CN2344860Y - Grid interrupter with V-termination - Google Patents

Abstract

A novel grid arc extinguishing chamber for direct-acting AC contactors. The grids are placed vertically, and the outermost grid has a V-shaped end protruding toward the contact area. This arc extinguishing chamber combines vertical and The advantage of placing the grids in parallel, on the one hand, the V-shaped end improves the electric field distribution of the arc extinguishing chamber, enhances the arc blowing magnetic field and promotes the smooth flow of air, and on the other hand allows the arc to contact the grids earlier, thus greatly improving the breaking time. The performance and electrical life of the contactor under the working condition of 660 volts AC-4 have been proved by the experiment of the nationally recognized testing center: After the CJ20-40A AC contactor is replaced with the above-mentioned arc extinguishing chamber, it can be used under the working condition of 660 volts AC-4 Can achieve equal current breaking.

Description

Grid interrupter with V-termination

The utility model belongs to the field of low-voltage electric appliances, and relates to a grid plate arc-extinguishing chamber with a V-shaped end used for a medium-capacity (rated current ranging from 40A to 80A) direct-acting AC contactor.

As a frequently operated control appliance, the electrical life of the contactor is one of its most important performance indicators. Among them, the working conditions of the AC4 use category are extremely harsh, because it requires frequent jogging of the squirrel-cage motor, that is, switching on and off at the rated voltage 6 times the rated current, and the power factor of the line is low. The existing contactors at home and abroad must reduce the rated current by one level under the working condition of 660 volts.

The purpose of this utility model is to overcome the above-mentioned shortcomings of the prior art, and to propose a grid arc extinguishing chamber with a V-shaped end used in an AC contactor. The AC contactor with this structure can greatly improve the The breaking ability and electrical life are improved, so it can be used with equal current under the working condition of 660 volts AC4.

To improve the electrical life and breaking capacity under the condition of 660 volts AC4, we can start from two aspects, one is to shorten the arc stagnation time, and the other is to reduce the arcing time. The arc stagnation time is an inherent feature of the switching arc. When the contact opens the circuit and generates an arc, the arc needs to stagnate on the contact for a period of time. It will not move until the arc is stretched to a certain length, and runs to the arc extinguishing grid through the arc running track. move. The period from the generation of the arc to the start of running is called the arc stagnation time. Reducing the arc stagnation time is not only beneficial to reduce the arc damage to the contacts, but also allows the arc to enter the arc extinguishing chamber as soon as possible, which is also conducive to reducing the arcing time. The arc stagnation time is related to many factors, the most important of which is the arc blowing magnetic field. Enhancing the arc blowing magnetic field can not only effectively reduce the arc stagnation time, but also increase the electric power of arc blowing and increase the arc movement speed, which is beneficial to arc extinguishing. Whether the arc of the AC contactor can be extinguished depends on the comparison between the dielectric recovery strength and the voltage recovery process when the arc crosses zero. The former is stronger than the latter, and the arc is extinguished. The dielectric recovery strength is mainly determined by the performance of the interrupter. On the one hand, the voltage recovery process is determined by the inherent parameters of the breaking line, and on the other hand, it is determined by the electric field distribution of the arc extinguishing chamber. The latter can obtain an ideal electric field distribution through a reasonable design of the arc extinguishing chamber.

Fig. 1 is a structural principle diagram of the utility model.

Fig. 2 is a structural principle diagram of the grid sheet (1) of the present invention, wherein (a) is a left view, and (b) is a front view.

Fig. 3 is a schematic diagram of the structure of the grid sheet (2) of the present invention, wherein (a) is a left view, and (b) is a front view.

Fig. 4 is a comparison diagram between the utility model structure (figure d) and three prior art structures (figure a-c).

Fig. 5 is a comparison chart of dielectric recovery strength curves between the structure of the utility model and three structures of the prior art.

Below in conjunction with accompanying drawing, structural principle and working principle of the present utility model are described in detail.

Referring to Figures 1, 2 and 3, the ferromagnetic grid sheet group of the present utility model is placed vertically; it is composed of two grid sheets (1) and (2) with different structures, and the outermost grid sheet (1) has a There are V-shaped ends that protrude toward the moving and static contacts (3), while the front grid pieces (2) are shorter in size because they need to avoid the V-shaped ends, and the heads of the V-shaped protruding parts are close to the moving and static contacts. Static contact (3), its lower end plane is parallel with static contact conducting plate (7), and the upper end face is made arc, so that arc striking. The whole arc extinguishing chamber is composed of a grid plate group, a U-shaped arc leading plate (4) and an arc extinguishing cover (5) made of arc-resistant plastic. There are ventilation holes (6) on both sides of the arc chute, the outermost grid piece (1) with a V-shaped protruding end forms a gap with the inner wall of the arc chute (5), and this gap forms an air flow with the ventilation hole (6). aisle.

When in use, when the dynamic and static contacts (3) are disconnected, arcs are generated on the dynamic and static contacts (3), and the V-shaped end of the grid piece (1) made of the magnetic conductor is separated from the dynamic and static contacts. (3) Very close, on the one hand, the blowing magnetic field of the arc is strengthened, and the arc is pulled into the V-shaped end; , (2), the V-shaped end of the grid sheet (1) is equivalent to a grid sheet placed in parallel, and when the arc enters the V-shaped end part, it is divided into two sections. The presence of the V-shaped end also improves the distribution of the electric field in the arc chute.

In the arc extinguishing chamber with a V-shaped protruding end proposed by the utility model, the upper end surface of the V-shaped protruding part is made into an arc shape, and the V-shaped protruding end is very close to the contact. Therefore, when the arc is generated, it can quickly enter the V-shaped protruding part, and under its guidance, it can quickly enter the arc-extinguishing grid group. Therefore, the grid with V-shaped protruding end not only acts as a grid, but also acts as a grid. The role of the arc starter.

The arc extinguishing chamber with V-shaped protruding end proposed by the utility model, due to the shape of the V-shaped protruding end and its spatial position in the arc extinguishing chamber, as well as its back and the side wall of the arc extinguishing chamber and the air outlet on the arc extinguishing cover. The air flow channels all promote the smooth flow of air in the arc extinguishing chamber, which is conducive to increasing the moving speed of the arc and ensuring that the arc enters the arc extinguishing grid plate group smoothly.

In order to evaluate the arc extinguishing performance of the utility model, we compared the utility model (Fig. 4(d)) with three prior art structures (Fig. 4(a)-(c)), and measured the first passing current Figure 5 shows the medium recovery strength of the four arc extinguishing chambers after zero. In Fig. 5, the abscissa is the time after the current crosses zero, and the unit is microseconds (μs), and the ordinate is the dielectric recovery strength, and the unit is expressed in voltage volts (V). It can be clearly seen from the curve in the figure that the dielectric recovery strength of the grids placed in parallel (structure (a) in Figure 4) is the lowest, which is due to the fact that the arc cannot enter the grids. By Gassmann E. A paper published in Ilmenau, Germany pointed out that before the arc enters the grid, its arc column must have sufficient voltage drop to ensure that after entering the grid, it can provide the sum of the required inter-electrode voltage drop after being divided into short arcs, as shown in Figure 4 Structure (a) Because the grid group is too close to the contact, the arc voltage cannot be established when the arc moves to the grid, so it cannot enter the grid. Although the grids of structure (b) are also placed in parallel, the grids are far away from the contacts, so the arc can barely enter the grids, but because the length of the grids is too short, the arc is easy to run out of the rear end of the grids and short-circuit, so The media recovery strength is also not high. The structure (c) is to place the grids vertically, and the arc can only enter the grids after a certain movement, so a sufficient voltage drop can be established before the arcs enter the grids, and the structure (d) has the advantages described above, its dielectric recovery Highest intensity.

In order to examine the new type of arc extinguishing chamber invented by this utility model, taking CJ20-40A as the object, two contactor prototypes with arc extinguishing chambers of structure c and structure d in attached drawing 4 were produced, and the nationally recognized Great Wall Electric was entrusted with the test and research According to the technical requirements of JB/DQ4172-86 of the Ministry of Machinery Industry for CJ20 series AC contactors, a comparative test was carried out under the working condition of 660 volts AC4, and the results are shown in Table 1.

Table 1 Comparison of prototype test results Compared skills requirement test results CJ20-40 CJ20-63 structure c structure d Rated working voltage (V) 660 660 660 660 Rated operating current (A) AC4 25 40 40 40 Electrical life (10,000 times) 4 1 0.96 >2 Operating frequency (times/hour) 120 120 120 120

It can be seen from the test results that the structure c fails to meet the conditions of electrical life of CJ20-63A under the working condition of 660 volts AC4, while the structure d of the utility model not only successfully improves the current level of CJ20-40A, but also has sufficient margin Spend.

Claims (2)

1. be with the grating arc-extinguishing chamber of V-arrangement termination, comprise an arc-extinguish chamber (5), dispose dynamic and static contact (3) in the arc-extinguish chamber (5), dispose U type striking sheet (4) above the dynamic and static contact (3), feature of the present utility model is, disposes grid sheet (1), (2) of two kinds of different structures in the arc-extinguish chamber (5), and outermost a slice (1) has the V-arrangement termination of locating to give prominence to dynamic and static contact (3), the following transverse plane of V-arrangement termination is parallel with fixed contact conductive plate (7), and camber is done in its upper surface.

2. grating arc-extinguishing chamber according to claim 1 is characterized in that, there is air vent hole (6) arc-extinguish chamber (5) side, two ends, and said grid sheet (1) forms a gap with arc-extinguish chamber (5) inwall, and this gap and air vent hole (6) form a gas channel.

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