DD131426B1 - SWITCH ASSEMBLY FOR LOW VOLTAGE VACUUM SHOULDERS - Google Patents

Description

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So holds piece arrangement for low voltage vacuum contactors

Field of application of the invention

The invention relates to a contactor assembly for low-voltage vacuum chüt ze with a rated current range up to about 630 Α, which have a very high switching element life. Such vacuum contactors are mainly used for switching motors and similar consumers.

In contrast to a vacuum circuit breaker, which has orders of magnitude smaller electrical and mechanical life, but orders of magnitude higher currents, d. H. Short-circuit currents, has to dominate, there is the Hauptkriteriuffi a Niedgrspannungs-Vakuwnschützes in achieving a very high Sohaltstücklebensdauer without maintenance and replacement of the contact pieces.

Characteristic of the known technical solutions

Low-voltage vacuum guns achieve this high switching element life in particular by exploiting the properties of the specific vacuum arc (type A) that are particularly favorable for this, which is associated with the existence of parallel cathode bottoms, no pronounced anode base point and no contraction of the anode batch. This results in a very low material erosion at the. Katode and a material gain at the anode, which significantly affects the contactor life. The ExJLstenzbereich the specific vacuum arc type A is here in addition to the current level above all by the selection of a suitable switching piece material, the utilization of the maximum possible Karcmerinnen

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pressure and the contactor dimensioning determined.

According to known investigations, the burnup at the cathode or in the parallel cathode base points of the specific vacuum arc type A decreases with increasing pressure (DD-PS 108 407). From the point of view of a longer service life, it would be useful to increase the pressure in the contact gap during the arc duration. However, for this purpose, the known for low-voltage vacuum contactors disc-shaped Schaltstückanordnungen are not suitable,

Next, it is important to completely prevent the leakage of the contact material vapor from the contact gap, but at least reduce it to a safe level to recover a large proportion of the vaporized contact material for further circuits and the Isolierstrecke the Vakuumschal tkaps el to protect against occupancy by metal vapor , After extensive investigations about 50 ^a k of the vaporized at the cathode contact material emerges from the contact gap of the known disk-shaped SehaltstückanOrdnung, condenses on the screen or other inner surfaces of the switching chambers and is lost for further switching operations or leads to an occupancy and thus bridging the insulating path.

For high-voltage vacuum circuit breaker switching piece assemblies are already known, which differ from the usual disc shape of the switching pieces. However, these switching pieces are suitable for their specific use for vacuum switching chambers for switching short-circuit currents (current ^ -5 kA, vacuum arc type E), in which the specific type A vacuum arc does not exist anymore. The then adjusting and the high-pressure arc-like vacuum arc type B with pronounced Sinzelanoden- and Katodenfußpimkt requires a different design and dimensioning of the contact arrangement. With these flows and this form of vacuum arc, it is imperative to prevent the ejected anode and cathode base or arc column from staying in motion, a rapid movement

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to force this arc to remove it from the actual contact point in order to maintain the turn-off capability and avoid excessive material burn-up, which would in turn lead to failure of the shutdown and re-ignition of the arc due to excessive metal vapor density.

Thus, switching piece arrangements are known (eg DE-PS 1 195 026, SU-PS 19 659), in which the arc of the actual origin or contact point driven by a magnetic field from a conically diverging cylinder into a closed cylinder and the Rotation is forced ·

The purpose of the known arrangement according to US Pat. No. 3,356,818 is similar, in which the arc is moved away from the actual contact point by means not described in greater detail and burns between the walls of the contacts, which are first cylindrical and then cone-shaped and intermeshing.

This also applies to the switching piece arrangement according to DD-PS 96 801, which is suitable for switching off very large currents and in which also by various measures the pronounced arc column of the vacuum arc type B should burn between the walls with two coaxial nested Topfschaltstücken.

In v / Eiterer improvement of this arrangement 117 190 further measures are known by DD-PS, with which the arc of the so-called rated current range, which forms the bottom of the contact pot, is driven into the lying between the cup walls Abbrandbereiche.

In a further arrangement according to DD-PS 128 192 is proposed for the purpose of a better and higher static withstand voltage, the usually existing shield arrangement and expand so that all distances between parts of different potential equal to or equal to the contact opening. Next should such by a suitable design of the screen that he the contours of the outer shell

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or the solid contact piece follows, be achieved that the unobstructed emerging from the contact gap metal vapor is kept away from the Isolierstrecke.

With this arrangement, however, the desired reduction of the consumption of material according to the inventive concept and thus a reduction of the metal vapor emerging from the contact gap can not be achieved from the outset. The shield arrangement is open on both sides and causes no significant pressure increase in the contact gap to reduce the material erosion.

These arrangements do not yet provide a solution useful to the idea of the invention, since these arrangements are provided for switching very large short-circuit currents, in which the arc is driven out of the contact gap by various means, the contact material vapor in the chamber is inadmissible for high numbers of operations May spread dimensions and are too expensive for contact arrangements for low-voltage vacuum gun for the intended current range and can not bring the desired increase in lifespan, or only provide precautions for a much higher static withstand voltage and redirect the metal vapor, so he can not get on the Isolierstrecke.

Object of the invention

The aim of the invention is to increase the life of the contact piece as a determining factor for the life of said vacuum contactor.

Explanation of the essence of the invention

The invention has the object of providing the contact pieces in such a way that the escape of metal vapor from the contact gap is largely reduced and the vaporized contact material again attaches to the switching pieces.

According to the invention, the two switching pieces are designed for this purpose in known per se as interlocking pots. The front sides of the pots consist of the actual contact

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Material and the cylindrical walls are made of a material that for the specific vacuum arc compared to the actual contact material unfavorable conditions of existence, eg, higher arc voltage has. The switching pieces are in this case designed as interlocking pots, wherein only an annular narrow opening is formed in the interior of the vacuum interrupter chamber.

In continuation of the inventive concept, the upper edge of the inner contact piece is bent over the edge of the outer contact piece and the cylindrical wall of the outer contact piece has in the region of the contact gap a bulge for material attachment to «

In another variant, the inner contact piece is disc-shaped, and the cylindrical wall surrounds the disc-shaped contact piece cup-shaped «

Furthermore, it is advantageous to manufacture the cylindrical walls of switching pieces made of a material with favorable condensation conditions for the contact material vapor.

embodiment

Reference to an embodiment of the invention will be explained in more detail.

In the drawing show:

Fig. 1: the contactor assembly in section Fig. 2: the bend of the inner Schaltstückwandung Fig. 3 u. 4: Formations of the outer Schaartstückwandung

^A n arranged in a vacuum housing electrodes 1; 2, the fixed contact 3 and the movable contact are fixed. The switching pieces 3; 4 are in this case designed topfpfformig and engage with their cylindrical walls 5; 6 in each other. The front sides of the cup-shaped switching pieces 3; 4 consist of the actual contact material, for. B. Cu or MoCu, and the walls 5; 6 from a cheaper and less favorable for the vacuum arc arc conditions of existence material, eg. Fe, Fe-Ni. Furthermore, it is advantageous for

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the cylindrical walls 5; 6 to use a material with a good condensation behavior for the contact material vapor · The cylindrical walls 5; 6 are attached in the simplest form by shrinking on the disc-shaped end faces of the contact pieces and have a very small distance 7, which is equal to or less than the maximum contact opening, preferably 1-3 mm, on.

A further reduction of the material outlet from the contact gap 8 is achieved when the upper edge of the inner contact piece 6 is bent outwards over the wall of the outer contact piece 5 (FIG. 2) or »the wall 5 of the outer contact piece 3 bulges 9 in the region of Contact gap 8 has (Fig. 3). The lower contact piece 4 may also be disc-shaped, and the wall surrounds the disk-shaped contact piece 3 cup-shaped and here forms the gap 10. The cup-shaped wall 5 is in this case attached to the electrode 2 (Fig. 4).

With the contactor assembly according to the invention is achieved over the known and designed for other applications and other arc characteristics switching piece assemblies that

- The parallel Katodenfußpunkte and thus the partial arcs remain in the narrow contact gap 8 and caused by the resulting larger pressure in the contact gap during discharge a lesser burnup, a much larger proportion of contact material vapor does not emerge from the contact gap 8, at the ever v / hurry Anode (contact piece 3, 4) is deposited and thus can be recovered for other circuits;

- condensed faster due to the larger condensation surface of the contact material vapor and thus an improvement in the recompression of the switching path is made possible.

Overall, thus a higher switching piece life and thus a greater total duration of the vacuum circuit breaker can be achieved with little effort.

Claims (4)

199 549 claim for damages 1. Switching piece arrangement, for low-voltage vacuum contactors with a rated current range up to about 630 A, characterized in that one or both switching pieces (3; 4) are formed topfförralg in a conventional manner, wherein the cup-shaped contact pieces mesh or the inner contact piece is disc-shaped uod the cylindrical wall, the disc-shaped contact piece cup-shaped surrounds that the end faces of the pots of the actual contact material and the cylindrical walls (5; 6) consist of a material which is less favorable for the specific vacuum arc compared to the actual contact material conditions of existence, eg. B · higher arc voltage, and that the distance (7) between the two cylindrical walls of the contact pieces is equal to or less than the maximum contact opening. 2. contact piece arrangement according to item 1, characterized in that the upper edge of the inner contact piece has a bend to the outside · 3 · Contact piece arrangement according to item 1, characterized in that the cylindrical wall (5) of the outer contact piece has a bulge (9) in the region of the contact gap (8). 4. contact piece arrangement according to item 1 »characterized in that the cylindrical walls of the contact pieces made of a material with -for the metal vapor favorable condensation conditions. To this end A side Zeichnungan  Λ I Ί Il I .. I Ί- 'I ... -Il 1 I T