JPS5855605B2 - Vacuum cutter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum breaker in which the electrode structure is improved so that the arc can be stably and uniformly distributed on the electrode surface.

Generally, as shown in FIG. 1, a vacuum breaker has a cylindrical body 1 made of an insulating material with openings at both ends connected to a lid body 2a.

A pair of electrodes 4.5 are placed in the vacuum container 3 closed by the electrode 2b.
are provided facing each other, and these are connected to the lid body 2a +
2b and inserted into the vacuum container 3,
7, and one of the conductive rods 7 is movable in the axial direction by an operation mechanism (not shown), so that the other electrode 5 can be brought into contact with and separated from the one electrode 4.

In this case, a bellows 8 is provided between the lid 2b and the conductive rod 7, which can hold the inside of the vacuum container 3 airtight and allow the conductive rod 7 to move in the axial direction.

Note that 9 in the figure is a shield provided so as to surround the electrodes 4 and 5 buttons and the conductive rods 6 and 7.

When the vacuum breaker 3 with such a configuration is energized, the electrodes 4 and 5 are in the closed state, but from this state, the conductive rod 7 is moved in the direction of the arrow shown in the figure by the operation of a control mechanism (not shown). When moving in the direction, it separates from the electrode 4 and both electrodes 4,
An arc occurs between 5 and 5.

This arc is maintained by the generation of metal vapor from the cathode, for example, the electrode 5 side, and when the current reaches a zero point, the generation of metal vapor stops, the arc can no longer be maintained, and the interruption is completed.

By the way, if the arc generated between the electrodes 4 and 5 has a large breaking current, the arc becomes extremely unstable due to the interaction between the magnetic field generated by the arc itself and the magnetic field created by the external circuit.

This arc moves along the electrode surface, localizes to the edge or periphery of the electrode, locally overheats that area, releases a large amount of steam, lowers the vacuum inside the container, and reaches the cut-off limit. decrease.

Conventional countermeasures for this problem include electrode structures in which the electrode surface has a wide area to reduce the current density (the former), and spiral-shaped slits in the electrode surface and the arc driven to rotate along the slits. There are various types of electrode structures such as the latter (the latter), but these also have the following drawbacks.

In other words, even with the former electrode structure, the arc is biased toward the edge or periphery of the electrode, as described above.
The electrode is partially melted, and as soon as the local vapor is generated from the electrode, it becomes impossible to shut off.

In the case of the latter electrode structure, the arc does not concentrate in one place but moves around the electrode, reducing the possibility of local heating, but the arc voltage increases (for example,
In the second wave of KAL or disconnection, the energy consumption between the electrodes increases (approximately 200 to 400 cm), so there is a problem in energy processing in a large current region and the drawback is that large current cannot be interrupted.

These phenomena are thought to be due to metal vapor or ionized metal vapor escaping between the electrodes during arc generation, resulting in a lack of ions necessary for arc fibers, making the arc between the electrodes unstable. .

In other words, arc current is generally expressed as ■=e−n・■・S(
However, e is a single charge, n is the plasma density, ■ is the speed of electrons, and S is the electrode area). Therefore, if metal vapor escapes between the electrodes, the plasma density n is insufficient. Therefore, the velocity V of the electrons increases, and as a result, the arc voltage increases.

As the arc voltage increases, more energy is supplied between the electrodes, which causes the temperature of the electrodes to rise and a portion of the electrode surface to melt.

It is already known that applying a magnetic field in a direction perpendicular to the electrode surface is effective as a means to prevent such a phenomenon, and an outline thereof will be described below.

It is generally said that the ratio of electrons, neutral atoms, and ionized atoms generated from the cathode spot of the arc is 100:10:1.

Therefore, when a magnetic field is applied in a direction perpendicular to the electrode surface, the electrons are captured by the magnetic field and travel a long distance because they move in a spiral pattern from the cathode to the anode.

Therefore, the electrons ionize neutral atoms (which have a high probability of being ionized), suppressing the rise in arc voltage.

Therefore, since the energy incident on the anode electrode is reduced,
The electrode no longer melts, and the magnetic field perpendicular to the electrode surface captures the ionized metal (plasma) that escapes to the outside of the electrode and prevents it from leaving the electrode, thereby stabilizing the arc.

Conventionally, as a concrete example of such an effect, as shown in Fig. 2, where the same parts as in Fig. 1 are given the same symbols,
A coil 10 is arranged around the outer periphery of the container 3 of the vacuum breaker, and a current is supplied to the electrode 4 from the conductive rod 7.
A magnetic field perpendicular to the five planes is generated (for example, Japanese Patent Publication No. 44-21607).

In addition, as shown in FIG. 3, in which parts that are the same as those in FIG. There is something like this.

However, in the case shown in FIG. 2, since the distance between the coil 10 and the electrodes 4 and 5 is long, it is difficult to effectively obtain a sufficiently strong axial magnetic field. requires a fairly large coil.

The vacuum vessel 3 itself that has been cut must be made thicker in order to accommodate the coil 10, which increases the size of the vacuum breaker as a whole, which poses major problems in terms of weight and economy.

Furthermore, since the conductive rod I is passed through the coil 10 to allow a cutoff current to flow therethrough, the structure must be mechanically strong.

If the number of turns of the coil 10 is increased, there is a risk that the coil will heat up due to heat loss during energization.

On the other hand, the one shown in FIG. 3 has the same problems as above, and the processing is complicated, and the effect of the magnetic field is relatively small.

The present invention was made in view of the above circumstances, and its purpose is to improve the electrode structure so that the electrode itself generates a strong axial magnetic field, thereby stably and uniformly spreading the arc on the electrode surface. The purpose is to provide a vacuum breaker that can be distributed.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is a longitudinal cross-sectional view of a vacuum breaker, with the same symbols attached to the same parts as in FIG. are provided facing each other, and each is attached to the end of a conductive rod 6.7.

That is, FIGS. 5a and 5b show one electrode 4 according to this embodiment.
1, 42 is a coil electrode, and 43 is a main electrode provided so as to be superimposed on the back of the coil electrode 42 (lower side in the figure).

As shown in FIGS. 6a and 6b, the coil electrode 42 has a plurality of arms having the same length and extending radially at equal intervals around a disk-shaped mounting base 42a attached to the conductive rod 6. 42b (four arms are shown in this example), and the protruding portion of each of these arm portions 42b is directed toward the adjacent arm, and the tip thereof is spaced at an appropriate distance from the protruding end of the adjacent arm. As shown in FIG. 2, the arcuate portions 42cJ- and the protrusions 42d protruding toward the main electrode 43 from each of these arcuate portions 42c are electrically connected to each other. It is integrally formed.

Therefore, a space region is formed in the quadrupled portion of the arm portion 42b and the circular arc portion 42c of the coil electrode 42.

The area of this spatial region in a cross section perpendicular to the conductive rod 6 is larger than the area of the arm portion 42b in the same cross section.

Further, as shown in FIG. 7, the main electrode 43 has a plurality of radial linear slits 43a (6 in this example) on its electrode surface.
(representing the slits in a book) are arranged at equal intervals.

Therefore, in order to combine the coil electrode 42 button and the main electrode 43, the coil electrode 42 and the main electrode 43 are provided so as to overlap, and the mounting base 42 of the coil electrode 42 is
A high-resistance metal 44 made of stainless steel, as shown in FIG. The protrusion 42d is connected to the main electrode 4
3 to form an electrode 41.

In this case, each slit 43 provided in the main electrode 43
The coil electrode 42 button and the main electrode 43 are combined in a positional relationship such that a is separated from each of the projections 42d.

Although the electrode 41 attached to the conductive rod 6 has been described above, the electrode 51 attached to the conductive rod 7 also has the same electrode structure as described above, and its explanation will be omitted here.

Therefore, when a vacuum breaker equipped with the electrode 4L51 having such a structure is used and the conductive rod 7 is moved in the electrode separation direction by operation of an operation mechanism (not shown), the arc current will flow as shown by the arrows in FIGS. 5a and 5b. Attachment base 4 of coil electrode 42 to
2a, from which the current is divided into radial currents (in this example, the total current is divided into 11) through each arm portion 42b.

The current divided in each radial direction flows along the circular arc portion 42c, and then flows from the other side of the latter circular arc portion 42c to the main electrode 43 through the protrusion 42d.

Therefore, the current flowing through the coil electrode 42 is
d to the arcuate portion 42c, it is equivalent to a loop-shaped current flowing through one turn, and 1
The magnetic field of the turn appears on the electrode surface of the main electrode 43 as an axial magnetic field.

The current thus led to the main electrode 43 enters the other electrode 51 configured in the same manner as described above as an arc current, and an axial magnetic field similar to that described above is generated here as well.

The axial magnetic field generated from the coil electrode surrounds the arc generated between the cathode and the anode, and prevents a shortage of plasma particles because it suppresses the release and diffusion of ionized metal from the arc to the outside.

Therefore, the arc generated when the electrodes are separated is stabilized on the electrode surface by this axial magnetic field, and the breaking performance can be greatly improved.

On the other hand, the main electrode 43 has a radial linear slit 43a.
By providing this, the following effects can be obtained.

That is, in the case where the main electrode 43 is not provided with a linear slit in the radial direction, if the arc is located at the shaded area in FIG. 9, the current will flow as shown by the arrow.
The flow is divided into two routes, a-+b and a-+e, and further flows to the coil electrode 42 in the order of b-+c-+d.
The latter flows in the order of e-+f-+g and reaches the conductive rod 6.

At this time, when pressing the button on the former current path a-+b→(, +d, the directions of the current a-+b and the current b→C are opposite to each other, so the magnetic fields due to the respective currents cancel each other out, An effective axial magnetic field cannot be created in the current path a→b-+c-+d.

However, a plurality of radial linear slits 43a are provided at equal intervals in the main electrode 43, and the slits 43a are provided at equal intervals.
a is the circular arc portion 42c of the coil electrode 42 as shown in FIG.
If the button is positioned near the tip (bonded part with the main electrode 43) and in the opposite direction to the notch and is not bridged by the coil electrode 42, the axial magnetic field can be reduced. can be generated effectively.

That is, in FIG. 10, if an arc occurs at the same position as in FIG. However, since the former current path is longer than the latter, more current flows in the latter path.

Moreover, even if the current flows in the former current path, the current h
→1 and i −) Since the directions of j and current j→ are not opposite to each other, the effect of canceling the axial magnetic field due to current J→k is small. It is possible to more effectively generate an axial magnetic field by using a main electrode provided with .

Furthermore, when an axial magnetic field is generated by the coil electrode 42, this magnetic field generates an eddy current in the main electrode 43, and the axial magnetic field decreases due to the magnetic field in the opposite direction. Since the linear slit 43a is provided, reduction in the axial magnetic field due to eddy current can be prevented by 1F.

In this case, the linear slit is at least connected to the coil electrode 42.
The number of divisions is necessary, and the length of the cut from the outer periphery of the main electrode 43 toward the center is required to be 50 to 70% of the electrode radius in order to prevent a decrease in the axial magnetic field.

Here, in contrast to the conventional one provided with a spiral slit, which is driven to rotate, the linear slit allows the arc to be stabilized and the energy consumption between the electrodes to be reduced.

The embodiments described above are only examples of the present invention,
The following electrode structure can also provide the same effects as described above.

As the coil electrode 42, as shown in FIGS. 11a and 11b, a plurality of linear sulins (42e) are used so that the current flowing through the conductive rod 6 is divided into a plurality of parts and each divided current draws an arc around the circumference. (four slits are shown in this example), and a protrusion 42f for attachment to the main electrode 43 may be provided at the tip of each arcuate portion formed by each slit 42e.

With such a coil electrode 42, the same effect as in the above-mentioned embodiment can be obtained by simply cutting a linear slit.
The electrode structure becomes simple and manufacturing becomes easy.

In the above embodiment, a coil electrode is provided on each of the pair of electrodes provided in the vacuum vessel 3 to generate an axial magnetic field, but perhaps the coil electrode is provided on only one electrode to generate an axial magnetic field. A magnetic field may also be generated.

In particular, the problem of heat generation can be solved by attaching the coil electrode to the fixed shaft and attaching the normal electrode to the movable shaft.

That is, the movable and fixed electrodes of a normal vacuum breaker are exactly the same, and the lengths of the current introduction rods are also approximately the same.

However, the movable shaft is connected to the bus bar through a flexible conductor, and the fixed shaft is connected to the bus bar after being fixed to the large lamp.

Therefore, heat generated inside the vacuum container is radiated through the flexible conductor on the movable shaft, and is radiated through the clamp on the fixed shaft.

For this reason, the temperature of the movable shaft is always higher than that of the fixed shaft, and the temperature may not meet the standards.

-The blade axis direction magnetic field type electrode is longer than a normal electrode by the length of the coil electrode, so it generates more heat.
Heat run (measuring the temperature rise in various parts after applying rated current for a long time) test is more severe.

However, in the case of an axial magnetic field type electrode, it is sufficient that a magnetic field of a certain level or more is generated on the electrode surface, and it is not necessarily necessary to provide coils on both electrodes.

Therefore, if a normal electrode is connected to the movable shaft, which is thermally severe, and an axial magnetic field type electrode is attached to the thermally easy fixed shaft, the generated heat will be dissipated through the fixed shaft, which has plenty of room. Therefore, even if an axial magnetic field type electrode is used, the heat run can be passed, and the weight of the movable shaft is reduced only in the coil portion, reducing the weight of the movable portion as a whole.

This makes the operation mechanism easier, and the opening speed can also be increased, resulting in improved breaking performance.

Further, the coil electrode 42 of the above embodiment is 1 due to the loop current.
Although a magnetic field of turns is generated, if it is desired to change the strength of this magnetic field, it can be adjusted by changing the number of loops.

For example, by increasing the number of loops to 3 or 2, the current flowing through the coil electrodes becomes easier than the total current, and the strength of the magnetic field is 1.3 times or 2 times that of the above example. be able to.

Furthermore, if it is desired to increase the current flowing through the coil electrode, the electrode itself may have a large cross-sectional area.

Furthermore, in each of the above embodiments, the coil electrode 42 and the main electrode 43 are separate, but it is also possible to configure them as an integrated structure.

It goes without saying that this invention can be modified and implemented in various ways without changing the gist thereof.

As described above, according to the present invention, the coil electrode is arranged so as to overlap the back of at least one of the main electrodes, and the coil electrode is attached to the protruding end of the arm extending from the conductive rod. One side of the outer periphery arranged on the locus of an arc drawn with the center at The end faces the back of the main electrode through a space or a high resistance material, and the main electrode is provided with a plurality of linear slits, so most of the current path is between the main electrode and the coil. Since it is formed between the electrode and the conductive rod through the electrode, the electrode itself can generate a strong axial magnetic field.

Therefore, the arc can be stably and uniformly distributed on the electrode surface, and there is no need to arrange a coil on the outer circumferential surface of the vacuum container or form a coil part on the conductive rod, as in the case of the conventional method. It can be easily and inexpensively done without increasing the size.

Even if the button is pressed when the main electrodes are closed, an axial magnetic field is always applied by the current flowing through the coil electrodes, so the axial magnetic field is effective against the arc generated between the main electrodes from the moment the main electrodes are opened. Furthermore, a uniform axial magnetic field is applied to the main electrode by the current flowing around the outer periphery of the coil electrode, which is placed on the locus of an arc centered on the conductive rod, so the arc is always stabilized. It can be measured.

In addition, it is possible to effectively generate an axial magnetic field no matter where the arc is located on the electrode surface, and it is possible to prevent the axial magnetic field from decreasing due to eddy currents. Since the area of the spatial region surrounded by 1 is larger than the area of the arm (the area of both in the cross section perpendicular to the conductive rod), the eddy current generated in the arm can be reduced. Furthermore, the axial magnetic field can be made stronger by reducing the solder current due to the plurality of linear slits provided in the main electrode, and the breaking current can be increased by 1 or more.

This also reduces the weight of the coil electrode, which not only reduces the weight of the vacuum breaker as a whole, but also reduces the weight of the vacuum breaker as a whole.
This is particularly useful for reducing the load on the operating device for the movable electrode.

Furthermore, since it is a linear slit, its processing is extremely easy.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view showing the principle configuration of a vacuum breaker, Figure 2
Figures 3 and 3 are vertical cross-sectional views showing different conventional vacuum breakers, Figure 4 is a vertical cross-sectional view showing one embodiment of the present invention, and Figure 5 a, bl/'i is a button in the same embodiment. Fig. 6 shows an enlarged view of the coil electrode; a is a side view, b is a plan view seen from the main electrode side, Fig. 6 a and b are a side view and plan view of the coil electrode, and Fig. 7 is the same A plan view of the main electrode, FIG. 8 is a side view of the high-resistance metal provided as a spacer between the coil electrode and the main electrode, and FIGS. 9 and 10 are plan views of the electrode necessary for explaining the operation of this embodiment. , Figure 11a, b
1 shows a coil electrode according to another embodiment of the present invention, in which a is a side view and b is a plan view. 3... Vacuum container, 6, 7... Conductive rod, 41, 51.
... Electrode, 42 ... Coil electrode, 43 ... Main electrode.

Claims (1)

[Claims] 1 A pair of main electrodes which are provided in a vacuum container so as to be freely accessible and detachable, and which are respectively attached to conductive rods, are used to turn on and cut off current, and are superimposed on the back of at least one of the main electrodes. The coil electrode has one end fixed to the mounting base of the conductive rod and has an arm extending from the mounting base, and one side is connected to the protruding end of the arm. A shape is formed by providing an outer peripheral portion disposed on the locus of an arc drawn with the conductive rod as the center,
An electrical connection is made to the back of the main electrode on the other side of the outer periphery of the coil electrode, and the end of the conductive rod provided with the coil electrode is connected to the main electrode through a space or a high resistance material. The arms and outer periphery of the coil electrode are arranged so that most of the current flows between the main electrode and the conductive rod through the electrical connection between the coil electrode and the main electrode. A space area is provided in the area surrounded by the area.
The area of this spatial region in the cross section perpendicular to the conductive rod is larger than the area of the arm in the cross section perpendicular to the conductive rod, and the main electrode combined with the coil electrode has a plurality of straight lines. A vacuum breaker characterized by having a slit.