Vacuum circuit breaker

Abstract

According to one embodiment of the present disclosure, a vacuum circuit breaker may include: a pressure vessel filled with an insulating gas of a predetermined pressure; a vacuum interrupter provided inside the pressure vessel and having a fixed electrode and a movable electrode in a vacuum tube in a vacuum state; a bellows provided to seal a gap between the vacuum tube and the movable electrode; a movable rod, one end of which is connected to an end portion of the movable electrode via an insulating link, and which is capable of penetrating the pressure vessel and reciprocating in an axial direction while maintaining airtightness; a drive rod which is provided outside the pressure vessel at the other end of the movable rod and which transmits the driving force of the drive unit to the movable rod; and a contact pressure spring, one end of which is supported by the movable rod and the other end of which is supported by the driving rod, in which a ratio of a self-closing force of the vacuum interrupter to a minimum closed contact pressure is set to a predetermined ratio.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a vacuum circuit breaker capable of applying appropriate self-closing force to secure the performance of a vacuum arc-extinguishing chamber disposed in a pressure vessel. BACKGROUND

[0002] In general, a vacuum circuit breaker can be a kind of circuit breaker installed in a high-voltage power system to protect the power system by breaking in the event of a dangerous condition such as a short circuit, overcurrent, etc., and can be designed by taking advantage of excellent insulation performance and arc-extinguishing ability in a vacuum state.

[0003] A core component of such a vacuum circuit breaker can be a vacuum arc-extinguishing chamber. The vacuum arc-extinguishing chamber can include a fixed electrode and a movable electrode, the movable electrode can be in contact with or separated from the fixed electrode in a sealed vacuum tube, and can perform the functions of energizing and breaking of an electric circuit by bringing the fixed electrode and the movable electrode into contact and separation.

[0004] In this case, since linear movement should be performed to bring the movable electrode into contact with or separation from the fixed electrode while maintaining the vacuum state inside the vacuum arc-extinguishing chamber, a bellows can be installed around the movable electrode.

[0005] The inside of the vacuum arc-extinguishing chamber can be in a vacuum state, and the outside thereof can be surrounded by a pressure vessel, to which an air pressure can be applied. Since the air pressure applied in the pressure vessel has a very significant influence on the operating characteristics of the vacuum arc-extinguishing chamber, the influence of the air pressure should be considered when designing a driving part or selecting a capacity.

[0006] For example, when the vacuum circuit breaker is applied to an extra-high voltage gas-insulated switch (hereinafter referred to as GIS), etc., the self-closing force of the vacuum arc-extinguishing chamber can change depending on the change in the air pressure in the pressure vessel depending on the operating temperature of the GIS. When the self-closing force has an inappropriate large value, an unnecessarily large degree of force can be required on the driving part, or an uneven contact load can be induced on the electrodes, which ultimately has a negative effect on the breaking performance of the vacuum arc-extinguishing chamber and the vacuum circuit breaker. SUMMARY TECHNICAL PROBLEM

[0007] An object of the present disclosure is to provide a vacuum circuit breaker capable of applying appropriate self-closing force to secure the performance of a vacuum arc-extinguishing chamber disposed in an inner space of a pressure vessel to stably maintain breaking performance regardless of a change in operating temperature.

[0008] In addition, another object of the present disclosure is to provide a vacuum circuit breaker capable of operating with the same driving force by a design capable of applying appropriate self-closing force. SOLUTION TO PROBLEM

[0009] According to an aspect of the disclosure, a vacuum circuit breaker can include a pressure vessel filled with an insulating gas of a predetermined pressure, a vacuum interrupter disposed in an inner space of the pressure vessel and having a fixed electrode and a movable electrode in a vacuum tube in a vacuum state, a bellows disposed to seal a gap between the vacuum tube and the movable electrode, a movable rod having one end connected to an end portion of the movable electrode through an insulating link and capable of reciprocating in an axial direction while penetrating the pressure vessel and maintaining airtightness, a drive rod disposed at the other end of the movable rod in an outer space of the pressure vessel and transmitting a driving force of a driving portion to the movable rod, and a contact pressure spring having one end supported by the movable rod and the other end supported by the drive rod, wherein a ratio of a self-closing force of the vacuum interrupter to a minimum contact point pressure is set to a predetermined ratio.

[0010] The ratio of the self-closing force of the vacuum interrupter to the minimum contact point pressure has a range greater than 0 and less than or equal to 0.1. Advantages of the Invention

[0011] According to an aspect of the disclosure, since a deviation of the self-closing force depending on a use temperature change does not affect the performance of the vacuum circuit breaker, an effect of eliminating a driving force variation can be achieved.

[0012] In addition, according to an embodiment of the disclosure, an effect of eliminating an unnecessary excessive driving force design element can be achieved by limiting the self-closing force to a predetermined range to minimize the influence of the self-closing force on the entire driving system. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a diagram illustrating a vacuum circuit breaker according to an embodiment of the disclosure. DETAILED DESCRIPTION

[0014] Hereinafter, the disclosure will be described in detail with the illustrative drawings. Figure 1 is a diagram illustrating a vacuum circuit breaker according to an embodiment of the disclosure.

[0015] The vacuum circuit breaker according to an embodiment of the disclosure can include a pressure vessel 10, a vacuum interrupter 20, a bellows 30, a movable rod 40, a drive rod 50, and a contact pressure spring 60.

[0016] The pressure vessel 10 can be a sealed container that accommodates the vacuum interrupter 20 of the vacuum circuit breaker. The outer space of the pressure vessel can be subjected to atmospheric pressure, and the inner space of the pressure vessel can be filled with an insulating gas having a pressure equal to or higher than the atmospheric pressure. For example, the air pressure in the pressure vessel can be 7.5 kgf / cm 2 but is not necessarily limited thereto.

[0017] The pressure vessel 10 can have a through-hole 11 formed on one side so that the movable rod 40 can pass through the pressure vessel and reciprocate in the pressure vessel. A sealing member 12 that maintains the internal airtightness of the pressure vessel can be interposed between the through-hole and the movable rod.

[0018] The vacuum interrupter 20 can be disposed in the internal space of the pressure vessel 10 and can include a fixed electrode 22 and a movable electrode 23 installed in a vacuum tube 21. The vacuum tube can be composed of a member formed of an insulating material, for example, in a cylindrical shape, but is not necessarily limited thereto. The internal space of the vacuum tube can be in a vacuum state close to 0 bar.

[0019] In the vacuum interrupter 20, the fixed electrode 22 can be installed to be fixed in the internal space of the vacuum tube 21.

[0020] In the vacuum interrupter 20, the movable electrode 23 can reciprocate in the axial direction, and one end portion can be in contact with or separated from the fixed electrode 22, and the other end portion can protrude outward through a through-hole 24 of the vacuum tube 21.

[0021] One side of the bellows 30 can be fixed to the vacuum tube 21 of the vacuum interrupter 20 and can seal a gap between the through-hole 24 of the vacuum tube and the movable electrode 23. The bellows can contract and extend in the axial direction so that the length in the axial direction can vary.

[0022] For example, the bellows 30 can be installed so that one end surrounds the through-hole 24 and the other end surrounds the outer peripheral surface of the movable electrode 23. The bellows can be disposed in such a manner that even if the bellows are expanded and contracted according to the operation of the movable electrode, the internal space of the vacuum tube 21 can be maintained in a vacuum state.

[0023] Accordingly, the bellows 30 can separate the vacuum pressure in the vacuum interrupter 20 and the air pressure in the pressure vessel 10.

[0024] One end of the movable rod 40 can be connected to the other end portion of the movable electrode 23 via an insulating link 41 and can transmit the driving force of the driving portion 5 to the movable electrode. The movable rod can reciprocate in the axial direction while maintaining the internal airtightness of the pressure vessel 10. To this end, the movable rod can be installed to slide by passing through the inside of the sealing member 12 installed in the through-hole 11 of the pressure vessel in a low-friction state.

[0025] This movable rod 40 can receive the driving force of the driving portion 5 from the driving rod 50 and transmit the driving force of the driving portion 5 to the movable electrode 23. In addition, the movable rod 40 can be subjected to the self-closing force of the vacuum interrupter 20 caused by the air pressure in the pressure vessel 10 and / or the force caused by the pressure difference between the internal space of the pressure vessel and the external space of the pressure vessel.

[0026] The insulation link 41 can be formed of an insulating material to electrically insulate the movable electrode 23 and the driving portion 5, and can transmit a driving force from the movable rod 40 to the movable electrode 23.

[0027] The driving rod 50 can be provided at the other end of the movable rod 40 outside the pressure vessel 10, and transmit a driving force from the driving portion 5 to the movable rod. The driving rod can reciprocate in the axial direction of the movable rod.

[0028] The driving rod 50 can be connected to the driving portion 5 via the driving link 51 and the rotation control rod 52, and can receive a driving force from the driving portion. The rotation control rod can be connected to the driving portion directly or through a reducer or the like to be rotated.

[0029] The driving portion 5 can include, for example, a motor or the like, and can generate a power by a control command or a manual operation of a user to rotate the rotation control rod 52.

[0030] The rotation force of the rotation control rod 52 can be transmitted to the driving link 51, and the position of the driving link can be changed according to the rotation of the rotation control rod such that the driving rod 50 can reciprocate in the axial direction of the movable rod 40.

[0031] The contact pressure spring 60 can be provided between the movable rod 40 and the driving rod 50, and one end can be supported by the movable rod and the other end can be supported by the driving rod. The contact pressure spring can be formed of, for example, a compression coil spring, but is not necessarily limited thereto, and can adopt any other shape of spring as long as it applies a force to the movable rod 40 toward the fixed electrode 22.

[0032] The contact pressure spring 60 can function to pressurize the movable electrode 23 and the fixed electrode 22 when the vacuum circuit breaker is thrown in. When the movable electrode is thrown in, the contact pressure spring under an assembled load at an open state can be compressed, and can provide a conductive contact pressure between the electrodes by pressing the electrodes in the vacuum arc chamber 20 with an increased operation load. In addition, the contact pressure spring can function to absorb an impact or a vibration generated when the vacuum circuit breaker is opened due to a short-circuit current.

[0033] For example, when the vacuum circuit breaker is applied to an ultra-high voltage GIS or the like, the gas pressure inside the pressure vessel can vary according to the operating temperature of the GIS. Accordingly, the self-closing force of the vacuum arc chamber 20 can vary, and the opening / closing speed of the vacuum circuit breaker can be affected, which can cause defects such as incomplete opening or excessively fast throw-in. Further, when the self-closing force has an inappropriately large value, the driving portion can be required with an unnecessarily large degree of force, or can cause an uneven contact load.

[0034] The vacuum circuit breaker according to an embodiment of the present disclosure is characterized in that a ratio of a self-closing force in the vacuum interrupter 20 to a minimum contact force can be set to a certain ratio.

[0035] For example, the self-closing force (F O ) of the vacuum interrupter 20 at a standard temperature (20℃) and a rated gas pressure can be defined as Equation 1 below.

[0036] [Equation 1]

[0037] F O = A B (P - P V ) - A R (P - P ATM )

[0038] In this case, A B is an effective cross-sectional area of the bellows 30, A R is a cross-sectional area of the movable rod 40, P is a gas pressure inside the pressure vessel 10, P V is a vacuum pressure inside the vacuum interrupter 20, and P ATM is an atmospheric pressure.

[0039] The effective cross-sectional area (A B ) of the bellows 30 can be obtained by, for example, dividing a pure pressure load (F N ) applied to the bellows by a pressure difference (△P) between an inner space of the bellows and an outer space of the bellows. The main load applied to the movable electrode can be a weight of the movable electrode 23, an elastic force of the bellows, and a pressure load caused by the pressure difference. Accordingly, the pure pressure load (F N ) can be obtained by subtracting a sum of the elastic force of the bellows and the weight of the movable electrode 23 from a total force applied to the bellows, and the pressure difference (△P) can be obtained by subtracting the vacuum pressure from the gas pressure.

[0040] When the rated breaking current of the vacuum circuit breaker is 40 kA, the contact force (F C ) of the vacuum interrupter 20 can be set to about 400 to 450 kgf. The contact force (F C ) can be defined as Equation 2 below.

[0041] [Equation 2]

[0042] F C = F O + F S

[0043] In this case, F S is an elastic force of the contact pressure spring 60.

[0044] The minimum contact force (F C.MIN ) of the vacuum interrupter 20 can be determined as a lower limit of the contact force (F C ).

[0045] In this case, the ratio of the self-closing force of the vacuum interrupter 20 to the minimum contact force can be F O / F C.MIN , and can have a range of -0.1 to 0.2. Preferably, the ratio has a range of about 0 < F O / F C.MIN ≤ 0.1.

[0046] As described above, according to one embodiment of the present disclosure, the interrelationship between the effective cross-sectional area (A B ) of the bellows 30, the cross-sectional area (A R ) of the movable rod 40, the pressure difference (P-P ATM ) between the inside and outside of the pressure vessel 10, and the pressure difference (P-P V ) between the inside and outside of the vacuum interrupter 20 can generate the self-closing force (F O ) of the vacuum interrupter, and by maintaining the self-closing force (F O ) of the vacuum interrupter at 0.1 times or less of the minimum contact force (F C.MIN ), the vacuum circuit breaker can be configured such that the deviation of the self-closing force depending on the temperature variation does not affect the performance of the vacuum circuit breaker.

[0047] Further, according to one embodiment of the present disclosure, the self-closing force can be limited within a predetermined range to eliminate an unnecessary excessive driving force design factor, and thus provide a vacuum circuit breaker in which the temperature variation and pressure fluctuation within the pressure vessel do not affect the opening / closing operation without increasing the number of components or costs.

[0048] The above description can be merely one example of the technical idea of the present disclosure, and those skilled in the art will understand that various modifications and changes can be made without departing from the essential characteristics of the present disclosure.

[0049] Therefore, the embodiments of the present disclosure are not intended to limit the technical idea of the present disclosure, but are for the explanation thereof, and the scope of the technical idea of the present disclosure is not limited by the embodiments. The scope of protection of the present disclosure should be interpreted by the appended claims, and all technical ideas within the equivalent scope thereof should be interpreted as being included in the scope of the right of the present disclosure. Industrial applicability

[0050] The present disclosure can be used in, for example, an extra-high voltage gas-insulated switchgear, etc.

Claims

1. A vacuum circuit breaker, comprising: a pressure vessel filled with an insulating gas at a predetermined pressure; a vacuum interrupter, the vacuum interrupter being provided in the inner space of the pressure vessel and having a fixed electrode and a movable electrode in a vacuum tube in a vacuum state; a bellows configured to seal a gap between the vacuum tube and the movable electrode; a movable rod having one end connected to the end of the movable electrode via an insulating connecting rod and capable of penetrating the pressure vessel and reciprocating in the axial direction while maintaining airtightness; a driving rod disposed at the other end of the movable rod in the external space of the pressure vessel and transmitting the driving force of the driving portion to the movable rod; as well as a contact pressure spring, one end of which is supported by the movable rod and the other end of which is supported by the drive rod, The ratio of the self-closing force of the vacuum interrupter to the minimum input contact pressure is set to a predetermined ratio. 2 . The vacuum circuit breaker according to claim 1 , wherein a ratio of the self-closing force of the vacuum interrupter to the minimum input contact pressure is -0.1 to 0.

2. 3 . The vacuum circuit breaker according to claim 2 , wherein a ratio of the self-closing force of the vacuum interrupter to the minimum input contact pressure is greater than 0 and equal to or less than 0.

1.

4. The vacuum circuit breaker according to any one of claims 1 to 3, wherein the self-closing force (F O ) is determined by equation 1 at a temperature of 20°C, the input contact pressure of the vacuum interrupter (F C ) is determined by equation 2, and the minimum input contact pressure of the vacuum interrupter (F C.MIN ) is determined as the input contact pressure (F C ) is: [Equation 1] F O =A B (P-P V )-A R (P-P ATM ) in, A B is the effective cross-sectional area of ​​the bellows, A R is the cross-sectional area of ​​the movable rod, P is the gas pressure in the pressure vessel, and P V is the vacuum pressure in the vacuum interrupter, P ATM is atmospheric pressure. [Equation 2] F C =F O +F S Among them, F S is the elastic force of the contact pressure spring.

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