KR101720633B1 - Gas circuit breaker - Google Patents

Abstract

SUMMARY OF THE INVENTION It is an object of the present invention to provide a gas circuit breaker capable of reducing the height dimension and effectively reducing the leakage of insulated gas in the shut-off tanks.
The present invention relates to an electric motor comprising a blocking tank (7) filled with an insulating gas and containing a fixed contactor (11) and a movable contactor (12) And a link mechanism part (8) for connecting the operation device (9) and the movable contactor (12) to each other, wherein the shutoff part tank (7), the link mechanism part (8) A gas seal chamber 18 communicating with the shut-off tanks 7 is formed between the shut-off tanks 7 and the actuator 9, and the gas- (21A, 21B) is formed at a portion of the gas seal chamber (18) through which the rotary shaft (20) passes, through the rotation shaft (20) passing through the rotary shaft (18) .

Description

Gas breaker {GAS CIRCUIT BREAKER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas circuit breaker used in a gas insulated switchgear. More particularly, the present invention relates to a gas circuit breaker in which a spring is used as a driving source of a movable contactor,

In a gas circuit breaker installed in a substation or a switchgear, a gas circuit breaker using a spring for a drive source of the movable contact is disclosed in, for example, Patent Document 1. The gas circuit breaker is connected to the actuator through a link mechanism using a spring as a drive source.

In the gas circuit breaker disclosed in Patent Document 1, a shut-off tanks in which insulating gas is enclosed are arranged in a horizontal direction, an operation box is provided below the shut-off tanks, and a drive source Are housed.

[Patent Document 1]

Japanese Patent Application Laid-Open No. 2007-87836

When the gas circuit breaker shown in Patent Document 1 is applied to the gas insulated switchgear, the total height of the gas circuit breaker can not be reduced because the operation device is disposed under the breaker tanks, and the factors that hinder miniaturization of the gas insulated switchgear Respectively.

As another problem, although the gas seal of the connection portion between the blocking portion provided in the blocking portion tank filled with the insulating gas at the predetermined pressure and the link mechanism outside the blocking portion tank is not described at all in Patent Document 1, An insulating rod connected to the movable contactor of the blocking portion is connected to the link mechanism and a gas seal is provided at a portion of the insulating rod penetrating the blocking portion tank in the moving direction of the movable contact. However, since the insulating rod is slid along the longitudinal direction with respect to the gas-tight penetrated portion of the shut-off tanks, the sliding range of the insulating rod with respect to the gas seal is widened to lower the sealing effect, and the insulating gas in the shut- There was concern.

SUMMARY OF THE INVENTION An object of the present invention is to provide a gas circuit breaker capable of reducing the height dimension and effectively reducing the leakage of the insulated gas in the shut-off tanks.

In order to achieve the above-described object, the present invention provides a shielding apparatus comprising: a shielding tank enclosing an insulating gas and including a shielding portion having a fixed contact and a movable contact; a spring for contacting and opening the movable contact with respect to the fixed contact, A gas circuit breaker comprising a manipulator as a driving source and a link mechanism portion connecting the manipulator and the movable contactor of the blocking portion, wherein the blocking portion tank, the link mechanism portion, and the manipulator are disposed adjacent to each other in the transverse direction, A gas seal chamber communicating with the shut-off portion tank is formed between the operation unit and the link mechanism portion through a rotation shaft passing through the gas seal chamber, and a gas seal means is provided at a portion of the gas seal chamber, .

According to the present invention, the height of the breaker can be reduced by providing the shut-off portion tank, the link mechanism portion and the actuator adjacent to each other in the transverse direction. As a result, the overall height of the gas- In addition, by providing the gas sealing means at the portion through which the rotating shaft of the gas sealing chamber penetrates, the rotating shaft can be gas sealed at the same position. As a result, the sliding range with respect to the gas sealing means is narrowed, It is possible to prevent leakage of the insulating gas in the shut-off tanks.

1 is a perspective view showing a first embodiment of a gas circuit breaker according to the present invention,
Fig. 2 is a partial longitudinal side view along the line AA in Fig. 1 illustrating the closing state of the gas circuit breaker, Fig.
Fig. 3 is a partial longitudinal side view along the line BB in Fig. 1 illustrating the closing state of the gas circuit breaker, Fig.
4 is an enlarged longitudinal sectional view along the CC line of the gas circuit breaker,
Fig. 5 is a view similar to Fig. 2 for explaining the cut-off state of the gas circuit breaker,
Fig. 6 is a view similar to Fig. 2 for explaining a closing state of the gas circuit breaker,
7 is an overall side view of a gas insulated switchgear to which a gas circuit breaker according to the present invention is applied.
Fig. 8 is a view similar to Fig. 2 showing the second embodiment of the gas circuit breaker according to the present invention,
Fig. 9 is a view corresponding to Fig. 8 illustrating the cut-off state of the gas circuit breaker shown in Fig. 8;

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a gas circuit breaker used in a gas insulated switchgear according to the present invention will be described with reference to Figs. 1 to 7. Fig.

7, the gas insulated switchgear 1 includes a horizontally arranged gas circuit breaker 2, current transformer units 3A and 3B provided in the upper and lateral directions of the gas circuit breaker 2, A breaker unit 4 provided adjacent to the installed current transformer unit 3B, a cable head 5 connected to the disconnector unit 4 and main bus vessels 6A, 6B connected to the current transformer unit 3A provided above, 6B). The gas-insulated switchgear 1 is arranged so that these constituent devices cross the plane in order to make the height dimension as low as possible.

The gas circuit breaker 2 applied to the gas insulated switchgear 1 configured as described above has a shut-off part tank 7, a link mechanism part 8 and an operation device 9, And is supported by a mount 10.

Next, details of the gas circuit breaker 2 will be described with reference to Figs. 2 to 4. Fig.

Insulating gas, for example, sulfur hexafluoride gas, is sealed in the shutoff tanks 7 at a specified pressure. Voltage power source in the substation via a bushing or a conductor not shown in the drawing, and is energized to a cut-off portion composed of the fixed contactor 11 and the movable contactor 12. [ 2 shows a state in which the movable contact is in contact with the fixed contact 11, in other words, the contact of the cut-off portion is put in.

In this state, when an unusual current flows through the system due to a lightning stroke or the like, a cutoff command is inputted to the gas circuit breaker 2, and the movable contactor 12 is removed from the fixed contactor 11 to cut off the current. The movable contact 12 is connected to the insulating rod 13 at the opposite end to the side in contact with the fixed contact 11.

The link mechanism portion 8 is provided on the extended end side of the insulating rod 13 and adjacent to the blocking portion tank 7 on the semi-fixed contact side of the movable contact 12. 4, a pair of partition walls 14A and 14B, an upper plate 15 and a lower plate 16, and a gas sealing chamber 18 surrounded by the end plate 17 are formed in the link mechanism portion 8 The gas sealing chamber 18 communicates with the shut-off tank 7 and is filled with an insulating gas at a prescribed pressure. The gas seal chamber 18 is provided with a first rotation shaft 20 which is configured to rotate through bearings 19A and 19B through the partition walls 14A and 14B. In the partition wall penetrating portion of the first rotary shaft 20, the gas sealing member is provided in the gas seal chamber more than the bearings 19A and 19B, for example, both the partition walls 14A and 14B and the first rotary shaft 20 O-rings 21A and 21B are provided so as to contact with each other.

A first lever 22 having one end fixed to the first rotating shaft 20 and the other end connected to an end of the insulating rod 13 is disposed in the gas sealing chamber 18. One end of the first lever 20 is fixed to the second lever 23 and the other end of the third lever 24 is fixed to one side of the first rotary shaft 20 penetrating the partition walls 14A and 14B outwardly . One end of the link 25 is rotatably connected to the other end of the third lever 24 and the other end of the link 25 is connected to the piston rod 27 of the shock absorber 26. The piston (28) at the tip of the piston rod (27) is configured to slide on the cylinder (29). An incompressible fluid, for example oil, is enclosed in the cylinder 29 of the shock absorber 26.

2, one end of the output link 30 is connected to the other end of the second lever 23, and the other end of the output link 30 is connected to one end of the fifth lever 31 of the actuator 9 It is connected to the end.

Next, the configuration of the operation device 9 will be described. The manipulator 9 is fixed to the end plate 17 of the link mechanism part 8 by a fixing plate 32. A cylindrical blocking spring case 34 and a cylindrical closing spring case 35 are fixed to the box body 33 supported by the fixing plate 32 in a longitudinal direction of the blocking tank 7, The movable contacts 12 are disposed adjacent to each other in the direction along the operating direction of the movable contact 12 so that the operating directions of the springs are the same. 2, the blocking spring 36 and the closing spring 37 housed in the blocking spring case 34 and the closing spring case 35, respectively, are in a compressed state.

One end of the blocking spring 36 is supported by the box body 33 and the other end is supported by a spring bearing 38. [ One end of the interrupting spring link 39 is connected to the spring bearing 38. [ The other end of the blocking spring link 39 is connected to one end of the fourth lever 40. The intermediate portion of the fourth lever 40 is fixed to the second rotary shaft 41 which is supported by the box body 33 and one end of the fifth lever 31 is fixed on the same axis. The other end of the output link 30 is connected to the other end of the fifth lever 31.

One end of the closing spring 37 is supported by the box body 33 and the other end is supported by a spring bearing 42. [ One end of the closing spring link (43) is connected to the spring bearing (42). The other end of the closing spring link 43 is connected with a closing cam 45 fixed to the third rotating shaft 44 which is supported by the box body 33.

Although not shown in the drawing, the actuator 9 is equipped with gear trains, an electric motor, an auxiliary switch, and an on / off indicator of a contact of a breaker, in order to compress the closing spring 37 after being released.

Next, the operation of the gas circuit breaker 2 will be described with reference to Figs. 2 to 6. Fig.

First, an operation of shifting the closing portion contact point from the closing state shown in Fig. 2 to the blocking state will be described. In Fig. 2, when the cutoff command is inputted to the gas circuit breaker 2, the gas circuit breaker 2 starts the cutoff operation. That is, the control mechanism, not shown, is operated to release the restriction of the blocking spring 36 in the compressed state, and the blocking spring 36 is fired. The fourth lever 40 is rotated in the counterclockwise direction via the interrupting spring link 39 by the discharge of the interrupting spring 36. [ Then, the fifth lever 31 is rotated in the counterclockwise direction via the second rotation shaft 41. Thereby, the output link 30 moves in the horizontal right direction. Then, the second lever 23 of the link mechanism portion 8 rotates counterclockwise. Thereby, the first rotary shaft 20 also rotates counterclockwise, and the first lever 22 fixed to the first rotary shaft 20 also rotates counterclockwise. Similarly, the third lever 24 fitted to the rotary shaft 20 also rotates in the same direction. In Fig. 3, the third lever 24 is rotated in the clockwise direction because the viewpoint is opposite to that in Fig. The third lever 24 moves the link 25 downward and accordingly the piston rod 27 also moves downward. Thereby, the piston 28 compresses the oil in the cylinder 29 to generate a buffering force.

On the other hand, in accordance with the rotation of the first lever 22, the insulating rod 13 is driven in the left direction in FIG. 2 (right direction in FIG. 3), and the movable contactor 12 And is then released from the fixed contact 11.

As shown in Fig. 5, the other end of the fourth lever 40 abuts against the outer peripheral surface of the closing cam 45 and stops .

Subsequently, the operation for shifting from the cutoff state of the breaker contact shown in Fig. 5 to the put-in state shown in Fig. 6 will be described below.

5, when a closing command is inputted to the gas circuit breaker 2, a control mechanism (not shown) operates to release the restriction of the closing spring 37 in the compressed state, . Thereby, the closing cam 45 and the third rotating shaft 44 are rotated in the counterclockwise direction via the closing spring link 43. With the rotation of the cam 45, the outer circumferential surface of the cam 45 presses the fourth lever 40 to rotate the fourth lever 40 clockwise. Whereby the blocking spring 36 is compressed via the blocking spring link 39 and the blocking spring receiver 38. [

At the same time, the output link 30 is moved in the horizontal left direction in Fig. 5 via the fifth lever 31 in accordance with the rotation of the fourth lever 40. [ Thereby, the second lever 23 and the first rotary shaft 20 of the link mechanism portion 8 rotate in the clockwise direction. The first lever 22 is rotated in the clockwise direction in accordance with the rotation of the first rotating shaft 20 to move the insulating rod 13 in the right direction. As a result, the movable contact 12 connected to the insulating operation rod 13 moves in the horizontal right direction and contacts the stationary contactor 11, and the breaker contact is inserted. When all the closing springs 37 are exhausted, the closing operation shown in Fig. 6 is completed.

Thereafter, an electric motor (not shown) and an input spring 37 that has been filled with the gear train are compressed to return to the closing state of the breaking contact shown in Fig. 2, and the closing spring 37 and the breaking spring 36 are compressed State.

However, the buffering force is generated by the shock absorber 26 provided adjacent to the link mechanism part 8 in the closing operation. The piston 28 of the shock absorber 26 is connected to the cylinder 29 via the link 25 and the piston rod 27. As a result, And receives the resistance of the oil to generate a buffering force.

According to the present embodiment, the actuator 9 using a spring is placed adjacent to the link mechanism 8 in the lateral direction of the drive source, and the link mechanism 8 is moved in the lateral direction of the shut- The operation unit 9 is disposed in the blocking tank (not shown), and the operation unit 9 is disposed in the blocking tank (not shown) The height of the mount 10 can be reduced as compared with the conventional gas circuit breaker arranged below the gas shutters 7, 7. As a result, since the total height of the gas circuit breaker 2 can be reduced, the gas insulated switchgear 1 to which the gas circuit breaker 2 is applied can be downsized.

Since the shock absorber 26 is provided adjacent to the lower portion of the link mechanism 8 located between the operation unit 9 and the shutoff unit tank 7, the movable contactor 12 and the shock absorber 26 As a result, the braking efficiency of the movable contactor 12 is improved, and the reliability of the gas circuit breaker 2 can be improved.

The output link 30 connecting the manipulator 9 and the link mechanism 8 and the third lever 24 connecting to the shock absorber 26 are connected to the link 25 via a box- And the outside of the partition walls 14A and 14B of the link mechanism portion 8 and the link mechanism portion 8 so that the maintenance and repair work can be carried out directly by the naked eye of these members, The reliability of the inspection can be improved. When the actuator 9 is detached from the gas circuit breaker 2 at the time of maintenance and inspection, the connection between the output link 30 and the fifth lever 31 is released and the link mechanism portion It is only necessary to release the fastening between the end plate 17 of the operating unit 9 and the fixing plate 32 of the operating unit 9, so that the maintenance and repair work can be performed easily.

In addition to the above, in the above-described embodiment, the following effects can be obtained by using the first rotating shaft 20 as the movable member passing through the gas seal chamber 18. That is, since the first rotary shaft 20 passes through the partition walls 14A and 14B of the gas seal chamber 18 and is supported by the bearings 19A and 19B at the penetrating portion thereof, And does not move along the axial direction to the inside or outside of the rotor 14A or 14B but rotates at the same position. As a result, there is no inclination during rotation of the partition walls 14A and 14B passing through the longitudinal direction of the first rotary shaft 20, so that the first rotary shaft 20 and the partition walls 14B and 14B of the gas sealing chamber 18 by inserting O-rings 21A and 21B in contact with both of the partition walls 14A and 14B Leakage from the space between the first rotating shafts 20 can be easily prevented. As a result, deterioration of the shutoff performance of the gas circuit breaker 2 can be prevented.

In addition, by forming the second lever 23 shorter than the first lever 22, the displacement distance of the output link 30 can be made smaller than the displacement distance of the insulating rod 13, The lateral dimension of the link mechanism 8 and the manipulator 9 can be reduced.

In the above embodiment, the output link 30 connected to the second lever 23 is disposed outside the partition 14B, but may be disposed outside the partition 14A.

Next, a second embodiment of the gas circuit breaker according to the present invention will be described with reference to Figs. 8 and 9. Fig. The same reference numerals as in Figs. 1 to 7 denote the same components, and a detailed description thereof will be omitted.

8 shows that the blocking portion contact is in the closing state and both the blocking spring 36 and the closing spring 37 are in a compressed state, and Fig. 9 shows a state in which the blocking operation is completed.

The link mechanism portion 8 and the operation device 9 are arranged adjacent to each other and the number of these constituent members is the same as that of the gas circuit breaker 2 in the first embodiment. In the second embodiment, a structure different from that of the first embodiment is an installation position of the shut-off spring 36 of the operation device 9. [ That is, although the closing spring 37 is provided so as to extend upward from the box body 33 of the manipulating device 9 so that the operating direction of the spring is the up and down direction, as in the first embodiment, And is disposed so as to face the side of the blocking portion tank 7 from the lower side of the mechanism portion 8 so that the operation direction is a transverse direction orthogonal to the operation direction of the closing spring 37. [ In addition, the closing spring case 35 is disposed so as to come into contact with or close to the fixing plate 32 of the manipulating device 9. In addition, the closing spring case 35 may be provided at the lower portion of the shutoff unit tank 7 in relation to the surrounding installation equipment.

According to the second embodiment, by using the lower space of the link mechanism portion 8 or the lower space of the blocking portion tank 7, as shown in Figs. 8 and 9, the size indicated by the two-dot chain line in the first embodiment It is possible to reduce the height dimension of the gas circuit breaker 2 as well as the dimension in the longitudinal direction.

The distance from the mount 10 to the interrupting spring 36 and the closing spring 37 of the drive source or in other words the length of the output link 30 is set to be at least equal to the distance between the interrupting spring case 34 It is possible to reduce the operating vibration of the gas circuit breaker 2 by the closing spring 36 and the closing spring 37. [

In addition, since the drive link 30 can be shortened, the drive efficiency of the movable contact 12 can be improved. Therefore, miniaturization of the gas insulated switchgear having the gas circuit breaker 2 and the gas circuit breaker 2 can be achieved It becomes possible more.

In the present embodiment, the height of the base 10 of the blocking portion tank 7 is the same as that of the first embodiment, provided that the outer diameter of the blocking spring case 34 is within the protruding dimension toward the lower side of the shock absorber 26 Do. However, when the outer diameter of the blocking spring case 34 exceeds the protruding dimension of the shock absorber 26 downward, it is necessary to increase the height of the base 10 so as to slightly exceed the outer diameter of the blocking spring case 34 Therefore, the height of the base 10 of the gas circuit breaker 2 is not excessively increased as compared with the first embodiment.

1: gas insulated switchgear 2: gas circuit breaker
7: shutoff part tank 8: link mechanism part
9: Actuator 10:
11: stationary contactor 12: movable contactor
13: Insulating rods 14A, 14B:
15: top plate 16: bottom plate
17: end plate 18: gas seal chamber
19A, 19B: a bearing 20: a first rotating shaft
21A, 21B: O-ring

Claims (15)

An operation device including a shut-off part tank in which an insulating gas is enclosed and a shut-off part having a fixed contact and a movable contact is built in, a drive spring as a drive source and a closing spring for contacting and opening the movable contact with the fixed contact, A gas circuit breaker comprising a link mechanism portion for connecting a movable contact of a blocking portion,
Wherein the shut-off portion tank, the link mechanism portion, and the manipulator are disposed adjacent to each other in the transverse direction, and a gas seal chamber communicating with the shut-off portion tank is formed between the shut-off portion tank and the operation device, And a gas sealing means is provided at a portion of the gas seal chamber through which the rotation shaft passes. Further, the rotation shaft extends through the partition wall constituting the gas seal chamber and extends outside the gas seal chamber And a second lever for connecting with the actuator is fixed to one side of the portion of the rotary shaft extending outside the gas seal chamber, and a second lever is connected to the other side of the rotary shaft extending outside the gas seal chamber, And a third lever for fixing the third lever. An operation device including a shut-off part tank in which an insulating gas is enclosed and a shut-off part having a fixed contact and a movable contact is built in, a drive spring as a drive source and a closing spring for contacting and opening the movable contact with the fixed contact, A gas circuit breaker comprising a link mechanism portion for connecting a movable contact of a blocking portion,
The link mechanism portion is provided adjacent to the blocking portion tank in the transverse direction and an actuator is provided adjacent to the link mechanism portion in the transverse direction and a gas seal chamber communicating with the blocking portion tank is formed in the link mechanism portion , The link mechanism portion is constituted through a rotation shaft passing through the gas seal chamber and a gas sealing means is provided at a portion of the gas seal chamber through which the rotation shaft passes, And a second lever for connecting with the actuator is fixed to one side of a portion of the rotary shaft extending outside the gas seal chamber through a partition wall of the constituent part and extending out of the gas seal chamber, And a third lever for connecting to the shock absorber is fixed to the other side of the gas block . 3. The method according to claim 1 or 2,
Wherein the blocking portion tank, the link mechanism portion, and the manipulator are arranged along a straight line in the transverse direction. 3. The method according to claim 1 or 2,
Wherein the blocking portion tank, the link mechanism portion, and the manipulator are arranged along the advancing / retreating direction of the movable contact. 3. The method according to claim 1 or 2,
Wherein the rotary shaft fixes a first lever for driving the movable contactor from the inside of the gas seal chamber. 3. The method according to claim 1 or 2,
Wherein the rotary shaft is configured to rotate through a bearing on a partition wall constituting the gas seal chamber and the gas seal means is provided so as to be in contact with both the partition wall and the rotary shaft inside the gas seal chamber more than the bearing Gas breaker. 3. The method according to claim 1 or 2,
The manipulator includes a fourth lever for transmitting a driving force of the blocking spring, a second rotation shaft for fixing the fourth lever, and a fifth lever fixed on the second rotation shaft, And the second lever is connected to the second lever. 8. The method of claim 7,
And the fifth lever is disposed outside the box body of the manipulating device. 3. The method according to claim 1 or 2,
Wherein the operating direction of the closing spring and the closing spring are all in the same direction. 3. The method according to claim 1 or 2,
And the operating direction of the closing spring and the closing spring are orthogonal to each other. 11. The method of claim 10,
Wherein either one of the blocking spring and the closing spring is provided below the link mechanism portion. An operation device including a shut-off part tank in which an insulating gas is enclosed and a shut-off part having a fixed contact and a movable contact is built in, a drive spring as a drive source and a closing spring for contacting and opening the movable contact with the fixed contact, A gas circuit breaker comprising a link mechanism portion for connecting a movable contact of a blocking portion,
Wherein the link mechanism portion is provided adjacent to the semi-fixed contact side of the movable contactor of the blocking portion tank in the transverse direction and adjacent to the link mechanism portion so as to be adjacent to the operation portion, A gas seal chamber communicating with the sub tank is formed and the link mechanism portion is formed through a rotation shaft passing through the gas seal chamber and gas sealing means is provided at a portion of the gas seal chamber through which the rotation shaft passes, The rotary shaft extends through the partition wall constituting the gas seal chamber and extends out of the gas seal chamber. A second lever for connecting to the actuator is fixed to one side of the portion of the rotary shaft extending outside the gas seal chamber And a third lever for connecting to the shock absorber is provided on the other side of the portion of the rotary shaft extending outside the gas seal chamber And, furthermore, a gas circuit breaker, characterized in that a breaking spring of the actuator in the lower part of the gas sealing chamber bottom or the cutoff unit tank of the link mechanism is operational direction so that the direction of motion in the same direction of the movable contact. An actuator having a driving source for contacting and raising the movable contact with respect to the stationary contactor and a movable contactor of the actuator and the movable contactor, And a shock absorber which is provided adjacent to the link mechanism and buffers the operation of the movable contactor via the link mechanism,
Wherein the actuator comprises a closing spring case housing a closing spring for closing the movable contact and a fixed contact and a blocking spring case for receiving a blocking spring for blocking the movable contact and the fixed contact,
A gas seal chamber communicating with the shut-off portion tank is formed between the shut-off portion tank and the operation unit, and the gas shut- And the link mechanism portion includes a rotation shaft passing through the gas seal chamber, a first lever fixed to the rotation shaft, and a second lever fixed to the first lever and having one end connected to the first lever and the other end connected to the movable contactor A second lever fixed to the rotating shaft, and an output link having one end connected to the second lever and the other end connected to the manipulator, wherein the first lever is connected to the second lever Wherein the first lever and the insulating rod are connected in the gas seal chamber and the second lever is connected to the output link Wherein the shock absorber is connected to the rotary shaft outside the gas seal chamber, and gas sealing means is provided at a portion of the gas seal chamber through which the rotary shaft penetrates. A breaker unit disposed horizontally, a disconnector unit provided adjacent to the transverse unit installed in the transverse direction, a cable head connected to the disconnector unit, A gas insulated switchgear comprising a main bus vessel connected to a current transformer unit,
Wherein the gas circuit breaker is the gas circuit breaker according to claim 1 or 2.
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