EP1780741A1 - 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 0 163 943 B1 , in particular embodiment according to FIG. 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. In order to improve the quality of the extinguishing gas, a protruding into the heating volume 5, tubular mouth part 9 and a molded into the inside of the mouth part 9 bottleneck 10 are provided at the mouth of the annular channel 6. 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 wrote "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 thorough mixing of a torus-shaped heating volume of a switching chamber, which gas flows axially with hot gas and contains cold gas is 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, an axially guided mouth portion at the transition from the heating channel to the heating volume outside of a trained as a ring, sharp edge is limited. This edge acts as a trailing edge of a flow body. Therefore, even at a relatively weak, ie generated by a low-power arc, hot gas flow, a demolition of the hot gas flow at the edge and thus the formation of vortices downstream of the edge favors. Inflowing hot gas and at least part of already existing cold gas are so effectively premixed in the heating volume. Optionally still existing unmixed cold gas remains in one, radially outward adjoining the sharp edge, the input of the heating volume and can approach be thoroughly mixed with the pre-mixed gas at the zero crossing of the current to be switched off after the flow reversal at the sharp edge. The sharpness is to be dimensioned so that when switching off medium short-circuit currents with a size between about 10% and about 30% of the nominal short-circuit breaking current of the high-voltage switch gas vortices are released from the hot gas flow. The radius of curvature of the edge is then generally less than 1 mm, preferably less than 0.1 mm.

In one embodiment of the switching chamber with a heating medium having a large length in the axial direction, the mouth section is bounded to the outside by a tube projecting into the heating volume. Through the pipe, the junction of the heating channel is moved into the heating volume in the axial direction. The free end of the tube therefore divides the heating volume in two successive partial volumes in the axial direction. Since in general only in one of these two volumes the hot gas is mixed with cold gas, this mixture 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 ersten Ausführungsform einer Schaltkammer nach der Erfindung,

Fig.2

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

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,
2. (b) bei einer 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 (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 zweiten 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 portion of a first embodiment of a switching chamber according to the invention,

Fig.2

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

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,
2. (b) upon a 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 (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 has the same dimensions as the switching chamber of Figure 1,

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 a second 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 of 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 has the same dimensions as the switching chamber of Figure 4, during the supply of hot gas from the arc chamber when switching off an average short-circuit current over a short arc time (5 bis 15 ms) is effective.

WAYS FOR CARRYING OUT THE INVENTION

The switching chamber of a high-voltage circuit breaker shown in FIG. 1 contains a housing 1 filled with a compressed insulating gas, for example based on sulfur hexafluoride or a sulfur hexafluoride, and largely axially symmetrical in design, and a contact arrangement 2 accommodated by the switching chamber housing 1 and also largely axially symmetrical a switch-off operation illustrated contact arrangement 2 has two switching pieces 3, 4, of which the switching piece 3 is 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 like a type 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, which - as Figure 1 can be removed - in an arc zone 9 burns. 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.

From Fig. 2, the advantageous 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 at a radially oriented rear Boundary wall 14 of the heating volume 7 directed radially outward. 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 now when approaching the current zero crossing, the flow reversal, the results of 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). As can be seen from the flow pattern (c) shown in FIG. 2, the intense hot gas flow H tearing away at the sharply formed edge 12 virtually completely swirls the cold gas C already present in the heating volume 7 and already forms an extinguishing gas of good quality Flow reversal can effectively blow the arc 8.

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 3 course (a) is visible - now also along the front boundary wall 15 into the heating volume 7. The cold gas C is therefore pushed back to the rear boundary wall 14 and - without interfering with the to mix incoming hot gas H - compressed in the rear of the heating 7. As can be seen from the course (b) of FIG. 3, after the flow reversal, only hot gas is present in the inlet region of the heating volume 7. The blowing out of the arc therefore initially takes place with hot extinguishing 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 can be seen from the flow pattern (c) shown in FIG. 3, in this case the cold gas C is pushed back into the rear area of the heating volume 7, so that hot and cold gas are not mixed very well in this case as well, and accordingly the shutdown capacity this switching chamber with respect to the inventive switching chamber of FIG. 1 is lower.

In the embodiment of the switching chamber according to the invention according to FIG. 4, identical parts are provided with the same reference numerals as in the embodiment according to FIG. 1, but the contact arrangement 2 is shown closed, so that the arc and the arc zone are not apparent from this figure. In contrast to the embodiment according to FIG. 1, in this embodiment the mouth section 11 is bounded outwardly 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 flow pattern (a) shown in FIG. 5, these two partial volumes are designated by the reference symbols 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 . For partial volume V ₁ , the ratio of length is I _{1 of} the torus in the axial direction to square root of the cross-sectional area A of the torus perpendicular to the axis 5 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 can be seen from the course of flow of FIG. 6, in contrast, in the case of a switching chamber according to the prior art with a heating volume 7 of great axial length, but without a premold, the hot gas H formed when switching medium or large short-circuit currents urges only the predominant part of the Cold gas C to the rear boundary wall 14 and thus 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 (10)

Switching chamber for a gas-insulated high-voltage switch with two along an axis (5) relative to each other movable switching pieces (3, 4), which limit an arc zone (9) axially in a switching operation, the switching pieces (3, 4) coaxially comprising heating volume (7) and a heating channel (10) which communicates with the arc zone (9) and which extends coaxially with the arc zone (9) and extends parallel to the axis (5) into the heating volume (7) and during a switching operation in the arc zone (9 ) formed hot gas (H) into the heating volume (7), characterized in that the 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. Switching chamber according to Claim 1, characterized in that the sharpness of the edge (12) is sufficient to eliminate gas swirls from the hot gas flow (H) when medium short-circuit currents with a size between approximately 10 and approximately 30% of the nominal short-circuit cut-off current of the high-voltage switch are switched off. to solve. Switching chamber according to one of claims 1 to 2, characterized in that the edge (12) has a radius of curvature smaller than 1 mm. Switching chamber according to one claim 3, characterized in that the radius of curvature is less than 0.1 mm. Switching chamber according to one of claims 1 to 4, characterized in that the mouth portion (11) to the outside of a heating volume (7) projecting tube (16) is limited. Switching chamber according to claim 5, characterized in that the tube (16) projects beyond a predominantly radially guided first wall (15) of the heating volume (7) with a free end, and that the edge (12) formed in the free end of the tube (16) is. Switching chamber according to claim 6, characterized in that the heating volume (7) has two successive partial volumes (V ₁ , V ₂ ) in the axial direction, of which the first (V ₁ ) is formed in the manner of a torus, between a predominantly radially aligned second wall (14) of the heating volume (7) and the free end of the tube (16) and in the circumferential direction has a predominantly rectangular cross-section. Switching chamber according to claim 7, characterized in that 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 first partial volume (V ₁ ) perpendicular to the axis (5) is about 0.5. Switching chamber according to one of claims 7 or 8, characterized in that the second partial volume (V ₂ ) extends between the first wall (15) of the heating volume (7) and the free end of the tube (16) and a smaller volume than the first Volume (V ₂ ) has. High-voltage switch with the switching chamber according to one of claims 1 to 9.

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