EP0013289B1 - Flat quench chamber for a load break switch - Google Patents

Abstract

1. A shallow quench chamber (30) for a load disconnection switch with pivotably mounted trailing blades (28), the shallow quench chamber comprising a synthetic shallow housing which accommodates a trailing blade contact (24) and consists of a material which gives off a quench gas, and which has a narrow quench chamber extending at least over the range of pivotal movement of the trailing blade, characterised in that the synthetic shallow housing consists of elastically deformable plates (42, 44) which form the sidewalls of the quench chamber and an essentially stiff L-shaped carrier frame (34) which is of substantially U-shaped cross-section, with the support and cover wall side edge regions of these plates (42, 44) being fastened to the inner sides of the limbs of the carrier frame (34) of U-shaped cross-section.

Description

The invention relates to a flat extinguishing chamber for a switch disconnector with pivotably mounted drag knives, consisting of a plastic flat housing which takes up a drag knife contact and is made of material which releases extinguishing gas and has a narrow extinguishing space which extends at least over the drag knife pivoting area.

Such an arcing chamber is known from AT-B-237 728. In this chamber, two flat plates are provided as flat housings, which are supported against one another via intermediate layers. and are clamped against each other with screws and nuts. However, the extinguishing properties of this known arrangement are unsatisfactory.

Furthermore, a flat arcing chamber is known ("BBC-Nachrichten", July 1963, pp. 366-371), in which the flat housing having the arcing chamber is pocket-shaped, i.e. is closed on both the support side and the cover wall side. This quenching chamber structure thus formed is fastened to a support via a type of clamp.

DE-B-1 094 336 describes a high-voltage switch with self-generated gaseous or vaporous extinguishing agent, in which the arc is drawn and blown within a pressure-resistant quenching chamber with a slit-shaped internal cross-section which is closed except for the outflow opening of the switching gases.

The object of the invention is to design a flat extinguishing chamber of the type mentioned at the beginning in such a way that it simultaneously simplifies production and improves the extinguishing properties while ensuring high operational reliability.

The object is achieved according to the invention in that the plastic flat housing consists of elastically deformable plates which form the side walls of the extinguishing space and an essentially rigid, L-shaped and essentially U-shaped support frame, the support-side and cover wall-side Edge areas of these plates are fastened to the inner sides of the legs of the support frame which is U-shaped in cross section.

By combining a support frame that can be optimally dimensioned in terms of the required strength properties with elastically deformable, i.e. relatively thin plates made of extinguishing gas-releasing material, on the one hand, an economical construction of the flat fire chamber from inexpensive, simple individual parts is made possible, and on the other hand, the functional advantage is achieved that a dimensionally dependent extinguishing current-dependent extinguishing space is obtained, since the elastically deformable plates at high currents increase their mutual distance and thus provide better pressure relief, while at low currents these plates are very close to the drag knife or can even lie against the drag knife and thus optimally extinguish the arc. Characterized in that the elastically deformable plates with their support-side and cover wall-side edge areas are attached to the substantially L-shaped support frame, the extinguishing gas-releasing plates are clearly fixed on two adjacent peripheral edge areas, while in the drag knife swivel area the desired elasticity of the plates is guaranteed.

The elastically deformable plates are preferably made of polyformaldehyde and are preferably made from plate material in a simple stamping process. Glass fiber reinforced plastic is preferably used as the material for the support frame. The components of the flat arcing chamber can thus be manufactured by using punching tools and injection molding tools, which significantly increases the economic efficiency of the production.

The elastically deformable plates are advantageously essentially rectangular.

Since, due to the elasticity of the plates emitting extinguishing gas, different distances between these plates in the drag knife swivel range, i.e. in the extinguishing space, are entirely permissible, it can even be provided according to a further embodiment of the invention that the free edge regions or edges of the elastically deformable plates lie directly against one another. This means that with regard to the fastening of the elastically deformable plates on the carrier frame, no high accuracy requirements have to be met, and moreover, in the event of the free edges of the elastically deformable plates abutting one another, even protection against undesired contamination of the extinguishing space is achieved in practical use.

In order to ensure problem-free entry of the drag knife into the extinguishing space during the switch-on process, the edge edges of the two elastically deformable plates in the drag knife entry area are preferably slightly offset from one another, so that the drag knife can always open the gap between the two plates safely and enter the extinguishing space.

Further advantageous embodiments of the invention are specified in the remaining subclaims.

• Fig. 1 eine Seitenansicht eines Lasttrennschalters mit einer erfindungsgemäßen Flachlöschkammer, und
• Fig. 2 eine in Bezug auf die Ansicht nach Fig. 1 um 90° gedrehte Seitenansicht des Lasttrennschalters.

An embodiment of the invention will explained in more detail with reference to the drawing; in the drawing shows:

• Fig. 1 is a side view of a switch disconnector with a flat arcing chamber according to the invention, and
• Fig. 2 is a 90 ° rotated side view of the switch disconnector with respect to the view of FIG. 1.

The switch disconnector provided overall with reference number 10 in FIGS. 1 and 2 is held by means of an upper and lower insulation support 12 and 14, respectively. Fastening elements 19 for an upper, stationary connecting plate 13 or a lower, stationary connecting plate 15 are attached to the two insulating supports 12 and 14 by screws 17.

On the lower, stationary connecting bracket 15, a double switching knife 20 is pivoted about an axis 21 (see FIG. 2). As can be seen from FIG. 2, the double switching knife 20 consists of two elongated, mutually parallel elements 20a and 20b, between which a contact 15a of the lower connecting lug 15 and a contact 13a of the upper connecting lug 13 are arranged at the lower end .

The two elements 20a, 20b can be pivoted together via an crank mechanism 18 by means of an insulated switching rocker 16, which is articulated on the double switching blade 20 on an axis 32.

As can be seen in FIG. 2, the axis 32 protrudes somewhat laterally from the left element 20b of the double switching knife 20; a drag knife 28 is freely rotatably mounted on this end of the axis 32. A spring 23 surrounding the axis 32 is attached at one end to the double switching knife 20 and at the other end to the drag knife 28.

The upper end of the pivotally mounted drag knife 28 projects into the gap of a flat arcing chamber 30, which will be described in detail later.

With the upper, stationary connecting plate 13, a leaf spring 22 is connected, which is provided at its free end with a contact for guiding a drag knife 24 serving slot. This trailing knife contact 24, which serves as a burning contact, protrudes from the leaf spring 22 arranged outside the flat quenching chamber 30 and abutting the flat quenching chamber wall through a recess in the wall of this shallow quenching chamber 30 into the gap of the shallow quenching chamber and lies in the path of the pivoting movement of the trailing knife 28. The slot guide of the as Burn-off or wiping contact serving drag knife contact 24 in the leaf spring 22 ensures that this contact can be axially displaced, so that the contact can dodge when the knife is knocked in, but retains its position when pulled out, so that the knife can strip off on it. The leaf spring 22 thus has a multiple function, namely the function of the contact pin guide and the power line.

The operation of this switch disconnector 10 will be described below. In this case, the switched-on state is assumed, ie the two upper ends of the elements 20a, 20b of the double switching knife 20 lie on the right and left of the contact 13a of the upper, stationary connecting plate 13, that is to say they close the contact 13a between them while the drag knife 28 is located in the gap of the flat extinguishing chamber 30 and is in contact with the drag knife contact 24. In this state, current flows essentially over the main current path, i.e. between the two connecting straps 13 and 15 via the two elements 20a, 20b of the double switching knife 20th

If the rocker arm 16 is now actuated by means of the crank mechanism 18, which is preferably designed as a spring drive, the double switching knife 20 is pivoted about the axis 21, and the upper ends of the two elements 20a, 20b come free from the contact 13a. However, there is no arc here, since the current via the secondary current path, i.e. can flow to the connecting plate 15 via the connecting plate 13, the leaf spring 22, the drag knife contact 24, the drag knife 28, the axis 32 and the lower part of the element 20b.

During the further pivoting movement of the double switching knife 20, the spring 23 is tensioned more strongly, and due to the geometric conditions according to which the axis of the drag knife 28 executes a circular movement, the drag knife strips off at the drag knife contact 24, so that the drag knife finally springs due to the prestressed spring 23 abruptly releases from the drag knife contact 24 and pivots about the axis 32. The arc that occurs between the drag knife contact 24 and the drag knife 28 leads to a strong heating of the walls of the flat extinguishing chamber 30, which immediately release an extinguishing gas. In this way, the arc is extinguished immediately, i.e. even during the period in which the drag knife 28 is located in the gap of the flat quenching chamber 30.

To switch on this load-break switch 10, the double switching knife 20 and thus also the drag knife 28 are pivoted into the position shown in FIGS. 1 and 2 by means of the switching rocker 16.

The structure of the flat arcing chamber 30 will be described in detail below.

The flat extinguishing chamber 30 consists of an L-shaped, essentially rigid support frame 34 made of glass fiber reinforced plastic, the short leg 34a of which is attached to the upper insulating support 12. This short leg 34a extends into the long leg 34c via an enlargement 34b above, which is provided at its front end as shown in FIG. 1 with a downwardly projecting projection 34d.

The widening 34b of the support frame 34 has a circular opening through which the drag knife contact 24 of the leaf spring 22 projects from the outside into the interior of the support frame 34, namely into the gap in the frame which is yet to be explained.

As can be seen in particular in FIG. 2, the support frame 34 has a U-shaped cross section, ie, as shown in FIG. 1, the lower edge of the long leg 34c and the widening 34b and the left edge of the short leg 34a of the support frame 34 has a continuous, gap-shaped or U-shaped recess 36. The drag knife contact 24 projects into this recess 36, in which the drag knife 28 is also located, on one side.

The slot-shaped recess 36 of the support frame 34 has a rectangular cross-section and is provided in its bottom surface with two grooves 38, which are separated from one another by a central web 40 and merge flush with the side surfaces of the recess 36 on their outer surfaces (see FIG. 2).

The edges of two thin plates 42, 44 made of polyformaldehyde (POM) are introduced into these grooves 38 in the recess 36 and fastened to the support frame 34 by rivets on the stiffeners 46 indicated in FIG. 1. It is also essential that plates of different sizes can be attached to the support or adjustment frame without any necessary changes, so that the appropriate and required plates can be used depending on the intended voltage.

Only the upper or right edge of the two plates 42 and 44 as shown in Fig. 1 is thus firmly attached to the support frame 34, ie in its U-shaped recess 36, so that the relatively large, remaining, almost rectangular Surface of the plates 42, 44 forming the side walls of the flat arcing chamber 30 can carry out a certain deformation and bending due to the elasticity of the polyformaldehyde.

In the switched-on position, the drag knife 28 is located between the inner surfaces of the two plates 42 and 44, as can be seen in FIG. 2.

The carrier frame 34 made of glass fiber reinforced plastic is produced by a conventional injection molding process, while the plates 42, 44 are punched out of plate-shaped polyformaldehyde semi-finished products. The plates 42, 44 are then riveted to the support frame 34.

Since the plates 42, 44 have a certain elasticity, they are pushed apart by the drag knife 28 when the load-break switch 10 is actuated even if their lower edge regions should lie against one another as shown in FIG. 1. In order to facilitate the entry of the drag knife 28 into the entry area between the two plates, that is to say at the lower left corner of the two plates 42, 44 as shown in FIG. 1, the edge edges of the two plates are offset somewhat from one another at this corner, such as is indicated by reference numerals 42a or 44a.

If, at least at the lower edge of the two plates 42, 44, the width of the gap between them is smaller than the width of the drag knife 28, the plates 42, 44 abut the drag knife 28 at low currents, as a result of which the arc is better extinguished leaves. At high currents there is a strong arc and a correspondingly strong heating, so that the plates 42, 44 emit even more gas and thereby open further accordingly. In this way, better pressure relief can be achieved.

If necessary, the two plates 42, 44 can be designed such that they come into contact with one another under a certain pretension, in order to ensure that they abut the drag knife 28 at least at low currents.

Claims (15)

1. A shallow quench chamber (30) for a load disconnection switch with pivotably mounted trailing blades (28), the shallow quench chamber comprising a synthetic shallow housing which accommodates a trailing blade contact (24) and consists of a material which gives off a quench gas, and which has a narrow quench chamber extending at least over the range of pivotal movement of the trailing blade, characterised in that the synthetic shallow housing consists of elastically deformable plates (42, 44) which form the sidewalls of the quench chamber and an essentially stiff L-shaped carrier frame (34) which is of substantially U-shaped cross-section, with the support and cover wall side edge regions of these plates (42, 44) being fastened to the inner sides of the limbs of the carrier frame (34) of U-shaped cross-section.

2. A shallow quench chamber in accordance with claim 1 and characterised in that the elastically deformable plates (42, 44) consist of polyformaldehyde.

3. A shallow quench chamber in accordance with claim 1 and characterised in that the carrier frame (34) consists of glassfibre reinforced plastic.

4. A shallow quench chamber in accordance with claim 1 or claim 2 and characterised in that the elastically deformable plates (42, 44) consist of flat stampings.

5. A shallow quench chamber in accordance with one of the preceding claims and characterised in that the carrier frame (34) consists of an injection molded part.

6. A shallow quench chamber in accordance with one of the preceding claims and characterised in that the elastically deformable plates (42, 44) are of substantially rectangular shape.

7. A shallow quench chamber in accordance with one of the preceding claims and charac-. terised in that the spacing between the two elastically deformable plates (42, 44) in the region of the carrier frame (34) is substantially the same as the thickness of the trailing blade (28).

8. A shallow quench chamber in accordance with claim 7 and characterised in that the spacing between the two elastically deformable plates (42, 44) at their free edge regions is smaller than the thickness of the trailing blade (28).

9. A shallow quench chamber in accordance with one of the preceding claims and characterised in that the free edge regions of the elastically deformable plates (42, 44) contact one another under a light bias.

10. A shallow quench chamber in accordance with claim 8 or claim 9 and characterised in that the marginal edges of the two elastically deformable plates (42, 44) are displaced relative to one another at the zone of entry of the trailing blade.

11. A shallow quench chamber in accordance with one of the preceding claims and characterised in that the base surface of the U-shaped cut-out (36) of the carrier frame (34) has two grooves (38) for accommodating the marginal regions of the elastically deformable plates (42, 44).

12. A shallow quench chamber in accordance with claim 11, characterised in that the two grooves (38) are separated from one another by a central web (40), and in that the outer surfaces of the grooves (38) are flush with the inner walls of the limbs of the U-shaped cut-out (36).

13. A shallow quench chamber in accordance with one of the preceding claims and characterised in that the marginal regions of the elastically deformable plates (42, 44) are secured to the carrier frame (34) by rivets.

14. A shallow quench chamber in accordance with one of the preceding claims and characterised in that the carrier frame (34) is constructed to accommodate plates (42, 44) of different sizes.

15. A shallow quench chamber in accordance with one of the preceding claims, characterised in that the trailing blade contact (24) extends through a cut-out in the plate (44) on the circuit breaking side and into the quench chamber space, and in that this trailing blade contact (24) is guided in a longitudinal slot of a leaf spring (22) which simultaneously forms the current path and contacts the outer side of the plate.

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