Multipolar power contactor

Abstract

Disclosed is multipolar power contactor with an electromagnetic drive having an armature, and at least two movable contacts arranged next to one another and connected to the armature. The armature is movable from an open position, where the movable contacts and the fixed contacts are not in contact with one another, into a closed position where the movable contacts come into contact with the fixed contacts. Each movable contact and a corresponding fixed contact, is assigned an arc quenching device, and a plasma barrier having a first and a second barrier is provided between the two movable contacts, whereby one of the two barriers is connected to the armature and the other of the two barriers to a stationary part of the power contactor. The first and the second barrier overlap with one another at least partially in each position of the armature between the open and the closed positions.

Claims

1. A multipolar power contactor (1) with an electromagnetic drive, a movable armature (2) and with at least two movable contacts (4) that are arranged next to one another and connected to the armature (2), whereby corresponding fixed contacts (5) of the power contactor (1) are assigned to the movable contacts (4), whereby the armature (2) can be moved from an open position, in which the movable contacts (4) and the fixed contacts (5) do not come into contact with one another, to a closed position, in which the movable contacts (4) come into contact with the fixed contacts (5), and whereby each contact point, which consists of a movable contact (4) and a corresponding fixed contact (5), is assigned an arc quenching device (6), whereby a plasma barrier is disposed between two movable contacts (4) that are arranged next to one another, whereby the plasma barrier has a first barrier (7) as well as a second barrier (8), whereby one of the two barriers (7) is connected to the armature (2) and the other one of the two barriers (8) to a stationary part (22) of the power contactor (1), and whereby the first barrier (7) and the second barrier (8) overlap at least partially with one another in each position of the armature (2) between the open and the closed position, wherein the armature (2) is connected to an actuation axis (14) made of metal, whereby the actuation axis (14) is enclosed at least partially by a stationary insulation sleeve (12) that is arranged in such a way that a contact of the actuation axis (14) with plasma, which is created by a switching arc that is formed during opening of the contact point, is prevented.

2. The power contactor (1) according to claim 1, wherein the first barrier (7) and the second barrier (8) interact in the way of a labyrinth seal.

3. The power contactor (1) according to claim 1, wherein the first barrier (7) and the second barrier (8) are each formed by at least one plate.

4. The power contactor (1) according to claim 3, wherein the first barrier (7) has at least two parallel plates (7.1, 7.2), whereby at least one plate of the second barrier (8) is arranged between the two parallel plates (7.1, 7.2) of the first barrier.

5. The power contactor (1) according to claim 1, wherein the barriers (7, 8) are made of plastic or ceramic.

6. The power contactor (1) according to claim 1, wherein the power contactor (1) has a yoke plate (9), whereby at least one component of the power contactor (1), which is installed in immediate proximity to one of the contact points on the yoke plate (9), is fixed on the yoke plate by means of one or multiple plastic screws (10).

7. The power contactor (1) according to claim 1, wherein the yoke plate (9) of the power contactor (1) is equipped at least partially with an insulation film (11) on the side that faces the contact points.

8. The power contactor (1) according to claim 1, wherein the actuation axis (14) is enclosed at least partially by a moved insulation sleeve (13) that is movable relative to the stationary insulation sleeve (12), whereby the moved insulation sleeve (13) is connected firmly to the actuation axis (14), and whereby the stationary insulation sleeve (12) and the moved insulation sleeve (13) interact telescopically.

9. The power contactor (1) according to claim 1, wherein the movable contacts (4) and/or the fixed contacts (5) are respectively designed with an arc guide horn (15), whereby the arc guide horns (15) are tapered at least in a sectional way.

10. The power contactor (1) according to claim 9, wherein the arc guide horn (15) is designed as a separate component and fastened on the corresponding fixed contact (5) and/or movable contact (4).

11. The power contactor (1) according to claim 1, wherein the yoke plate (9) of the power contactor (1) has a breakthrough (19) in the area of one of the contact points, whereby the breakthrough (19) is sealed with a foam rubber mat (21).

Description

(1) An embodiment of the present invention will be explained in greater detail by means of drawings in the following. The drawings show:

(2) FIG. 1: a partially sectional oblique view of a power contactor according to the invention,

(3) FIG. 2: a schematic longitudinal section through the power contactor according to the invention from FIG. 1,

(4) FIG. 3: a detail view of the contact bridges of the power contactor according to the invention from the FIGS. 1 and 2.

(5) In the following explanations, equal parts will be designated with equal reference signs. If a drawing contains reference signs that are not further described in the corresponding description of Figures, reference shall be made to preceding or subsequent descriptions of Figures.

(6) FIG. 1 shows a partially sectional oblique view of a power contactor 1 according to the invention. The power contactor has a three-polar design and comprises three switching points that are arranged next to one another. The armature 2 of the electromagnetic drive is connected to a contact support 3 through an actuation axis 14. The contact support 3 of the power contactor has three contact bridge supports 23 that are shown in greater detail in FIG. 2, whereby each of the three contact bridge supports carries one of the three contact bridges 4 that are arranged next to one another. The three contact bridges form the movable contacts of the power contactor. One of the three contact bridge supports is arranged on the upper end of the actuation axis 14, which is actuated by the electromagnetic drive 2. The contact support 3 can be moved by means of the armature 2 from an open position, in which the movable contacts 4 and the respectively assigned fixed contacts 5 are not in contact with one another, into a closed position in which the movable contacts 4 come into contact with the fixed contact 5 and thereby create an electric connection. During opening of the contacts, a switching arc is formed, which has to be quenched as fast as possible, in particular in case of high loads to be switched, in order to prevent damage of the contacts or further components of the power contactor. An arc quenching device is therefore assigned to each contact point that consists of a movable contact 4 and a corresponding fixed contact 5. The quenching chambers 6 of the arc quenching devices are shown for 4 of the total of 6 contact points in FIG. 1.

(7) In case of malfunction, it has to be possible to reliably switch off hundreds of kilowatts of electric power by means of the power contactor 1 under certain circumstances. The arc that is formed during switch-off creates a plasma that does not only remain in the direct area of the contact points for a short time, but that even moves to the adjacent switching point in the worst case. In this case, there is the risk of the arc flashing over onto the neighboring switching or contact point. To avoid this, a plasma barrier is provided between two adjacent contact points according to the invention. The plasma barrier essentially consists of separation walls that interact in the way of a labyrinth seal and that separate the corresponding contact points from one another. FIG. 2 shows that each plasma barrier has two plates 7.1 and 7.2 that are arranged in parallel to one another and that are connected firmly to the contact support 3. The contact support 3 and the plates preferably form one single component. The two plates 7.1 and 7.2 that are aligned in parallel to each other enclose between themselves another plate 8 that is connected to a stationary component of the power contactor. In the embodiment shown, a corresponding plastic plate 22, from which the central plate 8 essentially stands out perpendicularly, is installed on the yoke plate 9 of the power contact. The plates 7.1 and 7.2 cover the central plate 8 at least in part, and this in every position of the armature between the open and the closed position. Hence, the plates 7.1 and 7.2 interact with the plate 8 in the way of a labyrinth seal and therefore prevent effectively that plasma, which is created on one of the contact points by a switching arc, will move to the neighboring switching point.

(8) To prevent the plasma from coming into contact with the yoke plate 9 or a grounded component of the power contactor that is arranged underneath and therefore creates a short circuit, additional measures were taken for the power contactor according to the invention pursuant to the shown embodiment. On one hand, an insulation film 11 is provided between the yoke plate 9 and the plastic plate 22 that lies on said yoke plate. In addition, practice has shown that a short circuit can also occur if the plasma comes into contact with a metal screw that is used for fixing of any component on the yoke plate 9. For example the arc quenching devices 6 are fixed on the yoke plate 9 by means of appropriate screws. To increase switchability, high-strength plastic screws 10 are provided for the power contactor according to the invention in order to fix components in immediate proximity to the respective contact points on the yoke plate.

(9) In addition, a plasma barrier is provided opposite to the actuation axis 14 that is made of metal. It consists of a stationary insulation sleeve 12, which stands out from the plastic plate 22, and a moved insulation sleeve 13 that is part of the contact support 3. The stationary insulation sleeve 12 and the moved insulation sleeve 13 interact telescopically and in the way of a labyrinth seal. There is a very small distance between the sleeves, just as between the plates 8 and 7.1 and/or 7.2.

(10) In addition, an auxiliary switch is provided for the power contactor, which is actuated via the armature. Therefore, a connection part 20 is connected to the contact support 3 in the shown power contactor according to the invention. The connection part 20 actuates an auxiliary contact that is arranged under the yoke plate 9 and is therefore guided through a breakthrough 19 in the yoke plate. To prevent plasma, which is formed during in the switching process, from coming into contact with the yoke plate 9 or with the grounded components of the power contactor that are arranged underneath said yoke plate, the breakthrough 19 is sealed by means of a foam rubber mat 21. Of course, the foam rubber mat has a much smaller breakthrough compared to the breakthrough 19 of the yoke plate 9 through which the connection part 20 is guided.

(11) A further measure that was taken with regard to the power contactor according to the invention to increase switchability is shown in FIG. 3. FIG. 3 shows one of the three contact bridges 4 in detail. It displays the two contact areas 18 that come into contact with the corresponding fixed contacts 5 when the power contactor is closed. An arc guide horn 15, which essentially stands out perpendicularly, is arranged respectively on the two ends of the contact bridge 4. The arc guide horns 15 are made of bronze and riveted with the contact bridge 4. The riveting connections 17 are arranged in the central area of the contact bridge. The area 16 of the arc horns 15 that stands out perpendicularly is strongly tapered in order to achieve constriction of the magnetic field lines and hence reinforcement of the electromagnetic blowing effect.