase the power stroke of the magnetic drive can therefore be recorded. The arrangement of the movable contacts on the contact bridge a rectilinear opening movement is made possible, on a flexible strand can be omitted.

In one embodiment it can be provided that an arc guide plate is arranged adjacent to each contact point and isolated from the fixed contacts, and the respective blow coil is electrically conductively connected to the respective fixed contact and the respective arc guide plate. The coils are activated only when the resulting arcs when opening the contact points, driven by the strong permanent magnetic Blasfeldern, skip from the fixed contacts on the arc guide. As a result, a comparatively small dimensioning of the coils is possible and overheating is avoided.

According to a further embodiment, pole plates arranged adjacent to the contact points may be associated with the permanent magnets. The pole plates produce an enlarged, uniform permanent-magnetic blow field, which acts primarily in the area of the contact points. On the arcs that arise when opening the contacts so immediately affect the permanent magnetic blowing fields and drive the arcs quickly from the contact points. Contact erosion is thus reduced.

Furthermore, it can be provided that the bladder coils are assigned pole plates and these pole plates are arranged adjacent to the arc guide plates. The coils are only activated when the arcs jump over the arc guide plates after passing through the permanent magnetic areas. The polar plates of the coils form a homogeneous electromagnetic blowing field in the area of the arc guide plates and in the arc extinguishing area. The arcs located on the arc guide plates are thus driven away from the permanent magnetic areas independently of the direction of the current and stretched.

According to a further variant, exactly one extinguishing device is arranged adjacent to the arc guide plates. About the Blasfelder the arcs are driven into the extinguishing device and stretched there and cooled and thus extinguished. The quenching device may be, for example, quenching plates or ceramic bodies arranged parallel to one another. Since, depending on the current direction, the arcs of both contact points are blown into the same extinguishing device, a space-saving design of the contactor is possible.

Fig. 1

perspektivische Teilansicht eines Schützes im Schnitt im Öffnungsmoment,

Fig. 2

perspektivische Teilansicht eines Schützes im Schnitt nach Aktivierung der ersten Blasspule,

Fig. 3

perspektivische Teilansicht eines Schützes im Schnitt nach Aktivierung der zweiten Blasspule.

Embodiments of the invention will be explained in more detail with reference to a drawing. Show it:

Fig. 1

partial perspective view of a contactor in section at the moment of opening,

Fig. 2

partial perspective view of a contactor in section after activation of the first blow coil,

Fig. 3

partial perspective view of a contactor in section after activation of the second blower coil.

In Fig. 1 is a perspective view of the interior of a contactor 1 is shown. The contactor comprises two contact points 2, 3 each having a fixed contact 4, 5 and a respective movable contact 6, 7. The movable contacts 6, 7 are arranged on a common contact bridge 8. The contact bridge 8 can be moved by a magnetic drive (not shown) and transferred from a closed position in which the movable contacts 6, 7, the fixed contacts 4, 5, in an open position. In the open position, the movable contacts 6, 7 are separated from the fixed contacts 4, 5. Adjacent to the fixed contacts 4, 5, an arc guide plate 9, 10 is arranged at each contact point 2, 3. The arc guide plates 9, 10 are each insulated by an air gap 11, 12 of the fixed contacts 4, 5. At each contact point 2, 3 at least one permanent magnet 13, 14 is further arranged. The permanent magnets 13, 14 are mounted so that their magnetic field perpendicular to the arcs 15, 16 resulting from the opening of the contact points 2, 3 extends. In this case, the direction of the magnetic field of the permanent magnet 13 arranged at the contact point 2 is opposite to the direction of the magnetic field of the permanent magnet 14 arranged at the contact point 3.

The contactor 1 further comprises two coils 17, 18 which are arranged adjacent to the permanent magnets 13, 14. The coil 17 is electrically connected to the fixed contact 4 of the contact point 2 and the arc guide plate 9 arranged adjacent thereto. Likewise, the coil 18 is electrically conductively connected to the fixed contact 5 of the contact point 3 and the arc guide plate 10.

The Lichtbogenleitbleche 9, 10 are shaped so that they form adjacent to the contact points 2, 3 a Lichtbogenleitschacht 19 which is substantially perpendicular to the contact bridge 8 and through which the arcs 15, 16 are blown through the Blasfelder of the coils 17, 18. Following this arc duct 19, the arc guide plates 9, 10 extend. Adjacent to the arc guide plates 9, 10, an arc quenching device 24 is arranged.

The arranged at the contact point 2 permanent magnet 13 is associated with a Polplattenpaar 20, wherein the two pole plates are on opposite sides of the contact bridge 8. Since the contact point 3 is formed essentially analogously to the contact point 2, the permanent magnet 14 is likewise a pole plate pair 21 assigned, the pole plates are located on opposite sides of the contact bridge 8. In Fig. 1 For each contact point 2, 3 only one pole plate of the pole plate pairs 20, 21 can be seen. The pole plates of the pole plate pairs 20, 21 are made of magnetizable material and are polarized by the permanent magnets 13 and the permanent magnets 14 and thus produce a homogeneous permanent magnetic blowing field. The pole plate pairs 20, 21 are designed so that the magnetic fields generated by them penetrate the region of the contact points 2, 3.

Also, the coil 17 and the coil 18 is each associated with a Polplattenpaar 22 and a Polplattenpaar 23. The pole plates of the pole plate pairs 22, 23 are shaped in such a way that, above all, they extend over the region of the arc guide shaft 19 and the arc guide plates 9, 10. Since the coils 17, 18 are only activated when the first arc root jumps over to one of the arc guide plates 9, 10, the electromagnetic blowing fields must act primarily in this area.

The following are based on the FIGS. 1 to 3 now the operations in the contactor 1 when opening the contact points 2, 3 described.

In Fig. 1 the contactor is shown in the opening moment. Via the magnetic drive (not shown), the contact bridge 8 is moved downward, so that the movable contacts 6, 7 arranged thereon are separated from the fixed contacts 4, 5. The arcs 15, 16 produced by the permanent magnet 13 and the pole plates 20 and the permanent magnetic blown field generated by the oppositely polarized permanent magnet 14 and the pole plates 21 act immediately on the arcs 15, 16 ,

This is in Fig. 2 shown. Since the current direction in the arc 15 is opposite to that of the arc 16, the two arcs 15, 16 are blown by the permanent magnetic blowing fields in the same direction, in the illustrated case to the left. The arc 16 is thus blown in the direction of the arc guide shaft 19, thereby skipping the air gap 12. The circuit in the contactor is now still closed and the current flows from the fixed contact 4 via the arc 15, the contact bridge 8, the arc 16, the arc guide 10 and the coil 18 for fixed contact 5. The coil 18 is thus activated by the jump of the arc 16 on the arc guide plate 10 and now generates an electromagnetic blow field, which also acts on the arc 16. As a result, the second arc root point of the arc 16 generally jumps from the contact bridge 8 onto the arc guide plate 9 (see FIG Fig. 3 ). The arc 15 goes out.

The circuit in the contactor 1 is now still closed, the current from the fixed contact 4 via the coil 17, the arc guide plate 9, the arc 16, the arc guide plate 10 and the coil 18 to the fixed contact 5 flows. By the jump of the second arc root of the arc 16 from the contact bridge 8 to the arc guide plate 9, the coil 17 is now activated and also generates an electromagnetic blow field. As a result, the arc 16 is blown out of the arc guide shaft 19 and expands on the arc guide plates 9, 10 until it is finally extinguished in the arc quenching device 24.

At very low currents and at the same time high voltages (critical current range), it may be that the electromagnetic blow field of the coil 18 is insufficient to achieve the skipping of the second arc root of the arc 16 from the contact bridge 8 to the arc guide plate 9. The arc 15 does not go out in this case initially and burns in series to arc 16 on. The arc 15 is stretched in this case by the permanent magnetic blowing field of the permanent magnet 13 continues to extinction. As soon as the arc 15 has been extinguished, the arc 16 is also extinguished. The permanent magnet 13 thus advantageously contributes to the control of the critical current range.

Runs the current direction in the contactor in the opening moment opposite to the cases described above, so instead of the arc 16 of the arc 15 is passed into the arc duct 19 and jumps first on the arc guide plate 9 on. The arc quenching proceeds analogously to the examples described above.

The contactor 1 can also be used for alternating current operation, since one of the coils 17, 18 is activated by the jump of an arc 15, 16 on the arc guide surface 9, 10, which generates an electromagnetic blow field whose direction changes with the current direction and thus always leads to it in that the corresponding arc 15, 16 is driven into the extinguishing device 24 and extinguished there. The permanent magnets 13, 14 are selected so that either the arc 15 or the Arc 16 in AC operation during a half-wave to the respective arc guide plate 9, 10 is blown and the corresponding coil 17, 18 is activated. If the current direction changes at the next half-wave, the direction of the electromagnetic blowing field also reverses and the arc continues to be blown in the direction of the arc-quenching device 24.

Claims (6)

1. Contactor (1) for direct current and alternating current operation with at least two contact points (2, 3) with a fixed contact (4, 5) and a movable contact (6, 7), wherein the movable contacts (6, 7) are arranged on a contact bridge (8) and at least one permanent magnet (13, 14) is arranged adjacent to each contact point (2, 3), for the generation of a permanent magnetic blowout field and at least one coil (17, 18), arranged adjacent to each contact point (2, 3), for the generation of an electromagnetic blowout field, for blowing an arc (15, 16) that is formed when opening the contact points (2, 3) into at least one arc chamber (24), wherein the permanent magnets (13, 14) assigned to the two contact points (2, 3) are polarised in opposite directions, characterized in that the contactor (1) comprises two coils (17, 18) arranged adjacent to the permanent magnets (13, 14).
2. Contactor (1) according to Claim 1, characterised in that an arc guide plate (9, 10) is arranged adjacent to each contact point (2, 3) and isolated from the fixed contacts (4, 5) and that the respective coil (17, 18) is electroconductively connected to the respective fixed contact (4, 5) and the respective arc guide plate (9, 10).
3. Contactor (1) according to one of the Claims 1 or 2, characterised in that pole plates (20, 21) arranged adjacent to the contact points (2, 3) are assigned to the permanent magnets (13, 14).
4. Contactor (1) according to one of the Claims 1 to 3, characterised in that pole plates (22, 23) are assigned to the coils (17, 18) and that these pole plates (22, 23) are arranged adjacent to the arc guide plates (9, 10).
5. Contactor (1) according to one of the Claims 1 to 4, characterised in that exactly one arc chamber (24) is arranged adjacent to the arc guide plates (9, 10).
6. Contactor (1) according to one of the Claims 1 to 5, characterized in that the two blowout fields generated by the permanent magnets (13, 14) and oriented in opposing directions are oriented perpendicular to the longitudinal extension of the contact bridge (8) and perpendicular to the direction of motion of the contact bridge (8).

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