JP2018116852A - Gas-blast circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem of a gas-blast circuit breaker that it is required to increase strength of a nozzle for a withstanding pressure rise when configuring to increase a blast gas pressure for interrupting a larger current, but when increasing a thickness of a member for increasing the strength of the nozzle, a size of the nozzle increases and a degree of freedom of design decreases, and since a breaking speed decreases due to an increase in weight, blocking performance deteriorates.SOLUTION: In a nozzle for a gas-blast circuit breaker controlling flow of arc-distinguishing gas, a material 30 having higher mechanical strength than that of a material of the nozzle is disposed in a part of an outer periphery of a nozzle 1, and a protective material 31 is disposed so that the part does not come into direct contact with arc-distinguishing gas.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gas circuit breaker used for interrupting a short-circuit current in an electric power system, and more particularly to a circuit breaker that interrupts a current by utilizing a mechanical compression action and a heating pressure raising action by arc heat, or both. is there.

  In general, power switchgears installed in substations and switchgears are circuit breakers that cut off current in the event of a short circuit in the power system, disconnectors that open and close the power system, and grounds that ground high-voltage conductors during inspections, etc. It has a switch. A circuit breaker, which is one of the switchgears, has a role of preventing a power system accident from spreading by quickly interrupting the accident current. In recent years, there is a tendency to increase the short-circuit breaking capacity at the time of an accident due to the introduction of renewable energy, looping of the grid connection, and power supply enhancement. In power circuit breakers, gas circuit breakers that contain electrical devices such as current-carrying conductors and circuit breakers in tanks filled with sulfur hexafluoride (hereinafter referred to as SF6) gas, which has high insulation and circuit breaker performance, are the mainstream. ing.

  The structure of the gas circuit breaker includes a mechanical puffer system that cuts off the current by blowing SF6 gas, which is an insulating gas, to the arc generated between the electrodes by utilizing the mechanical compression action, and the pressure by the thermal energy of the arc itself. There is a heat puffer system that increases, and a system that has both. In particular, a gas circuit breaker that uses both a mechanical puffer and a thermal puffer can reduce the operating energy required for the breaking operation compared to the conventional method using only mechanical compression, and improve the breaking performance. Can do.

  Insulating nozzles are used for efficient spraying of SF6 gas onto the arc. The insulating nozzle is generally formed of an organic material based on a fluororesin. The organic material is ablated when exposed to an arc, and the shutoff performance can be improved by using the gas generated by the ablation to increase the pressure inside the nozzle and the heat puffer chamber. For example, there are those described in Patent Document 1 and Patent Document 2.

  Patent Document 1 describes a gas circuit breaker for improving the shut-off performance by utilizing the ablation effect of the nozzle while preventing the speed reduction at the initial stage of the shut-off operation, and the blowing gas to the throat portion of the nozzle By placing an insulating material with low ablation effect on the upstream side of the flow to suppress the pressure rise and placing an insulating material with high ablation effect on the downstream side, a strong spray force can be obtained at the timing when the acceleration is sufficiently increased Thus, a puffer type gas circuit breaker with improved breaking performance is described.

  Patent Document 2 describes a nozzle for a gas circuit breaker excellent in electrical strength and mechanical strength, and arranges a material having high mechanical strength in which glass fiber is blended in a portion where mechanical strength is required, A material with less arc wear is disposed in the nozzle throat portion close to the arc.

JP 2010-2323201 A JP 2002-373561 A

  However, Patent Document 1 has a problem of ensuring the mechanical strength of the nozzle when the cutoff current increases. Moreover, in patent document 2, the glass fiber mix | blended for the reinforcement | strengthening of mechanical strength reacts with the decomposition gas of SF6 gas, glass fiber may be damaged, and a mechanical characteristic may fall.

  The present invention has been made in view of the above points. The object of the present invention is to increase the mechanical strength of the nozzle without increasing the size and weight of the nozzle and not to be affected by the decomposition gas of SF6 gas. Thus, an object of the present invention is to provide a highly reliable gas circuit breaker with excellent circuit breaking performance.

  In the gas circuit breaker of the present invention, in the gas circuit breaker nozzle for controlling the flow of SF6 gas, a material having a mechanical strength higher than that of the nozzle material is arranged on a part of the outer peripheral portion of the nozzle, and the part directly contacts the SF6 gas. It is characterized by arranging a protective material that does not touch.

  With the nozzle structure of the present invention, the thickness of the entire nozzle can be reduced by locally strengthening the portion that is deformed by the internal pressure of the nozzle, so that the movable part is reduced in weight, and the blocking speed can be reduced even with the operating force of the same operating device. The speed can be increased and the blocking performance is improved. Further, since it is not necessary to increase the thickness of the member in order to increase the strength of the nozzle, a degree of freedom in design is ensured. Furthermore, since the reinforcing material does not directly touch the arc extinguishing gas, the reinforcing material is not deteriorated, and durability and reliability can be ensured.

Schematic which shows the structure of the gas circuit breaker of Example 1. FIG. Sectional drawing which shows the modification of a nozzle by the internal pressure rise of a nozzle Sectional drawing of the nozzle which shows Example 1. Sectional drawing of the nozzle which shows Example 2.

  The present invention will be described below with reference to the drawings. The following are merely examples of implementation, and are not intended to limit the content of the invention to the following specific embodiments. The invention itself can be carried out in various modes as long as it conforms to the contents described in the claims.

  FIG. 1 is a schematic diagram showing the configuration (loading position, blocking position) of the gas circuit breaker according to the first embodiment. The gas circuit breaker is housed in a tank 10 filled with an insulating gas. The fixed-side arc electrode 5 and the movable-side arc electrode 4 are electrically connected. However, when an opening command is transmitted in the event of a short circuit failure in the power system, the movable unit 20 is moved to the direction of the actuator by the operator 7 via the shaft 6. The stationary arc electrode 5 and the movable arc electrode 4 are physically separated from each other. The movable portion 20 includes a nozzle 1, a movable side arc electrode 4, a cylinder 11, a movable side main contact 2, a fixed side main contact 3, and a mover cover 12.

  Even after the electrodes are separated, a current flows between the fixed-side arc electrode 5 and the movable-side arc electrode 4 to generate an arc. The gas circuit breaker extinguishes the arc by blowing high-pressure insulating gas onto the arc. In order to form a blowing pressure, a thermal puffer chamber 9 that takes in arc heat and raises the pressure and a mechanical puffer chamber 8 that increases the pressure by mechanical compression of the space are provided. A check valve (not shown) is provided between the mechanical puffer chamber 8 and the thermal puffer chamber 9. When the pressure in the thermal puffer chamber 9 is lower than the pressure in the mechanical puffer chamber 8, the check valve is open. The insulating gas is blown to the arc from the mechanical puffer chamber 8 through the heat puffer chamber 9 and the nozzle 1. When the pressure in the heat puffer chamber 9 is higher than the pressure in the machine puffer chamber 8, the check valve is closed, and the insulating gas that has become hot from the heat puffer chamber 9 to the machine puffer chamber 8 does not enter the machine puffer chamber 8. It is like that. In this case, the insulating gas is blown to the arc through the nozzle 1 with the pressure of the heat puffer chamber 9. A pressure release valve (not shown) is provided on the operating side of the mechanical puffer chamber 8 so that the pressure rise in the mechanical puffer chamber does not become excessive, and the reaction force to the operating unit 7 is suppressed, so that the operating level of the operating unit 7 is reduced. The power is realized.

  FIG. 2 is a sectional view showing a modification of the nozzle 1 when the internal pressure of the nozzle 1 is increased. The nozzle 1 is shown in cross section. In this case, the insulating gas in the heat puffer chamber 9 increased by the arc heat is blown to the arc generated between the fixed side arc electrode 5 and the movable side arc electrode 4 through the nozzle 1 to cut off the current. At this time, when the internal pressure rises from the holding portion of the nozzle 1 and the cross-sectional area of the nozzle 1, the nozzle bulge portion 40 of the nozzle 1 having a relatively thin thickness is deformed. When the current to be cut off increases, the internal pressure also increases, so the deformation of the nozzle bulge portion 40 of the nozzle 1 also increases. As the material of the nozzle 1, polytetrafluoroethylene (PTFE) resin is often used, and boron nitride (BN) or the like may be mixed in order to prevent the arc from being consumed. PTFE to which boron nitride is added has lower mechanical strength than pure PTFE. Therefore, if the pressure increase in the thermal puffer chamber 9 is increased in order to increase the amount of insulating gas sprayed for the purpose of improving the shut-off performance, the amount of boron nitride added should be reduced in order to increase the mechanical strength of the nozzle 1. It is necessary to increase the thickness of the nozzle bulge portion 40 of the nozzle 1. When the thickness of the member is increased in order to increase the strength of the nozzle, the size of the nozzle is increased and the degree of freedom in design is reduced. In addition, there is a problem in that the interruption speed is slowed by an increase in weight and the interruption performance is reduced.

  FIG. 3 shows the configuration of the nozzle 1 according to the first embodiment. The nozzle bulge portion 40 of the nozzle 1 shown in FIG. 3 is provided with a dent 32 that does not affect the mechanical strength in a part of the outer peripheral portion of the nozzle 1, and a material 30 having a high mechanical strength is disposed in the dent 32. A protective material 31 is arranged so that the material 30 having high mechanical strength does not directly touch the SF6 gas or the decomposition gas of SF6. With such a configuration, the mechanical strength against the increase in internal pressure of the nozzle 1 can be increased without increasing the thickness of the nozzle bulge portion 40 of the nozzle 1, so that the movable portion can be reduced in weight and the shut-off speed can be increased. Therefore, the interruption performance can be improved.

  As the material 30 with high mechanical strength, para-aramid fiber, ultrahigh molecular weight polyethylene fiber, polyarate fiber, PBO fiber, carbon fiber can be used as the material having higher mechanical strength than polytetrafluoroethylene (PTFE) resin. Applicable. Any material having higher mechanical strength than polytetrafluoroethylene (PTFE) resin can be used without limitation.

  A polytetrafluoroethylene (PFA) material of a tetrafluoroethylene resin can be used as the protective material 31 that prevents the material 30 having high mechanical strength from directly touching the SF6 gas or the decomposition gas of SF6. The PFA material is the same fluororesin as PTFE, and has excellent heat resistance, chemical resistance, and weather resistance like PTFE. Furthermore, PTFE does not fluidize even at temperatures above the melting point, but PFA has melt fluidity and can also be used as an adhesive for PTFE, so the material 30 with high mechanical strength can be stably fixed, and is high. Reliability can be ensured. Also, a polytetrafluoroethylene (PTFE) tube that shrinks when heat is applied to the protective material 31 can be used. In this case, the work process can be shortened and simplified as compared with PFA, so that high work efficiency can be realized.

  According to the present embodiment, the thickness of the entire nozzle can be reduced by locally strengthening the portion that is deformed by the internal pressure of the nozzle, so the movable part is reduced in weight and the shut-off speed is increased even with the operating force of the same operating device. And the shut-off performance is improved. Further, since it is not necessary to increase the thickness of the member in order to increase the strength of the nozzle, a degree of freedom in design is ensured. Furthermore, since the reinforcing material does not directly touch the arc extinguishing gas, the reinforcing material is not deteriorated, and durability and reliability can be ensured.

  FIG. 4 is a sectional view of the nozzle 1 showing the second embodiment. The nozzle tip side outer peripheral diameter 50 is smaller than the nozzle mounting side outer peripheral diameter 51. By adopting such a shape, it is possible to insert and slide the material 30 having a high mechanical strength and the protective material 31 which are annular from the tip end side of the nozzle, thereby improving the assemblability.

  According to the present embodiment, in addition to the effects of the first embodiment, the assemblability can be improved.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1: Nozzle 2: Movable side main contactor 3: Fixed side main contactor 4: Movable side arc electrode 5: Fixed side arc electrode 6: Shaft 7: Operating device 8: Mechanical puffer chamber 9: Thermal puffer chamber 10: Tank 11 : Cylinder 12: mover cover 20: movable part 30: material with high mechanical strength 31: protective material 32: depression 40: nozzle bulge part 50: nozzle tip side outer diameter 51: nozzle attachment side outer diameter

Claims (7)

In a sealed tank filled with insulating gas,
A fixed arc electrode and a movable arc electrode that can be contacted and separated; and
A space for increasing the pressure of the insulating gas during the shut-off operation;
In the gas circuit breaker comprising a nozzle for guiding the insulating gas flowing from the space whose pressure is increased in the arc generated by the separation of the fixed side arc electrode and the movable side arc electrode,
A gas circuit breaker characterized in that a material having higher mechanical strength than the material of the nozzle is disposed in a part of the outer peripheral portion of the nozzle. The gas circuit breaker according to claim 1,
The gas circuit breaker characterized in that the outer peripheral diameter on the nozzle tip side is smaller than the outer peripheral diameter on the nozzle mounting side. In the gas circuit breaker in any one of Claim 1 or 2,
A gas circuit breaker characterized in that a protective material is arranged so that the material having high mechanical strength does not directly touch the insulating gas. The gas circuit breaker according to any one of claims 1 to 3,
The gas circuit breaker characterized in that the material having high mechanical strength is any one of para-aramid fiber, ultrahigh molecular weight polyethylene fiber, polyarate fiber, PBO fiber, and carbon fiber. The gas circuit breaker according to any one of claims 1 to 4,
A gas circuit breaker characterized in that the protective material is a polytetrafluoroethylene material of tetrafluoroethylene resin. In the gas circuit breaker according to claim 3,
A gas circuit breaker characterized in that the protective material is a heat shrinkable tube that shrinks when heat is applied. In the gas circuit breaker according to claim 6,
The gas circuit breaker characterized in that the heat shrinkable tube is polytetrafluoroethylene.

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