JP2012150969A - Vacuum valve and tank type vacuum breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent explosive breakage of a ceramic housing serving as a vacuum vessel even though an opening operation of a breaker is conducted in a state that a degree of vacuum of a tank type vacuum breaker is low.SOLUTION: A vacuum valve includes: a vacuum vessel 26 enclosed by an external tank 12 and making a vacuum state therein; a pair of electrodes 22, 23 disposed in the vacuum vessel 26 so as to be separated from each other and contact with each other; a hole 26b formed on a bottom wall part 26a of the vacuum vessel 26; an internal pressure increase detection mechanism part 29 sealing the hole 26b from the outer side of the vacuum vessel 26 to maintain the vacuum state of the vacuum vessel 26 and conducting mechanical state change in conjunction with the increase of an internal pressure of the vacuum vessel 26, and a partial breakage detection part 30 detecting abnormality from the mechanical state change of the internal pressure increase detection mechanism part 29.

Description

  The present invention relates to a vacuum valve (vacuum interrupter) and a tank type vacuum circuit breaker, and in particular, when the circuit breaker is opened while the vacuum degree of the vacuum valve is lowered, the ceramic housing of the vacuum valve is explosive. The present invention relates to a technique for preventing damage.

  Conventional tank-type vacuum circuit breakers (VCB) of 72 kV class or higher used in electric power systems are externally filled with low-pressure SF6 (sulfur hexafluoride) gas and high-pressure dry air, which have excellent insulation performance, as insulating gas. In the tank, a ceramic vacuum interrupter (VI) accommodated as a circuit breaker is used.

  In addition, a metal shield is provided inside the vacuum interrupter in order to reduce the electric field gradient and protect the ceramic insulator.

  FIG. 3 is a cross-sectional view showing an example of a vacuum interrupter. In FIG. 3, a vacuum interrupter 1 includes an insulating ceramic casing 2 as a vacuum container, a movable electrode 3 having one end facing from the inside of the ceramic casing 2, and one end from the other end of the ceramic casing 2 inside. The bellows-like bellows support 5 provided on the inner side of the ceramic casing 2 so as to allow displacement along the axial direction of the movable electrode 3 in order to maintain the confidential state of the fixed electrode 4 facing the ceramic casing 2. And an internal shield 6 disposed inside the ceramic housing 2 in a separated state so as to include the movable range of both electrodes 3 and 4.

  When a vacuum break occurs in the vacuum interrupter, SF6 gas and dry air around the vacuum interrupter enter the inside of the vacuum interrupter. The main causes of vacuum break after the start of operation are small holes due to metal fatigue, such as metal bellows, and small holes due to lightning surge penetration beyond design, and the location of the vacuum break is extremely small.

  Further, the breaking performance of the tank type vacuum circuit breaker is lost when a vacuum breakage occurs in the vacuum interrupter, and even the normal load current cannot be cut off.

  This is because the pressure in the tank is almost the same as the pressure in the tank at once when a hole is opened in the vacuum interrupter. For this reason, a device for monitoring the vacuum degree drop of the vacuum interrupter is set as an option, but such a monitoring device is expensive and the monitoring device is an electronic device, so the monitoring device is updated every 10 to 15 years Since it is necessary to do this, it is the actual situation that is not widely spread (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 06-060780

Therefore, the vacuum valves that are currently used generally have the following problems.
(1) Even if the vacuum interrupter 1 is broken by vacuum, generally there is no vacuum monitoring device, and the vacuum break is not noticed. When the tank type vacuum circuit breaker is opened in this state, if the tank type vacuum circuit breaker is used in a loop system, the load is passed through the internal shield 6 of the vacuum interrupter 1 even after the tank type vacuum circuit breaker is opened. As the current flows, the internal shield 6 is melted and the internal pressure of the vacuum interrupter 1 is suddenly increased, the ceramic casing 2 as a vacuum vessel is destroyed, the arc extends to the upper part of the tank, and finally a ground fault occurs. There is a risk of progressing to a large-scale blackout.
(2) Cases where the load current (loop current) is small or the SF6 gas tank type vacuum circuit breaker may be able to cut off the current. ) In some cases, the tank type vacuum circuit breaker failure (vacuum breakage) will not be noticed if it does not progress to.
(3) When the vacuum interrupter 1 is physically destroyed, the vacuum interrupter 1 is in an explosive state, so that fragments may be scattered around and a secondary failure may occur.
(4) Even if the vacuum interrupter 1 is broken, the breakage of the vacuum interrupter 1 cannot be determined unless the tank-type vacuum circuit breaker is cut off and a continuity test, insulation resistance measurement, or open / close characteristic measurement is performed. That is, while the hole opened in the vacuum interrupter 1 is extremely small, it is difficult to judge, while it is difficult to suppress an increase in internal pressure due to the flow of gas exiting from the small hole, and there is a possibility that the housing breaks down from a sudden increase in internal pressure. .

  The present invention has been made in view of the above-described circumstances, and even if the circuit breaker is opened in a state where the vacuum degree of the tank-type vacuum circuit breaker is lowered, the ceramic casing which is a vacuum vessel is provided. An object of the present invention is to provide a vacuum valve and a tank type vacuum circuit breaker capable of preventing explosive destruction.

In order to solve the above-described problems, a vacuum valve according to the present invention includes a vacuum vessel surrounded by an external tank and having a vacuum inside, and a pair of electrodes disposed in the vacuum vessel so as to be able to contact and separate. A vacuum valve having a hole formed in a wall surface of the vacuum vessel, and sealing the hole from the outside of the vacuum vessel so as to maintain a vacuum state of the vacuum vessel. An internal pressure increase detection mechanism part that releases the sealing and mechanically changes its state when the pressure of the pressure exceeds a certain value, a partial destruction detection part that detects that the internal pressure increase detection mechanism part mechanically changes, It is provided with.
In addition, the pressure at the time of releasing sealing shall be set lower than the intensity | strength which a vacuum vessel can endure internal pressure. Here, the mechanical state change means mechanical displacement / deformation.

  In the vacuum valve of the present invention, sealing is performed from the outside of the vacuum container with a stopper or the like, and the sealing is released when the internal pressure of the vacuum container exceeds a certain value, so that the vacuum container is prevented from being broken and abnormal. The occurrence can be detected.

  In the vacuum valve according to the present invention, the internal pressure increase detection mechanism section is disposed below the fixed side electrode of the pair of electrodes, and the partial destruction detection section is disposed directly below the internal pressure increase detection mechanism section of the external tank. It is arranged at a position shifted along the axial direction.

  According to the present invention, it is possible to avoid the state change of the internal pressure increase detection mechanism section from hitting the partial destruction detection section directly.

  Further, in the vacuum valve according to the present invention, the internal pressure rise detection mechanism unit is installed between a plug that seals the hole so as to seal the inside of the vacuum vessel, and between the plug and the partial destruction detection unit. And a rupture portion that is provided in the middle of the detection body and is more easily ruptured than other portions, and the load applied when the internal pressure of the vacuum vessel rises and the stopper is pulled out. The partial break detection unit is turned on or off when the broken portion is broken.

  Thereby, it becomes possible to detect an increase in the internal pressure of the vacuum vessel only with a simple mechanical configuration, and an inexpensive and safe vacuum circuit breaker can be configured.

  Further, the vacuum valve according to the present invention is characterized in that the detector is arranged in an inclined state so that an axis is shifted with respect to a direction in which the stopper is pulled out. Thereby, it is possible to concentrate the load when the stopper is pulled out on the broken portion of the detection body.

  Preferably, the partial destruction detection unit is arranged outside the external tank. This makes it possible to place the partial destruction detector at a position that is not easily affected by the external tank or vacuum vessel. In addition to mechanical switches with an inexpensive and simple configuration, it is also possible to install highly accurate electrical sensors. It becomes possible.

  Furthermore, the vacuum valve according to the present invention is a movable contact type limit switch in which the partial destruction detector is turned on or off in conjunction with a change in the state of the detection body, and the limit switch reduces the vacuum degree of the vacuum vessel. When it is turned ON or OFF along with this, an external alarm is operated.

  Thereby, the notification means of a vacuum degree fall can be easily installed according to ON / OFF of a switch.

  In addition, a tank type vacuum circuit breaker according to the present invention includes any one of the above-described vacuum valves according to the invention. By constructing a vacuum circuit breaker using the vacuum valve according to the present invention, an inexpensive and safe vacuum circuit breaker can be realized.

  According to the present invention, even if the circuit breaker is opened in a state where the vacuum degree of the tank-type vacuum circuit breaker is lowered, it is possible to prevent the ceramic casing that is a vacuum vessel from being broken, It is possible to avoid situations that spill over into accidents. Further, since the occurrence of abnormality can be detected, the tank type vacuum circuit breaker can be appropriately replaced.

It is explanatory drawing of the tank type vacuum circuit breaker carrying the vacuum valve which concerns on one Embodiment of this invention. The vacuum valve of one Embodiment of this invention is shown, (A) is sectional drawing of a vacuum valve, (B) is sectional drawing of the principal part. It is sectional drawing of the conventional vacuum valve.

  Next, a vacuum valve according to an embodiment of the present invention will be described with reference to the drawings. In addition, although the Example shown below is a suitable specific example in the vacuum valve of this invention, and there may be a technically preferable various limitation, the technical scope of this invention limits this invention especially. Unless otherwise stated, the present invention is not limited to these embodiments. In addition, the constituent elements in the embodiments shown below can be appropriately replaced with existing constituent elements and the like, and various variations including combinations with other existing constituent elements are possible. Therefore, the description of the embodiment described below does not limit the contents of the invention described in the claims.

  FIG. 1 is an explanatory view of a tank type vacuum circuit breaker equipped with a vacuum valve according to an embodiment of the present invention, FIG. 2 shows a vacuum valve of an embodiment of the present invention, and FIG. FIG. 2B is a cross-sectional view of the main part.

(Overall configuration of tank type vacuum circuit breaker)
As shown in FIG. 1, a tank-type vacuum circuit breaker 10 includes an external tank 12 that is installed on a gantry 11 and is electrically grounded, a support plate 13 that is fixed to both ends of the external tank 12, and an external tank 12. A pair of bushing current transformers 14 supported on the upper surface, a bushing 15 supported on the upper end of the bushing current transformer 14, and the lower end pass through the bushing current transformer 14 and the bushing 15 and the lower end is inside the external tank 12. High voltage conductors 16, 17 facing the bushing terminal 18 provided at the upper ends of the high voltage conductors 16, 17, a vacuum valve (hereinafter referred to as “vacuum interrupter”) 19 provided inside the external tank 12, and It has. In addition, since the bushing current transformer 14, the bushing 15, the high voltage conductors 16 and 17, and the bushing terminal 18 are well-known, the detailed description is abbreviate | omitted here.

  The external tank 12 is filled with low-pressure SF6 gas or the like having excellent insulation performance for insulation between the main circuit parts such as the high voltage conductors 16 and 17 and the vacuum interrupter 19 and the external tank 12 having the ground potential. ing. In addition, a movable electrode 22 having one end supported by a drive mechanism 21 fixed to the internal support plate 20 and a fixed electrode 23 having one end fixed to the support plate 13 are provided inside the external tank 12. ing.

  The movable electrode 22 and the fixed electrode 23 are covered with a movable side shield 24 and a fixed side shield 25 that are electrically connected to the lower ends of the high voltage conductors 16 and 17. The movable-side shield 24 and the fixed-side shield 25 arranged so as to cover both ends of the vacuum interrupter 19 are formed of a conductive material such as an aluminum alloy or a copper alloy, for example, in the vicinity of both ends of the vacuum interrupter 19. Reduce the electric field concentration. Further, the movable electrode 22 is displaced along the axial direction by the drive of the drive mechanism unit 21.

(Configuration of vacuum interrupter 19)
As shown in FIG. 2A, the vacuum interrupter 19 is disposed so as to be able to come into contact with and separate from a vacuum container (housing) 26 surrounded by the external tank 12 and having a vacuum inside. A movable contact 22a and a fixed contact 23a provided at each other end of the movable electrode 22 and the fixed electrode 23, and an interior disposed inside the vacuum vessel 26 in a separated state so as to include a movable range of each contact 22a, 23a. A shield 27 and a bellows-like bellows support 28 that allows displacement along the axial direction of the movable electrode 22 so as to maintain the internal vacuum state of the vacuum vessel 26 are provided. Furthermore, as shown in FIG. 2, the vacuum interrupter 19 communicates with the vacuum vessel 26 so as to maintain the vacuum state, and is disposed outside the vacuum vessel 26. The internal pressure rise detection mechanism unit 29 that changes state automatically, and the internal state of the internal pressure rise detection mechanism unit 29 that mechanically changes as the internal pressure of the vacuum vessel 26 rises is detected electrically. A partial destructive detection unit 30 for detecting the occurrence of the above.

(Configuration of internal pressure increase detection mechanism 29)
The internal pressure rise detection mechanism 29 is provided on the bottom wall 26a near the lower side of the fixed electrode 23 of the vacuum vessel 26, and includes a hole 26b formed at a position off the shield 27 in the bottom wall 26a. A plug 32 fixed on the outer surface of the bottom wall portion 26a via an adhesive 31 so as to seal 26b, and a rod-shaped detector 33 having one end connected to the plug 32 are provided.

  The plug 32 is composed of a multi-stage (two-stage) cylindrical body having a small diameter at a portion engaged with the hole 26b by hard rubber or the like. Further, the stopper 32 seals the inside of the vacuum vessel 26 to ensure the degree of vacuum of the vacuum vessel 26. The stopper 32 functions as a safety valve because it can be removed from the hole 26b when the internal pressure of the vacuum vessel 26 rises and exceeds a certain value.

  The detection body 33 is formed in a rod shape from an insulating material, and a breakage portion 34 that is smaller in diameter (or lower in strength) than other portions and easily breaks is provided in the middle portion. Further, the detection body 33 is arranged in an inclined state so that the load load at the fracture portion 34 is easily concentrated with respect to the direction (vertical direction) in which the plug 32 is removed. In particular, it is preferable to arrange the detection body 33 so that the portion below the breakage portion 34 is not directly below the plug 32.

(Configuration of Partial Destruction Detection Unit 30)
The partial destruction detecting unit 30 turns on a metal case 35 provided outside the outer case 12, a mechanical movable contact type limit switch 36 provided inside the case 35, and a contact of the limit switch 36 ( A coil spring 37 biased in the make-up direction and an insulating bushing 38 fixed to the case 35 are provided. Note that the bushing 38 holds a contact (not shown) to which the limit switch 36 is electrically connected, and through this contact, an alarm lamp, an alarm buzzer or other notification means, or a remote monitoring control device signal input. Electrically connected to the terminal.

  The other end of the detection body 33 is connected to the limit switch 36, and resists the bias of the coil spring 37 so that it is in an OFF (break) state when the hole 26 a is closed in a sealed state by the plug 32. And set to pull. In addition, the limit switch 36 can be a low-cost and durable detection means basically using a simple mechanical switch of a movable contact type, but it is disposed outside the external tank 12. Therefore, for example, an electrical switch such as an infrared sensor that is blocked by the displacement of the detection body 33 can be applied.

(Function)
According to the above configuration, when the internal pressure (atmospheric pressure) of the vacuum vessel 26 is equal to or higher than a certain value (a value lower than the breaking pressure of the vacuum vessel 26), the portion where the vacuum interrupter 19 is partially broken is provided. Large-scale destruction of the vacuum vessel 26 itself is suppressed. In the present embodiment, as a part to be partially destroyed, the vacuum interrupter 19 is installed at a position deviated from between the contacts 22a and 23a, and the internal pressure ejection direction is also set below the vacuum interrupter 19. Yes. In addition, by adopting a structure in which the limit switch 36 is operated from the part of the vacuum interrupter 19 that is partially destroyed through the detection body 33, it is possible to easily determine the occurrence of partial destruction due to the increase in the internal pressure of the vacuum interrupter 19 from the outside. It has become.

  Specifically, the vacuum interrupter 19 includes a path through which no current flows when the vacuum interrupter 19 is opened when the vacuum is reduced (the current is directly discharged between the electrodes 22 and 23 or the internal shield from each electrode 22 and 23 is provided. 27), a round hole 26b is formed in the bottom wall portion 26a of the vacuum vessel 26, and the hole 26b is sealed with a stepped stopper 32. The stopper 32 is bonded and fixed to the bottom wall portion 26a of the vacuum vessel 26 with, for example, an adhesive 31 so that the stopper 32 is not accidentally detached due to long-term stability and the influence of vibration or the like when the vacuum interrupter 19 is operating. Note that the inside of the vacuum interrupter 19 is in a vacuum state, and since the stopper 32 has a stepped structure, an adhesive force always works on the bonding surface.

  The outside of the plug 32 is connected to one end of the detection body 33 and is mechanically connected via the detection body 33 to a limit switch 36 installed outside (or inside) the external tank 12. The limit switch 36 is provided inside a case 35 fixed to the outer wall of the external tank 12 and is urged in the ON direction by a coil spring 37. Normally, the limit switch 36 is turned off against the bias of the coil spring 37 by connecting the other end of the detection body 33 and the limit switch 36.

  Thereby, when the internal pressure of the vacuum vessel 26 is changed and the stopper 32 operates so as to be separated from the adhesive 31, the breaking portion 34 provided in the middle portion of the detection body 33 is broken, At the same time that the limit switch 36 is pulled by the detection body 33, the limit switch 36 is turned on by the bias of the coil spring 37.

  That is, when the tank-type vacuum circuit breaker 10 is opened when the vacuum of the vacuum interrupter 19 is lowered (loop current is released), in the vacuum interrupter 19 in which the vacuum is lowered, the path of the fixed electrode 23, the internal shield 27, and the movable electrode 22 The load current flows, the metal inner shield 27 is melted and metal vapor is generated, and the internal pressure of the vacuum interrupter 19 rapidly increases.

  When the internal pressure rises to a pressure at which the plug 32 overcomes the adhesive force of the adhesive 31, the internal pressure of the vacuum interrupter 19 is lowered by operating the plug 32 to be removed, and the detection body 33 connected to the plug 32 is moved. When the limit switch 36 is turned ON, an alarm can be output by an external alarm device or the like. At this time, the detection body 33 is provided so as to be inclined so that the axis is displaced with respect to the direction in which the plug 32 is pulled out (vertically below), so that the load applied to the fracture portion 34 is large and is set so as to be easily fractured. Yes.

  In addition, since the stopper 32 of the vacuum interrupter 19 is operated, the vacuum vessel 26 itself is not destroyed, and the discharge inside the insulating cylinder is continued, so that the time until the progress to the ground fault is greatly increased. In addition, the accident can be avoided manually by being notified by the accident removal by another relay or by the alarm of the vacuum interrupter 19 being broken.

As described above, the vacuum interrupter 19 according to the present embodiment can provide the following effects.
(1) Extending the time until the ground fault accident progresses when the vacuum interrupter 19 is broken The destruction of the vacuum vessel 26 can be suppressed, and it is possible to extend the time until the ground fault accident progresses. It is possible to improve the effect of suppressing the tie-up accident. In addition, the extending | stretching time until a ground fault accident and the current interruption possibility differ with the magnitude | sizes of a distribution current and the gas (for example, dry air and SF6 gas) with which the inside of the vacuum interrupter 19 was filled.
(2) Suppressing explosive destruction of the vacuum interrupter 19 Since the vacuum interrupter 19 is difficult to explosively break and only the plug 32 is removed, the components of the vacuum interrupter 19 other than the plug 32 and the detector 33 are scattered. Such secondary damage can be suppressed. Note that if the operating pressure at which the stopper 32 is pulled out is set low (for example, it can be adjusted by the bonding area, the type of the adhesive 31, etc.), the effect of suppressing secondary damage can be further improved).
(3) Grasping the vacuum interrupter 19 breakage The breaker breakage of the vacuum interrupter 19 can be easily grasped, and an alarm is output, so it is easy to respond to an accident (disconnect the tank-type vacuum circuit breaker 10 where the accident occurred) from the system. This can be done, and spillover accidents due to misjudgment of the accident location can also be suppressed.
(4) Extending the service life of the breakage detection function of the vacuum interrupter 19 The breakage detection function of the vacuum interrupter 19 does not employ an electrical sensor such as an infrared sensor or a vibration sensor to detect a change in state. By configuring with a simple article such as a mechanical contact (limit switch 36), it is possible to expect the same life as the tank type vacuum circuit breaker 10, and until the tank type vacuum circuit breaker 10 is updated (replaced), Maintenance management can be eliminated (when main parts such as limit switch 36 (contact point) are installed in dry air or SF6 gas section).

10 ... Tank type vacuum circuit breaker 19 ... Vacuum valve (vacuum interrupter)
DESCRIPTION OF SYMBOLS 22 ... Movable electrode 23 ... Fixed electrode 26 ... Vacuum container 26a ... Bottom wall part 26b ... Hole 29 ... Internal pressure rise detection mechanism part 30 ... Partial destruction detection part

Claims (7)

A vacuum valve comprising a vacuum vessel surrounded by an external tank and having a vacuum inside, and a pair of electrodes disposed in the vacuum vessel so as to be capable of contacting and separating,
A hole is formed in the wall of the vacuum vessel, and the hole is sealed from the outside of the vacuum vessel so as to maintain the vacuum state of the vacuum vessel, while the pressure in the vacuum vessel is a certain value or more. Then, the internal pressure increase detection mechanism unit that releases the sealing and mechanically changes its state,
A partial destruction detection unit that detects that the internal pressure increase detection mechanism unit has changed mechanically and outputs an alarm to the outside;
A vacuum valve characterized by comprising:   The internal pressure rise detection mechanism portion is disposed below the fixed side electrode of the pair of electrodes, and the partial destruction detection portion is displaced along the axial direction of the external tank from directly below the internal pressure rise detection mechanism portion. The vacuum valve according to claim 1, wherein the vacuum valve is disposed on the surface. The internal pressure rise detection mechanism unit includes a plug that seals the hole so as to seal the inside of the vacuum vessel, a detection body that is installed between the plug and the partial destruction detection unit, Provided with a breakage part provided in the middle part and easily breakable compared with other parts of the detection body,
3. The partial fracture detection unit is turned on or off when the fractured part is broken by a load applied when the internal pressure of the vacuum vessel rises and the stopper is pulled out. The vacuum valve described.   The vacuum valve according to claim 3, wherein the detection body is arranged in an inclined state so that an axis line is deviated with respect to a direction in which the stopper is pulled out.   The vacuum valve according to any one of claims 1 to 4, wherein the partial destruction detection unit is disposed outside the external tank.   The partial destruction detection unit is a movable contact type limit switch that is turned on or off in conjunction with a change in the state of the detection body, and when the limit switch is turned on or off as the vacuum degree of the vacuum vessel decreases. 6. The vacuum valve according to claim 1, wherein an external alarm is operated.   A tank-type vacuum circuit breaker comprising the vacuum valve according to any one of claims 1 to 6.

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