EP1835520B2 - Switching chamber for gasisolated high voltage switch - Google Patents

Abstract

The switching chamber has an exhaust module that is provided in a coaxial arrangement over an exhaust unit (9). A housing (3) and a cup (16) limit a flow path (25) for the exhaust gas (24) with an electrically shielded, axially aligned discharge opening. The discharge opening is formed as an annular gap (20), where the flow path contains an additional volume (19). The cup is manufactured by casting, sheet forming and sheet welding, where the cup is removably connected with the exhaust unit.

Description

TECHNICAL AREA

The present invention relates to a gas-insulated high voltage switch according to the preamble of claim 1. Such a switch includes a switching chamber having an axis aligned along an axisymmetric housing formed and held in the housing arcing contact arrangement. An exhaust unit is integrated into the housing with an exhaust volume limited by the housing and an outlet for exhaust gases guided through the housing. The switching chamber is inserted into a contact-protected, insulating gas-filled metal container of the high-voltage switch. When operating the switch, the switching chamber is at high voltage potential. When switching off a short-circuit current hot exhaust gases generated by the switching arc through the outlet of the exhaust unit in the metal container and thus locally reduce temporarily the quality of the existing in the metal container insulating gas.

STATE OF THE ART

High voltage switch of the type mentioned are described in US Pat. No. 6,495,785 B1 and EP 1 691 389 A1 , The switches described each have a switching chamber arranged in an insulating gas-filled metal container. The switching chamber includes an axially symmetric housing carried by a post insulator in which an arcing contact assembly is disposed. The switching chamber housing is formed by an insulating tube and two, attached to both ends of the insulating, electrically conductive hollow bodies. Each of the two hollow bodies is electrically conductively connected to one of two current conductors guided through the metal container and to one of two contacts of the arcing contact arrangement. At least one of the two hollow bodies defines an exhaust volume for receiving hot switching arc gases which can pass into the metal container via an outlet as exhaust gas.

Amended part of the description according to the main request

DE 102 21 580 B3 . DE 102 21 576 A1 . EP 0 075 668 A2 . CH 655 612 A5 as well as the post-published earlier patent application EP 1 768 150 A1 each show a high voltage switch, in which the exhaust gas is guided in the axial direction of the exhaust volume in the insulating gas-filled metal container.

EP 1 605 485 A discloses a high voltage switch in which the exhaust gas exits the exhaust volume into the insulating gas filled metal container at an angle α of about 30 ° with respect to the axis of the axially symmetrical housing.

As another prior art will be WO 01/33594 A1 . WO 00/77809 A1 . FR 2 760 890 . US 4,236,053 . FR 1 391 951 . US 2,636,961 . US 2,533,545 . GB 571,118 GB 642,176 . DE 732,961 . DE 198 32 709 A1 and the German utility model G 93 14779.1 called.

PRESENTATION OF THE INVENTION

The invention, as indicated in the claims, the object is to provide a high voltage switch of the type mentioned, which is characterized by high reliability.

In the high-voltage switch according to the invention, a trained in the manner of a pot exhaust module in a coaxial arrangement is placed over the exhaust unit and releasably connected to the exhaust unit, sitting the bottom of the pot on a the exhaust volume limiting end face of the first hollow body, the wall of the pot is axially aligned and extends across the outlet, and the first hollow body of the housing and the pot define a flow path for the exhaust gases with an electrically shielded, axially aligned discharge opening.

Exhaust gases formed when switching off a high-power short-circuit current through the switching arc thus occur predominantly flowing in the axial direction and guided along the housing of the switching chamber in the container containing fresh insulating gas. The exhaust gases can therefore mix over a long way and a large period of time with the fresh insulating gas. It is thus avoided that comparatively poorly insulating, hot exhaust gases reach the vessel wall directly, in particular in the radial direction. In addition, it is achieved by the electrical shielding of the discharge opening, that at locations where due to the high flow velocity of the exhaust gases, the gas density is relatively small and thus the insulating properties of the gas are low, the effect of prevailing in the container strong electric field is largely eliminated. An exhaust unit which is dimensioned only for a comparatively low arc work of the switch can therefore be subsequently adapted with the aid of the module designed as a pot to a switch dimensioned for a higher arc work. Higher arc work can be caused by higher short-circuit currents or by a longer arc duration up to the current zero crossing, as they occur with a frequency change of, for example, 60 Hz to 50 Hz or even 16 2/3 Hz.

Since the pot can be easily manufactured and assembled, and since the existing exhaust unit is reusable, the adjustment of the exhaust to a higher arc work is done quickly and with little effort. Otherwise provided expensive special solutions can therefore be omitted.

Since the outflow opening is formed as an annular gap, in addition to the emission of the exhaust gases in the axial direction at the same time a uniform distribution of the exhaust gases is achieved in the container. Because of the predetermined by the annular gap cylinder symmetry provided for electrical shielding of the annular gap means can be produced with little effort and with good shielding effect.

An annular end portion of the pot wall, which delimits the annular gap to the outside, advantageously tapers towards the edge of the pot and then has an outer surface which, without forming edges, merges into the inner surface of the end section. A strong electric field thus acts only in the dielectrically uncritical region between the container wall and a portion of the pot wall remote from the mouth of the annular gap. Since there is fresh insulating gas in this area, this strong electric field is not critical. Starting from this area, the electric field strength on the way to the pot edge is considerably reduced because of the tapered end section of the pot wall. The reduced there by admixing comparatively small amounts of exhaust gases dielectric strength of the insulating gas is therefore also sufficiently large in this area. Because of the edged held surfaces of the annular gap in the region of its mouth in the Metal containers are there undesirably high local electric field strengths avoided and achieved a good dielectric strength despite the presence of hot exhaust gases of low density.

The limited by the housing and the pot flow path may contain an additional volume. The exhaust volume of the inventive switching chamber then has a particularly large volume. For a given outflow of the resulting exhaust gases, the exhaust unit is then relieved pressure and can switch off a switch containing the thus further developed switch even then sure when a very large arc work is implemented in the switching arc.

In a simple and cost-effective manner, the pot can be made by casting, sheet metal or sheet metal welding and releasably connected to the exhaust unit. The maximum arc work which can still be controlled in the case of a switching chamber with a predetermined nominal data during a switch-off process can thus be increased considerably considerably by retrofitting with the pot acting as an exhaust module.

In order to facilitate the assembly of the pot to the exhaust unit of the switching chamber, at least two openings are provided in the bottom of the pot, of which a first of the implementation of a guided along the axis conductor and the second opening of the implementation of means for releasably connecting the pot to the Exhaust unit is used. The thus realized embodiment of the switching chamber can be charged after installation in the metal container because of axially guided and mainly centrally arranged components, such as conductors and connecting means, advantageously with a high electric field. The releasable connection can be formed by screwing, clamping or pressing.

BRIEF DESCRIPTION OF THE FIGURES

With reference to drawings, an embodiment of the invention will be explained in more detail below. Here, the single figure shows a plan view of a guided along an axis section through a portion of a gas-insulated high-voltage switch with a switching chamber according to the invention.

WAYS FOR CARRYING OUT THE INVENTION

The switch pole shown in the single figure includes one with an insulating gas, such as sulfur hexafluoride, nitrogen, oxygen or carbon dioxide, or mixtures of these gases, such as air, with a pressure of up to several

Bar filled and largely tubular shaped metal container 1, in which a switching chamber 2 is arranged. The switching chamber is held electrically isolated in the metal container 1 by means of a not visible from the figure support insulator. The switching chamber 2 includes a housing 3 which is substantially symmetrical with respect to an axis A, and inside the housing holds an arcing contact assembly 4 with two relatively movable arcing contacts 5, 6. In general, the switching chamber housing also accommodates a rated current contact arrangement provided for guiding the continuous current and connected in parallel with the arcing contacts 5, 6, but this is not shown for reasons of clarity. The switching chamber housing is formed by an insulating tube 7 and two at the ends gas-tight fastened metal hollow bodies, of which only the upper end of the housing 3 forming the first hollow body 8 is shown. The second hollow body, not shown, forms the lower end of the housing 1 and is mounted on the also not apparent support insulator.

The two hollow bodies are generally made of cast metal, for example based on steel or aluminum, and are used to hold hot exhaust gases 24 which are formed in a switching operation in the contact assembly 4 and the leadership of the switch current and the shielding of parts of the switching chamber 2, in the operation of the switch, ie when subjected to high voltages of up to 100 kV and carrying 50 and more kA short-circuit currents, are exposed to strong electric fields. The hollow body 8 is part of an exhaust unit 9. This exhaust unit has an exhaust volume 10 delimited by the hollow body 8, a gas mixing device 11 arranged in the exhaust volume and an outlet 12 realized through openings in the hollow body 8 through which the exhaust gases 24 are expelled radially outward from the exhaust volume 10 can be dissipated. The switch current is fed from above through a current-conducting bolt 13, which is electrically connected in a cup-shaped sleeve 14. The bottom of the cup resp. the sleeve 14 carries the gas mixing device 11. The edge of the cup is guided radially outward and fixed by means of screw 15 to a border which limits an axially aligned opening of the hollow body 8, through which the pin 13 is guided to the outside.

On the exhaust unit 9, a trained in the manner of a pot 16 exhaust module is placed in a coaxial arrangement. The bottom of the pot 16 is seated on an upwardly facing end face of the hollow body 8 and has an axially aligned opening 17, through which the bolt 13 is guided. In the bottom not designated further openings are provided through which screws of the screw 15 are guided. The pot is so releasably fixed to the exhaust unit 9. The axially oriented wall 18 of the pot 16 is arranged at a distance from the hollow body 8 and extends over the outlet 12 away down. It is so formed by the hollow body 8 and the pot wall 18 additional volume 19 is formed, which via the outlet 12 with the exhaust volume 10 and via a designed as an annular gap 20 discharge opening with the interior of the Metal container 1 communicates.

The annular gap 20 is limited to the outside by an annular end portion 21 of the pot wall 18. The end portion 21 tapers towards the downwardly facing edge of the pot 16 and has an outer surface 22 which merges into the inner surface of the end portion 21 free of edges to form the pot edge. As a result, the annular gap 20 is effectively shielded against a strong electric field, which acts during operation of the switch between the then at ground potential metal container 1 and then lying at high voltage potential switching chamber 2.

An appropriately acting pot can also be arranged on the non-illustrated, the lower end of the switching chamber housing 3 forming hollow body.

When a short-circuit current is switched off, the arcing contact 5 is moved downwards by a drive 23 acting in the direction of the arrow. Between the opening contacts 5, 6 of the arcing contact arrangement 4, a switching arc S fed by the current to be disconnected is drawn. This arc heats surrounding insulating gas and can be extinguished at the zero crossing of the current. Hot gases formed by the switching arc S reach the exhaust unit 9 as exhaust gases 24 and are there precooled at the gas mixing device 11 and subsequently removed via the outlet 12 from the exhaust unit.

The exiting the exhaust unit 9 in the radial direction exhaust gases 24, an axially aligned flow path 25 is imposed by the pot 16. The exhaust gases 24 then pass predominantly in the axial direction flowing over the annular gap 20 in the fresh insulating gas containing metal container 1. The emerging from the annular gap 20 exhaust gases 24 have despite the pre-cooling in the exhaust unit 9 relatively high temperature and relatively low pressure and thus one for the Insulation strength unfavorably low gas density. However, since the annular gap 20 opens into an electrically well-shielded area in the interior of the metal container 1, and since the exhaust gases 24 also leaving the annular gap 20 flowing in the axial direction and kept along the switching chamber housing 3 maintain a large distance to the wall of the metal container 1, can the initially unfavorable insulating properties of the exiting exhaust gases 24 reduce the gas insulation between grounded metal container 1 and lying at high voltage potential switching chamber 2 only slightly. At the same time, the exhaust gases 24 can mix over a long way and a long time with the fresh insulating gas.

By trained as a pot 16 and suitably arranged on the exhaust unit 9 exhaust module is therefore avoided that comparatively poorly insulating, hot exhaust gases 24 directly, especially in the radial direction, reach the grounded wall of the metal container 1, and that by shielding the annular gap as the 20th formed outflow opening at points where due to the high flow velocity of the exhaust gases, the gas density is relatively small and thus the insulating properties of the gas are rather low, the effect of prevailing in the metal container 1 strong electric field is suppressed. Therefore, an exhaust unit dimensioned only for a comparatively low arc work of the switch can be subsequently adapted to a switch dimensioned for a higher arc work. Such higher arc work can be caused by higher short-circuit currents and / or by a longer arc length to zero current, as they occur at a frequency change of, for example 60 Hz to 50 Hz or even 16 2/3 Hz.

The fact that the annular gap 20 outwardly bounding annular end portion 21 of the pot wall 18 tapers towards the edge of the pot 16, the outer surface 22 of the end portion to form the pot edge edges and with a relatively large distance from the metal container 1 in the inner surface of the end portion 21 pass over. The electric field thus acts only in a dielectrically uncritical region between the metal container 1 and a region 26 of the end section 21 displaced downstream from the mouth of the annular gap 20. Starting from this region, the electric field strength reduces on the way to the pot edge because of the tapered end section 21 considerably. Since only comparatively small amounts of exhaust gases 24 are added to the wall region 26, the dielectric strength of the insulating gas is only marginally reduced there. Because of the edge-free held surfaces of the annular gap 20 in the region of its mouth in the metal container 1 undesirably high local electric field strengths are avoided at this point and a good dielectric strength despite the presence of hot exhaust gases 24 low gas density.

The additional volume 19 increases the volume of the exhaust volume 10 and thus reduces the high pressure caused by the large arc work high pressure of the exhaust gases in the exhaust unit. 9

LIST OF REFERENCE NUMBERS

1

metal containers

2

switching chamber

3

Switching chamber housing

4

Arcing contact arrangement

5, 6

Arcing contacts

7

Isollerrohr

8th

hollow body

9

exhaust unit

10

exhaust volume

11

Gas mixing device

12

outlet

13

Electricity conductor, bolts

14

shell

15

screw

16

pot

17

opening

18

pot wall

19

additional volume

20

annular gap

21

end

22

outer surface

23

drive

24

exhaust gases

25

flow

26

wall area

A

axis

S

Switching arc

Claims (7)

1. High-voltage switch having a switching chamber (2), which is arranged in an insulating-gas-filled, tubular metal container (1), having
   an axially symmetrical housing (3) which is aligned along an axis (A) and which is formed by an insulating tube (7) and two metallic hollow bodies (8) which are attached to the ends of the said insulating tube in a gas-tight manner,
   an arc contact arrangement (4) which is held in the housing, and
   an exhaust unit (9) which is integrated in the housing and has an exhaust volume (10), which is bounded by the housing (3), and an outlet (12), which passes through the housing, for exhaust gases (24),
   wherein the outlet (12) carries away the exhaust gases (24) from the exhaust volume (10) in a radially outward direction, and
   wherein a first (8) of the two hollow bodies is part of the exhaust unit (9), bounds the exhaust volume (10) and creates the outlet (12) through openings in the hollow body,
   characterized
   in that an exhaust module which is in the form of a pot (16) is placed in a coaxial arrangement over the exhaust unit (9) and is detachably connected to the exhaust unit (9),
   in that the bottom of the pot (16) sits on an end face of the first hollow body (8), which end face bounds the exhaust volume (10),
   in that the wall (18) of the pot (16) is axially aligned and is arranged at a distance from the hollow body and extends beyond the outlet (12),
   in that the first hollow body (8) of the housing (3) and the pot (16) bound a flow path (25) for the exhaust gases (24), with an electrically screened, axially aligned outlet opening, and
   in that the outlet opening is in the form of an annular gap (20).
2. Switching chamber according to Claim 1, characterized in that an annular end section (21), which bounds the annular gap (20) on the outside, of the pot wall (18) tapers towards the edge of the pot (16) and has an outer surface (22) which merges without any edges into the inner surface of the end section (21), forming the pot edge.
3. Switching chamber according to one of Claims 1 to 2, characterized in that the flow path (25) contains an additional volume (19).
4. Switching chamber according to one of Claims 1 to 3, characterized in that the pot (16) is produced by casting, sheet-metal forming or sheet-metal welding.
5. Switching chamber according to Claim 1, characterized in that a first opening (17) is provided in the bottom of the pot (16) and is used for an electrical conductor (13), which is routed along the axis (A), to pass through.
6. Switching chamber according to Claim 5, characterized in that at least one second opening is provided in the bottom of the pot (16) and is used to enable a means for detachable connection of the pot (16) to the exhaust unit (9) to pass through.
7. Switching chamber according to Claim 6, characterized in that the detachable connection is formed by screw connection, adhesive bonding or pressing.

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