EP0442409B1 - DC-contactor for high power - Google Patents

Abstract

DC contactor for high power, comprising a main conduction circuit with fixed contacts (4) and moving contact (3), and a cutoff circuit with fixed contact (7A) and lever (6) rotatable about an axis (8) and provided at its end with a contact (7), with operating member (16) provided with a thruster able to repel a moveable core (20A) towards the rotary lever by way of at least one spring. Its moving conduction contact (3) is arranged between the rotary lever (6) and the fixed conduction contacts (4) and is supported by the moveable core at a point situated between the axis (8) and the cutoff contact (7) of the rotary lever. <IMAGE>

Description

The present invention relates to a DC contactor for high powers according to the preamble of claim 1.

Such contactors (see for example US-A-2769062 constitute safety devices with electropneumatic or electromagnetic control arranged in electrical power blocks, or in rail traction in engine or car trunks. They must establish, maintain and interrupt the continuity of electrical networks with direct current of voltage in general 750 or 1500 volts, supplied at intensities between 0 and 1200 nominal amps, with peaks likely to temporarily reach 5000 amps. They often need, especially for electric traction, operate under very difficult conditions: fluctuations in the ambient temperature, polluted atmosphere, vibrations, electrical overload, and ensure prolonged service even in very heavy use.

Known contactors do not have a satisfactory longevity, due to fairly rapid wear, in particular of the contacts, under the effect of arcs which appear and which the blowing members do not make it possible to eliminate quickly enough. Furthermore, they are relatively bulky and heavy, and are difficult to adjust in order to adapt them to different electrical circuits or to mount them in different positions, in particular horizontal or vertical.

The object of the present invention is to provide a direct current contactor for high powers with improved durability, more compact, lighter, the cut-off circuit of which operates only for relatively short periods of time, and possibly which ensures the blowing of the air more quickly. 'arc, and is more easily adaptable to different circuits and to fixtures in different positions.

The invention therefore relates to a DC contactor for high powers according to claim 1.

• Un premier ressort disposé entre le noyau mobile et le levier rotatif est de force suffisante pour assurer la pression d'appui du contact mobile de coupure sur le contact fixe, un ressort précontraint est disposé dans une cartouche placée entre la tête du poussoir et le noyau mobile, et la course du poussoir est telle qu'après mise en appui du contact de conduction mobile sur ses contacts fixes, il vienne comprimer le ressort précontraint en assurant la pression d'appui des contacts de conduction.
• Un ressort de rappel s'appuyant sur un épaulement du noyau mobile permet de ramener le poussoir dans le sens de la direction d'écartement des contacts principaux lorsque la commande est supprimée.
• Il comprend des contacts auxiliaires de contrôle de son état de fermeture ou d'ouverture et un tiroir à cames coulissant actionnant ces contacts, qui sont montés dans un boîtier commun amovible.
• Pour un montage en position soit horizontale, soit verticale, il comprend deux jeux d'organes de fixation par pions des connexions, adaptés à l'un ou à l'autre montage.
• Il comporte une bobine de création du champ magnétique de soufflage de l'arc, disposée en série dans le circuit de coupure.
• Sa cheminée de soufflage de l'arc comporte entre des cornes une série de plaques métalliques disposées en éventail, séparées par un intervalle précis croissant de leur extrémité plus proche des contacts de coupure à leur extrémité plus éloignée.
• Sa cheminée de soufflage d'arc est fixée à son boîtier par un doigt escamotable poussé par un ressort de maintien en position.

It also preferably meets at least one of the following characteristics:

• A first spring disposed between the movable core and the rotary lever is of sufficient force to ensure the contact pressure of the movable breaking contact on the fixed contact, a pre-stressed spring is placed in a cartridge placed between the head of the pusher and the core mobile, and the stroke of the pusher is such that after the mobile conduction contact has been pressed on its fixed contacts, it comes to compress the prestressed spring while ensuring the contact pressure of the conduction contacts.
• A return spring resting on a shoulder of the movable core allows to return the pusher in the direction of the main contacts spacing direction when the command is deleted.
• It includes auxiliary contacts for controlling its closing or opening state and a sliding cam drawer actuating these contacts, which are mounted in a removable common housing.
• For mounting in either a horizontal or vertical position, it includes two sets of fixing members by connection pins, suitable for one or the other mounting.
• It comprises a coil for creating the magnetic arc blowing field, arranged in series in the breaking circuit.
• Its arc blowing chimney comprises between horns a series of metal plates arranged in a fan, separated by a precise interval increasing from their end closer to the breaking contacts to their more distant end.
• Its arc blowing chimney is fixed to its housing by a retractable finger pushed by a spring to hold it in position.

It is described below, by way of example and with reference to the figures of the accompanying drawing, a DC contactor for large powers according to the invention.

FIG. 1A represents the contactor in the open position of the cut-off and conduction circuits, with the exception of the arc extinguishing chimney.

Figure 1B shows the arc extinguishing chimney.

Figure 2 shows on a larger scale the cartridge ensuring the contact pressure.

FIG. 3 represents the contactor in the closed position of the cut-off circuit, the conduction circuit remaining open (without the arc extinguishing chimney).

FIG. 4 shows it in the closed position of the cut-off and conduction circuits (also without the arc extinguishing chimney).

FIG. 5 shows on a larger scale the device for fixing the chimney to the contactor.

Figure 6 shows on a larger scale the plastic housing comprising the attachment of the auxiliary control contacts and the cam slide actuating them.

Figure 7 shows on a larger scale the fixing system by pins of the connections in two different positions.

The description will relate more specifically to an electropneumatic contactor, the control member being constituted by a jack and the pusher being constituted by the piston of the jack.

In FIG. 1A, the main conduction circuit comprises two current input and output connections 1, 2 made of copper provided with silver pellets 4, and a movable contact made of copper 3 also provided with silver pellets 5, intended to be driven in the closed position by a movable core to which it is integral, this movable core being actuated by the rod 17 of a jack 16.

The cut-off circuit includes a movable insulating lever 6 provided with a cut-off contact 7 made of copper-tungsten at one end and rotating around an axis 8 at the other end under the effect of the pressure of the movable core. This contact is electrically connected to connection 2 by means of a copper plate 9A passing through the lever and connected by a braid 10 to connection 2. A blowing coil 11 comprising numerous turns of fine enameled wire, connected to the main circuit by connection 1, ends with a fixed breaking contact 7A, also made of copper-tungsten.

As shown on a larger scale in FIG. 2, the contact pressure generated by the rod 17 of the jack 16 is exerted on the spring 18 housed in the cage 19. It is transmitted by the latter to the bottom 20 of a movable core 20A, surrounded by a return spring 9. The bottom 20 supports in a bowl the end of a spring 21, the other end of which bears on the plate 22 disposed below the insulating movable lever 6. The movable contact 3 is integral with the movable core 20A but has a small angle of rotation around the axis of rotation 36 (see Figure 7) attached to the end of the movable core.

The contact pressure is thus ensured independently of the air pressure of the pneumatic circuit of the jack, in a reduced size and by limiting to the minimum the connection between the pneumatic control system and the internal mechanical members of the contactor.

The blowing chimney 12 (FIG. 1B) is removably fixed to the body of the contactor by a retractable finger 23 pushed by a spring 24 on a lug 26 (FIG. 5). This provides mechanical support and reliable electrical continuity between the chimney and the contactor. This chimney comprises symmetrical horns 13, 14 flaring outwards. The arc extinction zone is constituted by a series of metal plates 15, arranged in a fan along a determined radius, and spaced by a precise interval and increasing towards the outside. They lead to a closure device 16 formed by insulating plates perforated with multiple holes.

A molded plastic case 25 (FIG. 6) has six auxiliary contacts 25A fixed by Rp bolts 27A and a cam slide 27 sliding inside and actuating these auxiliary contacts, the role of which is to control the closing or opening state of the contactor. This box, which integrates all the low voltage control functions, is fixed by bolts 27B on the contactor body, but can be quickly detached from it to be replaced if necessary by another.

The contactor connections can take two different positions, shown respectively in FIG. 7 in 1 and 2 in solid lines, or 1A and 2A in dashed lines, depending on the horizontal or vertical position in which the contactor must be placed. In the position shown in solid lines, the connection 1 is fixed by pins at 28 and 30, and the connection 2 by pins at 31 and 33. In the position shown in broken lines, the connection 1A is fixed by pins at 28 and 34, and connection 2 by pins at 33 and 35.

The operation of the closing contactor is as follows, starting from the position where the breaking and conducting contacts are open (Figure 1A).

When air is admitted into the jack 16, the piston rod 17 goes up towards the top of the figure and drives the movable core 20A as well as the cut-off lever 6 via the spring 21. When the movable core, the return spring 9 located around this cartridge is compressed. When this movable core has made a stroke of approximately 8 mm, the movable breaking contact 7 at the end of the lever 6 comes to touch the fixed breaking contact 7A. The current is then established in the cut-off circuit (Figure 3).

The cutting lever 6 in support no longer moves, but the movable core 20A can continue its ascent, then compressing the spring 21 located under the lever, and thus providing the contact pressure necessary for the good conduction of the current in the breaking circuit.

The movable core continuing to climb, pushes up the movable contact 3 which closes the conduction contacts 4 and 5, closing the conduction circuit. The current flowing until then entirely in the breaking circuit is transferred almost entirely in the conduction circuit much less resistive.

Once the conduction contacts are closed, the movable core no longer moves. On the other hand, the piston rod performs an additional stroke of approximately 2 mm before reaching the stop in the jack, by pushing in the pre-stressed spring 18 placed in the cage 19, which will provide the contact pressure necessary for good conduction. of current in the main circuit passing through the contacts 4, 5. The contactor is then closed.

In the opposite direction, when the contactor is opened, when the jack 16 is vented, the return spring 9 as well as the spring 18 in the cage 19 quickly relax and strongly repel the movable core 20A, the contact mobile 3 and the piston rod 17 towards the bottom of the figure.

During the displacement of the movable core, the spring 21 placed under the cut-off lever 6 relaxes, while keeping this lever stationary and therefore the cut-off circuit closed. On the other hand, the conduction circuit opens. The current is then diverted in its entirety from the conduction circuit to the breaking circuit.

When the movable core has made a certain downward stroke, the underside of the movable contact 3 comes to touch the lever 6 and to drive the latter. There is then opening of the contacts 7, 7A of the cut-off circuit and the appearance of an electric arc between them.

Under the effect of the return spring 9 which continues to relax, the movable core 20A and the cut-off lever 6 end their downward stroke. The arc extends between the contacts 7, 7A. However, thanks to the magnetic blowing of the arc generated by the coil 11 inserted in the cut-off circuit, the arc is blown in the arc quenching chimney 12 between the horns 13, 14 towards the plates 15 where it disappears . The coil 11, made up of numerous fine wire turns, does not heat up when the contactor is closed, since it then only passes about 1% of the total current in the breaking circuit. On the other hand, it is transiently crossed at the opening of the contactor by the totality of the current, which then passes through the breaking circuit, even before the opening of the breaking contacts and the appearance of the arc. The magnetic circuit is thus magnetized in advance, and creates a large field. As soon as the arc appears, it is therefore blown very quickly and very vigorously towards the interior of the chimney and the plates 15. It easily enters the range of plates and splits into multiple small arcs. The arc voltage then increases to reach a value greater than the mains recovery voltage, and the arc is extinguished.

The shutter device 16A channels the flow of outlet gases and stabilizes the arc in the metal plates 15 and avoids the appearance of arcs outside. The high efficiency of the fan-shaped plate system, with increasing spacing outwards, makes it possible to reduce the dimensions of the chimney compared to the dimensions adopted so far.

The above arrangement of the conduction contacts and of the breaking contacts, as well as of the lever, of the movable core and of the springs makes it possible to transfer the current from one circuit to the other during the transient phases of closing and opening, by specializing in the types of contact and making the most of their advantages. The silver conductive contacts are not damaged by electric arcs which only appear on the breaking contacts. This limits the wear of the contacts and increases their longevity.
The breaking contacts are made of copper-tungsten, making it possible to withstand the arc well. This limits the wear of these contacts.

Claims (10)

1. High-power direct current contactor comprising a main conduction circuit including input and output connections (1, 2) with fixed main contacts (4) adapted to be connected by a mobile contact (3), the contactor also comprising an interrupter circuit adapted to shunt the main conduction circuit, the interrupter circuit including a first interrupter contact (7A) electrically connected to one of said connections and including a lever (6) provided with a second interrupter contact (7) electrically connected to the other of said connections, said lever being adapted to pivot about a pin (8) so that the second interrupter contact (7) can electrically contact the first interrupter contact (7A) and including an insulative part between the second interrupter contact (7) and the pin (8), the contactor also including means for closing and opening the main conduction and interrupter circuits, characterised in that said closing and opening means comprise, disposed in alignment in the contactor, an actuator member (16) having a plunger (17), a mobile core (20A) on which the plunger acts, a spring (21) disposed on the mobile core, the lever (6) and the mobile contact (3) fastened to the mobile core, the disposition of the closing and opening means being such that:

   - on closing of the contactor, the plunger (17) moves towards the fixed main contacts (4) pushing the mobile core (20A) and the spring which acts on the lever to pivot it to a fixed position in which the interrupter circuit is closed, the mobile contact fastened to the mobile core then closing the main conduction circuit and the spring (21) being compressed,

   - on opening of the contactor, the withdrawal of the plunger causes the mobile core to be retracted by return spring means (9) and the spring (21) to expand and the main conduction circuit to be opened by retraction of the mobile contact (3), the interrupter circuit then opening because of entrainment of the lever (6) by the mobile contact as it is retracted on the lever (6).
2. Contactor according to claim 1 characterised in that the spring (21) between the mobile core (20A) and the rotary lever (6) produces sufficient force to provide the contact pressure of the mobile interrupter contact (7) on the fixed contact (7A), in that a prestressed spring is disposed in a cartridge placed between the head of the plunger (17) and the mobile core (20A), and in that the travel of the plunger is such that after the mobile conduction contact (3) is brought into bearing engagement on its fixed contacts it compresses the prestressed spring (18) to provide the contact bearing pressure for the conduction contacts.
3. Contactor according to claim 1 or claim 2 characterised in that a return spring (9) bearing on a shoulder of the mobile core (20A) returns the plunger in the direction of separation of the main contacts (3, 4) on opening of the contactor.
4. Contactor according to any one of claims 1 to 3 comprising auxiliary contacts for monitoring its closed or open condition and a sliding cam module actuating said contacts, characterised in that said auxiliary contacts and the cam module are mounted in a removable common casing (25).
5. Contactor according to any one of claims 1 to 4, adapted to be mounted in horizontal or vertical positions, characterised in that it comprises two sets (28, 30, 28, 34; 31, 33, 33, 35) of fixing members using connecting pins suitable for either mounting arrangement.
6. Contactor according to any one of claims 1 to 5 having an arc extinguishing chute (12), characterised in that it includes a coil (11) adapted to create an arc extinguishing magnetic field disposed in series in the interrupter circuit.
7. Contactor according to any one of claims 1 to 6 having an arc extinguishing chute (12) formed by a series of metal plates (15) disposed between horns (13, 14), characterised in that said metal plates are disposed in a fan arrangement, separated by a precise distance which increases from their end nearest the interrupter contacts to their end farthest therefrom.
8. Contactor according to any one of claims 1 to 7 having an arc extinguishing chute, characterised in that the latter is fixed to its casing by a retractable finger (23) spring-loaded by a spring for holding it in position (24).
9. Contactor according to any one of the preceding claims characterised in that the actuator member is a cylinder, the plunger comprising the piston of the cylinder.
10. Contactor according to any one of claims 1 to 8 characterised in that the actuator member is a solenoid, the plunger comprising the mobile armature of the solenoid.

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