EP1780741B2 - Chambre d'interruption d'un interrupteur très haute tension avec un volume de chauffage pour l'admission de gaz sous pression - Google Patents

Abstract

The chamber has two switching units (3, 4) that are movable relative to each other longitudinal to an axis (5), and axially limiting an arc zone (9) during a switching operation. One of the switching units coaxially includes heating volumes (7), and a heating channel (10) that communicates with the arc zone. The heating channel flows to a section, into the heating volumes, which runs parallel to the axis. An orifice section (11) is limited at a transition from the heating channel to the heating volumes external to a sharp edge (12) designed as a ring.

Description

TECHNICAL AREA

The present invention relates to a switching chamber of a high voltage switch with a heating volume according to the preamble of claim 1. The invention also relates to a switch with such a switching chamber.

In the switching chamber of the type mentioned in a switching operation, two switching pieces movable relative to one another along an axis limit an arc zone in the axial direction. By a switching arc formed hot compressed gas is passed from the arc zone via a heating channel in a coaxial switching parts comprehensive heating volume. In the heating volume, the supplied hot compressed gas is mixed with already existing cold gas and performed at approach of the current to be disconnected to a zero crossing as quenching gas for blowing the switching arc in the arc zone.

The breaking capacity of this switching chamber resp. a equipped with this switching chamber high-voltage switch depends on the pressure and the temperature of the extinguishing gas. Pressure and temperature are determined by the shape and volume of the heating volume. While the volume only influences the pressure build-up, the shape of the heating volume significantly influences the gas mixing and thus also the extinguishing temperature.

STATE OF THE ART

A switching chamber of the type mentioned is described in EP 1 372 172 A1 , This switching chamber has two along an axis relatively movable switching pieces, which limit a switching path axially during a switching operation. The switching path is connected via a channel 7, 15 with a coaxial with the switching pieces gas storage space 9. In the gas storage space 9 an axially aligned partition 10 is present, the two coaxially arranged subspaces 13, 14 of the gas storage space 9 separates from each other. An adjoining the channel 7, 15 and acting as an extension of this channel subspace 13 serves as Einströmteilraum, whereas a partial space 14 surrounding the subspace 13 serves as Ausströmteilraum. The intermediate wall 10 ends above a floor 25 of the gas storage space 9 with a circumferential, slot-shaped opening 12, which connects the two subspaces 13, 14 with each other. The intermediate wall 10 therefore acts as a projecting into the gas storage space 9 tube, which limits two axially successive partial volumes of the gas storage space 9, of which a first axially bounded by the wall 25 and the free end of the tube and the second is formed by the discharge part space 14.

In this switching chamber, the heated in the high-current phase of a current to be disconnected by a switching arc gas from the switching path through the channel 7, 15, the Einströmteilraum 13 and the opening 12 and provided in the intermediate wall 10 further openings 9, 11 in the Ausströmteilraum 14 out. Bein approximation to a zero crossing of the current to be disconnected is then generated by mixing with existing in the gas storage chamber 9 already cool quenching gas and by heat to the partition cool quenching gas, which flows through the openings 9, 11 and 12 and the channel 7, 15 in the switching path and there blown the switching arc.

A switching chamber with a heating volume into which an axially oriented heating channel opens DE 196 29 475 A1 be removed. In this switching chamber, the heating channel is formed at the confluence with the heating volume as an annular gap and the annular gap is arranged in a radially oriented transverse wall of the heating volume. The outside of the annular gap is formed by an edge formed as a ring.

Another switching chamber of a high voltage switch is in EP 0 163 943 B1 , in particular embodiment according to Fig.2 shown. This switching chamber is designed axially symmetrical and has a designed in the manner of a torus heating volume 5. The heating volume 5 is connected by an axially guided annular channel 6 with a limited when switching off a current of two switching pieces 2, 3 arc zone 8. Through the channel 6 in the heating volume 5 passing hot compressed gas is mixed with cold gas, which is already present in the heating volume 5. It is such a good quality extinguishing gas available, which flows when approaching the current to be disconnected at a zero crossing via the annular channel 6 in the arc zone 8 and the arc burning in this zone 7 can effectively blow. To improve the quality of the quenching gas; At the mouth of the annular channel 6, a tubular mouth part 9 projecting into the heating volume 5 and a constriction 10 formed in the inside of the mouth part 9 are provided. As a result, the jet effect of the hot gas flowing into the heating volume and accordingly also the mixing of hot and cool gas in the heating volume are improved.

A switching chamber for a high voltage circuit breaker with a compression device and a heating volume is in DE 199 10 166 A1 described. This switching chamber also has a heating volume into which the heating channel enters with a mouth part projecting into the heating volume. This mouth part widens conically outward and, in contrast to the aforementioned prior art, increases the flow cross-section in the mouth region of the heating channel.

In the of D. Yoshida, H. Ito, H. Kohyama, T. Sawada, K. Kamei and M.Hidaka report "Evaluation of Current Interrupting Capability of SF6 Gas Blast Circuit Breakers, Proceedings of the XIV International Conference on Gas Discharge and their Applications (Liverpool, 2-6 Sept.2002 ), it is shown that it is advantageous for a good mixing of an axially fed with hot gas and cold gas containing toroidal heating volume of a switching chamber when the ratio of the length L of this volume in the axial direction to the square root of the cross-section A perpendicular to the axis is about 0.5 ,

Further describe Georges Gaudart, Pierre Chévrier, Vicenzo Girlando and Antonio Lubello in the report "New Circuit Breaker 245 kV 50 kA 50 Hz and 60 Hz with a Very Low Operating Energy", 2nd European Conference on HV & MV Substation Equipment (Lyon, France, 20- 21 November, 2003 ), a switching chamber for a high-voltage circuit breaker, in which a torus-shaped heating volume is provided for driving support, in which the heating channel opens axially. To improve the mixing of inflowing hot gas and already existing cold gas formed at the mouth of the heating volume as a pipe and axially guided in the heating volume guide elements for the hot gas.

PRESENTATION OF THE INVENTION

The invention, as indicated in the claims, the object is to provide a switching chamber of the type mentioned, are effectively mixed in the cold gas and a hot gas generated at shutdown to form a high quality extinguishing gas with simple means and so a good Switching power of the switching chamber and a switch equipped with this switching chamber is ensured.

In the switching chamber and the switch according to the invention, a trained as a ring, sharp edge is formed in the free end of the pipe at the transition from the heating channel to the heating volume, the sharpness is sufficient to turn off medium short-circuit currents with a between about 10 and about 30% of the nominal short-circuit cut-off current of the high-voltage switch size gas vortex dissolve from the hot gas flow, and to mix after flow reversal premixed and pre-cooled gas from the first sub-volume at the edge and cool gas from the second sub-volume with each other, the edge has a radius of curvature smaller 1 mm. This edge acts as a trailing edge of a flow body. Therefore, even with a relatively weak, i. Hot gas flow generated by a low power arc promotes cracking of the hot gas flow at the edge, thereby promoting the formation of vortices downstream of the edge. Inflowing hot gas and at least a portion of already existing cold gas are so effectively premixed in the first part volume. Still existing unmixed cold gas remains in the second sub-volume and is well mixed when approaching the zero crossing of the current to be turned after the flow reversal at the edge with the pre-mixed in the first sub-volume and pre-cooled gas and passed as high-quality extinguishing gas through the heating channel in the arc zone. In order to achieve a release of the hot gas flow from the pipe which delimits the mouth section to the outside when switching off average short-circuit currents with a size between approximately 10% and approximately 30% of the rated short-circuit breaking current, the radius of curvature of the edge is less than 1 mm, preferably less than 0.1 mm.

Since only in the first part volume, the hot gas is mixed with cold gas, this sub-volume can be geometrically formed so that it has the most favorable for a good mixing dimensions. In a mixing volume designed as a torus with a circumferentially predominantly rectangular cross section, the geometrical dimensions can now be selected in a manner known per se so that the ratio of the length of the torus in the axial direction to the square root of the cross-sectional area of the mixing volume perpendicular to the axis is approximately 0.5 is.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig.1

eine Aufsicht auf einen axial geführten Schnitt auf einen oberhalb der Achse gelegenen Teil einer Schaltkammer.

Fig.2

den Verlauf einer Gasströmung in einem Heizvolumen der Schaltkammer gemäss Fig.1

• (a) bei der Zufuhr von heissem Gas aus einer Lichtbogenzone, in der das heisse Gas beim Abschalten eines mittleren Kurzschlussstroms gebildet wird, der über eine auf wenige (typischerweise 0,5 bis 1,5) Halbwellen begrenzte, kurze Lichtbogenzeit (typischerweise 5 bis 15 ms) wirksam ist,
• (b) bei einer Umkehr der Gasströmung gemäss (a) während der Annäherung des Stroms an einen Nulldurchgang, und
• (c) bei der Zufuhr von heissem Gas gemäss (a), wobei nun jedoch der mittlere Kurzschlussstrom über eine längere (typischerweise 1,5 bis 3 Halbwellen umfassende) Lichtbogenzeit (typischerweise 15 bis 30 ms) wirkt oder aber ein grosser Kurzschlusstrom wirkt, dessen Lichtbogenzeit auf wenige (typischerweise 0,5 bis 1,5) Stromhalbwellen begrenzt ist,

Fig.3

den Verlauf einer Gasströmung im Heizvolumen einer Schaltkammer nach dem Stand der Technik, welche die gleichen Abmessungen wie die Schaltkammer nach Fig.1 aufweist,

1. (a) bei der Zufuhr von heissem Gas aus der Lichtbogenzone, in der das heisse Gas beim Abschalten eines mittleren Kurzschlussstroms gebildet wird, der über eine kurze Lichtbogenzeit (typischerweise 5 bis 15 ms) wirksam ist,
2. (b) bei der Umkehr der Gasströmung gemäss (a) während der Annäherung des Stroms an einen Nulldurchgang, und
3. (c) bei der Zufuhr von heissem Gas gemäss (a), wobei nun jedoch der mittlere Kurzschlussstrom über eine längere Lichtbogenzeit (typischerweise 15 bis 30 ms) wirkt oder aber ein grosser Kurzschlussstrom wirkt, dessen Lichtbogenzeit auf wenige (typischerweise 0,5 bis 1,5) Stromhalbwellen begrenzt ist,

Fig.4

eine Aufsicht auf einen axial geführten Schnitt auf einen oberhalb der Achse gelegenen Teil einer Ausführungsform einer Schaltkammer nach der Erfindung,

Fig.5

den Verlauf einer Gasströmung im Heizvolumen der Schaltkammer nach Fig.4 während der Zufuhr von heissem Gas aus der Lichtbogenzone beim Abschalten eines Kurzschlussstroms,

1. (a) der eine mittlere Grösse aufweist und der über kurze Lichtbogenzeit (typischerweise 5 bis 15 ms) wirksam ist, und
2. (b) der eine mittlere Grösse aufweist und über eine längere Lichtbogenzeit (typischerweise 15 bis 30 ms) wirkt oder aber gross ist und auf eine Lichtbogenzeit von wenigen (typischerweise 0,5 bis 1,5) Stromhalbwellen begrenzt ist,

und

Fig.6

den Verlauf einer Gasströmung im Heizvolumen einer Schaltkammer nach dem Stand der Technik, welche die gleichen Abmessungen wie die Schaltkammer nach Fig.4 aufweist, während der Zufuhr von heissem Gas aus dem Lichtbogenraum beim Abschalten eines mittleren Kurzschlussstroms, der über eine kurze Lichtbogenzeit (5 bis 15 ms) wirksam ist.

With reference to drawings, embodiments of the invention will be explained in more detail below. Hereby shows:

Fig.1

a plan view of an axially guided section on an above-axis part of a switching chamber.

Fig.2

the course of a gas flow in a heating volume of the switching chamber according to Fig.1

• (a) when hot gas is supplied from an arc zone in which the hot gas is formed upon shutting off a medium short circuit current exceeding a short arc time (typically 5 to 5) limited to a few (typically 0.5 to 1.5) half cycles 15 ms) is effective,
• (b) upon a reversal of the gas flow according to (a) during the approach of the flow to a zero crossing, and
• (c) when supplying hot gas according to (a), but now the average short-circuit current over a longer (typically 1.5 to 3 half-wave comprehensive) arc time (typically 15 to 30 ms) acts or a large short-circuit current acts whose Arc time is limited to a few (typically 0.5 to 1.5) current half-waves,

Figure 3

the course of a gas flow in the heating volume of a switching chamber according to the prior art, which the same dimensions as the switching chamber after Fig.1 having,

1. (a) upon supply of hot gas from the arc zone, where the hot gas is formed upon shutdown of a medium short-circuit current that is effective over a short arc time (typically 5 to 15 ms),
2. (b) in the reversal of the gas flow according to (a) during the approach of the flow to a zero crossing, and
3. (c) when supplying hot gas according to (a), but now the average short-circuit current over a longer arc time (typically 15 to 30 ms) acts or a large short-circuit current acts whose arc time to a few (typically 0.5 to 1 , 5) current half-waves is limited,

Figure 4

a plan view of an axially guided section on an above-axis part of an embodiment of a switching chamber according to the invention,

Figure 5

the course of a gas flow in the heating volume of the switching chamber after Figure 4 during the supply of hot gas from the arc zone when switching off a short-circuit current,

1. (a) which has a medium size and which is effective over a short arc time (typically 5 to 15 ms), and
2. (b) which is of medium size and operates over a longer arc time (typically 15 to 30 ms) or is large and limited to an arc time of a few (typically 0.5 to 1.5) current half cycles;

and

Figure 6

the course of a gas flow in the heating volume of a switching chamber according to the prior art, which the same dimensions as the switching chamber after Figure 4 during the supply of hot gas from the arc chamber when switching off an average short-circuit current, which is effective over a short arc time (5 to 15 ms).

WAYS FOR CARRYING OUT THE INVENTION

In the Fig.1 illustrated switching chamber of a high voltage circuit breaker contains a filled with a compressed insulating gas, such as based on sulfur hexafluoride or a sulfur hexafluoride, filled and largely axially symmetric designed housing 1 and a received from the switching chamber housing 1 and also largely axially symmetrical contact arrangement designed the contact assembly shown during a shutdown has two switching pieces 3, 4, of which the switching piece 3 arranged along an axis 5 movable and the switching piece 4 is held stationary in the housing 1. The switching piece 4 does not necessarily have to be fixed, it may also be designed to be movable.
The two switching pieces are coaxially covered by an insulating nozzle 6 and a heating volume 7 for storing pressurized gas. The heating volume is designed in the manner of a torus with a rectangular cross section in the circumferential direction. This torus has a perpendicular to the axis 5, annular cross-sectional area of size A and extends in the axial direction over a length 1. The volume V of the heating volume 7 is therefore determined from the product of the cross-sectional area A and the length I to: V = A · I. With a rated voltage of 200 to 300 kV and a rated short-circuit breaking current of typically 50 kA certain high voltage switch, the heating volume 7 can generally accommodate about 1 to 2 liters of compressed gas.

In the switch-on position of the chamber, not shown, the right end of the contact piece 4 is inserted in an electrically conductive manner in the left end of the tubular contact piece 3. When you turn off, the two switching pieces 3, 4 separate from each other and this forms a footing on the two ends of the switching pieces arc 8, the - like Fig.1 is removable - burns in an arc zone 9. The arc zone is bounded axially by the two contact pieces 3, 4 and radially by the insulating nozzle 6. The arc zone 9 communicates with a heating channel 10 which opens into the heating volume 7 coaxially with the arc zone 9 coaxially extending, parallel to the axis 5 extending portion 11. In a half-wave of the current to be disconnected, the pressure in the arc zone 9 is generally greater than in the heating volume 7. The heating channel 10 then leads from the arc 8 formed hot gas in the heating volume 7. Leaves the heating effect of the arc 8 as it approaches the zero crossing of the current , so there is a flow reversal. Gas stored in the heating volume 7 flows as quenching gas via the heating channel 10 into the arc zone 9 and there blows the arc 8 at least until it is extinguished in the current zero crossing.

If the amount and / or the quality of the extinguishing gas delivered by the heating volume 7 are insufficient when switching off small currents, then additional extinguishing gas can be fed into the arc zone 9 with a blowing aid, for example a piston-cylinder compression device 13 actuated by the switch drive. Small currents are up to about 10% of the rated short-circuit breaking current of the high-voltage circuit breaker and are generally in the range of a few kA, for example 4 to 6 kA.

The quality of the extinguishing gas stored in the heating volume 7 for arc blowing and thus also the breaking capacity of the switch chamber depend on the pressure and the temperature of the extinguishing gas. Pressure and temperature are determined by the shape and the volume V of the heating volume 7. While the size of the heating volume 7 only affects the pressure build-up, the shape of the heating volume influences the gas mixing and thus the extinguishing temperature. However, the quality of the extinguishing gas also depends substantially on the flow behavior of the hot gas on the way from the arc zone 9 into the heating volume 7. An extinguishing gas with good extinguishing properties is achieved in that the axially parallel aligned mouth portion 11 at the transition from the heating channel 10 to the heating volume 7 outside of a trained as a ring, sharp edge 12 is limited. This edge was formed during machining of the switching chamber by machining the Isolierdüse 6. It has a radius of curvature of about 0.1 mm and acts as a trailing edge of a flow body formed by the insulating nozzle 6 in the case of a weak flow directed into the heating volume 7 by the arc zone 9. The edge 12 shows even with a radius of curvature of about 1 mm nor the function of a trailing edge, but this function is all the more effective the lower the radius of curvature, respectively. the sharper the edge 12 is. By the material of the edge, in general an insulating material, in particular PTFE, the size of the radius of curvature is limited downwards.

Out Fig. 2 the beneficial effect of the edge 12 can be seen. If a mean short-circuit current which generally amounts to approximately 10 to 30% of the rated short-circuit breaking current and which operates over a short arc time (typically 5 to 15 ms) limited to 0.5 to 1.5 current half-cycles is switched off, then, as shown in FIG .2 (a) form a hot gas flow H that enters far into the heating volume 7. Since the edge 12 is made sharp, it acts as a trailing edge of a flowing flow of hot gas flow body. Even with relatively sluggish hot gas flows, which are generated by low-power arcs, therefore, a stall at the edge 12 and thus the formation of vortices downstream of the edge 12 are favored. In addition, the flow H is directed radially outwards on a radially oriented rear boundary wall 14 of the heating volume 7. Inflowing hot gas H and a part of already existing cold gas are already premixed. Unmixed cold gas C remains in an adjacent to a radially oriented front boundary wall 15 and in the radial direction of the sharply formed edge 12 subsequent input area of the heating volume 7. If the current reversal occurs when approaching the current zero crossing, it results from Fig.2 apparent flow path (b). The remaining cold gas C and the premixed gas designated H 'are mixed at the sharp edge 12 and thus a relatively cool quenching gas L is generated for the effective blowing of the electric arc 8.

In the course of flow according to FIG. 2 (a), a particularly good mixing of cold and hot gas is achieved only after the flow reversal according to FIG. 2 (b). Good mixing of the supplied hot gas H and the present in the heating volume 7 cold gas C before the flow reversal is achieved when switching off a mean short-circuit current at least one to two, but generally up to three half-waves act (arc time of typically 15 to 30 ms) or when the short-circuit current has at least approximately 60% of the rated short-circuit breaking current, the arc burning time is only 0.5 to 1.5 half-waves (5 to 15 ms). Like that Fig. 2 apparent flow path (c) can be taken, the tearing at the sharp edge 12 intensive hot gas flow H vortexes already in the heating volume 7 existing cold gas C practically completely and this already forms a good quality extinguishing gas, which effectively blow the arc 8 after the flow reversal can.

In a switching chamber according to the prior art, the opening in the heating volume 7 section 11 of the heating channel widens steadily outward and opens without edge formation in the heating volume 7. Therefore eliminates in such a switching chamber, the detachment of the hot gas flow H and flows - as from the in Figure 3 The course of the cold gas C is therefore pushed back to the rear boundary wall 14 and - without mixing with the incoming hot gas H - compressed in the rear of the heating volume 7 , As from the course (b) of Figure 3 can be seen, is located after flow reversal only hot gas in the entrance of the heating volume 7. The blowing of the arc is therefore initially with hot quenching gas L.

Is the arc work at a longer-acting medium or a short-acting large short-circuit current, so while the pressure in the heating volume 7 is increased, but the mixing of hot H and cold gas is not significantly improved. As from the in Figure 3 shown flow curve, c, the cold gas C is in this case pushed back into the rear of the heating volume 7, so that hot and cold gas are not mixed very well in this case and accordingly the turn-off of this switching chamber against the inventive switching chamber after Fig. 1 is lower.

In the embodiment of the inventive switching chamber according to Figure 4 are equally effective Parts with the same reference numerals as in the embodiment according to Fig.1 However, the contact assembly 2 is shown closed, so that the arc and the arc zone of this figure are not apparent. In contrast to the embodiment according to Fig.1 In this embodiment, the mouth portion 11 is bounded to the outside by a tube 16 protruding into the heating volume 7. This tube projects beyond the predominantly radially guided front wall 15 of the heating volume 7 with a free end. In this free end of the sharp edge 12 is formed. Through the pipe 16, the junction of the heating channel is moved in the axial direction to the right. The free end of the tube 16 therefore divides the heating volume in two successive partial volumes in the axial direction.

In the out Figure 5 apparent flow course (a), these two sub-volumes are designated by the reference numerals V ₁ and V ₂ . The partial volume V ₁ is formed in the manner of a torus, which extends between the predominantly radially oriented rear wall 14 of the heating volume 7 and the free end of the tube 16 and has a predominantly rectangular cross-section in the circumferential direction. The length of the subvolume V ₁ is I ₁ , that of the subvolume V ₂ is I ₂ . In the partial volume V ₁ , the ratio of length I _{1 of} the torus in the axial direction to the square root of the cross-sectional area A of the torus perpendicular to the axis 5 is about 0.5. As a result, good mixing of cold C and hot gas H is achieved in the high-flow phase of the arc in the partial volume V ₁ . Evidently remains cold gas in the smaller sized partial volume V ₂ . After the flow reversal upon approach of the current to be disconnected to the zero crossing then mix well pre-mixed and pre-cooled gas from the subvolume V ₁ at the edge 12 and from the subvolume V ₂ inflowing cold gas C to a high-quality extinguishing gas.

A particularly intensive mixing of cold C and hot gas H is achieved if, as can be seen from the course according to (b), the short-circuit current to be disconnected has a medium or large amplitude and over a longer arc time (typically 15 to 30 ms) or is effective over a 0.5 to 1.5 half-wave limited short arc time (typically 5 to 15 ms).

By virtue of the opening of the heating channel 10 or of the channel section 11 into the heating volume 7, which has been advanced into the heating volume 7 with the aid of the tube 16, thorough mixing of the cold C and the hot gas H is thus achieved in heating volumes, which have a large length in the axial direction ,

As from the flow of Figure 6 It can be seen, however, urges in a switching chamber according to the prior art with a heating volume 7 large axial length, but without an advanced junction, the formed when switching medium or large short-circuit currents hot gas H only the majority of the cold gas C to the rear boundary wall 14 and makes effective mixing much more difficult.

Since the outer diameter of the heating volume 7 should be kept low for cost reasons, but the required volume of the heating volume is specified by the prescribed for the switching chamber Abschaltleistung, thus by advancing the mouth portion 11 into the heating volume 7 by means of the tube 16, the diameter of the heating volume. 7 and thus also kept the diameter of the switching chamber small and costs accordingly saved.

LIST OF REFERENCE NUMBERS

1

casing

2

Contact configuration

3, 4

contact members

5

axis

6

insulating

7

heating volume

8th

Electric arc

9

Arc zone

10

heating duct

11

mouth portion

12

edge

13

Piston-cylinder compression device

14, 15

boundary walls

16

pipe

V

volume

V ₁ , V ₂

partial volumes

A

Cross-sectional area of the heating volume 7

I

Length of heating volume 7

I ₁ , I ₂

Lengths of the partial volumes V ₁ , V ₂

C

cold gas

H

hot gas

H'

premixed gas

L

cold gas

Claims (6)

1. Switching chamber for a gas-insulated high-voltage switch with two switching pieces (3, 4), which are capable of moving relative to one another along an axis (5) and axially delimit an arc zone (9) during a switching operation, a heating volume (7), which coaxially surrounds the switching pieces (3, 4), and a heating channel (10), which communicates with the arc zone (9) and opens out into the heating volume (7) with a section (11), which coaxially surrounds the arc zone (9) and runs parallel to the axis (8), in which switching chamber the mouth section (11) is delimited on the outside by a tube (16), which protrudes into the heating volume (7) and whose free end splits the heating volume (7) into two subvolumes (V₁, V₂), which follow on from one another in the axial direction, and in which switching chamber, during a switching operation, hot gas (H) formed in the arc zone (9) in the high-current phase of a current to be disconnected flows via the heating channel (10) into the heating volume (7) and, when the current comes close to a zero crossing, quenching gas (L) flowing in the opposite direction is guided out of the heating volume (7) into the arc zone (9), characterized in that a sharp edge (12) in the form of a ring is formed into the free end of the tube (16) at the transition between the heating channel (10) and the heating volume (7), the sharpness of said edge (12) being sufficient for releasing gas eddies from the hot gas flow (H) when switching off mean short-circuit currents with a size which is between approximately 10 and approximately 30% of the rated short-circuit switch-off current of the high-voltage switch and, after the reversal of flow, for premixed and precooled gas (H') from the first subvolume (V₁) at the edge (12) and cool gas (C) from the second subvolume (V₂) to mix with one another, wherein the edge (12) has a radius of curvature of less than 1 mm.
2. Switching chamber according to Claim 1, characterized in that the radius of curvature is less than 0.1 mm.
3. Switching chamber according to one of Claims 1 or 2, characterized in that the first subvolume (V₁) is in the form of a toroid and has a predominantly rectangular cross section in the circumferential direction.
4. Switching chamber according to Claim 3, characterized in that the ratio of the length (1₁) of the toroid in the axial direction to the root means square of the cross-sectional area (A) of the first subvolume (V₁) perpendicular to the axis (5) is approximately 0.5.
5. Switching chamber according to either of Claims 3 and 4, characterized in that the second subvolume (V₂) has a smaller capacity than the first subvolume (V₁).
6. High-voltage switch with the switching chamber according to one of Claims 1 to 5.

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