FR2458883A1 - POWER SWITCH OR PROTECTION SWITCH FOR LOW VOLTAGE SWITCHING INSTALLATIONS - Google Patents

Abstract

POWER SWITCH OR PROTECTION SWITCH FOR LOW VOLTAGE SWITCHING SYSTEMS, WITH A PACKAGE OF ARC EXTINGUISHING SHEETS WITH ARC INPUT SLOTS, IT IS AVAILABLE, IN THE REGION WHERE IT IS EXPECTED THAT THE ELECTRIC ARC ENTERING ARC EXTINGUISHING GUIDELINES 10 PERPENDICULAR TO ARC EXTINGUISHING TOLES AND WHICH FORM A BOTTLE SIMILAR TO A NOZZLE IN THE ELECTRIC ARC PENETRATION PATH.

Description

The invention relates to a power switch or

a protection switch for communication installations

  low voltage, for example an automatic circuit breaker,

with a bundle of sheets placed in a deionization chamber

tion and formed of large area arc extinguishing sheets, kept at a distance from each other and having

  preferably arc entry slots, and with direct walls

  arc arcs for guiding or deflecting the electric arc.

  During the development or improvement of switches of the kind thus defined, efforts have been made, for reasons of economy of space, to make them as small as possible and even, if necessary, to make them under the so-called thin form; in addition, efforts have been made to further improve the breaking capacities or - in the case of automatic circuit breakers or the like - the ability to interrupt

short circuits, i.e. to be able to interrupt currents

  higher current, without this affecting the service life of the switches. A very considerable improvement in breaking capacity compared to primitive switching devices has been obtained by the arrangement, in the region of the path of the electric arc, of what is called a deionization chamber in which sheets are provided. arc extinction. Other improvements have been

  obtained by giving the most diverse forms to the different

  arc quenching sheet annuities, as well as using guiding sheets or arc guiding walls (see inter alia patent AT-PS 235 385). However, there are also numerous other provisions which aim to control the triggering arc more surely, that is to say for example to subdivide it by means of said arc extinguishing plates and to bring it as quickly as possible to cool down and turn off. This can be achieved with even better results if one "forces the trigger arc to penetrate" more quickly into the pack of arc extinguishing sheets by

  more effective arrangements that can be prevented

  cement that it persists for a certain time before the arc extinguishing stains. This trend decreases with increasing

of the speed of the electric arc.

The object of the present invention is to achieve with simple means an acceleration of the speed of the electric arc, at least shortly before it enters the pack of arc extinguishing sheets, and above all prevent that, following the subdivision of the electric arc, the different roots of it persist in the region of entry of the arc extinguishing sheets, which can easily give rise to

unwanted reverse primers.

  To achieve this goal, it is proposed according to the invention

tion to have, in the region of the intended entry of the electric arc in the pack of arc extinguishing plates, arc directing walls which are preferably perpendicular to the extinguishing plates and are applied in places against these, walls which form a bottleneck some may similar to an adjustment in the path of penetration of the electric arc. This nozzle-shaped bottleneck causes, in the region located upstream of it (considering the direction of penetration of the electric arc), an increase in pressure and, consequently, a greater speed of penetration

  of electric arc in the arc quenching sheet package.

  Therefore, the risk of persistence of the immersed electric arc

  directly before the area of penetration into the pack of arc extinguishing sheets is reduced and, at the same time, the risk of unwanted reverse strikes is largely excluded.

Regarding the realization of the idea of in-

vention, some suitable forms of execution are proposed, consisting for example of making the arc guiding walls

  as a single piece, approximately contoured

  U-shaped. Such an embodiment has the advantage that a single additional element suffices which, because of its shape in space, can moreover be fixed by means

simple inside the arc extinguishing box.

  With such a U-shaped embodiment of the

guiding arc walls, it is proposed - according to a develop-

pement appropriate of the invention - to provide the back connecting the free wings of the U-shaped piece which constitutes the arc guide walls, at least one slot-shaped opening or several circular or polygonal openings located very close each other. These openings constitute the bottleneck mentioned, the effect of which can be further improved if the free wings are produced so that they converge obliquely, at least over part of

their extent.

  So that the dynamic pressure upstream of the bottleneck is not excessive, it may be advantageous to also make circular, polygonal or slit-shaped openings in the free wings of the U-shaped piece which constitutes the guiding walls of 'bow. Such openings are conveniently placed at points such as free wings that they are already at the entry slots.

  electric arc in the extinguisher sheets.

As we have just indicated, it is therefore preferable to provide arc guiding walls made in one piece with a U-shaped profile in switches whose sheets

  extinguishers have arc entry slots.

- In this case, provision is made for the U-shaped part which constitutes

kills the arc guide walls penetrates widely into the arc entry slots, the back that connects the

  free wings of the U-shaped part being directed towards the end

  mite slots and, in addition, the free wings being adapted at least approximately to the shape of the arc input slots. This arrangement has the advantage that the magnetic suction effect of the arc extinguishing sheets

  is already exercised in the region located upstream of the bottleneck

  which translates into a further acceleration of the

  penetration of the electric arc into the pack of extinguishing sheets

arc.

  But instead of the possibilities of realization which have just been described concerning a wall system in one piece, it is also possible to produce the guiding walls of the electric arc in the form of two separate flat wall elements. This offers advantages from the point of view of manufacturing technique and - in particular in the case of large electric arcs - the penetration of the arc into the

package of sheets of extinction is improved.

When using a pair of direct walls

  electric arc, it is opportune, according to a proposal

advantageous embodiment, to arrange the two guide walls of flattened shape so that they are approximately perpendicular to the arc extinguishing plates and directed towards the entry slots of the electric arc and to provide them with flanges or obtuse angle cambering, extending in a direction approximately perpendicular to the extinguishing plates and formed symmetrically with respect to each other, so that the space formed between the guiding walls of the electric arc and constituting a part of the arc penetration path has a bottleneck disposed perpendicular to the arc extinguishing plates, neck which is formed by these edges or camber. Apart from the greater speed of penetration of the electric arc into the pack of extinguishing sheets, such an arrangement improves the distribution of the electric arc over the entire pack of sheets. These are switches whose proportions in

volume are particularly narrow, and in particular inter-

  breakers which are designed for low breaking powers, it may be advisable, according to an alternative embodiment, to arrange the two guiding walls of the electric arc so that they end up on the metal sheets. extinction near the point of the desired penetration of the electric arc in the pack of arc extinguishing sheets. But instead of this, it is also possible, in the case of guide walls of the electric arc in two parts, to make them penetrate by one of their ends into the entry slots of the electric arc, in which case it it is advantageous that they adapt at least to a large extent, as regards the outline of their surfaces, to that of the entry slots of the electric arc. Under these conditions, the edges of the guide walls of the electric arc which penetrate into the entry slots of

  the arc may have at least slightly directed curvatures

  one towards the other, which gives rise to the bottleneck

  according to the invention. A tilting in cone of the two guiding walls of the electric arc towards each other is

able, in this case, to further improve the desired effect.

  Such paxois guiding the electric arc can be made of a material resistant to the electric arc, such as for example a ceramic material. Next another

  characteristic of achievement, an improvement can be achieved

  the extinguishing properties of the electric arc produced by it

as the guiding walls of the electric arc in a material which produces a gas under the effect of the electric arc. In this regard, it is proposed in particular to use a material which gives off electronegative gases under the effect of the electric arc, such as

  for example an acrylic resin or a polyalketal. The use

tion of materials producing a gas under the effect of the electric arc

stick in arc extinguishing boxes has already been proposed,

but only in the sense that the outer boundary walls

of the arc extinguishing box are made of such material. It should be mentioned, as advantageous variants of the possibilities of realization indicated last, that it is possible to cover at least in part the guide walls of the electric arc with a thin layer of material producing a gas. under the effect of the electric arc, or to furnish them in another way with such a layer, for example by imbibition. It is thus assured that even after a large number of switching operations, the guide walls of the electric arc, which are nonetheless exposed to certain gas pressures, will not be subject to mechanical weakening, but will lose at most some little of their effect as far as

  relates to their properties of producing a gas.

Another proposed variant consists in giving the guiding walls of the electric arc a composition made partly of a material resistant to the electric arc and, for the rest, of a material producing a gas under the effect of the electric arc, this composition being obtainable by mechanical means (riveting or the like), by thermal arrangements (welding) or finally by chemical means, for example by bonding, so that the elements united together with a directing wall arcs appear during assembly as a single piece. In such an embodiment, the zone of the guiding walls of the electric arc which is

  first reached by the electric arc during its penetration

tion in the arc extinguishing sheets is made of material producing a gas under the effect of the electric arc and that the area intended to be traversed thereafter by the electric arc is made of material resistant or more resistant to the 'electric arc. The invention is illustrated and explained in more detail below with the aid of exemplary embodiments shown on

  the accompanying drawings and the following description therein

  reports. Fig. 1 represents the guiding walls of the electric arc produced as a single-piece element,

  with slits in the region of the planned arc passage

stick. Fig. 2 shows the guiding walls of the electric arc produced as a single-piece element, with multiple openings in the union back of the free wings of this U-shaped element and with slots in these wings. Fig. 3 is a side view showing a number of arc extinguishing plates in the mounted position, with guide walls of the corresponding electric arc

in fig. 2.

Fig. 4 is a top view of the assembly

- shown in fig. 3.

  Fig. 5 is a view, corresponding to that of FIG. 4, of a pack of arc extinguishing sheets with an entrance slot of another type and with arc directing walls

electric produced in composite form.

Figs. 6 and 7 illustrate other possible embodiments for arc extinguishing sheets, adjacent to which are arranged conductive walls of the electric arc. Fig. 1 represents a U-shaped element 10,

  formed in one piece and usable as direct walls

trices of the electric arc, element whose back 11 which connects the free wings is provided with slots 12 and 13. An arrow 14 indicates

  the intended direction of penetration for an electric arc.

  Fig. 2 shows a U-shaped element 15, the outline of which is practically similar to that of the element 10 described above and shown in FIG. 1; but here, several circular openings (one of them is designated by the number 22) arranged side by side at a short distance from each other are made in the junction back and slots 16 to 21 are made in the wings free from U. The intended direction of penetration of the electric arc corresponds to that of element 10 in FIG. 1 and was not

indicated again in fig. 2.

Figs. 3 and 4 are a side view and a top view of a mounted package of arc extinguishing plates, the highest of which is designated by the number 23. These arc extinguishing plates (23) have a entry slot 24 into which is inserted a U-shaped element 25 which corresponds to the element 15 shown in FIG. 2. An arrow 26 in FIG. 4 indicates the direction of penetration of a trigger arc in the element 25. The two free wings of the element 25 here form the guiding walls of the electric arc, so that this arc can come out in the pack of arc extinguishing plates (23) by simply passing through the slots 16 to 21 indicated in fig. 2 or the openings 22 made in the junction back

  of element 25. Arrows 27 to 29 drawn in indi-

the possible points of penetration of the electric arc into the pack of extinguisher sheets. By establishing a pressure in the enclosed space at least in part by

Element 25 profiled in U and through the constriction points

  formed by the slots 16 to 21 and the openings 22 (see fig. 2), the speed of the tripping arc which penetrates into the pack of arc extinguishing sheets is greater than in the absence of the walls directing of the electric arc and the openings mentioned, so that a persistence of the electric arc thus divided, in the region of its points of penetration in the pack of arc extinguishing sheets and reverse strikes who

  resulting are practically excluded.

  Fig. 5 is a view of a pack of fire extinguishing sheets

tion of arc, corresponding to the representation of fig. 4.

  However, unlike the latter, the entry slots

  in the different extinguisher sheets (the extinguisher sheet-

  arc 31 located at the top of the package is visible) are reali-

sées in another form and the guide walls of the electric arc also have a different form from that which they had in the example described above. In fact, in the present case, two arc directing walls 32 and 33 which are not joined together are arranged on the pack of arc extinguishing sheets and constitute, by the shape which is given to them and by their mutual position, a bottleneck 34 comparable to a nozzle which produces the already mentioned effect of acceleration of the triggering arc at its entry. In the present case, the two guide walls of the electric arc 32 and 33 are made of a material which produces a gas under the effect of

electric arc, for example acrylic resin or poly-

  acetal and they are provided with extension walls 35 and 36 fixed on them and made of a material resistant or more resistant to electric arc. By the position of these guiding walls of the electric arc 32 and 33, the latter have a very intimate contact with a tripping arc which penetrates into the pack of arc extinguishing sheets (31), which makes

that their property of producing a gas manifests quickly.

  A particularly advantageous fact, this release of gas and the resulting increase in pressure occurs in a space where they can be particularly opposed

  favorable to reverse priming phenomena.

  Fig. 6 illustrates another exemplary embodiment with regard to a pack of arc extinguishing sheets (again, the extinguishing sheet 37 located at the top of the pack is visible) with guide walls of the electric arc 38 and 39 arranged on this package. These arc extinguishing sheets (37) also have an entry slit 40, but the arc guide walls 38 and 39 do not penetrate there: instead, these arc guide walls 38 and 39 abut on the front edges of the arc extinguishing plates (37), on both sides of the inlet slot 40. Here again, the guiding walls of the electric arc 38 and 39 delimit, by the shape "bent" towards each other which is given to them, a bottleneck 41 which behaves like a nozzle and communicates to the tripping arc which passes between them a greater speed of penetration into the pack of sheets arc extinction (37). A

  bar 42 which passes completely through the pack of extinguishing sheets

  tion and which can serve at the same time to maintain the different arc extinguishing sheets, opposes that the partial arcs which,

as already explained, penetrate with particular speed

  fully elevated in the pack of fire extinguishing sheets, run in a straight line towards the rear edges opposite to the entry sides of the fire extinguishing sheets and strike them there

  reverse. This bar 42 can be made of a material which

  produces a gas under the effect of the electric arc, according to what has already been mentioned previously, which can favor a

  faster extinction of the various partial arcs, in particular

  especially when it comes to materials which give off electric gases

truncated by the action of the electric arc.

  Fig. 7 finally illustrates yet another alternative embodiment of the object of the invention. Here again, a visible arc extinguishing plate 43, located at the top of the package, shows a package of extinguishing plates in the inlet slots 44 from which two electric arc guide walls 45 and 46 partially penetrate. These electric arc guide walls 45 and 46 are bent one towards. the other at their ends penetrating into the entry slot 44 and in this way they form a bottleneck 47 comparable to a nozzle which produces the acceleration effect already mentioned on a triggering arc which penetrates. It should be mentioned in particular, with regard to these electric arc directing walls 45 and 46, that they are partially covered, in the zones facing one another and indicated by crosses 48, with a layer thin of a material producing a gas under the effect of the electric arc. With this pack of arc extinguishing sheets, a bar 49 is also provided - produced with a square profile in this case which fulfills the same role as the bar 42 already described with reference to FIG. 6 and which is also made of a gas-producing material under

the effect of the electric arc.

  As already mentioned at the beginning of the description

tion of the figures, it is simply, with regard to the embodiments shown, of embodiments which can be modified in multiple ways without that

  departs from the principles of the invention.

he

Claims (17)

- CLAIMS -   1. Power switch or protection switch for low voltage switching installations, for example automatic circuit breaker, with a pack of sheets placed in a deionization box and formed of large area arc extinguishing sheets, kept at a distance from each other and preferably having arc entry slots, as well as with arc guide walls for guiding or deflecting the electric arc, characterized in that it is arranged, in the region where the electric arc is expected to penetrate into the pack of arc extinguishing sheets (23, 31, 37, 43), arc directing walls (10; 15; 25; 32, 33; 38 , 39; 45, 46) which are preferably perpendicular to the arc quenching plates and are applied in places against them, walls which form a bottleneck somewhat similar to a nozzle (34, 41, 47 ) in the journey of arc penetration.   2. Switch according to claim 1, characterized in that the guide walls of the electric arc are made in the form of a single piece, profiled element   approximately in U (10, 15, 25) (fig. 1, 2, 3 and 4). 3. Switch according to claim 2, characterized in that the back (11) connecting the free wings of the U-shaped piece (10, 15, 25) which constitutes the guiding walls of the electric arc is provided with at least a slot-shaped opening (12, 13) or several circular (22) or polygonal openings, located side by side at a short distance from each other others (fig. 1 and 2). 4. Switch according to claim 3, characterized in that circular, polygonal or slot-shaped openings (16 ... 21) are formed in the free wings of the U-shaped element (15) which constitutes the guide walls electric arc (fig. 2 and 3). 5. Switch according to any one of the claims. cations 2 to 4, the arc extinguishing sheets of which have entry slots for the electric arc, characterized in that the U-shaped element (25) which constitutes the guiding walls of the electric arc penetrates widely in the entry slots   arc (24) arc extinguishing plates (23), the back of the element   ment U-shaped, which connects the free wings thereof, being directed towards the end of the slots and the free wings conforming at least approximately to the shape of the arc entry slots (fig. 4). 6. Switch according to claim 1, characterized in that the guide walls of the electric arc are made in the form of two separate wall elements of shape flattened (32, 33; 38, 39; 45, 46). 7. Switch according to claim 6, characterized in that the two arc guide walls of flattened shape   (32, 33; 38, 39; 45, 46) are approximately perpendicular to   with arc extinguishing sheets (31, 37, 43) and directed towards the arc entry slots (30, 40, 44), in that they   have obtuse edges or curvatures that extend   tooth in a direction approximately perpendicular to arc extinguishing sheets and in that they are symmetrically formed only one with respect to the other, the space delimited between the arc guiding walls and constituting a part of the entry path of the electric arc having a bottleneck (34, 41, 47) which is directed perpendicular to the arc extinguishing sheets and which is formed by said edges or curvatures.   8. Switch according to. claim 6 or 7, charac-   terized in that the two guiding walls of the electric arc are joined to the arc extinguishing plates (37) near the   desired point of penetration of the electric arc (fig. 6).   9. Switch according to claim 6 or 7, the arc extinguishing plates have slots for the electric arc, characterized in that the two guide walls of the electric arc (32, 33) penetrate by one of their ends in the entry slots of the electric arc, the contour of their surfaces matching, at least in a wide   measurement, that of the arc input slots (fig. 5).   10. Switch- according to any one of the claims   cations 6 to 9, characterized in that the ends of the two arc directing walls (45, 46) looking in the direction of penetration of the electric arc have a directed curvature   at least slightly towards each other (fig. 7). 11. Switch according to any one of the claims. cations 1 to 10, characterized in that the guide walls of the electric arc are made of metal or a resistant material   with an electric arc (such as a ceramic material). 12. Switch according to any one of the claims.   cations 1 to 10, characterized in that the guide walls of the electric arc are made of a material which produces a gas under the effect of the electric arc.   13. Switch according to claim 12, characterized in that the guide walls of the electric arc are made of a material which gives off electro-negative gases under the effect of the electric arc, gases which produce cooling and   additional deionization of the electric arc.   14. Switch according to claim 12 or 13, characterized in that the guide walls of the electric arc   are made of acrylic resin or polyacetal.   15. Switch according to claim 11, charac-   characterized in that the guide walls of the electric arc (45, 46), made of a material resistant to the electric arc, are covered at least in part with a thin layer of material producing a gas under the effect electric arc (in the region of the crosses 48) or are furnished with such a material in another way (for example by imbibition) (fig. 7). 16. Switch according to any one of the claims.   cations 1 to 10, characterized in that the guide walls of the electric arc (32, 33) are made for a part of material resistant to the electric arc and for another part of material producing a gas under the effect of the electric arc and in that these parts are joined together in a composite unit, this meeting being able to be carried out by arrangements and / or mechanical means (riveting or the like), thermal (welding) or chemical (bonding) so that '' we obtain an element in one piece or in two parts in the direction of   claims 2 and 6 respectively (fig. 5).   17. Switch according to claim 16, charac- characterized in that the area of the arc directing walls (32, 33) which is first reached by the electric arc when it penetrates into the arc extinguishing sheets is made of gas-producing material under the effect of the electric arc, while the area of the arc directing walls which is then traversed by the electric arc is made of resistant material   or more resistant to electric arc (fig. 5).