JPH0265022A - Puffer-formed sf6 gas-blast circuit-breaker with delay puffuer - Google Patents

Abstract

PURPOSE:To aim at improving the insulation restoring characteristic after the circuit breaking by providing a delay puffer part for performing the blowoff of SF6 gas into an arc-extinguishing nozzle continuously even after the termination of the blowoff of the SF6 gas by means of the puffer part. CONSTITUTION:When a movable contact shoe 2 starts moving against a fixed contact shoe 1 by the circuit-breaking action command, the gas pressure in the main puffer part A rises, and an auxiliary puffer cylinder 7 integrated with one movable contact shoe 2 also moves so as to start pressing on a coil-formed spring body 8. The compressing action of the gas in the auxiliary puffer cylinder 7 is started with the delay of a certain period of time from the start of gas compression by the main puffer part A. When the gas pressure exceeds the gas pressure in the main puffer cylinder 3, the blowoff of the gas into an arc nozzle 5 by the cylinder 3 as well as the blowoff of the gas into an arc-extinguishing nozzle 5 by the auxiliary puffer cylinder 7 are started, Accordingly, the blowoff of the gas into the arc-extinguishing nozzle 5 can be performed continuously even after the maximum separation between the fixed contact shoe 1 and the movable contact shoe 2. The insulation restoring characteristic between the poles immediately after the circuit-breaking can be thus improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improving the breaking performance of buffer type SFs and gas circuit breakers.

(Prior art and its problems) A buffer type SF or gas circuit breaker, abbreviated as GCB, has a fixed contact (1), a movable contact ( 2), a buffer cylinder (3) with a gas blowing hole (3a) at the bottom that moves together with the movable contact (1), a fixed piston (4) coaxial with the cylinder (3), and a movable contact (2). ) and coaxial arc extinguishing nozzle (
5), etc., and operates as follows.

When a breaking operation command is given, the movable contact (2) moves to the first
It moves in the direction of the arrow shown in Figure (b) and starts separating from the fixed contact (1). On the other hand, the movement of the buffer cylinder (3) with respect to the fixed piston (4) during this opening operation process compresses the SFb gas in the cylinder (3), and the SF and gas with increased pressure are thereby discharged to the gas blowout hole. (3a) and is blown into the arc extinguishing nozzle (5). Therefore, the arc (6) generated between the fixed contact (1) and the movable contact (2) is quickly extinguished and interrupted.

However, with this conventional circuit breaker, for example, if the circuit breaker receives a second lightning strike due to multiple lightning strikes after cutting off the current, it may re-ignite and become unable to shut off the circuit, so it cannot ensure complete protection of the system.

(Objective of the Invention) The present invention aims to improve insulation recovery characteristics after current interruption, and maintains interruption ability in the event of re-ignition caused by multiple lightning strikes or the like.

(Means of the present invention for solving the problem) In the conventional buffer type SF6 gas circuit breaker, the buffer cylinder (3
) starts moving at the same time as the movable contact (1) starts moving, and stops at the same time it stops. Therefore, the buffer cylinder (3
), the gas pressure rises from the opening start point (near the opening point) and flows into the arc extinguishing nozzle (5) through the blowout hole (3a), as shown in the relationship between gas pressure and time shown in Figure 2. Start blowing out gas.

This gas blowout increases as the gas pressure within the cylinder increases and reaches its maximum near the midpoint. Thereafter, the pressure drops dramatically and reaches zero before the maximum opening, and the gas blowing almost ends before the maximum opening.

Therefore, if an overvoltage with a voltage value higher than the transient recovery voltage of the grid, for example due to multiple lightning strikes, enters immediately after the shutdown, flashover between the poles due to insufficient recovery of the insulation can be prevented, but a re-ignition state will occur, and the 2 It becomes impossible to shut off as shown in the current waveform shown in Figure 2. Note that during no-load interruption, no arc is generated and there is no pressure rise within the arc-extinguishing nozzle (5). Therefore, as shown by the dotted line in FIG. 2, the increase in gas pressure inside the buffer cylinder (3) is much smaller than that when the current is cut off, and the force of the gas blowing is also weak.

From the above, the present invention allows SF to continue to flow in the arc extinguishing nozzle for the required time even after the maximum separation point between the fixed contact and the movable contact.
This idea was created based on the idea that if gas could be blown out, sufficient insulation could be restored to prevent re-ignition caused by multiple lightning strikes, thereby improving the performance of buffer type SF6 gas circuit breakers. Next, the present invention will be specifically explained with reference to Examples.

(Embodiment) FIG. 3 is an explanatory diagram of an embodiment of the present invention, in which a conventional gas circuit breaker is provided with the following mechanism.

That is, as shown in the cross-sectional view of the closed state shown in FIG. 3(a), there is a hole inside the buffer cylinder (3) near the bottom on the outer periphery of the main buffer part A consisting of the buffer cylinder (3) and the fixed piston (4). An auxiliary cylinder (7) equipped with a communication hole (7a)
), an auxiliary piston (9) with one end open housing a coiled spring body (8) therein, and a fixed piston operating rod 00) that presses one end of the coiled spring body (8). Part B is provided so that the following effects can be obtained.

(Function) As mentioned above, when the movable contact (2) begins to move relative to the fixed contact (1) in response to the interruption operation command, the gas pressure in the main buffer section A increases as shown in Figure 4. .

On the other hand, as the movable contactor (2) moves, the auxiliary buffer cylinder (7) integrated with it also moves to the fixed piston operating rod 0.
0) direction. For this reason, the piston movement rod is 00)
starts pressing one end of the coiled spring body (8), and when the compression of the spring body (8) progresses beyond a certain value as shown in the diagram in the middle of the cutoff in FIG. 3(b), the spring body (8) A pressing force acts on the auxiliary piston (9) via. Therefore, as shown in Fig. 4, the compression operation of the gas in the auxiliary buffer cylinder (7) is started after a delay of time t from the start of gas compression by the main buffer section A, and the gas pressure is equal to the main buffer cylinder (3). ), the gas pressure in the cylinder (
3) starts blowing gas into the arc extinguishing nozzle (5), and the auxiliary buffer cylinder (7) starts blowing gas into the arc extinguishing nozzle (5), thereby reducing the pressure.

Therefore, if the strength of the coiled spring body (8) and the capacity of the auxiliary buffer cylinder (7) are selected, the maximum separation point between the fixed contact (1) and the movable contact (2) can be determined as shown in Fig. 4. Thereafter, SF6 gas can be continuously blown into the arc extinguishing nozzle (5), thereby improving the insulation recovery characteristics between the electrodes immediately after the interruption. Therefore, even if a flashover occurs between the poles due to a lightning strike caused by multiple lightning immediately after the current is interrupted, the interruption can be successfully accomplished as shown by the current in FIG. Note that the shaded area in FIG. 4 is the gas pressure enhancement effect bone according to the present invention.

Note that even in the case of no-load cutoff, the gas pressure is increased by the slow acting buffer section B of the present invention, as shown by the hatched area in FIG.

(Other Embodiments) The present invention has been described above with respect to a single flow type SF6 gas circuit breaker.
As shown in Figure (a) (the same reference numerals as in Figure 3 indicate the same parts), there is an exhaust hole (ll
A gas passage 01) having a) is provided, thereby creating a total of two gas flows, one into the arc extinguishing nozzle (5) and the other into the gas passage (11), as shown by the arrow in the figure. , it can also be applied to a device that promotes extinguishing of the generated arc (6) by providing a slow-acting buffer section B similar to that shown in FIG. 6 on the outer periphery of the main buffer section A. It is possible to improve the insulation recovery characteristics between Although FIG. 6(b) shows a state in which a cutoff operation is in progress, a description of that operation will be omitted.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a conventional single flow buffer type SF6 gas circuit breaker, Fig. 2 is an explanatory diagram of the general operation of a buffer type SF gas circuit breaker, and Fig. 3 is an explanatory diagram of an embodiment of the present invention. Figures 4 and 5 are explanatory diagrams of the operation during current cutoff and no-load current cutoff, and Fig. 6 is a double flow buffer type SF. FIG. 1 is a diagram showing an embodiment of the present invention in a gas circuit breaker. (1)...Fixed contact, (2)...Movable contact, A
...Main buffer section, (3)...Buffer cylinder,
(3a)... Gas blow-off hole, (4)... Fixed piston, (5)... Arc extinguishing nozzle, (6)... Generated arc, B... Slow acting buffer part, ( 7)... Auxiliary buffer cylinder, (8)... Coiled spring body, (9)
...Auxiliary movable piston, θ0)...Fixed piston operating rod, (IQ...Gas passage, (lla)...
Gas exhaust hole. Note 11 First 2nd illustration ■ Opening page ■ Poetry history If1 first edition 6th illustration

Claims (1)

[Claims] (1) In a buffer type SF_6 gas circuit breaker equipped with a buffer section that starts compressing SF_6 gas when the movable contact is opened and blows out SF_6 gas into the arc extinguishing nozzle due to the pressure increase, the movable contact It operates together with the opening to start compressing the SF_6 gas with a delay from the start of compression of the SF_6 gas by the buffer part, and continues to blow out the SF_6 gas into the arc extinguishing nozzle even after the buffer part finishes blowing out the SF_6 gas. A buffer SF_6 type gas circuit breaker with a slow acting buffer, characterized by being provided with a slow acting buffer section.