Electric device and circuit breaker

Abstract

An electric device (40) comprises: a tank (1) in which an insulating gas is sealed; a high-voltage conductor (2) that is installed inside the tank (1) and to which DC voltage is applied; and a foreign matter removal apparatus (4) that removes conductive foreign matter (61) inside the tank (1). The foreign matter removal apparatus (4) comprises: a shield ring (41) that has a ring shape having a curved surface at the outer circumferential part thereof, and that is installed on the high-voltage conductor (2); and a firefly-suppressing part (42) that is installed on the outer circumferential part of the shield ring (41), and that prevents the conductive foreign matter (61) from being able to maintain a firefly state in which the conductive foreign matter floats around the high-voltage conductor (2).

Description

Electrical equipment and circuit breakers

[0001] The present disclosure relates to an electrical device and a circuit breaker that include a high-voltage conductor to which a DC voltage is applied, inside a tank filled with insulating gas.

[0002] In electrical equipment that has a high-voltage conductor to which a DC voltage is applied inside a tank filled with insulating gas, a method is used in which a shield ring made of a conductive material is attached to the high-voltage conductor to reduce the electric field in order to prevent corona discharge from the high-voltage conductor.

[0003] If a conductive foreign object gets into the tank and a high DC voltage is applied to the high-voltage conductor, the conductive foreign object on the bottom of the tank will float toward the high-voltage conductor due to electrostatic force and will be restrained and floating near the high-voltage conductor, creating a state known as a "firefly."A conductive foreign object in this state will be referred to as a "firefly foreign object" below.

[0004] Because firefly particles tend to move toward areas with higher electric fields, when a shield ring is attached to a high-voltage conductor, firefly particles move toward the tip of the shield ring. When firefly particles reach the tip of the shield ring, the electric field mitigation effect of the shield ring is reduced.

[0005] Patent Document 1 discloses a gas-insulated device that provides a different characteristic area in a high-voltage conductor where the electric field is low, so that when a conductive foreign object reaches the different characteristic area, it can no longer maintain a firefly state, causing the firefly foreign object to fall into a foreign object collection area and be captured.

[0006] Japanese Patent Application Publication No. 11-262144

[0007] However, the gas-insulated equipment disclosed in Patent Document 1 has a problem in that the electric field at the location of the different characteristics is low, making it difficult for firefly foreign matter to gather at the location of the different characteristics, and conductive foreign matter cannot be efficiently removed.

[0008] The present disclosure has been made in view of the above, and has an object to provide an electrical device equipped with a foreign matter removal device that can efficiently remove conductive foreign matter.

[0009] To solve the above-mentioned problems and achieve the object, the electrical device according to the present disclosure includes a tank filled with insulating gas, a high-voltage conductor installed inside the tank and to which a DC voltage is applied, and a foreign matter removal device that removes conductive foreign matter from inside the tank. The foreign matter removal device includes a ring-shaped shield ring with a curved outer periphery that is installed on the high-voltage conductor, and a firefly suppression unit that is installed on the outer periphery of the shield ring and prevents conductive foreign matter from maintaining a firefly state in which the conductive foreign matter floats around the high-voltage conductor.

[0010] According to the present disclosure, it is possible to obtain an electric device equipped with a foreign matter removal device that can efficiently remove conductive foreign matter.

[0011] FIG. 1 is a diagram showing the configuration of an electrical device according to embodiment 1. FIG. 2 is a diagram showing the configuration of an electrical device according to embodiment 2. FIG. 3 is an enlarged view of a foreign matter removal device for an electrical device according to embodiment 2. FIG. 4 is a diagram showing the behavior of conductive foreign matter in a foreign matter removal device for an electrical device according to embodiment 2. FIG. 5 is an enlarged view of a foreign matter removal device for an electrical device according to embodiment 3. FIG. 6 is an enlarged view of a foreign matter removal device for an electrical device according to a modified example of embodiment 3. FIG. 7 is a diagram showing the behavior of conductive foreign matter in a foreign matter removal device for an electrical device according to a modified example of embodiment 3. FIG. 8 is a diagram showing the configuration of a foreign matter removal device for an electrical device according to embodiment 4. FIG. 9 is a diagram showing the closed state of a circuit breaker according to embodiment 5. FIG. 10 is a diagram showing the open state of a circuit breaker according to embodiment 5.

[0012] Hereinafter, an electric device and a circuit breaker according to an embodiment will be described in detail with reference to the drawings.

[0013] Embodiment 1. Figure 1 is a diagram showing the configuration of an electrical device according to embodiment 1. The electrical device 40 includes a tank 1 filled with insulating gas, a high-voltage conductor 2 installed inside the tank 1, an insulating spacer 3 supporting the high-voltage conductor 2 within the tank 1, and a foreign matter removal device 4 that removes conductive foreign matter 61 from within the tank 1. The foreign matter removal device 4 includes a shield ring 41 installed on the high-voltage conductor 2, a firefly suppression unit 42 that prevents firefly foreign matter from maintaining a firefly state, a low electric field unit 47 provided on the high-voltage conductor 2, and a foreign matter capture container 43 formed below the tank 1. A high-voltage DC voltage is applied to the high-voltage conductor 2. The high-voltage conductor 2 has a structure in which the surface of a metal conductor is covered with an insulating coating.

[0014] The shield ring 41 has a curved tip portion that is a high electric field portion. The firefly suppression portion 42 is disposed at the curved tip portion of the shield ring 41. In the foreign matter removal device 4 of the electrical device 40 according to the first embodiment, the firefly suppression portion 42 is an insulator formed of an insulating material. Here, the electrical resistance is 10 １５ A material having a resistance greater than Ω·m is considered an insulating material. The outer diameter of the firefly suppression portion 42 is the same as that of the shield ring 41. In the first embodiment, a structure in which the disk-shaped firefly suppression portion 42 is sandwiched between the shield rings 41 is exemplified. However, the firefly suppression portion 42 may be formed in a ring shape and disposed in a recess on the outer periphery of the shield ring 41. The low electric field portion 47 is formed by partially thickening the insulating coating covering the metal conductor of the high-voltage conductor 2, and the electric field on the surface is lower than in parts of the high-voltage conductor 2 other than the low electric field portion 47. Note that, although the low electric field portion 47 is formed below the high-voltage conductor 2 in FIG. 1 , this is not limiting. The low electric field portion 47 may also be formed in a ring shape around the entire circumference of the high-voltage conductor 2.

[0015] Conductive foreign matter 61 in tank 1 floats near the surface of high-voltage conductor 2 and moves toward the high-electric field area where the electric field is higher. If conductive foreign matter 61 on the bottom surface of tank 1 floats and becomes a firefly foreign matter on shield ring 41, the firefly foreign matter moves toward the high-electric field area at the tip of shield ring 41 and reaches firefly suppression unit 42. Firefly foreign matter can continue to float by receiving charge from high-voltage conductor 2, but because the firefly suppression unit 42 made of an insulating material is sandwiched between the curvature tip of shield ring 41, which forms the high-electric field area, firefly foreign matter that reaches firefly suppression unit 42 loses the supply of charge from high-voltage conductor 2 and can no longer maintain its firefly state. Conductive foreign matter 61 that is no longer in a firefly state falls to the bottom of tank 1 and enters foreign matter capture container 43. Also, when the firefly foreign matter reaches the low electric field section 47, the firefly foreign matter can no longer maintain the firefly state, and the conductive foreign matter 61 that is no longer in the firefly state falls to the bottom of the tank 1 and enters the foreign matter capturing container 43.

[0016] The foreign object capture container 43 captures the conductive foreign object 61 so that it cannot re-float. By increasing the depth of the foreign object capture container 43, the electric field at the bottom of the foreign object capture container 43 can be made lower than the electric field at the bottom of the tank 1, and can be made to be strong enough to prevent the conductive foreign object 61 from re-floating. This prevents the conductive foreign object 61 captured in the foreign object capture container 43 from becoming a firefly foreign object again, and ensures that the conductive foreign object 61 is captured reliably.

[0017] The electrical device 40 according to embodiment 1 can efficiently capture the conductive foreign matter 61 by guiding the firefly foreign matter to the firefly suppression section 42 installed in the high electric field section of the shield ring 41, thereby cutting off the charge supply from the high voltage conductor 2 and preventing the firefly state from being maintained.

[0018] Although the firefly suppression portion 42 is made of an insulating material, the firefly suppression portion 42 may be made of a semiconductive material. ９Ω・m or greater than 10 １５ Materials with a resistance of Ω·m or less are considered semiconductive materials.

[0019] If a firefly foreign particle approaches the firefly suppression portion 42 made of insulating material and the firefly suppression portion 42 becomes electrically charged by the charge carried by the firefly foreign particle, the firefly foreign particle may adhere to the surface of the firefly suppression portion 42. If an excessive voltage such as an impulse is applied to the high-voltage conductor 2 while the firefly foreign particle is attached to the firefly suppression portion 42, dielectric breakdown may occur, and corona discharge may occur. If the firefly suppression portion 42 is made of a semiconductive material, the charge carried by the firefly foreign particle will flow to the high-voltage conductor 2 via the semiconductive firefly suppression portion 42 and be lost, so the firefly foreign particle will not adhere to the surface of the firefly suppression portion 42.

[0020] Embodiment 2. Figure 2 is a diagram showing the configuration of an electric device according to embodiment 2. The foreign matter removal device 4 of electric device 40 according to embodiment 2 differs from embodiment 1 in that the firefly suppression unit 42 is recessed further than the shield ring 41. In embodiment 2, the distance between the firefly suppression unit 42 and the tank 1 is greater than the distance between the shield ring 41 and the tank 1.

[0021] 3 is an enlarged view of a foreign matter removal device for electrical equipment according to embodiment 2. Because the distance between the firefly suppression unit 42 and the tank 1 is greater than the distance between the shield ring 41 and the tank 1, the strength of the electric field E2 on the surface of the firefly suppression unit 42 is lower than the strength of the electric field E1 on the surface of the shield ring 41. Because the electrostatic force acting on the conductive foreign matter 61 is the product of the charge stored in the conductive foreign matter 61 and the electric field strength at the location where the conductive foreign matter 61 is present, the electrostatic force acting on the conductive foreign matter 61 at the firefly suppression unit 42 is smaller than the electrostatic force acting on the conductive foreign matter 61 at the shield ring 41.

[0022] 4 is a diagram illustrating the behavior of conductive foreign particles in the foreign particle removal device for electrical equipment according to the second embodiment. As shown in FIG. 4 , electric field lines EL1 generated on the surface of the shield ring 41 and electric field lines EL2 generated on the firefly suppression unit 42 move in a parallel motion so as to substantially converge in a space away from the shield ring 41 and the firefly suppression unit 42. The firefly foreign particles move by jumping along the electric field lines EL1 and EL2. In this situation, in the space where the electric field lines EL1 generated on the surface of the shield ring 41 and the electric field lines EL2 generated on the firefly suppression unit 42 move in a parallel motion, a phenomenon in which the firefly foreign particles move from the electric field lines EL1 generated on the surface of the shield ring 41 to the electric field lines EL2 generated on the surface of the firefly suppression unit 42, and a phenomenon in which the firefly foreign particles move from the electric field lines EL2 generated on the surface of the firefly suppression unit 42 to the electric field lines EL1 generated on the surface of the shield ring 41, occur randomly. This creates an opportunity for firefly foreign matter that would normally move toward the shield ring 41, which has a higher electric field, to move toward the firefly suppression unit 42, which has a lower electric field than the shield ring 41. Firefly foreign matter that reaches the firefly suppression unit 42 can no longer maintain its firefly state. Conductive foreign matter 61 that is no longer in a firefly state falls to the bottom of the tank 1 and enters the foreign matter capture container 43.

[0023] In the foreign matter removal device 4 of the electrical device 40 according to the second embodiment, the firefly suppression section 42 may be formed using an antistatic material or a conductive material. ９ A material with a resistance of Ω·m or less is considered a conductive material. When the fire-fly suppression section 42 is made of an antistatic material, the same effect as when the fire-fly suppression section 42 is made of an insulating material can be obtained. Furthermore, when the fire-fly suppression section 42 is made of a conductive material, the effect of cutting off the supply of charge to fire-fly foreign matter cannot be obtained, but the fire-fly foreign matter can be guided to the fire-fly suppression section 42, which has a low electric field, and therefore the fire-fly foreign matter can be efficiently removed.

[0024] 5 is an enlarged view of a foreign matter removal device for an electric device according to embodiment 3. In the foreign matter removal device 4 for an electric device 40 according to embodiment 3, a gap is provided between the firefly suppression portion 42 and the shield ring 41, forming a first groove portion 44. The rest of the foreign matter removal device 4 is the same as embodiment 2.

[0025] 5 is a diagram illustrating the behavior of conductive foreign particles in the foreign particle removal device for electrical equipment according to the third embodiment. As shown in FIG. 5 , electric field lines EL1 generated by the shield ring 41 and electric field lines EL2 generated by the firefly suppression unit 42 move in parallel so as to substantially converge in a space away from the shield ring 41 and the firefly suppression unit 42. The firefly foreign particles move by jumping along the electric field lines EL1 and EL2. In this situation, in the space where the electric field lines EL1 generated on the surface of the shield ring 41 and the electric field lines EL2 generated by the firefly suppression unit 42 move in parallel, a phenomenon in which the firefly foreign particles move from the electric field lines EL1 generated on the surface of the shield ring 41 to the electric field lines EL2 generated on the surface of the firefly suppression unit 42, and a phenomenon in which the firefly foreign particles move from the electric field lines EL2 generated on the surface of the firefly suppression unit 42 to the electric field lines EL1 generated on the surface of the shield ring 41, occur randomly. This creates an opportunity for firefly foreign matter that would normally move toward the shield ring 41 , which has a high electric field, to move toward the firefly suppression section 42 , which has a lower electric field than the shield ring 41 .

[0026] Similarly, the electric field lines EL2 generated in the fire-fly suppression unit 42 and the electric field lines EL3 generated in the first grooves 44 move in parallel so as to substantially merge in a space away from the fire-fly suppression unit 42 and the first grooves 44. Therefore, in the space where the electric field lines EL2 generated in the fire-fly suppression unit 42 and the electric field lines EL3 generated in the first grooves 44 move in parallel, a phenomenon in which a fire-fly foreign particle moves from the electric field lines EL2 generated on the surface of the fire-fly suppression unit 42 onto the electric field lines EL3 generated in the first grooves 44, and a phenomenon in which a fire-fly foreign particle moves from the electric field lines EL3 generated in the first grooves 44 onto the electric field lines EL2 generated on the surface of the fire-fly suppression unit 42, randomly occurs. This creates an opportunity for a fire-fly foreign particle that would normally move toward the fire-fly suppression unit 42, which has a higher electric field, to move toward the first grooves 44, which has a lower electric field than the fire-fly suppression unit 42.

[0027] In a configuration in which the firefly suppression portion 42 is recessed further than the shield ring 41, the greater the recession of the firefly suppression portion 42, the weaker the electric field, thereby significantly preventing firefly contaminants from maintaining a firefly state. On the other hand, if the difference between the strength of the electric field generated by the firefly suppression portion 42 and the strength of the electric field generated by the shield ring 41 increases, the probability that firefly contaminants will be attracted to the stronger electric field generated by the shield ring 41 increases, making it more difficult for the firefly contaminants to reach the firefly suppression portion 42. In the foreign matter removal device 4 of the electric device 40 according to the third embodiment, the firefly contaminants are first guided to the firefly suppression portion 42, and then to the first groove portion 44. Therefore, the foreign matter removal device 4 of the electric device 40 according to the third embodiment can efficiently guide the firefly contaminants to the first groove portion 44, where the electric field is weak, and remove the conductive foreign matter 61.

[0028] As with the foreign matter removal device 4 of the electrical device 40 according to the second embodiment, the firefly suppression section 42 can also be made of an antistatic material or a conductive material.

[0029] 6 is an enlarged view of a foreign matter removal device for an electrical device according to a modification of the third embodiment. In the foreign matter removal device 4 for an electrical device 40 according to the modification of the third embodiment, the firefly suppression unit 42 is composed of two ring-shaped insulating materials, and a second groove 45 is provided between the firefly suppression units 42. Because the distance between the firefly suppression unit 42 and the tank 1 is greater than the distance between the shield ring 41 and the tank 1, the strength of the electric field E3 on the surface of the firefly suppression unit 42 is lower than the strength of the electric field E1 on the surface of the shield ring 41. Furthermore, because the distance between the first groove 44 and the tank 1 is greater than the distance between the firefly suppression unit 42 and the tank 1, the strength of the electric field E4 of the first groove 44 is lower than the electric field E3 on the surface of the firefly suppression unit 42.

[0030] As described above, the electrostatic force acting on the conductive foreign object 61 is the product of the charge stored in the conductive foreign object 61 and the electric field strength at the location where the conductive foreign object 61 is present, and therefore the electrostatic force acting on the conductive foreign object 61 at the firefly suppression portion 42 is smaller than the electrostatic force acting on the conductive foreign object 61 at the shield ring 41. In addition, the electrostatic force acting on the conductive foreign object 61 at the first groove portion 44 is smaller than the electrostatic force acting on the conductive foreign object 61 at the firefly suppression portion 42.

[0031] 7 is a diagram showing the behavior of conductive foreign matter in a foreign matter removal device for an electrical device according to a modification of embodiment 3. In foreign matter removal device 4 for electrical device 40 according to the modification of embodiment 3, second grooves 45 are provided between firefly suppression sections 42, which makes it easier for firefly foreign matter to reach first grooves 44 or second grooves 45, thereby further improving the performance of removing conductive foreign matter 61.

[0032] Fourth Embodiment. Figure 8 is a diagram showing the configuration of a foreign matter removal device for electrical equipment according to a fourth embodiment. In the foreign matter removal device 4 according to the fourth embodiment, a recess is formed on the outer periphery of the shield ring 41, and a firefly suppression portion 42 is disposed inside the recess. The firefly suppression portion 42 is formed in a ring shape from a positively charged insulating material. An example of the positively charged insulating material is nylon, but other materials may also be used. A negative high-voltage DC voltage is applied to the high-voltage conductor 2. Furthermore, in the foreign matter removal device 4 according to the fourth embodiment, the high-voltage conductor 2 does not have a low-voltage portion.

[0033] Firefly foreign matter that has entered a firefly state on the shield ring 41 moves toward the outer periphery, which has a higher electric field. Because firefly foreign matter that has moved to the outer periphery of the shield ring 41 is negatively charged, it is attracted to the firefly suppression portion 42, which is likely to be positively charged. If the firefly foreign matter adheres to the firefly suppression portion 42, it is captured by the firefly suppression portion 42 and is no longer able to maintain the firefly state. The captured conductive foreign matter 61 remains attached to the surface of the firefly suppression portion 42, but because the firefly suppression portion 42 is disposed inside the recess and the surface of the firefly suppression portion 42 is recessed relative to the surface of the shield ring 41, there is no risk of the insulation performance deteriorating even if the conductive foreign matter 61 remains attached to the firefly suppression portion 42.

[0034] Although the above example shows a configuration in which a negative high-voltage DC voltage is applied to the high-voltage conductor 2, the same effect as above can be obtained by using a firefly suppression portion 42 formed in a ring shape from a negatively charged insulating material when a positive high-voltage DC voltage is applied to the high-voltage conductor 2. In other words, if the firefly suppression portion 42 is formed from an insulating material that has the property of being charged with an attribute opposite to that of the high-voltage DC voltage applied to the high-voltage conductor 2, firefly foreign matter can be attached to the firefly suppression portion 42 and captured.

[0035] Embodiment 5. Figure 9 is a diagram showing a closed state of a circuit breaker according to embodiment 5. Figure 10 is a diagram showing an open state of a circuit breaker according to embodiment 5. A circuit breaker 50 comprises a cylindrical tank 1, an opening / closing unit 24 having a movable electrode portion 51 and a fixed electrode portion 52, and a movable outer conductor 34 and a fixed outer conductor 36 disposed in a pair of bushings 22 extending above the tank 1. In the circuit breaker 50 according to embodiment 5, the tank 1 and the bushings 22 are integrally formed to form a sealed container in which insulating gas is sealed.

[0036] The movable-side end of the tank 1 is plate-shaped with a hole formed in the center. In the arrangement direction of the movable-side electrode section 51 and the fixed-side electrode section 52, the direction from the fixed-side electrode section 52 toward the movable-side electrode section 51 is referred to as the "movable side," and the direction from the movable-side electrode section 51 toward the fixed-side electrode section 52 is referred to as the "fixed side." In Figures 9 and 10, the movable-side electrode section 51 and the fixed-side electrode section 52 are aligned in the left-right direction on the paper, so the right side of the paper is the movable side and the left side is the fixed side.

[0037] The circuit breaker 50 has a cylindrical movable side frame 18 connected to the lower end of the movable side outer conductor 34, and a cylindrical fixed side frame 16 connected to the lower end of the fixed side outer conductor 36. The movable side frame 18 and the fixed side frame 16 are made of a conductive material.

[0038] The movable electrode section 51 includes a cylindrical puffer cylinder 92, a movable shield 93 provided at the fixed end of the puffer cylinder 92, a puffer piston 91 installed inside the puffer cylinder 92, a conductor rod 14 having a smaller diameter than the puffer cylinder 92 and fixed to the puffer piston 91, a movable contact 5a fixed to the conductor rod 14, and a nozzle 11 arranged around the movable contact 5a. The conductor rod 14 is connected to an insulating rod 12 which is connected to the shaft of an operating device (not shown) installed outside the tank 1 to operate the movable contact 5a. The puffer piston 91 surrounds the conductor rod 14 from the outer periphery of the tank 1, closing the gap between the conductor rod 14 and the puffer cylinder 92.

[0039] The fixed-side end of the movable-side frame 18 is a cylindrical portion 18a that is inserted into the puffer cylinder 92. A through-hole 18b extending in the axial direction of the cylindrical portion 18a is formed in the movable-side frame 18, and at least one point on the inner circumferential surface of the through-hole 18b is in contact with the conductor rod 14. Therefore, the movable-side outer conductor 34 is electrically connected to the movable-side contactor 5a via the movable-side frame 18 and the conductor rod 14. Furthermore, the fixed-side outer conductor 36 is electrically connected to the fixed-side contactor 5b via the fixed-side frame 16.

[0040] Between the movable-side outer conductor 34 and the fixed-side outer conductor 36, a DC current flows through the movable-side outer conductor 34, movable-side frame 18, conductor rod 14, movable-side contactor 5a, fixed-side contactor 5b, fixed-side frame 16, and fixed-side outer conductor 36. Therefore, each of the movable-side frame 18, conductor rod 14, movable-side contactor 5a, fixed-side contactor 5b, and fixed-side frame 16 forms part of the high-voltage conductor 2 to which a high DC voltage is applied.

[0041] The fixed electrode portion 52 has a fixed contactor 5b and a cylindrical fixed shield 15 that surrounds the fixed contactor 5b from the outer periphery of the tank 1. The fixed contactor 5b and the fixed shield 15 are supported by a fixed frame 16.

[0042] The movable electrode portion 51 is installed inside the tank 1 so as to be movable in the axial direction of the tank 1. In the fifth embodiment, a state in which the movable contactor 5a and the fixed contactor 5b are in contact is referred to as a "closed state," and a state in which the movable contactor 5a is separated from the fixed contactor 5b is referred to as an "open state." An operation of transitioning from the closed state to the open state is referred to as an "interrupting operation," and an operation of transitioning from the open state to the closed state is referred to as an "closing operation." The circuit breaker 50 switches between the open state and the closed state when the movable electrode portion 51 moves, causing the movable contactor 5a to come into contact with the fixed contactor 5b, or when the movable contactor 5a, which was in contact with the fixed contactor 5b, separates from the fixed contactor 5b.

[0043] In a closed state where the movable contact 5 a and the fixed contact 5 b are in contact, the fixed shield 15 and the movable shield 93 are in contact. In an open state where the movable contact 5 a is separated from the fixed contact 5 b, the movable shield 93 is not in contact with the fixed shield 15.

[0044] A through hole 91a is formed in the puffer piston 91. Therefore, a puffer chamber 32, which is a space surrounded by the puffer cylinder 92, the puffer piston 91, and the cylindrical portion 18a, is connected to the nozzle 11. During a breaking operation in which a closed state transitions to an open state, the volume of the puffer chamber 32 decreases, and insulating gas is sprayed from the nozzle 11 toward the fixed contact 5b. That is, during a breaking operation in which a closed state in which the movable contact 5a is in contact with the fixed contact 5b transitions to an open state in which the movable contact 5a is separated from the fixed contact 5b, the movable electrode portion 51 sprays insulating gas from the puffer chamber 32, which is a space formed between the puffer cylinder 92, the puffer piston 91, and the cylindrical portion 18a, toward the fixed contact 5b. An arc formed between the movable contact 5a and the fixed contact 5b during a breaking operation is cooled and extinguished by the insulating gas sprayed from the nozzle 11.

[0045] The movable frame 18 is provided with a foreign matter removal device 4a. The foreign matter removal device 4a is composed of a hollow movable shield ring 41a, a first air hole 42a connecting the interior space of the movable shield ring 41a with the puffer chamber 32, and a second air hole 43a connecting the interior space of the movable shield ring 41a with the space outside the movable shield ring 41a. The puffer chamber 32 is connected to the space outside the movable shield ring 41a through the first air hole 42a, the interior space of the movable shield ring 41a, and the second air hole 43a. In the foreign matter removal device 4a, the first air hole 42a and the second air hole 43a are movable firefly suppression units that prevent firefly foreign matter from maintaining a firefly state.

[0046] The fixed frame 16 is also provided with a foreign matter removal device 4b. The foreign matter removal device 4b is composed of a hollow fixed shield ring 41b, a third air hole 42b connecting the internal space of the fixed shield ring 41b with the internal space of the cylindrical fixed shield 15, and a fourth air hole 43b connecting the internal space of the fixed shield ring 41b with the external space of the fixed shield ring 41b. The internal space of the cylindrical fixed shield 15 is connected to the external space of the fixed shield ring 41b through the third air hole 42b, the internal space of the fixed shield ring 41b, and the fourth air hole 43b. In the foreign matter removal device 4b, the third air hole 42b and the fourth air hole 43b are fixed firefly suppression units that prevent firefly foreign matter from maintaining a firefly state.

[0047] When the volume of the puffer chamber 32 increases during the closing operation to transition from the open state to the closed state, insulating gas is sucked from the outside of the movable shield ring 41a through the second air holes 43a into the space inside the movable shield ring 41a. At this time, firefly foreign matter adhering to the movable shield ring 41a is sucked into the space inside the movable shield ring 41a through the second air holes 43a together with the insulating gas. Because the electric field strength inside the movable shield ring 41a is zero, the firefly foreign matter sucked into the space inside the movable shield ring 41a can no longer maintain its firefly state, so it falls into the interior of the movable shield ring 41a and is captured.

[0048] Furthermore, when the volume of the puffer chamber 32 increases during the closing operation, insulating gas is sucked from the outside of the fixed shield ring 41b through the fourth air hole 43b into the space inside the fixed shield ring 41b. At this time, firefly foreign matter adhering to the fixed shield ring 41b is sucked into the space inside the fixed shield ring 41b through the fourth air hole 43b together with the insulating gas. Because the electric field strength inside the shield ring is zero, the firefly foreign matter sucked into the space inside the fixed shield ring 41b can no longer maintain its firefly state, and falls into the interior of the fixed shield ring 41b and is captured.

[0049] When the volume of the puffer chamber 32 decreases during an interruption operation that transitions from a closed state to an open state, the insulating gas in the puffer chamber 32 is sprayed out of the movable shield ring 41 a through the first air holes 42 a, the space inside the movable shield ring 41 a, and the second air holes 43 a. At this time, firefly foreign matter adhering to the movable shield ring 41 a is blown away by the insulating gas blown out from the second air holes 43 a.

[0050] Furthermore, during the breaking operation, the insulating gas sprayed from the nozzle 11 toward the fixed contact 5b flows into the space inside the cylinder of the fixed shield 15 and is sprayed to the outside of the fixed shield ring 41b through the third air hole 42b, the space inside the fixed shield ring 41b, and the fourth air hole 43b. At this time, firefly foreign matter adhering to the fixed shield ring 41b is blown away by the insulating gas sprayed out from the fourth air hole 43b.

[0051] The circuit breaker 50 according to the fifth embodiment can efficiently capture and remove firefly foreign matter that has gathered on the surfaces of the movable shield ring 41 a and the fixed shield ring 41 b, which are subject to a high electric field, by sucking it into the space inside the movable shield ring 41 a and the fixed shield ring 41 b. Furthermore, firefly foreign matter that has not been sucked into the interior of the movable shield ring 41 a and the fixed shield ring 41 b is blown off from the surfaces of the movable shield ring 41 a and the fixed shield ring 41 b, which are subject to a high electric field, thereby preventing a decrease in insulation performance due to firefly foreign matter adhering to the surfaces of the movable shield ring 41 a and the fixed shield ring 41 b.

[0052] The configurations shown in the above embodiments are merely examples of the content, and may be combined with other known technologies, or parts of the configurations may be omitted or modified without departing from the spirit of the invention.

[0053] REFERENCE SIGNS LIST 1 Tank, 2 High voltage conductor, 3 Insulating spacer, 4, 4a, 4b Foreign object removal device, 5a Movable side contactor, 5b Fixed side contactor, 11 Nozzle, 12 Insulating rod, 14 Conductor rod, 15 Fixed side shield, 16 Fixed side frame, 18 Movable side frame, 18a Cylindrical portion, 18b, 91a Through hole, 22 Bushing, 24 Opening and closing portion, 32 Puffer chamber, 34 Movable side outer conductor, 36 Fixed side outer conductor, 40 Electrical equipment, 41 Shield ring, 41a Movable side shield ring, 41b Fixed side shield ring, 42 Firefly suppression portion, 42a First air hole, 42b Third air hole, 43 Foreign object capture container, 43a Second air hole, 43b Fourth air hole, 44 First groove portion, 45 Second groove portion, 47 Low electric field portion, 50 Circuit breaker, 51 movable electrode portion, 52 fixed electrode portion, 61 conductive foreign matter, 91 puffer piston, 92 puffer cylinder, 93 movable shield.

Claims

1. An electrical device comprising: a tank filled with insulating gas; a high-voltage conductor installed inside the tank and to which a DC voltage is applied; a foreign matter removal device for removing conductive foreign matter from inside the tank, wherein the foreign matter removal device comprises a ring-shaped shield ring with a curved outer periphery installed on the high-voltage conductor; and a firefly suppression unit installed on the outer periphery of the shield ring for preventing the conductive foreign matter from maintaining a firefly state in which it floats around the high-voltage conductor.

2. The electrical device according to claim 1, wherein the firefly suppression portion is a ring-shaped member made of an insulating material or an antistatic material.

3. The electrical device according to claim 2, wherein the firefly suppression portion is disposed recessed from the curved surface.

4. The electrical device according to claim 3, wherein a first groove is provided between said firefly suppression portion and said shield ring.

5. The electrical device according to claim 4, characterized in that it comprises a plurality of the firefly suppression parts, the plurality of firefly suppression parts being installed at intervals, and a second groove part being formed between the firefly suppression parts.

6. An electrical device according to any one of claims 1 to 4, characterized in that it is provided with a foreign object capturing container for capturing the conductive foreign object that falls when it is no longer able to maintain the firefly state.

7. The electrical device described in claim 2, characterized in that the firefly suppression portion is a ring-shaped member formed of an electrostatically charged material that has the property of being charged with the opposite polarity to the DC voltage applied to the high-voltage conductor, and is positioned recessed from the curved surface.

8. A device comprising: a cylindrical tank filled with insulating gas; a fixed electrode section having a fixed contactor installed inside the tank, and a movable electrode section having a movable contactor installed movably inside the tank, the device closing when the movable contactor comes into contact with the fixed contactor, and opening when the movable contactor separates from the fixed contactor; a movable frame supporting the movable electrode section inside the tank; a fixed frame supporting the fixed electrode section inside the tank; and a foreign matter removal device removing conductive foreign matter from inside the tank, each of the movable frame and the fixed frame being a high-voltage conductor to which a DC voltage is applied; the movable electrode section comprising: a puffer chamber whose volume decreases when the switching section is in an interrupting operation and whose volume increases when the switching section is in an closing operation; and a nozzle for spraying the insulating gas pushed out of the puffer chamber toward the fixed contactor when the switching section is in an interrupting operation; and the fixed electrode section comprising a cylindrical fixed shield covering the fixed contactor from the radially outer side of the tank. the foreign object removal device comprises: a movable shield ring, which is ring-shaped with a curved surface on its outer periphery and is installed on the movable frame; a fixed shield ring, which is ring-shaped with a curved surface on its outer periphery and is installed on the fixed frame; a movable firefly suppression unit, which is installed on the outer periphery of the movable shield ring and prevents the conductive foreign object from maintaining a firefly state in which it floats around the high-voltage conductor; and a fixed firefly suppression unit, which is installed on the outer periphery of the fixed shield ring and prevents the conductive foreign object from maintaining the firefly state.

9. The movable side shield ring and the fixed side shield ring have a hollow structure, the movable side firefly suppression part is a first air hole connecting the puffer chamber and the internal space of the movable side shield ring, and a second air hole connecting the internal space of the movable side shield ring and the external space of the movable side shield ring, the fixed side firefly suppression part is a third air hole connecting the internal space of the fixed side shield and the internal space of the fixed side shield ring, and a fourth air hole connecting the internal space of the fixed side shield ring and the external space of the fixed side shield ring, 9. The circuit breaker according to claim 8, wherein, during an interruption operation of the switching unit, the insulating gas pushed out of the puffer chamber is sprayed through the first air hole, the space inside the movable shield ring, and the second air hole into the space outside the movable shield ring, and the insulating gas blown out from the nozzle and flowing into the inside of the fixed shield is sprayed through the third air hole, the space inside the fixed shield ring, and the fourth air hole into the space outside the fixed shield ring; and during a closing operation of the switching unit, the insulating gas in the space outside the movable shield ring is sucked into the puffer chamber through the second air hole, the space inside the movable shield ring, and the first air hole, and the insulating gas in the space outside the fixed shield ring is sucked into the puffer chamber through the fourth air hole, the space inside the fixed shield ring, the space inside the fixed shield, and the nozzle.

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