JPS6282616A - Arc extinguisher - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a circuit breaker, and more particularly to an improvement of an arc extinguishing device for a circuit breaker equipped with a main contact and an arc contact.

[Conventional technology]

In a switchgear with a large current carrying capacity, the contact is divided into a main contact and an arc contact, and the main contact opens first, and the arc contact opens slightly later. This has been done conventionally, but due to the current carried by the main contact in the closed state, an arc is generated when the main contact opens, and as the breaking current increases or the number of times of switching increases. There is a problem in that the main contactor is damaged by arcing and the current carrying capacity is reduced. especially,
In a switchgear in which a movable contact device rotates around a fixed fulcrum to open and close, the length of the arm of the main contact is generally shorter than the length of the arm of the arc contact. The main contact is shorter than the L-shaped contact, and the main contact is located further away from the arc extinguisher than the arc contact, so the main contact is shorter during the breaking process. Once an arc occurs, it tends not to be extinguished easily, and high-speed arc extinguishing may not be possible in all the breaking current ranges imposed on the switchgear.

A contact device having such a structure is generally used in an air circuit breaker or a molded case circuit breaker with a relatively large rated current.

Therefore, in a circuit breaker with such a contactor device, when a large current is interrupted, the main contactor opens first to generate an arc, and then the arc contactor opens. The arc current initially generated in the main contactor is immediately commutated to the arc contactor, and the arc concentrated in the arc contactor is connected to the arc contactor or the arc contactor without commutating it to the main contactor again. It is necessary for the arc runner to carry the arc and finish the arc extinguishment.

An arc extinguishing method called the de-ion grid method has traditionally been used to extinguish arc current in large current type low voltage circuit breakers such as those mentioned above, and this has a figure-7 notch on one side. The arc extinguishing device includes a plurality of rectangular arc extinguishing plates made of magnetic material that are mutually insulated and integrally supported, and a movable arc contactor moves inside the notch space formed by each arc extinguishing plate of the arc extinguishing device. The arc extinguishing device is arranged to open and close, and the movable main contact faces the tip of the leg of each arc extinguishing plate of the arc extinguishing device.

In addition, arc extinguishing devices generally do not cover the legs of the multiple metal arc extinguishing plates at all, but
As disclosed in Japanese Patent No. 1417, all the legs and the tips of the legs of a plurality of arc-extinguishing plates are covered with a heat-resistant insulator.

However, the conventional method of covering the legs of the entire arc-extinguishing plate with a heat-resistant insulator is to prevent the legs of the arc-extinguishing plate from being abnormally worn out by the arc generated between the main contacts. .

[Problem that the invention seeks to solve]

By the way, in a circuit breaker in which a movable arc contact and a movable main contact are electrically arranged in parallel to an arc extinguishing device, the arc current of the main contact is transferred to the arc contact as quickly as possible. By rapidly moving and cooling the arc generated on the main contact to increase the arc voltage, the arc current is commutated to the arc contact that has not yet opened at this point. The movement and cooling of the arc of the main contactor is effectively extinguished by the leg portion on the notch side of the arc extinguishing plate of the arc extinguishing device that faces the movable main contactor.

Next, even once all the current is commutated to the arc contact, the arc pressure in the arc contact space increases as the arc energy increases, and the ionized arc gas tends to diffuse into the surroundings.

Most of this arc gas is sucked toward the arc extinguishing plate, but some of it flows backwards, which reduces the space dielectric strength between the main contacts, which are usually separated by a shorter distance than the arc contacts. This has the drawback that it can re-ignite between the two, causing re-commutation and making it difficult to shut off.

Therefore, the main purpose of this invention is to prevent recommutation of arc gas to the main contact due to backflow when the arc contact is interrupted;
Another object of the present invention is to provide an arc extinguishing device that can be effectively used to extinguish the arc current of the main contact.

[Means for solving problems]

The arc extinguishing device according to the present invention includes a shielding plate made of an insulator in which a portion necessary for moving the arm of a movable arc contactor and a lower portion of the arc extinguishing plate near the closing position of the main contactor are cut out. The movable main contact is attached to the end of the movable main contact to prevent arc gas from flowing back into the movable main contact in the process after the initial opening process of the main contact.

〔Example〕

An embodiment of the arc extinguishing device of the present invention is shown in FIGS. 1 to 4 of the drawings, and as shown in the drawings, the arc extinguishing device of the present invention includes a circuit breaker that can be opened and closed, and It mainly consists of arc-extinguishing plates made of a plurality of magnetic bodies supported and insulated at intervals corresponding to the movable contact device.

As shown in the figure, in a circuit breaker provided with the arc extinguishing device of the present invention, a second fixed terminal conductor 2 is provided at a distance from the first fixed terminal conductor 1. A fixed main contact 3 and a fixed arc contact 4 are attached. Further, the movable main contact device 5 has a movable main contact 6 mounted so as to come into contact with and separate from the fixed main contact 6, and an arm 7 of the movable main contact, and an arm 7 of the movable main contact that is mounted so as to come into contact with and separate from the fixed arc contact 4. The arms 9 of the movable arc contactor 6 having the movable arc contactor 8 arranged in parallel with each other are arranged in parallel with each other, and the arm 7 of the movable main contactor 6 is provided with the arms 9 of the movable arc contactor 8 on both sides.
The contact holder 11 is integrally attached to the contact holder 11 by a common shaft 10. The tail ends of the arms 7 and 9 of the movable main contactor 6 and the movable arc contactor 8 are connected to the second fixed terminal conductor 2 via flexible conductors 12 and 13, respectively.
A contact spring 14,15 is installed between the arms 7, 9 of each movable contact and the contact holder 11, and the movable main contact 6 and the movable arc contact 8
applying contact pressure to the

The contact holder 11 of the movable contact device 5 has a fixed frame (
contact holder shaft 16 (not shown)
The contact holder shaft 16 is pivoted to the open/close position by the movement of the opening/closing operation of the opening/closing mechanism member 18 which is supported by the contact holder 11 and connected to the contact holder 11 by a pin 17. An insulating crossbar 19 mounted on the upper part of the contact holder 11 is connected to the contact holder of the other pole so that the six poles of the circuit breaker operate together.

Rotation of the movable contact device 5 of such a circuit breaker.

During the operation, when opening the circuit, the movable main contact 6 first separates from the fixed main contact 6, and a little later, the movable arc contact 8 separates from the fixed arc contact 4. At this time, the movable arc contact 8 first comes into contact with and separates from the fixed arc contact 4, and a little later, the movable main contact 6 comes into contact with the fixed main contact 6.

The arc extinguishing device 20 of the present invention has a V-shaped notch 2 on one side.
Arc-extinguishing plate 21 made of a plurality of rectangular magnetic bodies having 1a
are arranged so as to be stacked at intervals and held on the support plate 22 in an insulated state. Notches 21a of a plurality of arc extinguishing plates 21 of such an arc extinguishing device 20
The movable arc contact 8 is inserted into the arc extinguishing device 20 so as to be able to open and close within the notch space 23 formed by the Arc-extinguishing plate leg portions 2 formed on both sides of the notch portion 21a of
The arc extinguishing device 20 is installed so as to face the tip edge 21C of the arc extinguisher 20.

Further, in the arc extinguishing device 20 of the present invention configured as described above, the portion 24 necessary for the movement of the arm 9 of the movable arc contactor 8, and the lower portion of the fixed and movable main contacts 6, 6 in the vicinity of the closed circuit state. A shielding plate 26 made of an insulator with the arc-extinguishing plate portion 25 cut out.
is attached to the end face of the arc extinguishing device 120 on the side facing the fixed and movable main contacts 3 and 6.

The breaking operation in a circuit breaker equipped with such an arc extinguishing device of the present invention begins with the fixed and movable main contacts 6. At the beginning of the opening of B, the arc generated between the fixed and movable main contacts 3 and 6 is magnetically driven toward the arc extinguishing plate portion 25 of the lower part where the shielding plate 26 of the arc extinguishing device 20 is not provided, and is extinguished. By dividing and cooling the arc with the arc plate 21, the arc voltage between the fixed and movable main contacts 6, 6 is increased, and the current of the fixed and movable main contacts 6, 6 is transferred to the fixed and movable arc contacts 4, 8. A part of the high-pressure, high-temperature arc gas caused by the arc generated between the fixed and movable arc contacts 4 and 8 during the subsequent opening process that is commutated and commutated to the fixed and movable arc contacts 4 and 8 is fixed. The shielding plate 26 prevents the flow from flowing backward toward the movable main contacts 3 and 6, and prevents the flow from recommuting between the fixed and movable main contacts 6 and 6.

5 to 8 show another embodiment of the arc extinguishing device of the present invention, in which the same parts as in the previous embodiment are given the same reference numerals, and the different parts will be explained below. , the shield plate 26 made of an insulator attached to the end face of the arc extinguishing device 20 on the side facing the main contacts 3 and 6 is deformed to create a slight gap between both sides of the arm 9 of the movable arc contact 8. Furthermore, opposing wing portions 26a are integrally added to the shielding plate 26, and a portion of the wing portion 26a is formed in the cutout portion 21 of the arc-extinguishing plate 21.
A further part projects toward the inside of the arc extinguisher, and another part projects toward the outside of the arc extinguishing device.

By providing the wing portions 26a on the shielding plate 26 in this way, fluid resistance is increased against the backflow of high-temperature, high-pressure arc gas generated between the fixed and movable arc contacts. The shielding effect for the main contact can be improved.

Furthermore, FIG. 9 shows a modification of the shielding plate 26 shown in FIG.
A groove 27 is provided on the surface facing the arm 9 of the wing section 26a to form an uneven surface.By forming the surface facing the wing section 26a unevenly, the airflow passing through against the reverse flow of arc gas becomes turbulent, and the fluid flow is further increased. This can increase the resistance and enhance the shielding effect.

〔Effect of the invention〕

As described above, according to the present invention, when the current is cut off, the initial arc generated between the fixed and movable main contacts 5 and 6 immediately after they are opened is removed from the lower stage not covered by the shielding plate 26. into the arc extinguishing device 20 through the arc extinguishing plate portion 25 of the arc extinguisher 20 to extinguish the arc between the fixed and movable main contacts, and quickly commutate the fixed and movable main contact current to the fixed and movable arc contacts. It also has the effect of preventing the high-temperature, high-pressure arc gas generated by the arc that is commutated and flowing between the fixed and movable main contacts from flowing back toward the fixed and movable main contacts. This has the effect of preventing re-ignition and re-commutation and improving the interrupting performance.

[Brief explanation of drawings]

1 to 4 show an embodiment of the arc extinguishing device of the present invention, in which FIG. 1 is a plan view, FIGS. 2 and 6 are side sectional views showing a closed circuit state and an open circuit state, respectively, and FIG. FIG. 4 is a perspective view of the main parts, and FIGS. 5 to 8 show other embodiments of the arc extinguishing device of the present invention. FIG. 5 is a plan view, and FIGS. 6 and 7 are in a closed circuit state. FIG. 8 is a perspective view of a main part, and FIG. 9 is a perspective view of a main part showing still another modification of the shielding plate of the arc extinguishing device of the present invention. In the figure, 1, 2:
Fixed terminal conductor, 3: Fixed main contact, 4: Fixed arc contact, 5: Movable contact device, 6: Movable main contact, 7, 9:
Arm, 8: Movable arc contactor, 11: Contact holder, 12.15: Flexible conductor, 14.15: Contact spring, 18: Opening/closing mechanism member, 19: Cross bar,
20: arc extinguishing device, 21: arc extinguishing plate, 21a: notch, 2
1b: arc extinguishing plate leg, 21C: tip edge, = 22: support plate,
26: Notch space, 25: Arc-extinguishing plate portion, 26: Shielding plate, 26a: Wing portion, 27: Groove.

Claims (1)

[Claims] 1. A fixed and movable main contact that can be opened and closed, and a main contact that is electrically installed in parallel with the fixed and movable main contact, and that contacts in advance when closing and opens after a delay when breaking. An arc extinguishing device is provided in which fixed and movable arc contacts are spaced apart from each other, and arc extinguishing plates made of a plurality of rectangular magnetic bodies each having a V-shaped notch on one side are supported in an insulated state at a distance from each other. The movable arc contactor is disposed to open and close within a notch space formed by each of the arc extinguishing plates, and the movable main contact is disposed to face a tip of a leg of each of the arc extinguishing plates. A shielding plate made of an insulator is provided, in which a portion necessary for the movement of the arm of the movable arc contactor and a lower arc extinguishing plate portion near the closing position of the fixed and movable main contacts are cut out. It is attached to the end face of the arc extinguisher on the side opposite to the fixed and movable main contacts, and prevents arc gas from flowing back to the movable main contacts in the process after the initial opening process of the fixed and movable main contacts. arc extinguishing device. 2. The arc extinguishing device according to claim 1, wherein the cutout portion of the shielding plate has wing portions facing both sides of the arm of the movable arc contact with a slight gap. . 3. The arc extinguishing device according to claim 2, characterized in that the wing portion of the shielding plate has irregularities on the surface facing the arm of the movable arc contactor.