JPH03245431A - Buffer type gas-blast circuit breaker - Google Patents

Abstract

PURPOSE:To enhance a breaking characteristic by supplying gas in a first buffer chamber into a second buffer chamber through a space between a stationary contact and a movable contact and a passing hole at the initial of a breaking operation, and shielding the passing hole of a partition plate by means of a projection of a buffer piston at the final of the operation so as to spray the compressed gas in the first buffer chamber to a space between the stationary and movable contacts. CONSTITUTION:In case where an advance small current is cut when a stationary arc contact 1 is brought into contact with a movable arc contact 5, the current can be cut despite of a short arc time since the current is small even if a movable contact unit 2 is moved with application of an opening command. After that, a buffer cylinder 4 is moved to compress gas at a speed relative to a movable partition plate 10, and consequently, gas in a first buffer chamber 9a is supplied into a second buffer chamber 9b through a space between the contacts 1 and 5 and a gas passing hole 11. The partition plate 10 is moved toward a buffer piston 8 by the effect of the compressed gas. With further movement, the partition plate 10 reaches a projection 8a of a piston 8 to shield the hole 11, and then, gas in a chamber 3a is compressed by the partition plate 10, to be thus sprayed between the contacts 1 and 2.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a puffer-type gas circuit breaker that compresses gas through the movement of a movable part to create a gas flow to cool and interrupt an arc when current is interrupted. In particular, the present invention relates to a gas circuit breaker with improved small current interrupting characteristics.

(Prior Art) Conventionally, when increasing the rated voltage of a circuit breaker, a multi-point disconnection structure was usually used because there was a limit to the withstand voltage value per one disconnection point. However, in recent years, due to improvements in breaking technology, circuit breakers with a reduced number of breaking points have appeared. On the other hand, as the number of breaking points of circuit breakers has decreased, the rated voltage per breaking has increased, making the duty of small currents more severe.

This advanced small current interruption can be performed even if the opening distance is small because the current is small, and after the current is interrupted, a voltage twice as high as the voltage before interruption is applied between the electrodes. Furthermore, as power transmission capacity increases, the breaking capacity of circuit breakers has also increased. For this reason, in conventional puffer type gas circuit breakers as shown in Figure 4, in order to improve the breaking performance, a large puffer cylinder is moved at a high opening speed to make the gas in the puffer chamber high pressure and spray it onto the arc. There is.

(Problems to be Solved by the Invention) As described above, when the gas pressure blown onto the arc is increased, the gas flow becomes faster, so the gas pressure decreases along the nozzle. As a result, under conditions where the current is small, such as when the current is required to interrupt a small current, the circuit will be shut off even with a short opening distance, and a high voltage will then appear between the poles, resulting in the possibility of re-ignition.

SUMMARY OF THE INVENTION An object of the present invention is to provide a puffer-type gas circuit breaker that does not cause re-ignition during small current interruption.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the above object, the present invention provides a first puffer chamber and a second puffer chamber.
A gas flow is blown between the fixed arc contact and the movable arc contact by causing gas to flow from the ml puffer chamber into the second puffer chamber through the gas flow hole in the movable partition plate provided between the ml puffer chamber and the second puffer chamber. The gas in the puffer chamber is compressed and blown between the arc contacts by closing the hole in the movable partition plate in the latter stage of electrode opening.

(Function) At the initial stage of electrode opening, the gas is fixed so as to flow from the first puffer chamber to the second puffer chamber through the gas flow hole of the movable partition plate provided between the first and second puffer chambers. A reduced gas flow is blown between the arc contact and the movable arc contact to minimize pressure drop and withstand the voltage applied across the arc contact after interruption.

(Example) FIG. 1 shows the structure of a gas circuit breaker according to an embodiment of the present invention.

The figure shows only the cut-off part and does not show the driving device.

In the figure, 1 is a fixed arc contactor. Reference numeral 2 denotes a movable contact portion, to which an operating rod 3, a puffer cylinder 4, a movable arc contact 5, a movable energizing contact 6, and a nozzle 7 are fixed.

The puffer cylinder 4 and the puffer piston 8 form a puffer chamber 9. The puffer chamber 9 has a movable partition plate 10
It is divided into a first puffer chamber 9a and a second puffer chamber 9b. The movable partition plate 10 is provided with a gas circulation hole 11 and is further fixed to the puffer piston 8 with a spring 12.

When the circuit breaker is in the closed state, the fixed arc contact 1 and the movable arc contact 5 are in contact. If the small current is cut off at this point, an open command is issued and the movable contact portion 2 moves to generate an arc. Since the current is small, the arc is interrupted even under conditions where the arc time is short. Thereafter, the puffer cylinder 4 continues to move and compresses the gas at a relative speed with the movable partition plate 1o. At this time, the gas in the first puffer chamber 9a flows into the second puffer chamber 9b through the space between the fixed arc contact 1 and the movable arc contact 5 and the gas communication hole 11. Furthermore, the movable partition plate 1o moves toward the puffer piston 8 side due to the compressed gas.

As the opening operation progresses further, the movable partition plate l appears as shown in Figure 2.
O reaches the protrusion 8a of the puffer piston 8, and the gas flow hole II is closed by the protrusion 8a. Thereafter, the gas in the first puffer chamber 9a is compressed by the movable plate lo and blown between the fixed arc contact 1 and the movable arc contact 5. FIG. 3 shows a comparison of the gas pressure at the tip of the fixed arc contactor 1 after current interruption between the conventional circuit breaker and the circuit breaker of the present invention. In the circuit breaker of the present invention, the first puffer chamber 9
The compressed gas in a is connected to the second puffer chamber and the fixed arc contact l.
In contrast to the conventional circuit breaker, the current flows only between the fixed arc contact 1 and the movable arc contact 5.

As a result, the pressure at the tip of the fixed arc contactor 1 is higher in the conventional circuit breaker. As the opening progresses further, the gas flow becomes faster near the point where the cross-sectional area created between the insulated nozzle 7 and the fixed arc contact 1 becomes larger than the cross-sectional area of the throat of the insulated nozzle 7. The pressure at the tip decreases (section A in Figure 3). Here, in the circuit breaker of the present invention, the drop in pressure is smaller than in the conventional circuit breaker (section B in FIG. 3). As a result, insulation recovery characteristics after current interruption are improved.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a puffer-type gas circuit breaker with improved advance breaking characteristics since the pressure drop at the initial stage of opening can be reduced compared to the conventional example.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the initial stage of opening of a puffer-type gas circuit breaker according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the subsequent opening process of the puffer-type gas circuit breaker shown in FIG. , 3rd
This figure is a diagram showing changes in pressure at the tip of the fixed arc electrode shown in FIG. 1. 1... Arc contactor, 2... Movable contactor, 4.
... Puffer cylinder, 5... Arc contactor, 8... Puffer piston, 8a... Projection, 9a... First buffer chamber, 10... Movable partition plate, 12... Spring. 7... Nozzle, 9... Puffer chamber, 9b... Second buffer chamber, 11... Gas distribution hole,

Claims (1)

[Claims] A container filled with arc-extinguishing gas has a separable fixed contact part and a movable contact part, and by compressing a puffer chamber consisting of a puffer piston and a puffer cylinder provided in the movable contact part. In a puffer-type gas circuit breaker, which compresses gas and guides it to a nozzle part, and blows it onto an arc occurring between a fixed arc contact and a movable arc contact, thereby cooling and extinguishing the arc, the It was fixed to the puffer piston with a spring so that it could move freely. A movable partition plate is provided to define the puffer chamber as a first puffer chamber and a second puffer chamber, and a communication hole is provided in the center of the movable partition plate to communicate the first puffer chamber and the second puffer chamber. In the early stage of the shutoff operation, the gas in the first puffer chamber flows into the second puffer chamber between the fixed arc contact and the movable arc contact and through the conduction hole, and in the latter stage of the shutoff operation, the gas in the first puffer chamber flows into the second puffer chamber between the fixed arc contact and the movable arc contact and through the conduction hole. A puffer-type gas circuit breaker characterized in that the communication hole is blocked by a protrusion of the puffer piston, so that the compressed gas in the first puffer chamber is blown between the fixed arc contact and the movable arc contact. .