JPH06150784A - Vacuum valve - Google Patents

Abstract

PURPOSE:To provide a vacuum breaker which can increase the breaking capacity without enlarging the size. CONSTITUTION:The minor diameter side of a current feed electrode 4 is brazed to the center of the tip of a movable side current feed shaft. A cylindrical part 5a of a coil electrode 5 is brazed to the tip of the movable side current feed shaft. The back face of the central part of a contacting piece 2 is brazed to the tip of the current feed electrode 4, and the periphery of the back face of the contacting piece is brazed to the connection part 5d at the tip of the coil part 5c of the coil electrode 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a vacuum valve having an improved electrode structure.

[0002]

2. Description of the Related Art A vertical sectional view of a conventional vacuum valve used in a vacuum circuit breaker is shown in FIG.

In FIG. 3, a vacuum valve 10 is an insulating cylinder.
A fixed electrode 14 and a movable electrode 15 are placed inside a vacuum container formed by sealing both ends of 11 with a fixed flange 12 and a movable flange 13.
Are arranged so that they can be brought into and out of contact with each other.

Of these, the fixed electrode 14 is the fixed flange 12
Is fixed to the tip of a fixed shaft 16 penetrating airtightly by brazing, and is connected to the outside of the vacuum container via the upper end of the fixed shaft 16. On the other hand, the movable electrode 15 is fixed by brazing to the tip of a movable shaft 17 that penetrates airtightly through a bellows cover 19 having an inverted U-shaped cross section, and is connected to the outside of the vacuum container via the lower end of the movable shaft 17. Connected.

The movable shaft 17 has a bellows 18 brazed between the movable flange 13 and a bellows cover 19, and a guide 20 having a convex cross-section inserted at the center of the movable flange 13 to allow the movable flange 13 to move. It is supported by and is driven by an operation mechanism portion (not shown) connected to the lower end of the movable shaft 17 while maintaining the vacuum in the vacuum container, so that the electrodes can be brought into and out of contact with each other. I have to.

By the way, as is well known, the vacuum valve is
Since the excellent dielectric strength of vacuum is used, the gap between the electrodes can be made smaller and the outer diameter can be made smaller than that of a gas circuit breaker that uses an insulating medium such as sulfur hexafluoride gas. it can. Also, the breaking capacity can be increased by improving the structure of the electrode.

As one means for improving the breaking performance of the vacuum valve, there is a method of suppressing local heating of the electrodes due to an arc generated between the electrodes. That is, by suppressing the generation of abnormal charged particles due to local heating, the generation of arcs is suppressed and the breaking performance is improved. As an electrode structure for this purpose, there are a method of applying a magnetic field parallel to the arc generated between the electrodes and a method of applying a magnetic field in a direction orthogonal to the arc.

Among them, an electrode adopting a method of applying a magnetic field parallel to an arc has a so-called longitudinal magnetic field electrode structure. In this method, the arc generated between the electrodes is dispersed over the entire electrode by the effect of the magnetic field to improve the breaking performance. On the other hand, there is a so-called spiral electrode as an electrode adopting a method of applying a magnetic field orthogonal to an arc. This method is a method in which an arc concentrated on the electrode surface when a large current is cut off is rotated on the electrode surface to improve the breaking performance. In other words, by moving the concentrated arc,
This is a method of improving the breaking performance by preventing partial melting of the contacts due to local heating of the electrodes.

By the way, in order to apply the vacuum valve to a high voltage circuit, it is necessary to increase the gap between the electrodes to increase the withstand voltage between the electrodes. However, if a magnetic field orthogonal to the arc generated between the electrodes with this wide gap is applied, the arc may be extended outward from the circumferential direction when the arc rotates on the surface of the electrode, and may fly out from the electrode. There is. Then, the arc generated between the electrodes
There is a risk of ignition to the arc shield 20 shown in FIG. 3 mounted around the electrodes. If the arc is ignited on the arc shield 20, the arc stays at that position, the electrode and the arc shield 20 are partially melted due to a local temperature rise, and not only the breaking performance is deteriorated, but further,
The contact wear is also increased, which shortens the switching life.

On the other hand, the arc generated between the electrodes of the longitudinal magnetic field electrode adopting the electrode structure for applying a magnetic field in the axial direction parallel to the arc spreads uniformly over the entire electrode, and the local excessive heat of the electrode is generated. It can prevent input and improve blocking performance. Further, even when the gap between the electrodes is wide with respect to the high voltage, by appropriately setting the strength of the magnetic field, the arc can be limited only between the electrodes, and the breaking performance can be improved. Further, since the arc form is a distributed arc, the contact wear is small even when a large current is interrupted, and the switching life can be extended.

A conventional representative electrode for generating a magnetic field in the axial direction will be described with reference to the plan view of FIG. This electrode is provided with a coil electrode 20 on its back surface, and an electric field flowing in the coil electrode 20 generates an axial magnetic field between the electrodes. Coil electrode 20
The current that flows in the four arms is radially extending from the center.
20a, and the arc-shaped coil portion 20 from the tip of each arm portion 20a.
b, and flows from the tip 20c of the coil portion 20b to the contactor. This coil electrode 20 is attached to a movable electrode and a fixed electrode, and a magnetic field in the axial direction is generated between the electrodes by the current flowing in the coil portion 20b. Further, although FIG. 4 shows the case where the number of the arm portions 20a is four, the strength of the magnetic field in the axial direction can be changed by changing the number of the arm portions 20a.

Further, as another electrode structure for generating a magnetic field in the axial direction, as shown in Japanese Patent Publication No. 32007/1990, a spiral groove is formed in the cylindrical portion of a cup-shaped electrode to form an axial direction. There is a vacuum valve that generates a magnetic field. in this case,
By making the current path of the cylindrical portion spiral, a magnetic field in the axial direction is generated between the electrodes by the current flowing spirally through the cylindrical portion. The strength of the magnetic field in the axial direction can be changed by changing the inclination of the groove of the cylindrical portion.

On the other hand, in the vacuum valve, it is necessary to reduce the switching surge in order to improve the reliability of the system to which the vacuum circuit breaker is connected. Furthermore, the short-circuit capacity of the grid is increasing with the increase in the installed capacity of general consumers.

To meet such demands, a special alloy such as a silver tungsten carbide (hereinafter referred to as Ag-WC) alloy is used as a contact material for improving the electrode structure and the contact material to reduce the switching surge. It is used.

On the other hand, in a vacuum valve employing a longitudinal magnetic field electrode for generating a magnetic field parallel to the arc generated between the contacts, the relationship between the magnetic field strength and the arc voltage was investigated, and as a result, the arc voltage was It has been shown to show a minimum value. By applying the strength of the magnetic field in which the arc voltage exhibits the minimum value, the energy consumed between the electrodes when the current is cut off is suppressed, and the breaking performance is improved.

The strength of the magnetic field that minimizes the arc voltage differs depending on the contact material, and is higher than that of the above-mentioned Ag-WC alloy compared to the copper-chromium (Cu-Cr) alloy widely used in general-purpose vacuum valves. With the contactor, it is necessary to increase the strength of the magnetic field. In the vacuum valve using the coil electrode shown in FIG. 4, as described above, the strength of the magnetic field can be increased by reducing the number of arms 20a.
For example, by reducing the number of arms from four to three and two, the strength of the magnetic field increases stepwise by about 1.3 times and about twice.

[0017]

However, in such a conventional vacuum valve, the strength of the magnetic field between the electrodes can be changed only in a stepwise manner. If this is not possible, the strength of the magnetic field may be increased in that case. At that time, since the electrodes must be made large, the outer shape of the vacuum valve becomes large.

On the other hand, if the number of arm portions 20a of the coil electrode shown in FIG. 4 is reduced to increase the strength of the magnetic field, the current flowing through each arm portion 20a also increases, and if the breaking capacity is increased, the short-time current capacity also increases. In order to withstand the electromagnetic force due to this short-time current, the cross-sectional area of each arm portion 20a and coil portion 20b must be increased, and the outer shape of the electrode becomes large. Therefore, an object of the present invention is to obtain a vacuum valve capable of increasing the breaking capacity without increasing the outer shape.

[0019]

According to a first aspect of the present invention, a fixed electrode and a movable electrode, which are connected to the outside via a current-carrying shaft, are housed in a vacuum container so that they can come into contact with and separate from each other. In a vacuum valve in which a contact is provided at the tip of a movable electrode via a coil electrode, a second energizing shaft is provided in parallel with the coil electrode at the axial center between the tip of the energizing shaft and the contact. Characterize.

According to a second aspect of the present invention, a fixed electrode and a movable electrode, which are connected to the outside via a current-carrying shaft, are housed in a vacuum container so that they can come into contact with and separate from each other. In the vacuum valve in which the contact is provided via the coil electrode, a second energizing shaft is provided in parallel with the coil electrode at the axial center between the tip of the energizing shaft and the contact,
The value of the current flowing through the second current-carrying shaft is set to 5 to 30% of the value of the current flowing through the current-carrying shaft.

Further, according to a third aspect of the invention, a fixed electrode and a movable electrode which are connected to the outside through a current-carrying shaft are housed in a vacuum container so that they can come into contact with and separate from each other, and the tips of the fixed electrode and the movable electrode. In a vacuum valve in which a contactor is provided via a coil electrode, at the axial center between the tip of the energizing shaft and the contactor,
A second current-carrying shaft is provided in parallel with the coil electrode, and a hollow portion is formed in the second current-carrying shaft so that the outer diameter of the contactor side is larger than the outer diameter of the current-carrying shaft side. To do.

Further, according to a fourth aspect of the present invention, a fixed electrode and a movable electrode which are connected to the outside via a current-carrying shaft are housed in a vacuum container so that they can come into contact with and separate from each other, and the tips of the fixed electrode and the movable electrode. In a vacuum valve in which a contactor is provided via a coil electrode, at the axial center between the tip of the energizing shaft and the contactor,
A second current-carrying shaft is provided in parallel with the coil electrode, and a recess smaller than the outer diameter of the contactor side of the second current-carrying shaft is formed in the center of the surface of the contactor.

[0023]

According to the first aspect of the invention, the cut-off current shunted to the coil electrode can be varied by changing the material and shape of the second current-carrying shaft. Further, in the invention according to the second aspect, the temperature rise of the coil electrode is suppressed by setting the breaking current shunting the second energizing shaft to 5 to 30% of the total breaking current.

Further, in the invention according to claim 3, the resistance value of the second current-carrying shaft can be varied by the thickness of the hollow portion, and the central portion of the contact is firmly connected to the second current-carrying shaft. Will be done. Further, in the invention according to claim 4, the pressing force applied between the contact elements at both ends is evenly applied to the annular portion outside the concave portions of both contact elements.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the vacuum valve of the present invention will be described below with reference to the drawings. The structure of the entire vacuum valve is
Since it is the same as FIG. 3, the electrode structure is shown in a plan view of FIG. 1 (note: the right half shows a state in which a contactor 2 which will be described later is removed) and a sectional view taken along the line AA of FIG. Described in.
1 and 2 show the case of the movable side electrode 1, the structure of the fixed side electrode is exactly the same.

1 and 2, a counterbore hole 3a is formed at the tip of the movable side current-carrying shaft 3, and this counterbore hole 3a is formed.
Further, a counterbored hole 3b having a smaller diameter than the counterbored hole 3a is further formed in the.

Of these, the counterbore 3b has a substantially convex outer shape and a flange 4b formed at the upper end, and the lower end of the cylindrical portion 4a of the tubular current-carrying electrode 4 made of a phosphor bronze rod is inserted. And is brazed to the bottom surface and the side surface of the spot facing hole 3b. Further, the lower end of the cylindrical portion 5a formed at the center of the coil electrode 5 is brazed to the tip of the movable-side energizing shaft 3 coaxially with the movable-side energizing shaft 3 by a jig (not shown).

The coil electrode 5 is made of a copper material, and as shown in FIG. 1, a pair of arm portions 5b is provided on the outer periphery of the cylindrical portion 5a.
Arc-shaped coil portions 5c are formed at the tips of the arm portions 5b, and the connection portions 5d projecting upward are formed at the tips of the coil portions 5c. Regarding the resistance values of the energization electrode 4 and the coil electrode 5, the resistance value from the brazed portion to the movable side energization shaft 3 to the upper end is the resistance value of the coil electrode 5 as R, and the resistance value of the energization electrode 4 as r. Then, 19R>r> 2.33R.

On the other hand, on the upper surface of the current-carrying electrode 4, the contactor base material 2b on the back surface of the disk-shaped contactor 2 is placed on the same axis by a jig (not shown), and the lower surface is the upper part of the current-carrying electrode 4. Is brazed to the upper surface of the flange portion 4b. Contact base material 2
Grooves 2d1 are radially formed at intervals of 90 ° in b, and a groove 2d1 shorter than the groove 2d1 is formed between the grooves 2d1.
2 are also formed radially at intervals of 90 °.

The contactor 2 has an upper surface of the contactor base material 2b.
The contact 2a of Ag-WC material having the same outer diameter as that of the contact base material 2b is placed and brazed to the contact base material 2b in advance. A counterbore 2c having a diameter d smaller than the outer diameter D of the flange 4b of the current-carrying electrode 4 is formed in the center of the upper surface of the contact 2a in advance. Next, the operation of the vacuum valve thus constructed will be described.

The current flowing between the electrodes at the time of energization and interruption is supplied from the movable side energizing shaft 3 through the coil electrode 5 and the energizing electrode 4 brazed to the tip of the movable side energizing shaft 3 to the contact mother of the contactor 2. It flows to the material 2b, and from the contact 2a,
It flows to the contact (not shown) on the fixed side which is opposed. Here, a vertical magnetic field parallel to the arc generated between the contacts is generated by the current flowing through the coil electrode 5, particularly the current flowing through the arc-shaped coil portion 5c. Further, the resistance value R of the coil electrode 5 and the resistance value r of the current-carrying electrode 4 are connected in parallel between the movable-side energizing shaft 3 and the contact 2.

Therefore, the relationship between the resistance values is as described above.
When R>r> 2.33R is satisfied, 5 to 30% of the total current flowing through the movable side current-carrying shaft 3 flows to the current-carrying electrode 4, and the rest flows to the coil electrode 5. 5% of the current value flowing in the current-carrying electrode 4
In order to make it less than the above, it is necessary to narrow the cross-sectional area of the cylindrical portion 5a, which is difficult to manufacture due to problems in processing and strength.
Further, by providing the counterbore 2c on the surface of the contact 2a, the portion contacting the facing contact becomes the outer peripheral portion than the counterbore 2c. The effects of the above-described embodiment of the present invention will be described below.

As described above, the strength of the longitudinal magnetic field parallel to the arc generated between the contacts is the coil portion 5 of the coil electrode 5.
It is proportional to the value of the current flowing in b. That is, the strength of the magnetic field increases in inverse proportion to the number of arm portions 5a of the coil electrode 5. Therefore, when the strength of the magnetic field is 100 when the number of the arm portions 5a of the coil electrode 5 is 2, the strength of the magnetic field gradually increases to 67,50 as the number of the arm portions 5a increases to 3,4. Fall to. As described above, since the strength of the magnetic field changes stepwise, in the conventional vacuum valve, only the change in the number of the arm portions 5a of the coil electrode 5 causes the optimum magnetic field strength peculiar to the above-mentioned contact material, That is, the strength of the magnetic field that minimizes the arc voltage cannot be obtained.

However, according to the vacuum valve of the present invention,
The value of the current flowing in the coil electrode 5 can be changed to an arbitrary value by the current diverted to the current-carrying electrode 4. Energizing electrode 4
The current shunted into can be arbitrarily selected depending on, for example, the type of phosphor bronze used for the current-carrying electrode 4 (that is, the phosphorus content). The number of arms 5a of the coil electrode 5 is 2
In the case of a book, by setting the value of the current flowing through the current-carrying electrode 4 to 5 to 30% of the total current value, the strength of the magnetic field is 95 to 70%.
The range can be changed. Therefore, the strength of the magnetic field can be set to an almost arbitrary value by changing the number of coil electrodes 5 between 2 and 4 and setting the value of the current flowing through the energizing electrode 4 to 5 to 30% of the total current value. it can. This allows
The optimum magnetic field strength peculiar to the contact material described above, that is, the magnetic field strength that minimizes the arc voltage can be obtained, and the breaking performance can be improved.

On the other hand, since the loss when the current is applied is proportional to the square of the current, the loss when the current is applied can be reduced by reducing the current flowing through the coil electrode 5. For example, by passing 30% of the total current value to the current-carrying electrode 4 and passing 70% of the current to the coil electrode 5, the loss at the coil electrode 5 is reduced to 49% compared to a vacuum valve without the current-carrying electrode 4. To do. Since the loss can be reduced in this way, the current-carrying capacity of the vacuum valve can be increased without increasing the outer shape.

Further, by forming the counterbore 2c on the surface of the contact 2a, the contact pressure of the outer peripheral portion of the counterbore 2c can be increased and the contact area between both electrodes is increased. Further, by making the outer diameter of the end of the energizing electrode 4 on the contact 2a side larger than the diameter of the counterbore 2c, an electric path flowing from the energizing electrode 4 to the contact 2c can be secured. Thereby, the magnetic field generated in the current path flowing in the electrode portion, that is, the magnetic field that disturbs the magnetic field generated in the coil portion 5b of the coil electrode 5 can be reduced. Therefore, the distribution of the magnetic field between both electrodes can be made uniform, and the blocking performance of the vacuum valve can be improved.

Also in a conventional vacuum valve provided with a coil electrode, an electrode structure in which a reinforcing member is arranged at the center of the coil electrode is disclosed in Japanese Patent Application Laid-Open No. 54-20373.
However, in the conventional vacuum valve, a high resistance member is used as the reinforcing member, and it is premised that the reinforcing member is hardly energized.

Therefore, the current flowing through the coil electrode can be controlled only by the number of arms of the coil electrode described above. In particular, in the case of a contact such as Cu-Cr having excellent contact breaking performance and a relatively low magnetic field strength that minimizes the arc voltage, three or more arm portions of the coil electrode are sufficient.
Even in the conventional technique, a value close to the optimum magnetic field was obtained.

However, when an Ag-WC type alloy is used as the contact material, the strength of the magnetic field at which the arc voltage is minimized is strong. In such a case, changing the number of arm portions of the coil electrode from 3 to 2 causes the magnetic field strength to increase by about 1.5 times as described above. I couldn't. In this way, the strength of the magnetic field, which is not possible with the conventional reinforcing member, can be easily achieved by controlling the value of the current flowing through the current-carrying electrode 4.

Although the contact base material 2b is used in this embodiment, the contact base material 2b is omitted and the tip end of the coil electrode 5 and the current-carrying electrode 4 are directly brazed to the contact 2a. Can also obtain the same effect.

[0041]

As described above, according to the invention of claim 1,
A vacuum valve in which a fixed electrode and a movable electrode, which are connected to the outside via a current-carrying shaft, are housed in a vacuum container so that they can come into contact with and separate from each other, and a contact is provided at the tip of these fixed electrode and movable electrode via a coil electrode. In, in the axial center between the tip of the current-carrying shaft and the contactor, by providing a second current-carrying shaft in parallel with the coil electrode, by changing the material and shape of the second current-carrying shaft,
Since the breaking current shunted to the coil electrode is variable, it is possible to obtain a vacuum valve capable of increasing the breaking capacity without increasing the outer shape.

According to the second aspect of the invention, the fixed electrode and the movable electrode, which are connected to the outside through the current-carrying shaft, are housed in the vacuum container so that they can come into contact with and separate from each other. In a vacuum valve in which a contactor is provided at the tip of a coil electrode via a coil electrode, a second current-carrying shaft is provided in parallel with the coil electrode at the axial center between the tip of the current-carrying shaft and the contactor, and a second current-carrying device is provided. Since the temperature value of the coil electrode was suppressed by setting the value of the current flowing through the shaft to 5-30% of the value of the current flowing through the energizing shaft, it is possible to obtain a vacuum valve that can increase the breaking capacity without increasing the external shape. You can

Further, according to the invention of claim 3,
A vacuum valve in which a fixed electrode and a movable electrode, which are connected to the outside via a current-carrying shaft, are housed in a vacuum container so that they can come into contact with and separate from each other, and a contact is provided at the tip of these fixed electrode and movable electrode via a coil electrode. A second energizing shaft is provided in parallel with the coil electrode at the axial center between the tip of the energizing shaft and the contactor, and a hollow portion is formed in the second energizing shaft to provide an outer diameter on the contactor side. Is larger than the outer diameter of the current-carrying shaft side, the resistance value of the second current-carrying shaft can be varied by the thickness of the hollow portion, and the central part of the contact is firmly connected to the second current-carrying shaft. Because I did
It is possible to obtain a vacuum valve capable of increasing the breaking capacity without increasing the outer shape.

Further, according to the invention described in claim 4,
A vacuum valve in which a fixed electrode and a movable electrode, which are connected to the outside via a current-carrying shaft, are housed in a vacuum container so that they can come into contact with and separate from each other, and a contact is provided at the tip of these fixed electrode and movable electrode via a coil electrode. In the above, a second current-carrying shaft is provided in parallel with the coil electrode at the axial center between the tip of the current-carrying shaft and the contactor, and the contactor side of the second current-carrying shaft is provided at the center of the surface of the contactor. By forming a recess that is smaller than the outer diameter, the pressing force applied between the contacts at both ends was applied to the annular portion outside the recess of both contacts, so that the breaking capacity can be increased without increasing the outer shape. A vacuum valve that can be obtained can be obtained.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a vacuum valve of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a vertical sectional view showing an example of a conventional vacuum valve.

FIG. 4 is a plan view showing an example of a vertical magnetic field type electrode incorporated in a conventional vacuum valve.

[Explanation of symbols]

1 ... Movable side electrode, 2 ... Contactor, 2a ... Contact point, 2b ... Contactor base material, 2c ... Counterbore hole, 3 ... Movable side energizing shaft, 4 ... Energizing electrode, 4a ... Cylindrical part, 4b ... Flange part, 5 ... Coil electrode, 10 ... Vacuum valve.

Claims (4)

[Claims] 1. A fixed electrode and a movable electrode, which are connected to the outside via an energizing shaft, are housed in a vacuum container so as to be able to come into contact with and separate from each other, and a contactor is provided at the tip of these fixed electrode and the movable electrode via a coil electrode. A vacuum valve provided, wherein a second current-carrying shaft is provided in parallel with the coil electrode at a shaft center between a tip of the current-carrying shaft and the contactor. 2. The vacuum valve according to claim 1, wherein the value of the current flowing through the second energizing shaft is set to 5 to 30% of the value of the current flowing through the energizing shaft. 3. The second current-carrying shaft has a hollow portion, and the outer diameter on the contact side is larger than the outer diameter on the current-carrying shaft side. Vacuum valve. 4. The vacuum valve according to claim 1, wherein a concave portion having a diameter smaller than the outer diameter of the second energizing shaft on the contact side is formed in the center of the surface of the contact.