JP2015170544A - Gas-blast circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas-blast circuit breaker in which exhaust structure is made compact and besides, a high insulation recovery property between electrodes can be secured.SOLUTION: The gas-blast circuit breaker comprises a first tube body, a second tube body, a first hollow contact, a bar-like second contact, a gas blasting mechanism and a gas flowing mechanism. The first hollow contact is arranged near a position of a center axis of the first tube body. The second bar-like contact is fixed to a position of an approximate center axis of the second tube body and can be contacted with/separated from the first contact. The gas blasting mechanism blasts arc-extinguishing gas against an arc generated at a space between both contacts when the contacts are separated from each other when operating current breakage. The gas flowing mechanism has a plurality of blades arrayed in the first tube body into which gas flows and has a cross section area of a flow passage for gas, determined by intervals between the blades in a region where the plurality of blades exist, enlarged continuously toward an exhausting direction.

Description

  Embodiments described herein relate generally to a gas circuit breaker.

  2. Description of the Related Art A gas circuit breaker is known in which a movable contact and a fixed counter contact are disposed in a container filled with an arc extinguishing gas.

  In the case of this kind of gas circuit breaker, in order to obtain high arc extinguishing performance between both contacts, that is, between electrodes, it is necessary to efficiently exhaust the hot gas discharged from between the electrodes.

  In particular, a short-distance line failure (SLF) interruption causes a very steep transient recovery voltage to increase immediately after the current zero point, so that a sufficient amount of hot gas can be exhausted in a very short time of several microseconds after the zero point. It is necessary to complete and ensure high insulation recovery characteristics between the electrodes.

  In order to realize this quick exhaust of hot gas, for example, a structure is known in which an exhaust part having an enlarged flow path cross-sectional area is provided.

  In the gas circuit breaker having such a structure and good insulation recovery characteristics between the electrodes, quick exhaust is performed, so that the hot gas easily reaches the tip of the cooling cylinder.

  In particular, when a very high temperature and high pressure hot gas is discharged by a large arc energy, such as a terminal short-circuit fault (T100a) interruption at an asymmetric current of 100% of the rated breaking current, the open end of the cooling cylinder has been reached. The hot gas may cause dielectric breakdown (hereinafter referred to as a ground fault) in the space between the cooling cylinder and the container. For this reason, it is necessary to prepare a long cooling cylinder so that the hot gas does not reach the open end, and it is difficult to make the entire breaker compact.

  On the other hand, in order to make the gas circuit breaker compact, a device for efficiently cooling the discharged hot gas and enabling the use of a short cooling cylinder has been proposed.

  For example, by providing a structure such as a blade in the cooling cylinder and deflecting the hot gas in the circumferential direction, the mixing of the hot gas and the cold gas is promoted, and both quick cooling of the hot gas and recovery of the insulation performance are achieved. A technique has been proposed (see Patent Document 1).

Japanese Patent Application Laid-Open No. 08-161985

  However, installing a structure such as a blade in the flow path of the hot gas causes a reduction in the cross-sectional area of the flow path, so that an increase in static pressure occurs in the upstream flow path of the structure.

  Further, promoting mixing of hot gas and cold gas by flow deflection causes an increase in entropy and an increase in pressure loss, so that the dynamic pressure (kinetic energy) of the flow is significantly reduced.

  Therefore, a structure that causes a deflection of the gas flow hinders quick exhaust of the hot gas, which causes a decrease in insulation recovery characteristics between the electrodes. That is, in order to construct a compact gas circuit breaker, it is necessary to provide a margin for the arc extinguishing performance between the electrodes.

  In summary, the conventional gas circuit breaker has a problem that it is difficult to ensure a high insulation recovery characteristic between the electrodes when a large current is interrupted and to form a compact exhaust structure.

  The problem to be solved by the present invention is to provide a gas circuit breaker capable of ensuring high insulation recovery characteristics between electrodes while making the exhaust structure compact.

  The gas circuit breaker according to the embodiment includes a first cylindrical body, a second cylindrical body, a hollow first contactor, a rod-shaped second contactor, a gas blowing mechanism, and a gas flow mechanism. The first cylinder is filled with an arc extinguishing gas and is movable in the axial direction. The second cylinder is fixed in the movable direction of the first cylinder. The hollow first contact is arranged at a position substantially on the central axis of the first cylinder. The rod-shaped second contact is fixed at a substantially central axis position of the second cylinder, and can be contacted / separated from the first contact. The gas spray mechanism sprays an arc-extinguishing gas against an arc generated in a space between the contacts when the contacts are separated from each other during the current interruption operation. The gas flow mechanism includes at least one of the first cylinder, the second cylinder, the hollow first contact, and the space between the hollow first contact and the first cylinder through which gas flows. A plurality of blades are arranged in a row, and the cross-sectional area of the gas flow path determined by the interval between the blades in a region where the plurality of blades exists is continuously widened in the discharge direction.

It is a figure which shows the structure of the gas circuit breaker of 1st Embodiment. It is the figure which looked at the gas circuit breaker of FIG. 1 from the direction of the code | symbol A. It is BB sectional drawing of FIG. It is a figure which shows the structure of the gas circuit breaker of 2nd Embodiment. It is a figure which shows the structure of the gas circuit breaker of 3rd Embodiment. It is a figure which shows the structure of the gas circuit breaker of 4th Embodiment. It is a figure which shows the structure of the gas circuit breaker of 5th Embodiment.

Hereinafter, embodiments will be described in detail with reference to the drawings.
(First embodiment)
Drawing 1 is a figure showing the composition of the gas circuit breaker of an embodiment.

  As shown in FIG. 1, the gas circuit breaker according to the first embodiment includes a cylinder 24 as a first cylinder, a cooling cylinder 14 as a second cylinder, and a hollow disposed substantially at the position of the central axis of the cylinder 24. The operation rod 25 as the first contact, the counter arc contact 11 as the rod-shaped second contact fixed to the position of the substantially central axis of the cooling cylinder 14, the piston 31, and the tip of the piston 31. A gas spraying mechanism having an insulating nozzle 23 and a support 32, a movable energizing contact 22 provided around the insulating nozzle 23, a support 13 projecting from the cooling cylinder 14, and a counter supported by the support 13 A gas flow mechanism and a support 32 in which a plurality of blades 51 are arranged on the base portion 52 (support portion) of the arc contactor 11 are provided.

  The insulating nozzle 23 is for ensuring insulation between the central portion of the cooling cylinder 14 and the outer portion. A movable energizing contact 22 is provided around the insulating nozzle 23. The movable energizing contact 22 is fitted (contacted) to the inner wall of the cooling cylinder 14.

  The support 32 supports the cylinder 24 slidably. The support 32 is provided with a support opening 33. The support opening 33 is for escaping the gas in the support 32 to the outside. The end of the support 32 has a flange shape, and is fixed to another member (not shown).

  The piston 31 (valve) is fixed to the support 32 and partitions the open end of the cylinder 24. The counter arc contact 11 is fixed to the position of the central axis in the cooling cylinder 14 by a support 13.

  An arc extinguishing gas is filled in the cylinder 24, the cooling cylinder 14, and the hollow operation rod 25. The cylinder 24 is movable in the axial direction. The cooling cylinder 14 is provided fixed in the movable direction of the cylinder 24.

  The operation rod 25 is provided with an operation rod opening 25a. The operating rod opening 25a is for releasing the gas in the operating rod 25 to the outside. A movable arc contact 21 is provided at the tip of the operation rod 25. The movable arc contact 21 can be contacted (fitted) / separated from the opposing arc contact 11 according to the movement of the operation rod 25.

  The gas blowing mechanism is composed of a cylinder 24, an operating rod 25, a piston 31, a support 33, and the like. When the current interrupting operation is performed, the contacts (movable arc contact 21 and counter arc contact 11) are separated from each other. The arc extinguishing gas filled in the operating rod 25 and in the cylinder 24 is blown to the arc generated in the space between the two contacts in such a manner that it is pushed out to the piston 31 at the fixed position by the movement of the cylinder 24.

  The gas distribution mechanism includes a row of a plurality of blades 51 protruding from the counter arc contact 11 at a height corresponding to the width of the cooling cylinder 14 so that the gas rotates and flows in the cooling cylinder 14. The row of the plurality of blades 51 has at least a narrow interval (reference S2 in FIG. 3) through which gas passes and a wide interval (reference S3 in FIG. 3) after this narrow interval.

  In other words, the gas flow mechanism has a plurality of blades 51 arranged in a row on the base portion 52 of the counter arc contact 11, and a cross-sectional area of a gas flow path determined by an interval between the blades 51 in a region where the plurality of blades 51 exist. (Width) is continuously widened in the discharge direction.

  As shown in FIG. 2, the plurality of blades 51 are provided radially (petals) with the base 52 as the central axis, and the gas passing through the space between the blades 51, that is, the row of the blades 51 is spiral. To be flown into.

  That is, this gas circuit breaker is provided with a region 50 (widening portion) in which the flow path cross-sectional area continuously expands in the cooling cylinder 14, and the blades 51 are accelerated so as to accelerate the flow of hot gas toward this region 50. The columns are arranged.

  As shown in FIG. 3, the wings 51 have different widths at the front edge portion, the central portion, and the rear end portion. The rows of the blades 51 are arranged so that the center line of the front edge portion of the blades 51 is oriented in the same direction as the axial direction. The cross-sectional shape of each blade 51 is uniform in the radial direction.

  The distance between the blades 51 is a distance L1 at the front edge, a distance L2 at the center, and a distance L3 at the rear end, and the relationship between the distances is L1> L2 <L3. That is, the distance L2 at the center is narrower than the other distances L1 and L3.

  In this example, the blade 51 is formed such that the angle of the center line of the front edge portion becomes thicker (changes) in the radial direction toward the discharge direction. Further, the blade 51 is formed such that the angle of the center line of the rear edge thereof becomes narrower (changes) in the radial direction toward the discharge direction.

[Operation of First Embodiment]
In the first embodiment, when the hot gas discharged from the insulating nozzle 23 to the cooling cylinder 14 passes through the region of the row of blades 51, a part of the thermal energy of the hot gas is converted into kinetic energy. Is done. At the same time, the circumferential velocity component V3θ is induced at the outlet of the row of blades 51, so that the axial velocity component V3z (see FIG. 3) is smaller than the axial velocity V1 of the inlet of the row of blades 51. Become. For this reason, even when the cooling cylinder 14 with a short length is used, the time for the hot gas to reach the tip can be delayed.
[Effect of the first embodiment]
According to the first embodiment, the following effects can be obtained.
That is, in the row of blades 51 provided on the rod-shaped contact, the space between the blades 51 plays the role of a nozzle, so that the flow of hot gas flows when the hot gas passes through the gap between the rows of blades 51. It is accelerated in an isentropic manner.

  In the acceleration of the hot gas, the thermal energy of the hot gas is converted into kinetic energy, so that the gas velocity at the outlet of the row of blades 51 increases and the temperature decreases compared to the inlet. This is different from the conventional process in which the hot gas is cooled by promoting the mixing with the cold gas, and an increase in entropy and an increase in pressure loss when the hot gas is cooled can be minimized.

  At this time, the distance L2 between the blades 51 shown in FIG. 3 is the throat portion having the smallest flow path cross-sectional area. However, by providing the region 50 with the flow path cross-sectional area widened, the throat relative to the inlet distance L1 is provided. The throttling rate of the distance L <b> 2 can be suppressed, and the pressure increase on the upstream side of the row of blades 51 can be prevented.

  That is, it is possible to minimize the adverse effect on the insulation recovery characteristics between the electrodes by installing the structure such as the blades 51 in the flow path of the hot gas.

  The conditions for smoothly exhausting the hot gas in the row of blades 51, that is, the conditions for choking at the throat portion, are the cross-sectional area S1, the Mach number M1 of the blade row inlets M1, and the throat cross-sectional area S2. When used, it is expressed as follows from the relational expression of the compressible fluid.

  Here, γ represents a specific heat ratio and depends on the type of arc-extinguishing gas used. This equation (1) means that the optimum ratio of the inlet cross-sectional area S1 and the throat cross-sectional area S2 of the row of blades 51 depends on the blade row inlet Mach number. The gas circuit breaker needs to be compatible with all the breaking currents from the large current to the small current with the same shape.

の範囲で設定すればよい。 As a comparative example, a thermal fluid analysis was performed by changing the breaking current value for a breaker having an existing exhaust structure. As a result, the Mach number at the inlet portion of the row of blades 51 was 1.1 when a large current was cut off, and 0.2 when a small and medium current was cut off. It became about. That is, the optimum ratio of the cross-sectional area S1 and the throat cross-sectional area S2 of the inlets of the blades 51 depends on the most severe breaking current condition of the circuit breaker.

It may be set within the range.

The hot gas discharged downstream from the row of blades 51 becomes a swirl flow deflected in the circumferential direction according to the angle α with respect to the axial direction of the center line at the blade trailing edge. The relationship between the inlet velocity V1 of the row of blades 51 and the axial component V3z of the outlet velocity V3 of the row of blades 51 is
V1 <V3cos α = V3z (Formula 3)
By determining the angle α so as to be, even when the length of the cooling cylinder 14 is made shorter than before, the time for the hot gas to reach the open end of the cooling cylinder 14 can be delayed. And grounding of the container 3 can be prevented.

  When the present invention is applied to a gas circuit breaker that does not cause a ground fault between the cooling cylinder 14 and the container 3, for example, an insulator-type gas circuit breaker, the hot gas should be quickly moved away from the gap. For the purpose, the center line angle α = 0 of the trailing edge of the blade 51 may be set.

  Moreover, since the circumferential swirl flow can be obtained by the row of the blades 51, it is possible to expect a radial gas diffusion effect due to centrifugal force.

  Thereby, if the gas flow is stagnated downstream of the row of blades 51, the mixing effect of the cold gas and the hot gas can be promoted, and the length of the cooling cylinder 14 can be set shorter. The ratio of the cross-sectional area of the narrow portion of the throat portion of the row of blades 51 (the cross-sectional area of the portion at the distance L2) to the cross-sectional area of the outlet throat portion (the cross-sectional area of the portion at the distance L3) is appropriately determined, or By imparting a diffuser effect to the structure downstream of the row of blades 51, it is possible to control the flow downstream of the row of blades 51 and stagnate the gas flow.

  Even when the gas flow is stagnated downstream of the row of blades 51, choking at the throat portion of the row of blades 51 produces a supersonic flow, so that the insulation recovery characteristics between the electrodes are not affected.

  In this example, for the purpose of increasing the diffusion effect of the hot gas in the radial direction, the base portion 52 near the central axis that supports the row of blades 51 is tapered so that the hot gas is guided radially outward. It has a structure that guides.

  Although FIG. 3 shows an example of a cross section of the row of blades 51, the shape of this cross section may not be uniform in the radial direction. For example, although not shown, when the center line and the axial angle α at the trailing edge of the blade 51 are adjusted according to the radial position, the circumferential velocity V3θ of the hot gas is reduced in each radial direction downstream of the row of blades 51. Since it changes depending on the position, a shearing stress in the circumferential direction is generated, and the effect of further promoting the mixing of hot gas and cold gas can be obtained.

  Furthermore, as described above, it is important in this circuit breaker to realize isentropic acceleration in the row of blades 51 and convert the thermal energy into kinetic energy to lower the temperature of the hot gas.

  For this reason, although not shown in the figure, two or more rows of blades 51 may be arranged in series with the flow of the hot gas, and the effect of acceleration / cooling of the hot gas may be obtained a plurality of times.

  At this time, if sufficient cooling of the hot gas is achieved by the rows of the multistage blades 51, the cooling cylinders 14 downstream from the row of blades 51 may be omitted.

  As a result, by accelerating the hot gas while deflecting it in the circumferential direction, the mixing of the hot gas and the cold gas is promoted by the short cooling cylinder 14, and both the rapid cooling of the hot gas and the recovery of the insulation performance are compatible. Can do. That is, it is possible to ensure high insulation recovery characteristics between the electrodes while making the exhaust structure compact.

(Second Embodiment)
FIG. 4 is a view showing the arrangement of the blades of the gas circuit breaker according to the second embodiment.
As shown in FIG. 4, the row of blades 51 is arranged such that the center line V5 of the leading edge of the blades 51 is inclined by an angle β with respect to the axial direction (broken line) V2.

[Operation and Effect of Second Embodiment]
The gas circuit breaker described in the first embodiment has a sufficiently small circumferential velocity component of the hot gas generated between the electrodes. For this reason, as shown in FIG. 3, it may be considered that the flow direction of the hot gas at the inlet of the row of blades 51 has only the component of the axial direction V1, and the center line of the leading edge of the blade 51 is axially The row of wings 51 was configured to face in the same direction as V1.

  Thus, by directing the center line of the front edge portion of the blade 51 in the same direction as the axial direction, the hot gas in the row of the blades 51 can be smoothly accelerated.

  By the way, in a so-called rotary arc type gas circuit breaker in which an arc is rotated by a magnetic field, the hot gas is discharged at a circumferential speed by the interaction between the magnetic field and the arc.

  In order to adapt to such a case, in the second embodiment, the angle of the center line V5 of the leading edge of the blade 51 is set in the axial direction V1 according to the circumferential gradient β of the flow velocity at the inlet of the row of blades 51. Is inclined by an angle β to smoothly accelerate the hot gas in the row of blades 51.

  As a result of the magnetohydrodynamic analysis of the rotary arc type circuit breaker, the circumferential velocity component of the hot gas in the vicinity of the outlet of the insulating nozzle is at most equal to or less than the axial velocity component.

  Although it is necessary to optimize the angle of the center line V1 of the leading edge of the blade 51 depending on the configuration of the gas circuit breaker, the optimum angle is preferably between 0 ± 45 degrees with respect to the center line V1.

  Further, as described above, in the gas circuit breaker in which the hot gas is discharged from the insulating nozzle 23 with the circumferential rotational speed, there is a distribution in which the circumferential speed is present at the outlet portion of the insulating nozzle 23. For this reason, the angle and shape of the blades 51 may be optimized according to the distribution of the inflowing gas velocity to the row of blades 51 by changing the angle of the center line V1 at the leading edge of the blades 51 in the radial direction.

  As described above, according to the second embodiment, the row of the blades 51 is arranged such that the center line V5 of the leading edge portion of the blades 51 is inclined by the angle β with respect to the axial direction (dashed line) V2. The hot gas passing through the row of blades 51 with a circumferential speed is smoothly accelerated by the interaction between the arc and the arc.

(Third embodiment)
FIG. 5 is a diagram showing the configuration of the gas circuit breaker according to the third embodiment.
As shown in FIG. 5, in the gas circuit breaker of the third embodiment, a row of blades 51 similar to that of the first embodiment is arranged in a hollow operation rod 25.

  According to the third embodiment, when the gas filled in the hollow rod 25 is discharged from the hollow rod 25 through the operation rod opening 25a as the movable arc contactor 21 moves, the insulation between the electrodes is performed. The gas can be cooled without affecting the recovery characteristics. As a result, a ground fault between the support opening 33 and the container 3 can be prevented.

(Fourth embodiment)
FIG. 6 is a diagram showing the configuration of the gas circuit breaker according to the fourth embodiment.
As shown in FIG. 6, the gas circuit breaker of the fourth embodiment has a blade 51 similar to that of the first embodiment between the support 32 after the gas is discharged from the hollow operation rod 25 and the operation lot 25. The columns are arranged.

  According to the fourth embodiment, the hot gas that passes through the exhaust support 32 downstream of the hollow operation rod 25 and is discharged from the support opening 33 to the filling gas atmosphere space affects the insulation recovery characteristics between the electrodes. It can be cooled without any problems. As a result, a ground fault between the support opening 33 and the container 3 can be prevented.

(Fifth embodiment)
FIG. 7 is a diagram showing the configuration of the gas circuit breaker according to the fifth embodiment.
As shown in FIG. 7, in the gas circuit breaker of the fifth embodiment, the taper of the base portion 52 of the opposed arc contactor 11 is reversed from that of the first embodiment. That is, the taper is formed so that the diameter of the base portion 52 is continuously narrowed in the discharge direction.

  The cooling cylinder 14 has the same diameter without providing a widened portion. In the base portion 52, blades 51a whose heights to the cooling cylinder 14 continuously change in accordance with the taper are arranged. The blades 51a are continuously widened in the radial direction toward the gas outlet direction (discharge direction).

  In the fifth embodiment, the cooling cylinder 14 is provided with a region in which the cross-sectional area of the flow path continuously expands (arranged portion of the blades 51aa), so that when the hot gas passes through this region, the hot gas Can be accelerated isentropically.

  According to the fifth embodiment, the cross-sectional area of the gas flow path determined by the interval between the blades 51 in the region where the blades 51 exist is continuously widened in the discharge direction, that is, the arc extinguishing gas. Since the structure and arrangement of the blades 51 are such that they are accelerated when passing through the gaps between the blades 51, the flow of hot gas can be accelerated isentropically.

  That is, similarly to the first embodiment, the mixing of the hot gas and the cold gas can be promoted by the short cooling cylinder 14 to quickly cool the hot gas. As a result, high insulation recovery characteristics between the electrodes can be ensured while making the exhaust structure compact.

  Although the embodiment of the present invention has been described, this embodiment is presented as an example and is not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 3 ... Container, 10 ... Opposing contact part, 11 ... Opposing arc contact, 12 ... Opposing energizing contact, 13 ... Support member, 14 ... Cooling cylinder, 20 ... Movable contact part, 21 ... Movable arc contact, 22 DESCRIPTION OF SYMBOLS: Movable energizing contact, 23 ... Insulating nozzle, 24 ... Cylinder, 25 ... Operation rod, 25a ... Operation rod opening part, 31 ... Piston, 32 ... Support, 33 ... Support opening part.

Claims (8)

A first cylinder that is filled with arc-extinguishing gas and is movable in the axial direction;
A second cylinder fixedly provided in a movable direction of the first cylinder;
A hollow first contact element disposed substantially at the position of the central axis of the first cylindrical body;
A rod-shaped second contactor fixed at a substantially central axis position of the second cylinder and capable of contacting / separating with the first contact;
A gas blowing mechanism that blows off an arc extinguishing gas against an arc generated in a space between the two contacts when the contacts are separated during a current interruption operation;
A plurality of at least one position in the first cylinder, the second cylinder, the hollow first contact, and the space between the hollow first contact and the first cylinder through which the gas flows. And a gas flow mechanism in which the cross-sectional area of the gas flow path determined by the interval between the blades in a region where the plurality of blades exist is continuously widened in the discharge direction. Circuit breaker. The gas distribution mechanism is
A narrow space portion projecting from the rod-shaped second contactor at a height corresponding to the width of the second cylinder so that the gas rotates and flows through the second cylinder, and through which the gas passes. 2. The gas circuit breaker according to claim 1, comprising a plurality of blades having a wide interval portion after the narrow interval.   The gas circuit breaker according to claim 1, wherein the width of the gas flow path determined by the inner diameter of the cooling cylinder and the shaft diameter of the second contactor is continuously widened in the discharge direction. The ratio of the cross-sectional area S1 and the throat cross-sectional area S2 between the inlet portions of the blades into which the gas is introduced is as follows:
When expressed using the specific heat ratio γ of the gas,

The gas circuit breaker according to claim 1, wherein the gas circuit breaker is in a range of   5. The gas circuit breaker according to claim 1, wherein an angle of a center line of a leading edge portion of the blade is in a range of 0 ± 45 degrees with respect to an axial direction.   The gas circuit breaker according to any one of claims 1 to 5, wherein the blade is formed such that an angle of a center line of a front edge portion thereof changes in a radial direction.   The gas circuit breaker according to any one of claims 1 to 6, wherein the blade is formed such that an angle of a center line of a rear edge thereof changes in a radial direction.   The gas circuit breaker according to any one of claims 1 to 7, wherein a height in a radial direction of the blade is continuously increased toward an outlet direction of the gas.

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