Gas-insulated switching device

Abstract

The present invention has such a configuration that: a fixed-side terminal (1) is provided with an electric field relaxing shield (12d) at a portion opposite to a movable-side terminal (2); an electric field relaxing shield unit (12) is capable of moving toward the movable-side terminal (2); and functions are separated such that an energization function is performed by the fixed-side terminal (1) and a function for relaxing an electric field between the terminals is performed by the electric field relaxing shield unit (12). When the fixed-side terminal (1) and the movable-side terminal (2) are relatively close to each other, the electric field of the blocking electrode (8) is relaxed and a restrike due to a recovery voltage rising when a circuit is opened can be restrained. Thus, a speed for driving the blocking electrode (8) can be lowered.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a gas-insulated switchgear.BACKGROUND ART

[0002] A disconnector stored in a gas-insulated switchgear does not have a function of interrupting current in most cases. For example, Patent Document 1 discloses that, in a disconnector in which a fixed-side terminal and a movable-side terminal including a movable electrode rod are arranged opposite to each other, a quick acting mechanism for interrupting current is provided in the fixed-side terminal.

[0003] The quick acting mechanism includes a shaft rod electrically connected to the fixed-side terminal, a blocking electrode disposed at a shaft rod tip for receiving an arc generated when current is interrupted, an engaging unit for engaging the shaft rod with the movable electrode rod, and an opening spring that drives the blocking electrode along with the shaft rod in a direction opposite to the movable electrode rod.

[0004] The quick acting mechanism has such a configuration that: when a circuit between the fixed-side terminal and the movable-side terminal is closed by the movable electrode rod, the movable electrode rod and the shaft rod are engaged; and when the circuit is opened, the shaft rod is pulled by the movable electrode rod to compress the opening spring so as to store a force, the engaging unit is caused to perform separation at a predetermined position, and the opening spring is released to drive the shaft rod, whereby the blocking electrode is separated in a direction opposite to the movable electrode rod to interrupt current.

[0005] Document JP 2010 027479 A, according to its abstract, states that, to provide a switch capable of installing a quick-acting mechanism for current cutoff irrelevantly to an installation space of a movable electrode rod, and capable of stably cutting off current between a fixed side terminal and a movable side terminal, in the switch, when carrying out closing, continuity between the fixed side terminal and the movable side terminal is secured by moving the movable electrode rod housed in the movable side terminal disposed facing the fixed side terminal, and when carrying out opening, the current between the fixed side terminal and the movable electrode rod is cut off by the quick-acting mechanism provided in the fixed side terminal.CITATION LISTPATENT DOCUMENT

[0006] Patent Document 1: Japanese Patent No. 5179278SUMMARY OF THE INVENTIONPROBLEMS TO BE SOLVED BY THE INVENTION

[0007] In Patent Document 1, in a condition in which the circuit between the fixed-side terminal and the movable-side terminal is opened, the circuit is a circuit between disconnecting electrodes, and thus needs to have withstand voltage performance higher than that between earth electrodes and that between phases. Accordingly, the distance between the fixed-side terminal and the movable-side terminal is relatively long.

[0008] In addition, in interruption of current, in order to restrain a restrike of arc due to a recovery voltage generated after current interruption, the withstand voltage performance required for the recovery voltage that rises immediately after the movable electrode rod has been separated from the blocking electrode needs to be ensured.

[0009] As one of measures to ensure the withstand voltage performance, a solution to relax an electric field between terminals by storing the blocking electrode inside the fixed-side terminal is provided. However, as described above, the disconnecting electrodes are separated from each other, and thus the blocking electrode needs to be quickly driven to be stored into the fixed-side terminal in a short time. Particularly, when interruption involving a relatively high recovery voltage is performed as in current interruption during cable charging, the blocking electrode needs to be more quickly driven.

[0010] The present disclosure has been made to solve the above problem, and an object of the present disclosure is to provide a configuration of a gas-insulated switchgear that enables reduction in a speed for driving the blocking electrode compared to that of the conventional configuration even when an interruption involving a recovery voltage is performed.SOLUTION TO THE PROBLEMS

[0011] According to the present disclosure, a gas-insulated switchgear as defined in independent claim 1 is provided. Further embodiments of the claimed invention are defined in the dependent claims. Although the claimed invention is only defined by the claims, the below embodiments, examples, and aspects are present for aiding in understanding the background and advantages of the claimed invention.EFFECT OF THE INVENTION

[0012] In the gas-insulated switchgear according to the present disclosure, the blocking electrode is stored in the electric field relaxing shield. Thus, when the movable-side terminal and the fixed-side terminal are relatively close to each other, an electric field of the blocking electrode is relaxed and a restrike due to a rising recovery voltage can be restrained, thereby enabling reduction in a speed for driving the blocking electrode.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] [FIG. 1] FIG. 1 is a sectional view of a major part of a gas-insulated switchgear according to Embodiment 1, when a disconnector is in an open-circuit condition. [FIG. 2] FIG. 2 is a sectional view of a major part of a blocking electrode mounted to the disconnector of the gas-insulated switchgear according to Embodiment 1. [FIG. 3] FIG. 3 is a sectional view of a major part of an electric field relaxing shield unit mounted to the disconnector of the gas-insulated switchgear according to Embodiment 1. [FIG. 4] FIG. 4 is a sectional view of a major part of the gas-insulated switchgear according to Embodiment 1, when the disconnector is in a closed-circuit condition. [FIG. 5] FIG. 5 is a sectional view of a major part of the gas-insulated switchgear according to Embodiment 1, immediately after an engaged part has been engaged in the middle of switching from the closed-circuit condition of the disconnector to the open-circuit condition thereof. [FIG. 6] FIG. 6 is a sectional view of a major part of the gas-insulated switchgear according to Embodiment 1, immediately before the engaged part of the disconnector is released and separated. [FIG. 7] FIG. 7 is a sectional view of a major part of the gas-insulated switchgear according to Embodiment 1, immediately after the engaged part of the disconnector has been released and separated. [FIG. 8] FIG. 8 is a sectional view of a major part of the gas-insulated switchgear according to Embodiment 1, immediately after the blocking electrode mounted to the disconnector has been stored at an inside of an electric field relaxing shield. [FIG. 9] FIG. 9 is a sectional view of a major part of a shaft rod base end and an electric field relaxing shield base end mounted to a disconnector of a gas-insulated switchgear according to Embodiment 2. DESCRIPTION OF EMBODIMENTS

[0014] Hereinafter, a preferred embodiment of a gas-insulated switchgear according to the present disclosure will be described with reference to the drawings. In the drawings, the same reference characters denote the same or corresponding parts, and detailed description thereof will be omitted. Similarly, also in the subsequent embodiment, redundant description of the components denoted by the same reference characters is omitted.Embodiment 1

[0015] FIG. 1 is a sectional view of a major part of a gas-insulated switchgear according to Embodiment 1, when a disconnector is in an open-circuit condition. A basic function for opening and closing an electrical path is configured by a fixed-side terminal 1, a movable-side terminal 2, and a movable electrode rod 3. These components are arranged inside an airtight container with insulation gas sealed therein. Hereinafter, each component will be described in detail.

[0016] A cylindrical conductor 11 has one end surface mechanically and electrically connected coaxially to one end of a fixed-side terminal 1. In addition, the other end surface is mechanically and electrically connected to a base conductor 5b. As a mechanical connection method, bolt fixing may be performed, and a contact surface may be silver plated to obtain electrical connection. In addition, a base conductor 5a having an outer periphery formed by a curved surface is fixed so as to cover a base conductor 5b.

[0017] A piston 6 is mechanically and electrically connected perpendicularly to the base conductor 5b and coaxially with an opening formed in the fixed-side terminal 1. Thus, needless to say, the piston 6 is fixed and does not move. As a mechanical connection method, bolt fixing may be performed, and a contact surface may be silver plated to obtain electrical connection.

[0018] A cylinder 7 having a cylindrical shape is inserted in the piston 6, and a contact 9 for piston ensures electrical conduction between the cylinder 7 and the piston 6. The cylinder 7 slides along the piston 6, and the details of the operation will be described below.

[0019] A projection 13 is formed or arranged at an outer circumference of an opening end portion of the cylinder 7. The projection 13 has an outer diameter approximately the same as an inner diameter of the cylindrical conductor 11, and thus can move on an inner circumferential surface of the cylindrical conductor 11 in the right and left directions, as the cylinder 7 moves.

[0020] A stopper 14 has an inner diameter smaller than the outer diameter of the projection 13, and is formed at a predetermined position inside the cylinder of the cylindrical conductor 11. This predetermined position is determined according to an elastic force of an opening spring 10 or the like. In addition, the opening spring 10 having a helical shape is arranged along an outer circumference of the cylinder 7. The opening spring 10 has one end fixed to a spring holder disposed at an end portion of the projection 13 and the other end fixed to a spring holder disposed inside the cylinder on the fixed-side terminal 1 side.

[0021] A rod-like blocking electrode 8 mechanically and electrically connected coaxially to the cylinder 7 is connected at a distal end on the fixed-side terminal 1 side of the cylinder 7. FIG. 2 is a sectional view of a major part of the blocking electrode 8. The blocking electrode 8 is composed of a shaft rod base end 8a as a base, a shaft rod 8b extending from the shaft rod base end 8a, a contact-pressure spring 8c arranged around the shaft rod 8b, a male-side engagement part 8d mounted to the shaft rod 8b, and an auxiliary electrode 8e slidable on the shaft rod 8b. The contact-pressure spring 8c is helical, is arranged around the shaft rod 8b coaxially with the male-side engagement part 8d, and has one end fixed to the shaft rod base end 8a and the other end fixed to the auxiliary electrode 8e. On the shaft rod base end 8a, a contact end surface 8f that comes into contact with a contact end surface 12e disposed at an electric field relaxing shield base end 12a described below according to a state of the opening spring 10 described below is formed.

[0022] One end portion of the male-side engagement part 8d is inserted into the shaft rod 8b and mounted thereto. The other end portion thereof is engaged with a female-side engagement part 3a of the movable electrode rod 3 described below when the circuit is closed. In addition, when the contact-pressure spring 8c is in a released state, a distal end of the male-side engagement part 8d is positioned on the inner side from the auxiliary electrode 8e.

[0023] The auxiliary electrode 8e has a ring shape having, at the center, a hole part through which the shaft rod 8b can penetrate, and is slidable on the shaft rod 8b in the axial direction. With such a configuration, when the movable electrode rod 3 described below is moved from right to left of the drawing sheet of FIG. 1 to come into contact with the auxiliary electrode 8e and the auxiliary electrode 8e is further pressed, the contact-pressure spring 8c having one end mounted to the auxiliary electrode 8e is contracted to move the auxiliary electrode 8e to the shaft rod base end 8a side, whereby the male-side engagement part 8d protrudes from an opening of the auxiliary electrode 8e to be engaged with the female-side engagement part 3a (see FIG. 4 described below). When the contact-pressure spring 8c is contracted, a load for abutting the auxiliary electrode 8e on the movable electrode rod 3 is applied, whereby the auxiliary electrode 8e serves as conduction from the movable electrode rod 3 to the blocking electrode 8.

[0024] FIG. 3 is a sectional view of a major part of an electric field relaxing shield unit 12. The electric field relaxing shield unit 12 is composed of an electric field relaxing shield base end 12a as a base, a pillar 12b extending from the electric field relaxing shield base end 12a, a shield spring 12c arranged around the pillar 12b, and an electric field relaxing shield 12d mounted to a distal end of the pillar 12b.

[0025] The electric field relaxing shield base end 12a has, at the center, a hole part 12g through which the cylinder 7 can penetrate. Further, when the circuit is open as in FIG. 1, since an end portion of the electric field relaxing shield base end 12a is in contact with the cylindrical conductor 11 and an elastic force of the opening spring 10 is set greater than that of the shield spring 12c, a contact end surface 12f is engaged so as to press a contact end surface 8g formed on the shaft rod base end 8a. The pillar 12b penetrates the fixed-side terminal 1 and has the distal end to which the electric field relaxing shield 12d is mounted. The shield spring 12c has one end connected to the pillar 12b and the other end connected to a recess formed in an outer part of the fixed-side terminal 1. The electric field relaxing shield 12d has a surface formed by a smooth curved surface so as to relax concentration of an electric field. When the circuit is open as shown in FIG. 1 and after disengagement as shown in FIG. 8, a distal end of the electric field relaxing shield 12d is located closer to the movable-side terminal 2 side than a distal end of the auxiliary electrode 8e, so that the blocking electrode 8 is stored at an inside of the electric field relaxing shield 12d.

[0026] Next, the movable-side terminal 2 in FIG. 1 will be described. The movable electrode rod 3 mounted to the movable-side terminal 2 is formed into a hollow shape, and the female-side engagement part 3a is provided in this hollow part. The female-side engagement part 3a has a contact 4 for movable electrode rod at an outer circumferential surface thereof and is electrically connected to the movable-side terminal 2. The movable electrode rod 3 is configured to be slidable inside a through hole 2a penetrating the movable-side terminal 2, in the right and left directions of the drawing sheet of FIG. 1. In such a configuration, as described below in FIG. 4, the movable electrode rod 3 is moved to an inside of the fixed-side terminal 1 when the circuit is closed, the female-side engagement part 3a is engaged with the male-side engagement part 8d on the fixed-side terminal 1 side, and the movable-side terminal 2 and the fixed-side terminal 1 are electrically connected, so that an electrical path is formed.

[0027] Operation of the disconnector of the gas-insulated switchgear configured as described above will be described.

[0028] The opening spring 10 is set to have an elastic force stronger than that of the shield spring 12c in a compressed state when the circuit is open as shown in FIG. 1. Accordingly, a force in the left direction of the drawing sheet is generated to the shaft rod base end 8a mechanically connected to the cylinder 7 that receives the elastic force of the opening spring 10, and thus the blocking electrode 8 is maintained in the vicinity of an end surface of the cylindrical conductor 11 together with the electric field relaxing shield unit 12. The shield spring 12c is in a compressed state. The piston 6 is inserted to the deepest position of the cylinder 7, the auxiliary electrode 8e is positioned at a distal end of the shaft rod 8b, and the male-side engagement part 8d is provided inside the auxiliary electrode 8e.

[0029] FIG. 4 shows a closed-circuit condition in which a driving unit not shown drives the movable electrode rod 3 to move from the through hole 2a of the movable-side terminal 2 toward the fixed-side terminal 1 in the left direction of the drawing sheet, whereby the movable electrode rod 3 and the auxiliary electrode 8e are abutted on each other. In this condition, the auxiliary electrode 8e is pushed by the movable electrode rod 3, is pushed in a left side of the drawing sheet, and moves on the shaft rod 8b. Accordingly, the contact-pressure spring 8c having one end fixed to the auxiliary electrode 8e is also pushed in the left side of the drawing sheet along with the auxiliary electrode 8e and compressed. At this time, the male-side engagement part 8d protrudes from the auxiliary electrode 8e and enters the hollow part of the movable electrode rod 3. An outer diameter of the male-side engagement part 8d is smaller than an inner diameter of the female-side engagement part, and thus the male-side engagement part 8d smoothly enters the inside of the movable electrode rod 3. In this closed-circuit condition, a main circuit current flows through the movable-side terminal 2, the movable electrode rod 3, and the fixed-side terminal 1.

[0030] Next, open-circuit operation will be described. In FIG. 5, the movable electrode rod 3 is moved to the movable-side terminal 2 side in the right direction of the drawing sheet, while the closed-circuit condition in FIG. 4 is returned to the open-circuit condition. Until the movable electrode rod 3 has been moved to the movable-side terminal 2 side, the blocking electrode 8 is also moved to the movable-side terminal 2 side while the male-side engagement part 8d and the female-side engagement part 3a are maintained to be engaged with each other. In addition, the movable electrode rod 3 and the blocking electrode 8 are in contact with each other and are maintained to be electrically connected with each other. In such a state, as the movable electrode rod 3 and the blocking electrode 8 are moved from a state in FIG. 5 to a state in FIG. 6, that is, to the movable-side terminal 2 side, a series of components, such as the shaft rod 8b, the auxiliary electrode 8e, the contact-pressure spring 8c, and cylinder 7, which are fixed to the male-side engagement part 8d are also moved to a right side of the drawing sheet along with the movable electrode rod 3 and the female-side engagement part 3a. As the cylinder 7 moves, the opening spring 10 is compressed so as to store a force. In addition, when the blocking electrode 8 is moved, the electric field relaxing shield base end 12a is released from a force received from the shaft rod base end 8a. Thus, the shield spring 12c is released, and the electric field relaxing shield unit 12 is moved to the movable-side terminal 2 side.

[0031] FIG. 6 shows a state immediately before the movable electrode rod 3 is about to return to the movable-side terminal 2 side along with the blocking electrode 8 and returned to an open-circuit predetermined position, that is, immediately before an engaged part is separated. FIG. 6 shows the final position in the open-circuit operation in a state in which the male-side engagement part 8d and the female-side engagement part 3a are engaged, and the stopper 14 and the projection 13 are in contact with each other. At this time, the opening spring 10 is in the most compressed state. Even if the movable electrode rod 3 is made to further move to the right side of the drawing sheet, the cylinder 7 is obstructed by the stopper 14 and cannot be moved to the right side. The stopper 14 and the projection 13 function as release means, so that the male-side engagement part 8d and the female-side engagement part 3a are no longer able to hold the engagement, and thus start to release the engagement thereof.

[0032] In a state of FIG. 6, the main circuit current path is as follows: the movable-side terminal 2; the movable electrode rod 3; the auxiliary electrode 8e; the male-side engagement part 8d; the shaft rod 8b; the cylinder 7; the piston 6; the base conductors 5b, 5a; the cylindrical conductor 11; and the fixed-side terminal 1.

[0033] FIG. 7 shows a state immediately after the engaged part has been separated. The male-side engagement part 8d and the female-side engagement part 3a are disengaged, whereby the opening spring 10 is released and starts extending. The male-side engagement part 8d, the shaft rod 8b, the contact-pressure spring 8c, and the cylinder 7 swiftly start to move to the left side of the drawing sheet. However, the auxiliary electrode 8e to which a contact pressure to the movable electrode rod 3 side is applied by the contact-pressure spring 8c is in contact with the movable electrode rod 3 and maintains electrical connection, until the contact-pressure spring 8c extends to its end. In addition, since the electric field relaxing shield base end 12a and the shaft rod base end 8a remain separated, the electric field relaxing shield unit 12 does not move from a position shown in FIG. 6 and is in a state of being closest to the movable-side terminal 2. When the contact-pressure spring 8c extends to its end, the movable electrode rod 3 and the auxiliary electrode 8e start to separate. In this way, the use of the contact-pressure spring 8c allows the auxiliary electrode 8e and the movable electrode rod 3 to maintain electrical connection for a certain time period even immediately after the engaged part has been released and separated, thereby delaying a recovery voltage rising timing and increasing an initial separating speed of the blocking electrode.

[0034] In FIG. 8, the opening spring 10 is released, the blocking electrode 8 that includes the auxiliary electrode 8e separated from the movable electrode rod 3 moves to the inner side of the electric field relaxing shield 12d, and the electric field relaxing shield base end 12a is in contact with the shaft rod base end 8a. Although the recovery voltage rises because the auxiliary electrode 8e has been separated from the movable electrode rod 3, the blocking electrode 8 has already been stored at the inside of the electric field relaxing shield 12d. In such arrangement, a surface of the electric field relaxing shield 12d on the fixed-side terminal 1 side faces a surface on the movable-side terminal 2 side, that is, two smooth metal surfaces are facing each other. Thus, the electric field is suppressed from becoming stronger, and a possibility of occurrence of a restrike can be decreased. Subsequently, the opening spring 10 is further released, and the shaft rod base end 8a pushes the electric field relaxing shield base end 12a up to the end surface of the cylindrical conductor 11, thereby returning to the open-circuit condition shown in FIG. 1.

[0035] According to the present embodiment as described above, the blocking electrode 8 is stored at the inside of the electric field relaxing shield 12d that operates to a predetermined position. Thus, even when the fixed-side terminal 1 and the movable-side terminal 2 are relatively close to each other, the electric field of the blocking electrode 8 is relaxed and a restrike due to a rising recovery voltage can be restrained, thereby enabling reduction in a speed for driving the blocking electrode 8. Since the speed for driving the blocking electrode 8 is lowered, an elastic force of the opening spring 10 can be lowered and the lowered elastic force of the opening spring lowers an impact due to the operation. When the impact during operation is lowered, the mechanical strength of each component of the disconnector can be designed to be relatively lower, and thus simplification and size reduction of the configuration can be expected compared to the conventional configuration.Embodiment 2

[0036] The shaft rod base end 8a of the blocking electrode 8 in FIG. 2 and the electric field relaxing shield base end 12a of the electric field relaxing shield unit 12 in FIG. 3 are arranged such that two cylindrical bases each having a bottom portion are partially stacked in the open-circuit condition as shown in FIG. 1. That is, with reference to FIG. 2 and FIG. 3, the contact end surface 8f formed on the shaft rod base end 8a and the contact end surface 12e formed on the electric field relaxing shield base end 12a come into contact with each other at surfaces parallel to each moving direction, and the contact end surface 8g formed on a bottom portion of the shaft rod base end 8a and the contact end surface 12f formed on a bottom portion of the electric field relaxing shield base end 12a come into contact with each other at surfaces perpendicular to each moving direction. In this case, the elastic forces of the opening spring 10 and the shield spring 12c are applied on only the contact end surface 8g and the contact end surface 12f, and thus, repeating the open-circuit condition and the closed-circuit condition may cause damage.

[0037] Meanwhile, a shaft rod base end 8a and an electric field relaxing shield base end are caused to come into contact with each other at inclined surfaces thereof such that two truncated cone shaped bases are stacked, whereby the elastic force is dispersed in two directions. Specifically, as shown in FIG. 9, an inclined contact surface 8h formed on the shaft rod base end 8a and an inclined contact surface 12h formed on an electric field relaxing shield base end 12a are engaged, whereby the elastic force can be dispersed in a direction parallel to and a direction perpendicular to each moving direction. For example, such an inclined surface is formed by cutting a part of the vertical surface of the conventional shaft rod base end 8a, thus leading to the shaft rod base end 8a having a light weight and also contributing to improving the speed for driving the blocking electrode 8.

[0038] As described above, the contact part formed in an inclined shape allows the elastic forces of the opening spring and the shield spring to be dispersed in a movement direction of the spring and a direction perpendicular to the movement when the surfaces mechanically come into contact with each other after the opening spring has been released, and an improved speed for driving the blocking electrode can be expected by reducing the material.

[0039] It is therefore understood that numerous modifications which have not been exemplified can be devised without departing from the scope of the present disclosure.DESCRIPTION OF THE REFERENCE CHARACTERS

[0040] 1fixed-side terminal 2movable-side terminal 3movable electrode rod 3afemale-side engagement part 4contact for movable electrode rod 5a, 5bbase conductor 6piston 7cylinder 8blocking electrode 8ashaft rod base end 8bshaft rod 8ccontact-pressure spring 8dmale-side engagement part 8eauxiliary electrode 8f, 8gcontact end surface 8hinclined contact surface 9contact for piston 10opening spring 11cylindrical conductor 12electric field relaxing shield unit 12aelectric field relaxing shield base end 12bpillar 12cshield spring 12delectric field relaxing shield 12e, 12fcontact end surface 12ghole part 12hinclined contact surface

Examples

embodiment 1

[0015]FIG. 1 is a sectional view of a major part of a gas-insulated switchgear according to Embodiment 1, when a disconnector is in an open-circuit condition. A basic function for opening and closing an electrical path is configured by a fixed-side terminal 1, a movable-side terminal 2, and a movable electrode rod 3. These components are arranged inside an airtight container with insulation gas sealed therein. Hereinafter, each component will be described in detail.

[0016]A cylindrical conductor 11 has one end surface mechanically and electrically connected coaxially to one end of a fixed-side terminal 1. In addition, the other end surface is mechanically and electrically connected to a base conductor 5b. As a mechanical connection method, bolt fixing may be performed, and a contact surface may be silver plated to obtain electrical connection. In addition, a base conductor 5a having an outer periphery formed by a curved surface is fixed so as to cover a base conductor 5b.

[0017]A pist...

embodiment 2

[0036]The shaft rod base end 8a of the blocking electrode 8 in FIG. 2 and the electric field relaxing shield base end 12a of the electric field relaxing shield unit 12 in FIG. 3 are arranged such that two cylindrical bases each having a bottom portion are partially stacked in the open-circuit condition as shown in FIG. 1. That is, with reference to FIG. 2 and FIG. 3, the contact end surface 8f formed on the shaft rod base end 8a and the contact end surface 12e formed on the electric field relaxing shield base end 12a come into contact with each other at surfaces parallel to each moving direction, and the contact end surface 8g formed on a bottom portion of the shaft rod base end 8a and the contact end surface 12f formed on a bottom portion of the electric field relaxing shield base end 12a come into contact with each other at surfaces perpendicular to each moving direction. In this case, the elastic forces of the opening spring 10 and the shield spring 12c are applied on only the co...

TECHNICAL FIELD

[0001] The present disclosure relates to a gas-insulated switchgear.BACKGROUND ART

[0002] A disconnector stored in a gas-insulated switchgear does not have a function of interrupting current in most cases. For example, Patent Document 1 discloses that, in a disconnector in which a fixed-side terminal and a movable-side terminal including a movable electrode rod are arranged opposite to each other, a quick acting mechanism for interrupting current is provided in the fixed-side terminal.

[0003] The quick acting mechanism includes a shaft rod electrically connected to the fixed-side terminal, a blocking electrode disposed at a shaft rod tip for receiving an arc generated when current is interrupted, an engaging unit for engaging the shaft rod with the movable electrode rod, and an opening spring that drives the blocking electrode along with the shaft rod in a direction opposite to the movable electrode rod.

[0004] The quick acting mechanism has such a configuration that: when a circuit between the fixed-side terminal and the movable-side terminal is closed by the movable electrode rod, the movable electrode rod and the shaft rod are engaged; and when the circuit is opened, the shaft rod is pulled by the movable electrode rod to compress the opening spring so as to store a force, the engaging unit is caused to perform separation at a predetermined position, and the opening spring is released to drive the shaft rod, whereby the blocking electrode is separated in a direction opposite to the movable electrode rod to interrupt current.

[0005] Document JP 2010 027479 A, according to its abstract, states that, to provide a switch capable of installing a quick-acting mechanism for current cutoff irrelevantly to an installation space of a movable electrode rod, and capable of stably cutting off current between a fixed side terminal and a movable side terminal, in the switch, when carrying out closing, continuity between the fixed side terminal and the movable side terminal is secured by moving the movable electrode rod housed in the movable side terminal disposed facing the fixed side terminal, and when carrying out opening, the current between the fixed side terminal and the movable electrode rod is cut off by the quick-acting mechanism provided in the fixed side terminal.CITATION LISTPATENT DOCUMENT

[0006] Patent Document 1: Japanese Patent No. 5179278SUMMARY OF THE INVENTIONPROBLEMS TO BE SOLVED BY THE INVENTION

[0007] In Patent Document 1, in a condition in which the circuit between the fixed-side terminal and the movable-side terminal is opened, the circuit is a circuit between disconnecting electrodes, and thus needs to have withstand voltage performance higher than that between earth electrodes and that between phases. Accordingly, the distance between the fixed-side terminal and the movable-side terminal is relatively long.

[0008] In addition, in interruption of current, in order to restrain a restrike of arc due to a recovery voltage generated after current interruption, the withstand voltage performance required for the recovery voltage that rises immediately after the movable electrode rod has been separated from the blocking electrode needs to be ensured.

[0009] As one of measures to ensure the withstand voltage performance, a solution to relax an electric field between terminals by storing the blocking electrode inside the fixed-side terminal is provided. However, as described above, the disconnecting electrodes are separated from each other, and thus the blocking electrode needs to be quickly driven to be stored into the fixed-side terminal in a short time. Particularly, when interruption involving a relatively high recovery voltage is performed as in current interruption during cable charging, the blocking electrode needs to be more quickly driven.

[0010] The present disclosure has been made to solve the above problem, and an object of the present disclosure is to provide a configuration of a gas-insulated switchgear that enables reduction in a speed for driving the blocking electrode compared to that of the conventional configuration even when an interruption involving a recovery voltage is performed.SOLUTION TO THE PROBLEMS

[0011] According to the present disclosure, a gas-insulated switchgear as defined in independent claim 1 is provided. Further embodiments of the claimed invention are defined in the dependent claims. Although the claimed invention is only defined by the claims, the below embodiments, examples, and aspects are present for aiding in understanding the background and advantages of the claimed invention.EFFECT OF THE INVENTION

[0012] In the gas-insulated switchgear according to the present disclosure, the blocking electrode is stored in the electric field relaxing shield. Thus, when the movable-side terminal and the fixed-side terminal are relatively close to each other, an electric field of the blocking electrode is relaxed and a restrike due to a rising recovery voltage can be restrained, thereby enabling reduction in a speed for driving the blocking electrode.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] [FIG. 1] FIG. 1 is a sectional view of a major part of a gas-insulated switchgear according to Embodiment 1, when a disconnector is in an open-circuit condition. [FIG. 2] FIG. 2 is a sectional view of a major part of a blocking electrode mounted to the disconnector of the gas-insulated switchgear according to Embodiment 1. [FIG. 3] FIG. 3 is a sectional view of a major part of an electric field relaxing shield unit mounted to the disconnector of the gas-insulated switchgear according to Embodiment 1. [FIG. 4] FIG. 4 is a sectional view of a major part of the gas-insulated switchgear according to Embodiment 1, when the disconnector is in a closed-circuit condition. [FIG. 5] FIG. 5 is a sectional view of a major part of the gas-insulated switchgear according to Embodiment 1, immediately after an engaged part has been engaged in the middle of switching from the closed-circuit condition of the disconnector to the open-circuit condition thereof. [FIG. 6] FIG. 6 is a sectional view of a major part of the gas-insulated switchgear according to Embodiment 1, immediately before the engaged part of the disconnector is released and separated. [FIG. 7] FIG. 7 is a sectional view of a major part of the gas-insulated switchgear according to Embodiment 1, immediately after the engaged part of the disconnector has been released and separated. [FIG. 8] FIG. 8 is a sectional view of a major part of the gas-insulated switchgear according to Embodiment 1, immediately after the blocking electrode mounted to the disconnector has been stored at an inside of an electric field relaxing shield. [FIG. 9] FIG. 9 is a sectional view of a major part of a shaft rod base end and an electric field relaxing shield base end mounted to a disconnector of a gas-insulated switchgear according to Embodiment 2. DESCRIPTION OF EMBODIMENTS

[0014] Hereinafter, a preferred embodiment of a gas-insulated switchgear according to the present disclosure will be described with reference to the drawings. In the drawings, the same reference characters denote the same or corresponding parts, and detailed description thereof will be omitted. Similarly, also in the subsequent embodiment, redundant description of the components denoted by the same reference characters is omitted.Embodiment 1

[0015] FIG. 1 is a sectional view of a major part of a gas-insulated switchgear according to Embodiment 1, when a disconnector is in an open-circuit condition. A basic function for opening and closing an electrical path is configured by a fixed-side terminal 1, a movable-side terminal 2, and a movable electrode rod 3. These components are arranged inside an airtight container with insulation gas sealed therein. Hereinafter, each component will be described in detail.

[0016] A cylindrical conductor 11 has one end surface mechanically and electrically connected coaxially to one end of a fixed-side terminal 1. In addition, the other end surface is mechanically and electrically connected to a base conductor 5b. As a mechanical connection method, bolt fixing may be performed, and a contact surface may be silver plated to obtain electrical connection. In addition, a base conductor 5a having an outer periphery formed by a curved surface is fixed so as to cover a base conductor 5b.

[0017] A piston 6 is mechanically and electrically connected perpendicularly to the base conductor 5b and coaxially with an opening formed in the fixed-side terminal 1. Thus, needless to say, the piston 6 is fixed and does not move. As a mechanical connection method, bolt fixing may be performed, and a contact surface may be silver plated to obtain electrical connection.

[0018] A cylinder 7 having a cylindrical shape is inserted in the piston 6, and a contact 9 for piston ensures electrical conduction between the cylinder 7 and the piston 6. The cylinder 7 slides along the piston 6, and the details of the operation will be described below.

[0019] A projection 13 is formed or arranged at an outer circumference of an opening end portion of the cylinder 7. The projection 13 has an outer diameter approximately the same as an inner diameter of the cylindrical conductor 11, and thus can move on an inner circumferential surface of the cylindrical conductor 11 in the right and left directions, as the cylinder 7 moves.

[0020] A stopper 14 has an inner diameter smaller than the outer diameter of the projection 13, and is formed at a predetermined position inside the cylinder of the cylindrical conductor 11. This predetermined position is determined according to an elastic force of an opening spring 10 or the like. In addition, the opening spring 10 having a helical shape is arranged along an outer circumference of the cylinder 7. The opening spring 10 has one end fixed to a spring holder disposed at an end portion of the projection 13 and the other end fixed to a spring holder disposed inside the cylinder on the fixed-side terminal 1 side.

[0021] A rod-like blocking electrode 8 mechanically and electrically connected coaxially to the cylinder 7 is connected at a distal end on the fixed-side terminal 1 side of the cylinder 7. FIG. 2 is a sectional view of a major part of the blocking electrode 8. The blocking electrode 8 is composed of a shaft rod base end 8a as a base, a shaft rod 8b extending from the shaft rod base end 8a, a contact-pressure spring 8c arranged around the shaft rod 8b, a male-side engagement part 8d mounted to the shaft rod 8b, and an auxiliary electrode 8e slidable on the shaft rod 8b. The contact-pressure spring 8c is helical, is arranged around the shaft rod 8b coaxially with the male-side engagement part 8d, and has one end fixed to the shaft rod base end 8a and the other end fixed to the auxiliary electrode 8e. On the shaft rod base end 8a, a contact end surface 8f that comes into contact with a contact end surface 12e disposed at an electric field relaxing shield base end 12a described below according to a state of the opening spring 10 described below is formed.

[0022] One end portion of the male-side engagement part 8d is inserted into the shaft rod 8b and mounted thereto. The other end portion thereof is engaged with a female-side engagement part 3a of the movable electrode rod 3 described below when the circuit is closed. In addition, when the contact-pressure spring 8c is in a released state, a distal end of the male-side engagement part 8d is positioned on the inner side from the auxiliary electrode 8e.

[0023] The auxiliary electrode 8e has a ring shape having, at the center, a hole part through which the shaft rod 8b can penetrate, and is slidable on the shaft rod 8b in the axial direction. With such a configuration, when the movable electrode rod 3 described below is moved from right to left of the drawing sheet of FIG. 1 to come into contact with the auxiliary electrode 8e and the auxiliary electrode 8e is further pressed, the contact-pressure spring 8c having one end mounted to the auxiliary electrode 8e is contracted to move the auxiliary electrode 8e to the shaft rod base end 8a side, whereby the male-side engagement part 8d protrudes from an opening of the auxiliary electrode 8e to be engaged with the female-side engagement part 3a (see FIG. 4 described below). When the contact-pressure spring 8c is contracted, a load for abutting the auxiliary electrode 8e on the movable electrode rod 3 is applied, whereby the auxiliary electrode 8e serves as conduction from the movable electrode rod 3 to the blocking electrode 8.

[0024] FIG. 3 is a sectional view of a major part of an electric field relaxing shield unit 12. The electric field relaxing shield unit 12 is composed of an electric field relaxing shield base end 12a as a base, a pillar 12b extending from the electric field relaxing shield base end 12a, a shield spring 12c arranged around the pillar 12b, and an electric field relaxing shield 12d mounted to a distal end of the pillar 12b.

[0025] The electric field relaxing shield base end 12a has, at the center, a hole part 12g through which the cylinder 7 can penetrate. Further, when the circuit is open as in FIG. 1, since an end portion of the electric field relaxing shield base end 12a is in contact with the cylindrical conductor 11 and an elastic force of the opening spring 10 is set greater than that of the shield spring 12c, a contact end surface 12f is engaged so as to press a contact end surface 8g formed on the shaft rod base end 8a. The pillar 12b penetrates the fixed-side terminal 1 and has the distal end to which the electric field relaxing shield 12d is mounted. The shield spring 12c has one end connected to the pillar 12b and the other end connected to a recess formed in an outer part of the fixed-side terminal 1. The electric field relaxing shield 12d has a surface formed by a smooth curved surface so as to relax concentration of an electric field. When the circuit is open as shown in FIG. 1 and after disengagement as shown in FIG. 8, a distal end of the electric field relaxing shield 12d is located closer to the movable-side terminal 2 side than a distal end of the auxiliary electrode 8e, so that the blocking electrode 8 is stored at an inside of the electric field relaxing shield 12d.

[0026] Next, the movable-side terminal 2 in FIG. 1 will be described. The movable electrode rod 3 mounted to the movable-side terminal 2 is formed into a hollow shape, and the female-side engagement part 3a is provided in this hollow part. The female-side engagement part 3a has a contact 4 for movable electrode rod at an outer circumferential surface thereof and is electrically connected to the movable-side terminal 2. The movable electrode rod 3 is configured to be slidable inside a through hole 2a penetrating the movable-side terminal 2, in the right and left directions of the drawing sheet of FIG. 1. In such a configuration, as described below in FIG. 4, the movable electrode rod 3 is moved to an inside of the fixed-side terminal 1 when the circuit is closed, the female-side engagement part 3a is engaged with the male-side engagement part 8d on the fixed-side terminal 1 side, and the movable-side terminal 2 and the fixed-side terminal 1 are electrically connected, so that an electrical path is formed.

[0027] Operation of the disconnector of the gas-insulated switchgear configured as described above will be described.

[0028] The opening spring 10 is set to have an elastic force stronger than that of the shield spring 12c in a compressed state when the circuit is open as shown in FIG. 1. Accordingly, a force in the left direction of the drawing sheet is generated to the shaft rod base end 8a mechanically connected to the cylinder 7 that receives the elastic force of the opening spring 10, and thus the blocking electrode 8 is maintained in the vicinity of an end surface of the cylindrical conductor 11 together with the electric field relaxing shield unit 12. The shield spring 12c is in a compressed state. The piston 6 is inserted to the deepest position of the cylinder 7, the auxiliary electrode 8e is positioned at a distal end of the shaft rod 8b, and the male-side engagement part 8d is provided inside the auxiliary electrode 8e.

[0029] FIG. 4 shows a closed-circuit condition in which a driving unit not shown drives the movable electrode rod 3 to move from the through hole 2a of the movable-side terminal 2 toward the fixed-side terminal 1 in the left direction of the drawing sheet, whereby the movable electrode rod 3 and the auxiliary electrode 8e are abutted on each other. In this condition, the auxiliary electrode 8e is pushed by the movable electrode rod 3, is pushed in a left side of the drawing sheet, and moves on the shaft rod 8b. Accordingly, the contact-pressure spring 8c having one end fixed to the auxiliary electrode 8e is also pushed in the left side of the drawing sheet along with the auxiliary electrode 8e and compressed. At this time, the male-side engagement part 8d protrudes from the auxiliary electrode 8e and enters the hollow part of the movable electrode rod 3. An outer diameter of the male-side engagement part 8d is smaller than an inner diameter of the female-side engagement part, and thus the male-side engagement part 8d smoothly enters the inside of the movable electrode rod 3. In this closed-circuit condition, a main circuit current flows through the movable-side terminal 2, the movable electrode rod 3, and the fixed-side terminal 1.

[0030] Next, open-circuit operation will be described. In FIG. 5, the movable electrode rod 3 is moved to the movable-side terminal 2 side in the right direction of the drawing sheet, while the closed-circuit condition in FIG. 4 is returned to the open-circuit condition. Until the movable electrode rod 3 has been moved to the movable-side terminal 2 side, the blocking electrode 8 is also moved to the movable-side terminal 2 side while the male-side engagement part 8d and the female-side engagement part 3a are maintained to be engaged with each other. In addition, the movable electrode rod 3 and the blocking electrode 8 are in contact with each other and are maintained to be electrically connected with each other. In such a state, as the movable electrode rod 3 and the blocking electrode 8 are moved from a state in FIG. 5 to a state in FIG. 6, that is, to the movable-side terminal 2 side, a series of components, such as the shaft rod 8b, the auxiliary electrode 8e, the contact-pressure spring 8c, and cylinder 7, which are fixed to the male-side engagement part 8d are also moved to a right side of the drawing sheet along with the movable electrode rod 3 and the female-side engagement part 3a. As the cylinder 7 moves, the opening spring 10 is compressed so as to store a force. In addition, when the blocking electrode 8 is moved, the electric field relaxing shield base end 12a is released from a force received from the shaft rod base end 8a. Thus, the shield spring 12c is released, and the electric field relaxing shield unit 12 is moved to the movable-side terminal 2 side.

[0031] FIG. 6 shows a state immediately before the movable electrode rod 3 is about to return to the movable-side terminal 2 side along with the blocking electrode 8 and returned to an open-circuit predetermined position, that is, immediately before an engaged part is separated. FIG. 6 shows the final position in the open-circuit operation in a state in which the male-side engagement part 8d and the female-side engagement part 3a are engaged, and the stopper 14 and the projection 13 are in contact with each other. At this time, the opening spring 10 is in the most compressed state. Even if the movable electrode rod 3 is made to further move to the right side of the drawing sheet, the cylinder 7 is obstructed by the stopper 14 and cannot be moved to the right side. The stopper 14 and the projection 13 function as release means, so that the male-side engagement part 8d and the female-side engagement part 3a are no longer able to hold the engagement, and thus start to release the engagement thereof.

[0032] In a state of FIG. 6, the main circuit current path is as follows: the movable-side terminal 2; the movable electrode rod 3; the auxiliary electrode 8e; the male-side engagement part 8d; the shaft rod 8b; the cylinder 7; the piston 6; the base conductors 5b, 5a; the cylindrical conductor 11; and the fixed-side terminal 1.

[0033] FIG. 7 shows a state immediately after the engaged part has been separated. The male-side engagement part 8d and the female-side engagement part 3a are disengaged, whereby the opening spring 10 is released and starts extending. The male-side engagement part 8d, the shaft rod 8b, the contact-pressure spring 8c, and the cylinder 7 swiftly start to move to the left side of the drawing sheet. However, the auxiliary electrode 8e to which a contact pressure to the movable electrode rod 3 side is applied by the contact-pressure spring 8c is in contact with the movable electrode rod 3 and maintains electrical connection, until the contact-pressure spring 8c extends to its end. In addition, since the electric field relaxing shield base end 12a and the shaft rod base end 8a remain separated, the electric field relaxing shield unit 12 does not move from a position shown in FIG. 6 and is in a state of being closest to the movable-side terminal 2. When the contact-pressure spring 8c extends to its end, the movable electrode rod 3 and the auxiliary electrode 8e start to separate. In this way, the use of the contact-pressure spring 8c allows the auxiliary electrode 8e and the movable electrode rod 3 to maintain electrical connection for a certain time period even immediately after the engaged part has been released and separated, thereby delaying a recovery voltage rising timing and increasing an initial separating speed of the blocking electrode.

[0034] In FIG. 8, the opening spring 10 is released, the blocking electrode 8 that includes the auxiliary electrode 8e separated from the movable electrode rod 3 moves to the inner side of the electric field relaxing shield 12d, and the electric field relaxing shield base end 12a is in contact with the shaft rod base end 8a. Although the recovery voltage rises because the auxiliary electrode 8e has been separated from the movable electrode rod 3, the blocking electrode 8 has already been stored at the inside of the electric field relaxing shield 12d. In such arrangement, a surface of the electric field relaxing shield 12d on the fixed-side terminal 1 side faces a surface on the movable-side terminal 2 side, that is, two smooth metal surfaces are facing each other. Thus, the electric field is suppressed from becoming stronger, and a possibility of occurrence of a restrike can be decreased. Subsequently, the opening spring 10 is further released, and the shaft rod base end 8a pushes the electric field relaxing shield base end 12a up to the end surface of the cylindrical conductor 11, thereby returning to the open-circuit condition shown in FIG. 1.

[0035] According to the present embodiment as described above, the blocking electrode 8 is stored at the inside of the electric field relaxing shield 12d that operates to a predetermined position. Thus, even when the fixed-side terminal 1 and the movable-side terminal 2 are relatively close to each other, the electric field of the blocking electrode 8 is relaxed and a restrike due to a rising recovery voltage can be restrained, thereby enabling reduction in a speed for driving the blocking electrode 8. Since the speed for driving the blocking electrode 8 is lowered, an elastic force of the opening spring 10 can be lowered and the lowered elastic force of the opening spring lowers an impact due to the operation. When the impact during operation is lowered, the mechanical strength of each component of the disconnector can be designed to be relatively lower, and thus simplification and size reduction of the configuration can be expected compared to the conventional configuration.Embodiment 2

[0036] The shaft rod base end 8a of the blocking electrode 8 in FIG. 2 and the electric field relaxing shield base end 12a of the electric field relaxing shield unit 12 in FIG. 3 are arranged such that two cylindrical bases each having a bottom portion are partially stacked in the open-circuit condition as shown in FIG. 1. That is, with reference to FIG. 2 and FIG. 3, the contact end surface 8f formed on the shaft rod base end 8a and the contact end surface 12e formed on the electric field relaxing shield base end 12a come into contact with each other at surfaces parallel to each moving direction, and the contact end surface 8g formed on a bottom portion of the shaft rod base end 8a and the contact end surface 12f formed on a bottom portion of the electric field relaxing shield base end 12a come into contact with each other at surfaces perpendicular to each moving direction. In this case, the elastic forces of the opening spring 10 and the shield spring 12c are applied on only the contact end surface 8g and the contact end surface 12f, and thus, repeating the open-circuit condition and the closed-circuit condition may cause damage.

[0037] Meanwhile, a shaft rod base end 8a and an electric field relaxing shield base end are caused to come into contact with each other at inclined surfaces thereof such that two truncated cone shaped bases are stacked, whereby the elastic force is dispersed in two directions. Specifically, as shown in FIG. 9, an inclined contact surface 8h formed on the shaft rod base end 8a and an inclined contact surface 12h formed on an electric field relaxing shield base end 12a are engaged, whereby the elastic force can be dispersed in a direction parallel to and a direction perpendicular to each moving direction. For example, such an inclined surface is formed by cutting a part of the vertical surface of the conventional shaft rod base end 8a, thus leading to the shaft rod base end 8a having a light weight and also contributing to improving the speed for driving the blocking electrode 8.

[0038] As described above, the contact part formed in an inclined shape allows the elastic forces of the opening spring and the shield spring to be dispersed in a movement direction of the spring and a direction perpendicular to the movement when the surfaces mechanically come into contact with each other after the opening spring has been released, and an improved speed for driving the blocking electrode can be expected by reducing the material.

[0039] It is therefore understood that numerous modifications which have not been exemplified can be devised without departing from the scope of the present disclosure.DESCRIPTION OF THE REFERENCE CHARACTERS

[0040] 1fixed-side terminal 2movable-side terminal 3movable electrode rod 3afemale-side engagement part 4contact for movable electrode rod 5a, 5bbase conductor 6piston 7cylinder 8blocking electrode 8ashaft rod base end 8bshaft rod 8ccontact-pressure spring 8dmale-side engagement part 8eauxiliary electrode 8f, 8gcontact end surface 8hinclined contact surface 9contact for piston 10opening spring 11cylindrical conductor 12electric field relaxing shield unit 12aelectric field relaxing shield base end 12bpillar 12cshield spring 12delectric field relaxing shield 12e, 12fcontact end surface 12ghole part 12hinclined contact surface

Examples

embodiment 1

[0015]FIG. 1 is a sectional view of a major part of a gas-insulated switchgear according to Embodiment 1, when a disconnector is in an open-circuit condition. A basic function for opening and closing an electrical path is configured by a fixed-side terminal 1, a movable-side terminal 2, and a movable electrode rod 3. These components are arranged inside an airtight container with insulation gas sealed therein. Hereinafter, each component will be described in detail.

[0016]A cylindrical conductor 11 has one end surface mechanically and electrically connected coaxially to one end of a fixed-side terminal 1. In addition, the other end surface is mechanically and electrically connected to a base conductor 5b. As a mechanical connection method, bolt fixing may be performed, and a contact surface may be silver plated to obtain electrical connection. In addition, a base conductor 5a having an outer periphery formed by a curved surface is fixed so as to cover a base conductor 5b.

[0017]A pist...

embodiment 2

[0036]The shaft rod base end 8a of the blocking electrode 8 in FIG. 2 and the electric field relaxing shield base end 12a of the electric field relaxing shield unit 12 in FIG. 3 are arranged such that two cylindrical bases each having a bottom portion are partially stacked in the open-circuit condition as shown in FIG. 1. That is, with reference to FIG. 2 and FIG. 3, the contact end surface 8f formed on the shaft rod base end 8a and the contact end surface 12e formed on the electric field relaxing shield base end 12a come into contact with each other at surfaces parallel to each moving direction, and the contact end surface 8g formed on a bottom portion of the shaft rod base end 8a and the contact end surface 12f formed on a bottom portion of the electric field relaxing shield base end 12a come into contact with each other at surfaces perpendicular to each moving direction. In this case, the elastic forces of the opening spring 10 and the shield spring 12c are applied on only the co...

Claims

1. A gas-insulated switchgear comprising: a fixed-side terminal (1) disposed inside an airtight container with insulation gas sealed therein; a movable-side terminal (2) that is arranged opposite to the fixed-side terminal (1) and includes a movable electrode rod (3) contactable to ensure electrical conduction with the fixed-side terminal (1); and a driving mechanism for interrupting the electrical conduction between the movable-side terminal (2) and the fixed-side terminal (1), wherein the fixed-side terminal (1) includes a movable blocking electrode (8) that is engaged with the movable electrode rod (3) when a circuit is closed, characterized in that the fixed-side terminal (1) includes a movable electric field relaxing shield (12d), and when the movable electrode rod (3) and the blocking electrode (8) are disengaged, the electric field relaxing shield (12d) moves toward the movable-side terminal (2) in conjunction with operation of the blocking electrode (8) to store the blocking electrode (8) at an inside of the electric field relaxing shield (12d).

2. The gas-insulated switchgear according to claim 1, wherein, after the blocking electrode (8) is stored at the inside of the electric field relaxing shield (12d), the blocking electrode (8) and the electric field relaxing shield (12d) move toward the fixed-side terminal (1).

3. The gas-insulated switchgear according to claims 1 or 2, wherein the blocking electrode (8) includes an auxiliary electrode (8e) that comes into contact with an end portion of the movable electrode rod (3) when the circuit is closed, a male-side engagement part (8d) that is engaged with a female-side engagement part (3a) in the movable electrode rod (3), and a contact-pressure spring (8c) that energizes the auxiliary electrode (8e) so as to maintain contact with the movable electrode rod end portion for a certain time period even if the female-side engagement part (3a) and the male-side engagement part (8d) are separated, when the movable electrode rod (3) and the blocking electrode (8) are disengaged.

4. The gas-insulated switchgear according to any one of claims 1 to 3, wherein a shaft rod base end (8a) serving as a base for the blocking electrode (8) and an electric field relaxing shield base end (12a) serving as a base for the electric field relaxing shield (12d) each include a wall surface having an inclined surface, and when the shaft rod base end is engaged with the electric field relaxing shield base end, the inclined surfaces (8h, 12h) are in contact with each other.

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