JPH0282419A - Buffer type gas circuit-breaker - Google Patents

Abstract

PURPOSE:To permit to take advantage of a larger part of arc energy generated in the initial stage of shutting off an electric current to raise pressure in a buffer chamber, by forming a communicating hole opening into a buffer chamber from the hollow portion of an exhaust cylinder, and installing a check valve that gives the passage of only a flow of gas being directed toward the buffer chamber from the hollow portion of the exhaust cylinder in the communicating hole on the way or at the end portion. CONSTITUTION:A communicating hole 9a opening into a buffer chamber 12 from the hollow portion of an exhaust cylinder 9 is formed near the position of a ceiling surface in the buffer chamber 12 while a check valve 15 that gives the passage of only a flow of gas being directed toward the buffer chamber 12 from the hollow portion of the exhaust cylinder 9 is installed in the communicating hole 9a on the way or at the end portion. Accordingly, the gas that is heated into a high-pressure gaseous body by electric arc on the inlet side of the exhaust chamber 9 flows through this communicating hole 9a into the buffer chamber 12 while the gas inflow continues until a difference in pressure between the buffer chamber 12 and the cylinder 9 on a hollow portion side thereof becomes zero, which contributes to a rise of pressure in gas present within the buffer chamber 12. Thus, in the initial stage of shutting off an electric current by a point of time when a stationary contact is pulled out of an insulating nozzle, a large part of gas having passed through the circumference of the electric arc on the inlet side of the exhaust cylinder flows back into the buffer chamber and also in such a condition as being heated to a high temperature.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is a buffer type gas that compresses arc-extinguishing gas such as SF & gas by moving a movable contact and leads this compressed gas to an arc. Regarding the circuit breaker! :19 As the configuration of the shutoff part, a metal container filled with arc-extinguishing gas,
A buffer cylinder cooperating with a movable contact disposed coaxially with a rod-shaped fixed contact; a fixed piston forming a buffer chamber between the buffer cylinder; and a fixed piston surrounding and integral with the movable contact. an insulating nozzle that guides the gas compressed in the buffer chamber into the separation gap of the fixed and movable recontactors; The present invention relates to a pan-hood type gas circuit breaker including an exhaust pipe that guides and discharges gas into a free space within the metal container.

[Conventional technology]

FIG. 3 shows an example of the configuration of a current interrupting section in a conventional buffer type circuit breaker. Inside the cylindrical metal container 1 filled with diffused pressure SF gas as an arc-extinguishing gas, there is an end plate 1 on the left side of the container.
A movable contact is disposed coaxially with a rod-shaped fixed contact 4 supported coaxially with the metal container 1 via an insulator 3 and moves in the axial direction of the fixed contact 4 to approach and separate from the fixed contact 4. 6, a fixed piston 8 that forms a buffer chamber 12 between the buffer cylinder 7, and a fixed piston 8 that surrounds the movable contact 6 at intervals and is integrated with the buffer cylinder 7. The insulating nozzle 5 guides the gas compressed in the buffer chamber 12 along its inside to the separation gap of the fixed and movable recontactor by moving the movable contactor 6 to the right when the current is cut off. A buffer chamber 12 is provided on the opposite side of the movable contact 6 to the fixed contact, and the gas heated by the arc between the fixed and movable contacts is guided to the free space inside the metal container 1. An exhaust pipe 9 discharging into the space is housed as a main component of the current interrupting section, and when a driving force in the X direction is transmitted from a drive device (not shown) through an insulating rod 11 at the time of interrupting the current, the movable contact 6 And the movable part integrally connected to this is
move in the direction.

FIG. 4 shows the initial stage of current interruption in the current interruption section configured as described above. In a state where the arc 13 generated between the fixed contact 4 and the movable contact 6 does not escape from the l-edge nozzle 5, the arc diameter becomes large in a large current region and attempts to block the inlet side of the exhaust pipe 9. Therefore, it is compressed in the buffer chamber 12 and the insulating nozzle 5
The gas guided to the arc along the inside of the buffer chamber 12 cannot freely flow into the exhaust pipe, and therefore the gas pressure in the buffer chamber 12 increases compared to when no current is applied. - On the other hand, the gas that flows into the exhaust stack after passing around the arc at the entrance of the exhaust stack, which is a little blocked by the arc, is heated to a high temperature by the arc and becomes high-pressure gas whose pressure rises, filling the hollow part of the exhaust stack. It heads downstream and is discharged from the exhaust port 10 into a wide space inside the metal container 1.

This type of arc extinguishing method, which extinguishes the arc by causing a blockage of the exhaust pipe inlet side with an arc at the beginning of the current cutoff, increases the pressure rise in the buffer chamber. In recent years, it has been widely used for large-capacity circuit breakers because the amount of gas that can be blown onto the arc is large.

C invention tries to solve! ! Problem] However, as mentioned above, the increase in gas pressure in the buffer chamber due to such a blockage structure is only due to the increase in the gas pressure in the buffer chamber due to the blockage, which prevents the gas from passing through the exhaust pipe inlet. Although the remaining gas passing through the inlet side and heading downstream is heated to a high temperature and given energy by the arc, it is only wasted away into a wide space inside the metal container. The arc energy until the fixed contact escapes from the insulating nozzle is not fully utilized.
In reality, the increase in gas pressure in the buffer chamber is still dominated by mechanical compression caused by the movement of the buffer cylinder, and the shutoff part is becoming smaller.

There were limits to the miniaturization of drive devices.

Therefore, by communicating the inside of the exhaust stack with the buffer chamber and preventing this hole from communicating with the free space inside the metal container until the specified stroke of the exhaust stack, the arc energy at the initial stage of current cut-off is reduced. A configuration that uses 100% arc energy for lifting has been disclosed.
(Refer to Japanese Unexamined Patent Publication No. 62-216126.) However, in this configuration, the gas space whose pressure is increased includes the space inside the exhaust stack in addition to the buffer chamber, so the total volume of the gas space becomes large. A possible problem is that the pressure increase effect of arc energy is not noticeable.

An object of the present invention is to provide a buffer cylinder which is disposed in a metal container filled with an arc-extinguishing gas and which operates in cooperation with a movable contact disposed coaxially with a rod-shaped fixed contact, and a buffer chamber between the buffer cylinder and the buffer cylinder. an insulating nozzle that surrounds and is integral with the movable contactor and guides the gas compressed in the buffer chamber into the gap between the fixed and movable recontactors; and the movable contactor. In a buffer type gas circuit breaker, the buffer type gas circuit breaker is provided with an exhaust pipe provided on the side opposite to the fixed contact of the child and which guides the gas heated by the arc in the separation gap to the free space in the metal container and discharges it into the space, It is an object of the present invention to provide a configuration of a current interrupting section that can utilize a larger portion of the arc energy at the initial stage of current interrupting to increase the pressure in a buffer chamber.

[Means to solve the problem]

In order to solve the above problems, the present invention includes a buffer cylinder that moves together with a movable contact disposed coaxially with a rod-shaped fixed contact in a metal container filled with arc-extinguishing gas; A fixed piston forming a buffer chamber between the buffer cylinder and the movable contactor surrounds and is integral with the movable contactor to supply the gas compressed in the buffer chamber to the separation gap between the fixed and movable recontactor. an insulating nozzle that guides the gas heated by the arc in the separation gap, and an exhaust pipe that is provided on the opposite side of the movable contact to the fixed contact and that guides the gas heated by the arc in the separation gap to a free space in the metal container and discharges the gas into the space. The configuration of the shutoff part of the buffer type gas circuit breaker is such that a communication hole is formed from the hollow part of the exhaust pipe to the buffer chamber, and a communication hole is formed in the middle or at the end of the cough communication hole from the hollow part of the exhaust pipe to the buffer chamber. A check valve that allows only gas flow to pass shall be provided.

[Effect]

In this invention, the exhaust pipe passes through the buffer chamber in the axial direction and is formed to have a considerable length, so that the pressure gradient in the axial direction of the exhaust pipe is gentle, and the exhaust pipe is formed at the position of the ceiling surface on the movable contact side of the buffer chamber. This method focuses on the fact that the cylinder gas pressure has a fairly high value. Therefore, a communication hole leading from the hollow part of the exhaust tube to the buffer chamber is formed near the ceiling of the buffer chamber, and only the gas flow from the hollow part of the exhaust tube toward the buffer chamber passes through the middle or end of the communication hole. When a reverse valve is installed, the gas heated by the arc at the exhaust pipe inlet side and becomes high pressure flows into the buffer chamber through this communication hole, and the pressure inside the buffer chamber and the pressure on the hollow side of the exhaust pipe are combined. The influx continues until the difference in
Contributes to an increase in gas pressure in the buffer chamber. in this way,
During the initial stage of current interruption until the fixed contact escapes from the insulating nozzle, a large portion of the gas that has passed around the arc at the exhaust stack inlet returns into the buffer chamber and is heated to a high temperature. , the amount of gas in the buffer chamber at the time when the fixed contact escapes from the insulating nozzle retains almost the same value as before the buffer cylinder moved, and the gas pressure in the buffer chamber is lower than if this amount of gas had been compressed in a cold state. shows an even higher value, and the gas pressure necessary to interrupt the current can be secured by the time the fixed contact escapes from the insulating nozzle.

〔Example〕

FIG. 1 shows an embodiment of the present invention. In the figure, the same members as in FIGS. 3 and 4 are designated by the same reference numerals, and their explanations will be omitted. The left end face of the buffer cylinder 7 is thick around the exhaust pipe 9, and a communication hole 9a communicating from the hollow part of the exhaust pipe 9 to the buffer chamber 12 is formed here. The buffer chamber outlet side of the communication hole 9a is provided with a spherical valve body 15a made of stainless steel, a spring 15b, and a spring support plate 15c to withstand the high temperature of the gas for a short time. A plurality of check valves 15 are formed to allow only the gas flow from the hollow part of the exhaust pipe to the buffer chamber to pass, and to block gas flow in the opposite direction. The spring 15b that determines the opening point of the check valve 15 is selected to have a small spring force so that it operates without delay when a pressure difference occurs between the hollow part of the exhaust pipe and the buffer chamber.

Of the gas flow 14a that flows toward the arc generated between the fixed and movable contacts at the initial stage of current interruption, the gas 14d that passes around the arc and flows into the exhaust stack takes a long journey to reach the exhaust port 10. A gentle pressure gradient is formed in the axial direction, and high pressure is generated at the entrance of the communication hole 9a by the gas heated to a high temperature. For this reason, a pressure difference is created between the hollow part of the exhaust pipe and the buffer chamber at this position, and a large portion of the heated gas flows into the buffer chamber through the plurality of communication holes. Increase gas pressure.

In Fig. 2, which shows the time change of gas pressure in the buffer chamber, reference numeral 16a indicates no-load t1' where no arc occurs.
16b shows the pressure change when the current is cut off in the cutoff section configuration of FIG. 3, and 16c shows the pressure change when the current is cut off in the cutoff section configuration of FIG. 1. This is the time when the movable contact is separated from the fixed contact (hereinafter referred to as the "opening time"), and the time origin in the figure indicates the time when the circuit breaker begins to operate. Since there is no arc from the start of the interrupting operation to the opening point t0, the pressure change is the same in all of the above cases, but after the opening point there is an arc, and in the interrupter configuration shown in Figure 3, As shown in FIG. 4, the gas that has passed around the arc only passes through the hollow part of the exhaust pipe 9 and is released into the wide space inside the metal container 1, so the pressure increase in the buffer chamber is ! III 1
As shown in Fig. 6b, the arc becomes thicker than when no load is applied only by the effect that the arc becomes an obstacle to the flow on the inlet side of the exhaust stack. A large portion of the gas heated to high temperature and under high pressure flows back into the buffer chamber through multiple communication holes, further increasing the gas pressure inside the buffer chamber while keeping the amount of gas in the buffer chamber almost constant. Therefore, the time change of the gas pressure in the buffer chamber becomes as shown in 16c, and the gas pressure necessary for shutting off can already be obtained at the time the fixed contact escapes from the insulating nozzle.

〔Effect of the invention〕

As described above, according to the present invention, there is provided a buffer cylinder cooperating with a movable contact disposed coaxially with a rod-shaped fixed contact in a metal container filled with arc-extinguishing gas, and a fixed piston forming a buffer chamber between the cylinder and the fixed piston surrounding the movable contact and being integral with the fixed piston;

an insulating nozzle for guiding the gas compressed in the buffer chamber into the separation gap of the movable front contact; and an insulating nozzle provided on the opposite side of the movable contact to the fixed contact to direct the gas heated by the arc in the separation gap to the metal. The shutoff part of a buffer type gas circuit breaker is equipped with an exhaust pipe that leads to a free space inside the container and discharges the gas into the space. A check valve is placed in the middle or at the end of the communication hole to allow only the gas flow from the hollow part of the exhaust pipe toward the buffer chamber to pass through, so that when the current is cut off, the movable contact moves and the fixed contact does not move. During the no-arc stage up to fJH, the check valve blocks the wasteful flow of gas from the buffer chamber to the hollow part of the exhaust stack.
After the arc was generated, the gas flow that was compressed in the buffer chamber and moved toward the arc inside the insulating nozzle passed around the arc. Most of the high-temperature, high-pressure gas flows back into the buffer chamber, keeping the amount of gas in the buffer chamber almost constant and further increasing the gas pressure in the buffer chamber. This is the point at which the fixed contact escapes from the insulating nozzle. It is possible to obtain a buffer-type gas circuit breaker that can obtain a sufficiently high gas pressure and can develop higher interrupting performance with a smaller interrupting part and a smaller drive device compared to circuit breakers of the same rating. .

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing the configuration of the shutoff section of a buffer type gas circuit breaker according to an embodiment of the present invention, and FIG. 2 is a temporal change in the gas pressure in the buffer chamber in the configuration of the shutoff section according to the conventional example and the embodiment of the present invention. Fig. 3 is a longitudinal sectional view showing an example of the configuration of the interrupting section of a conventional buffer type gas circuit breaker, and Fig. 4 shows the flow of gas during current interruption in the interrupting section configuration shown in Fig. 3. It is an explanatory sectional view. metal container, 4: fixed contact, 5: insulated nozzle, 6: movable contact, 7: buffer cylinder, 8: fixed piston,
9: Exhaust pipe, 9a: Communication hole, 12: Buffer chamber, 13:
Arc, 14d, 14e: Gas flow, 15: Check valve,
15a: Valve body.

Claims (1)

[Scope of Claims] 1) A buffer cylinder cooperating with a movable contact disposed coaxially with a rod-shaped fixed contact in a metal container filled with arc-extinguishing gas, and the buffer cylinder. a fixed piston forming a buffer chamber; an insulating nozzle that surrounds and is integral with the movable contact and guides the gas compressed in the buffer chamber into the gap between the fixed and movable contacts; a buffer type gas circuit breaker, comprising: an exhaust pipe provided on the side opposite to the fixed contact of the movable contact, which guides the gas heated by the arc in the separation gap to a free space in the metal container and discharges it into the space; A communication hole communicating from the hollow part of the exhaust tube to the buffer chamber is formed, and a check valve is disposed in the middle or at the end of the communication hole to allow only the gas flow from the hollow part of the exhaust tube to pass through. A buffer type gas circuit breaker characterized by: 2) In the buffer type gas circuit breaker according to claim 1, the exhaust pipe side entrance of the communication hole communicating from the hollow part of the exhaust pipe to the buffer chamber is located near the joint between the exhaust pipe and the movable contact. A buffer type gas circuit breaker characterized by: 3) In the buffer type gas circuit breaker according to claim 1, the check valve disposed in the middle or at the end of the communication hole that communicates from the hollow part of the exhaust pipe to the buffer chamber is configured to connect the hollow part of the exhaust pipe from the buffer chamber to the hollow part of the exhaust pipe. 1. A buffer-type gas circuit breaker characterized by having a valve body made of a heat-resistant metal as a valve body for blocking gas flow toward the gas.