EP1826792B1 - Arcing chamber of a high voltage circuit breaker with a heating volume receiving the arc extinguishing gases generated by the arc - Google Patents

Abstract

The chamber (1) comprises contact arrangement (2), two arcing contacts (3,4) mobile along an axle (5), an insulating nozzle (6), an insulating secondary nozzle (11), a heating volume (7) and a heating channel (10). A section (12) of the heating channel flowing into the heating volume is bent inward against the axle. The angle of inclination (alpha ) lies between 10 degrees and 30 degrees. An independent claim is also included for the high voltage switch.

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.

The switching chamber of the type mentioned allows the switching off of short-circuit currents in the range of 50 and more kA in the voltage range of up to a few hundred kV. It contains an axially symmetrical contact arrangement with two along a axis relative to each other movable arcing contacts, an insulating, a lsolierhilfsdüse, a heating volume and between the insulating and Isolierhilfsdüse partially axially guided and an arc zone with the heating volume connecting heating channel. When switching off a short-circuit current, a high-power arc receiving arc zone is limited when switching off a short-circuit current in the axial direction of the two arcing contacts and in the radial direction of the insulating and the Isolierhilfsdüse. Hot gas formed by the switching arc is guided by the arc zone via a heating channel into a heating volume coaxial with the contact pieces. In the heating volume, the supplied hot gas is mixed with already existing cold gas and performed on approaching 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 a high-voltage switch equipped with this switching chamber, which is determined by the dielectric strength of the switching chamber, depends on the density of the extinguishing gas, ie on the pressure and the temperature of the extinguishing gas. If hot and cold gas are mixed only incompletely with each other, then, after the zero crossing of the short-circuit current in the heating volume, hot gas bubbles may still be present, which return to the arc zone with the extinguishing gas and may possibly lead to undesirable restrike.

STATE OF THE ART

Embodiments of a switching chamber of the type mentioned are described in DE 39 15 700 A1 and DE 199 36 987 C1 , At one off Figure 3 from DE 39 15 700 A1 apparent embodiment of this switch chamber opens an axially symmetric and designed as a hollow body heating channel with an inwardly inclined to the symmetry axis outer surface in a heating volume. At an in Fig.1 from DE 199 36 987 C1 illustrated embodiment of the switching chamber of the heating channel opens with an inwardly inclined to an axis of symmetry of the switching chamber and in the manner of a hollow truncated cone tapered section into the heating volume.

In US 4 716 266 A and US 4,774,388 A Switching chambers are described in which the heating channel in each case has a section opening into the heating volume, which contains a plurality of subchannels arranged offset from one another in the circumferential direction of the mouth section. In one of Fig.8 of US 4,474,388 A apparent embodiment of this switching chambers, the sub-channels on a run in the manner of a banana cross-sectional profile.

Another switching chamber is in DE 199 10 166 A1 described. In this switching chamber communicates formed during switching off and two arc contacts axially limited arc zone via an axisymmetric heating channel with a formed in the manner of a torus heating volume. The heating channel opens into the heating volume with a section inclined outwards relative to the axis of symmetry. Hot gas formed by a switching arc in the arc zone therefore enters the heating volume with a velocity component guided outwards away from the axis.

In the written by D.Yoshida, H.lto, H.Kohyama, T.Sawadä, 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.

Georges Gaudart, Pierre Chévrier, Vicenzo Girlando and Antonio Lubello also describe 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 in the cold gas and generated when switching off hot gas to form a high quality extinguishing gas are mixed with simple means effectively and so a good breaking performance the switching chamber and a switch equipped with this switching chamber is ensured.

In the switching chamber and the switch according to the invention, the heating channel opening into the heating volume with a portion inclined inwardly against an axis has a largely constant cross-section over its entire length.

By this measure, the flow rate of the hot gas is kept constant while maintaining an inwardly directed velocity component throughout the mouth portion. The likelihood of undesirable premature vortex formation in the heating channel due to flow inhomogeneities is thus reduced.

In addition, hot gas flowing into the heating volume has an inwardly directed velocity component and is guided along an axially aligned inner wall of the heating volume to a rear wall which limits the heating volume axially in the flow direction. The inward velocity component prevents detachment of the hot gas flow from the inner wall and therefore allows deep penetration of the hot gas into the heating volume in areas near the axis. At the same time then present in the heating volume existing cool quenching gas to the incoming hot gas only a relatively small flow resistance, so that the speed of the incoming hot gas is not significantly reduced. A vortex formation which promotes the mixing of the hot gas with cool quenching gas therefore only takes place in a relatively large distance from the mouth of the heating channel into the heating volume. Due to the low viscosity of the hot gas, the formed vortex remains largely stable over a comparatively large period of several milliseconds, so that cool gas is obtained over this period at the mouth of the heating channel into the heating volume. When approaching the current to be disconnected to a zero crossing and inserting a quenching gas flow from the heating volume in the arc zone is then already at the beginning of an arc extinguishing cool quenching gas for blowing the switching arc available. Thereby and by subsequent outflowing extinguishing gas with good extinguishing properties, which is formed by intensive mixing as a result of the long-acting vortex in a remote from the mouth part of the heating volume, it is ensured that short-circuit currents of different height and duration can be successfully interrupted.

In addition, the inwardly inclined course of the mouth portion allows a reduction of the dimensions of the heating volume in the radial direction. An insulating auxiliary nozzle delimiting the heating channel on its inside can be attached to the Opening point of the heating channel are bevelled into the heating volume, so that the inner wall of the heating volume is then formed by a small diameter having contact carrier of an arcing contact of the switching chamber. The outer diameter of the heating volume can therefore be reduced and thus the manufacturing costs of the switching chamber can be reduced.

Although large angles of inclination allow an economically advantageous reduction of the outside diameter of the heating volume, but the hot gas flow with increasing large angles of inclination increasingly the tendency to prematurely detach from the inner wall. Above an angle of inclination of 45 °, this tendency to detach at certain flow velocities may already be relatively pronounced. A particularly good axially oriented guidance of the hot gas into the interior of the heating volume at the same time kept small outside diameter of the heating volume was achieved with a lying between 10 ° and 30 ° tilt angle.

• Abschrägen einer Isolierhilfsdüse, Festsetzen der Isolierhilfsdüse am Kontaktträger des vorgenannten Lichtbogenkontakts, Einformen einer den Mündungsabschnitt nach aussen begrenzenden und eine Mantelfläche des hohlem Kegelstumpfs bildenden konischen Fläche in die Isolierdüse und Festsetzen der Isolierdüse.

Advantageously, the mouth portion is designed in the manner of a tapering in the direction of inclination, hollow truncated cone. Such a mouth section can be achieved by performing the following measures:

• Beveling of a Isolierhilfsdüse, setting the Isolierhilfsdüse on the contact carrier of the aforementioned arcing contact, forming a the mouth portion outwardly limiting and a lateral surface of the hollow truncated cone forming conical surface in the insulating and setting the insulating.

If this lateral surface at the transition from the mouth section to the heating volume is delimited by a sharp edge formed as a ring, this edge facilitates the detachment of the hot gas flow from the lateral surface and at the same time additionally favors the formation of the vortex on the rear wall of the heating volume. In a weak hot gas flow generated by a low power switching arc, a vortex promoting the mixing of hot gas and cold gas is thus reliably formed downstream of the edge, which leads to an extinguishing gas of good quality even in the case of low-power switching arcs. A further improvement of the leadership of the hot gas flow and thus also the dielectric properties of the quenching gas is achieved in that the sharp edge is arranged on a projecting in the manner of a nose into the heating volume ring.

The advantageous effects of the inclined heating channel are largely retained if the mouth section has at least two partial channels extending in the direction of inclination and arranged offset from one another in the circumferential direction. This is especially true when the sub-channels each have a running in the manner of a banana cross-sectional profile.

If the heating channel has a substantially constant cross section over its entire length, the flow rate of the hot gas can also be kept constant while maintaining an inwardly directed velocity component in the entire mouth section. The likelihood of undesirable premature vortex formation in the heating channel due to flow inhomogeneities is thus reduced.

If the mouth section is formed as a hollow truncated cone tapering in the direction of inclination, then the constant cross section in the mouth section is achieved in that the inner surface of the hollow Truncated cone is more inclined than the lateral surface. Such a sizing of the heating volume favors the formation and stabilization of the vortex in a portion of the heating volume downstream of the orifice.

If the heating volume is designed in the manner of a torus and has a predominantly rectangular cross-section in the circumferential direction, then it is advantageous for the formation and stabilization of the hot gas vortex and thus also for the quality of the extinguishing gas obtained by mixing hot and cold gas the ratio of the length of the torus in the axial direction to the height of the torus in the radial direction is between 1 and 3.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig.1

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

Fig.2

eine Aufsicht auf einen längs II-II geführten Schnitt durch die Schaltkammer nach Fig.1,

Fig.3

eine Aufsicht auf einen entsprechend Fig.2 geführten Schnitt durch eine zweite Ausführungsform der Schaltkammer nach der Erfindung,

Fig. 4

eine Aufsicht auf einen entsprechend Fig.2 geführten Schnitt durch eine dritte Ausführungsform der Schaltkammer nach der Erfindung, und

Fig.5

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

Reference to drawings, embodiments of the invention are explained in more detail below. Hereby shows:

Fig.1

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

Fig.2

a view of a longitudinal II-II guided section through the switching chamber after Fig.1 .

Figure 3

a supervision on one accordingly Fig.2 Guided section through a second embodiment of the switching chamber according to the invention,

Fig. 4

a supervision on one accordingly Fig.2 guided section through a third embodiment of the switching chamber according to the invention, and

Figure 5

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

WAYS FOR CARRYING OUT THE INVENTION

In all figures, like reference numerals refer to like-acting parts. The in the FIGS. 1 and 2 illustrated switching chamber of a high voltage circuit breaker contains a with a compressed insulating gas, such as based on sulfur hexafluoride, nitrogen, oxygen or carbon dioxide or mixtures of these gases with each other, for example, air, filled and largely axially symmetric designed housing 1 and a recorded from the switching chamber housing 1 and also largely axially symmetrical designed contact assembly 2. From the illustrated during a shutdown contact assembly 2, two arcing contacts 3, 4 are shown, of which the arcing contact 3 arranged along an axis 5 movable and the arcing contact 4 is held stationary in the housing 1. The arcing contact 4 does not necessarily have to be fixed, it can also be designed to be movable. The two arcing contacts 3, 4 are coaxially covered by an insulating nozzle 6 and a heating volume 7 for storing quenching gas. The heating volume 7 is designed in the manner of a torus with a rectangular cross-section in the circumferential direction. With a switch designed for nominal voltages of typically 200 to 300 kV and for a nominal short-circuit breaking current of typically 50 to 70 kA, the heating volume 7 can generally accommodate approximately 1 to 2 liters of pressurized extinguishing gas.

In the closed position of the chamber, not shown, the left end of the arcing contact 4 is inserted in an electrically conductive manner in the right end of the tubular arc contact 3. When you turn off the two arc contacts 3, 4 separate from each other and this forms a footing on the two ends of the arcing contacts arc 8, the - like Fig.1 is removable - burns in an arc zone 9. The arc zone 9 is axially bounded by the two arc contacts 3, 4 and axially by the insulating nozzle 6 and an insulating auxiliary nozzle 11. The arc zone 9 communicates with a heating channel 10. The heating channel 10 is partially axially guided between the insulating nozzle 6 and the insulating auxiliary nozzle 11 and opens into the heating volume 7 with an inwardly inclined portion 5 against the axis 5. The angle of inclination is α. The insulating auxiliary nozzle 11 comprises the free end of the arcing contact 3 formed by contact fingers in the circumferential direction.

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.

The quality of the extinguishing gas stored in the heating volume 7 for arc blowing and thus also the breaking capacity of the switching chamber depend on the gas density determined by the pressure and temperature of the extinguishing gas. Pressure and temperature are determined primarily by current intensity and duration of the switching arc, but also by the shape and volume 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, the gas mixing and thus the quenching gas temperature are affected , 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. Characterized in that the mouth portion 12 inclined inwardly into the heating chamber 7, receives the indicated by a double arrow 13 hot gas an inwardly directed velocity component and is guided along a tubular contact carrier 14 of the arcing contact 3 to a heating volume in the flow direction axially limiting the rear wall 15. The inward velocity component prevents detachment of the hot gas flow 13 from the contact carrier 14, which forms the axially aligned inner wall of the heating volume 7, and thus allows deep penetration of the hot gas flow 13 into the heating volume in areas near the axis. A mixing of the hot gas 13 with cold gas 16 promoting swirling therefore takes place only far from the junction of the heating channel 10 in the heating volume 7 away. Due to the low viscosity of the hot gas, a hot gas vortex 17 formed during the turbulence remains largely stable over a comparatively large period of several milliseconds, so that over this Period at the mouth of the heating channel into the heating volume of cold gas 18 is maintained.

When approaching the current to be disconnected to a zero crossing and inserting a quenching gas flow from the heating volume 7 in the arc zone 9 is then already at the beginning of an arc extinguishing operation, the cold gas 18 as a particularly high-quality quenching gas for blowing the switching arc available. Also, a later-acting portion of the extinguishing gas, which was formed by intensive mixing of the hot gas vortex 17 in the rear part of the heating volume 7 with the cold gas 16 is of high quality and thus ensures that short-circuit currents of different levels and duration can be successfully interrupted.

Out Fig.1 it can be seen that the inwardly inclined course of the mouth portion 12 reduces the dimensions of the heating volume 7 in the radial direction. As can be seen, the Isolierhilfsdüse 11 is chamfered in the mouth portion 12. The inner wall of the heating volume 7 is therefore formed by the contact carrier 14 of the arcing contact 3 having a smaller diameter than the insulating auxiliary nozzle 11, so that the outside diameter of this volume determining the volume of the heating volume 7 can be reduced.

The inclination angle α can be up to 45 °. At larger angles, the hot gas flow tends to prematurely detach from the contact carrier 14. A well-trained axial guidance of the hot gas 13 into the interior of the heating volume 7 at the same time kept small outside diameter of the heating volume is achieved with inclination angles α, which are between 10 ° and 30 °.

In the in the FIGS. 1 and 2 illustrated embodiment of the switching chamber according to the invention, the mouth portion 12 is designed in the manner of a tapering in the direction of inclination, hollow truncated cone. The hollow truncated cone can be formed by conically tapering the Isolierhilfsdüse 11 to form an inner surface 19 of the hollow truncated cone acting conical surface molding a acting as a lateral surface 20 of the truncated cone conical surface in the insulating nozzle 6 and then setting the Isolierhilfsdüse 11 on the contact carrier 14 and the insulating nozzle 6 at the marked with the reference numeral 21 outer wall of the heating volume 7 can be achieved.

The heating channel 10 has over its entire length largely constant cross-section. The flow rate of the hot gas is therefore largely constant in the entire heating channel, in particular in the mouth section 12. The probability of undesirable premature vortex formation in the heating channel 10 due to flow inhomogeneities is kept so low. The constant cross section in the mouth section 12 is achieved in that the surface 19 is inclined more than the surface 20.

Out Fig.1 It can be seen that the lateral surface 20 is delimited at the transition from the mouth section 12 into the heating volume 7 by a sharp edge 22 designed as a ring. This edge facilitates the detachment of the hot gas flow 13 from the lateral surface 20 and therefore favors the formation of the vortex 17 only at the rear wall 15 of the heating volume. The radius of the edge 22 is typically 0.1 to 1 mm.

In the embodiment of the switching chamber according to Figure 5 the edge 22 is arranged on a ring 23 protruding into the heating volume in the manner of a nose. The ring 23 provides improved guidance of the hot gas flow 13 in the mouth region.

Instead of a hollow truncated cone, the mouth portion 12 may also be shaped differently. From the FIGS. 3 and 4 it can be seen that the mouth portion circumferentially offset from each other arranged sub-channels 12 '( Figure 3 ) and 12 "( Figure 4 ), which, as in Figure 3 represented approximately circular cross-section or as out Figure 4 can be seen in the form of a banana cross-sectional profile.

For the quality of the extinguishing gas obtained by mixing hot and cold gas, it is favorable if the ratio of the length of the torus in the axial direction to the height of the torus in the radial volume is between 1 and 3 in the radial direction.

LIST OF REFERENCE NUMBERS

1

casing

2

Contact arrangement

3, 4

contacts

5

axis

6

insulating

7

heating volume

8th

Electric arc

9

Arc zone

10

heating duct

11

insulating auxiliary

12

mouth portion

12 ', 12 "

subchannels

13

Hot gas (fluid)

14

contact support

15

rear wall

16, 18

cold gas

17

(Hot gas) swirls

19

palm

20

lateral surface

21

outer wall

22

edge

23

ring

Claims (11)

1. Switching chamber for a gas-insulated high-voltage switch having a contact arrangement (2), containing two arcing contacts (3, 4) which move relative to one another along an axis (5), an insulating nozzle (6), an insulating auxiliary nozzle (11), a heating volume (7) and a heating channel (10) which is routed partially axially between the insulating nozzle (6) and the insulating auxiliary nozzle (11) and connects an arcing zone (9) to the heating volume (7), which heating channel (10) has a section (12) which is inclined inward with respect to the axis (5) and opens into the heating volume, characterized in that the heating channel has a largely constant cross section over its entire length.
2. Switching chamber according to Claim 1, characterized in that the inclination angle (α) is at most 45°.
3. Switching chamber according to Claim 2, characterized in that the inclination angle (α) is between 0° and 30°.
4. Switching chamber according to one of Claims 1 to 3, characterized in that the mouth section (12) is in the form of a hollow truncated cone which tapers in the inclination direction.
5. Switching chamber according to Claim 4, characterized in that a conical surface of the insulating auxiliary nozzle (11) which acts as the inner surface (19) of the truncated cone is more sharply inclined than a conical surface of the insulating nozzle (6) which acts as the casing surface (20) of the truncated cone.
6. Switching chamber according to Claim 5, characterized in that the casing surface (20) is bounded by a sharp edge (22), in the form of a ring, at the junction from the mouth section (12) into the heating volume (7).
7. Switching chamber according to Claim 6, characterized in that the sharp edge (22) is arranged on a ring (23) which projects into the heating volume (7) in the form of a tab.
8. Switching chamber according to one of Claims 1 to 3, characterized in that the mouth section (12) has at least two channel elements (12', 12'') which extend in the inclination direction and are arranged offset with respect to one another in the circumferential direction.
9. Switching chamber according to Claim 8, characterized in that the channel elements (12'') each have a cross-sectional profile in the form of a banana.
10. Switching chamber according to one of Claims 1 to 9, characterized in that the heating volume (7) is in the form of a torus and has a predominantly rectangular cross section in the circumferential direction, with the ratio of the length of the torus in the axial direction to the height of the torus in the radial direction being between 1 and 3.
11. High-voltage switch having a switching chamber according to one of Claims 1 to 10.

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