JP3101329B2 - Vacuum valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum switching device, and more particularly to a vacuum valve having a large breaking capacity and low surge characteristics (excellent cutting current characteristics).

[0002]

2. Description of the Related Art Vacuum switches have various excellent features such as small size, light weight, maintenance-free and environmental harmony compared with other switches, and their application range has been gradually expanded in recent years. The vacuum circuit breaker cuts off current in a high vacuum by utilizing arc diffusivity in a vacuum, and will be described with reference to FIG.

The vacuum circuit breaker has a vacuum chamber 1 kept in a vacuum-tight manner, which is provided with an insulating container 2 formed of an insulating material in a substantially cylindrical shape, and provided at both ends thereof with sealing fittings 3a and 3b. And metal lids 4a and 4b. A pair of fixed electrodes 7 and a movable electrode 8 attached to opposing ends of the conductive rods 5 and 6 are provided in the cutoff chamber 1. A bellows 9 is attached to the conductive rod 6 of the movable electrode 8, and the movable electrode 8 moves in the axial direction while maintaining vacuum tightness in the cutoff chamber 1. A metal arc shield 10 is provided on the upper part of the bellows 9 to prevent the bellows 9 from being covered with the arc vapor. Similarly, a metal arc shield 11 is provided so as to cover the fixed electrode 7 and the movable electrode 8 in the cutoff chamber 1 to prevent the insulating container 2 from being covered with the arc vapor. During energization, the movable contact 13a is in contact with the fixed contact 13b, and the current is interrupted by moving the conductive rod downward and breaking the contact between the two contacts.

Next, with respect to the mutual fixing structure between the conductive rods 5, 6 and the electrodes 7, 8, and between the electrodes 7, 8 and the contacts 13a, 13b, see FIG. 3 showing details around the movable electrode 8 in FIG. And explain. The movable electrode 8 is fixed to the conductive rod 6 by brazing indicated by reference numeral 12 or caulking (not shown), and the movable contact 13 a is fixed to the movable electrode 8 by brazing indicated by reference numeral 14 or caulking (not shown). The same applies to the method for fixing the fixed electrode 7 on the fixed side and the contact 13b.

[0005]

The requirements for a contact for a vacuum switch include (1) low weldability;
(2) high withstand voltage; (3) excellent wear resistance; and (4) low and stable contact resistance. In addition, expectations for the recent vacuum switchgear are further increased, and (5) a low surge function and (6) a high current cutoff function are required. These two requirements are contradictory. .

First, requirements for having a low surge function will be described. When the current is cut off by an induction circuit such as a motor load, an excessive surge voltage is generated,
There is a risk of breaking the insulation of the load equipment. The cause of this abnormal surge voltage is the current interruption phenomenon that occurs on the low current side during interruption in vacuum (current interruption is performed without waiting for the natural zero point of the AC current waveform.)
It is due to. The value of the abnormal surge voltage V _s is represented by the product of the surge impedance Z _{o of the} circuit and the current cut-off value I _c , that is, V _s proportional Z _o · I _c.
To lower the _s, that is to have a low surge capabilities, it is necessary to reduce the current chopping value I _c. Therefore, at the time of cutoff, a large amount of ions and metal particles evaporate from the surfaces of the movable contact 13a and the fixed contact 13b due to the arc, float between the two contacts, and the arc must be easily connected. Therefore, the contacts 13a, 13b
The material used is required to have a high vapor pressure and a high vapor pressure, not only when breaking a large current, but also when the switching current is small and the temperature rise of the contact is small.

As a material satisfying such a low surge function, an Ag-WC alloy containing Ag which is a high vapor pressure material is known. The contact made of this alloy has the following features: (1) the presence of WC facilitates the emission of ions from the contact surface; and (2) the evaporation of metal particles from the contact surface due to heating between the electrodes due to the collision of field emission electrons. (3) Carbide in the contact material is decomposed by an arc to form a charged body, and has an excellent low surge function.

On the other hand, in order to have a high current breaking function, which is another contradictory requirement, it is required that the contacts be made of a material having a low vapor pressure. When cutting off a large current, the contact surface temperature becomes extremely high, but even in such a case, the amount of evaporation from the contact surface due to the arc is small, and ions and metal particles hardly float between both contacts. If it is not in a state, the breaking performance will be impaired.
Therefore, generally, when one of the functions is pursued, the other function is reduced.

As a means for satisfying these two conflicting requirements, there is a method in which the contact is made of two kinds of materials, a high vapor pressure material and a low vapor pressure material. When both contacts that were in contact during energization to cut off the current are separated,
First, many ions from the part composed of high vapor pressure material,
The metal particles evaporate and float between the contacts, whereupon the arc is guided and connected to the high vapor pressure material at both contacts. After a lapse of time necessary for the low surge function to be satisfied, the arc connected to the high vapor pressure material at the two contacts is transferred to the low vapor pressure material at the two contacts. This is done by controlling the magnetic field H using the coil electrode 44 shown in FIG. 5, the spiral electrode 45 shown in FIG. It can be carried out by a method of causing the arc to be transferred.

However, the physical properties of a high vapor pressure material having a low surge function even at the time of low current interruption are significantly different from the physical properties of a low vapor pressure material having a large current interruption function in terms of vapor pressure. For this reason, even if the distribution of ions and metal particles existing between the two contacts is changed by a magnetic field, for example, a vertical magnetic field H, the arc stagnates on the boundary between the portion made of the high vapor pressure material and the portion made of the low vapor pressure material. Does not transition easily. Therefore, the low surge function and the large current interrupting function cannot be simultaneously satisfied by simply forming the contact by simply combining the high vapor pressure material and the low vapor pressure material.

In view of the above circumstances, the present invention facilitates the transition of an arc from a high-vapor-pressure material to a low-vapor-pressure material during current interruption without stagnation, and provides a low surge function and a large current interruption function. It is an object of the present invention to provide a contact for a vacuum switch having two opposing functions.

[0012]

According to the present invention, there is provided a vacuum valve comprising:
A vacuum valve having a contact composed of first and second composition regions having different compositions and an intermediate region sandwiched between the first and second composition regions. That is, a vacuum valve according to the present invention is a vacuum valve comprising a contact made of a highly conductive material and an arc-resistant material, wherein the contact has a first composition having a different composition.
The first composition region [I], the second composition region [II], and the intermediate region [M] interposed between the first composition region [I] and the second composition region [II]. The region [I] is made of a low-surge Ag-WC alloy, the second composition region [II] is made of a large current blocking Cu-Cr alloy, and the intermediate region [M] is made of the first composition. It is made of an alloy having an intermediate property between the region [I] and the second composition region [II], and the amount of the conductive component of [M] is [II] with respect to the amount of the conductive component in each of the regions. ]>[M]>
A contact point characterized by being in the range of [I].

In a preferred embodiment of the present invention, the first
In the composition region [I], the high-conductivity material is composed of 10 to 50% by weight of Ag, and the remaining arc-resistant material is composed of WC. In the second composition region [II], the high-conductivity material is composed of 20 to 80% by weight. % C
u, a contact whose remaining arc-resistant material is made of Cr.

In another preferred embodiment of the present invention, the intermediate region [M] includes a contact made of Ag or / and Cu as the highly conductive material and Cr or / and WC as the arc resistant material. can do.

In another preferred embodiment of the present invention, the highly conductive material in the first composition region [I] comprises Ag and Cu, and the content of the highly conductive material is in the range of 10 to 50% by weight. , Cu contact is 40% or less of the Ag content.

In another preferred embodiment of the present invention, the arc resistant component Cr + WC in the intermediate region [M] is connected to the second composition region [II] from one end contacting the first composition region [I]. Cr / WC toward the other end in contact
Wherein the ratio of the arc resistance component of the first composition region [I] changes stepwise or continuously from the arc resistance component amount of the second composition region [II]. It can be provided.

In another preferred aspect of the present invention, each of the first composition region [I], the second composition region [II], and the intermediate region [M] is radially shifted from the center of the contact. II] [M] [I] or [I] [M]
And contacts arranged in the order of [II].

[0018]

The contact used in the vacuum valve of the present invention has a first composition region [I] and a second composition region [I] having different compositions.
I], and an intermediate region [M] interposed at an intermediate position between [I] and [II], wherein the first composition region [I] is an Ag-WC alloy excellent in low surge property, and the second composition region Area [II]
Is a Cu-Cr based alloy excellent in large current interrupting property, the intermediate region [M] is composed of an alloy having an intermediate property between [I] and [II], and the amount of the conductive component of this [M] is It is configured so that the amount of the conductive component in each region is in the range of [II]>[M]> [I]. Therefore, the amount of the conductive component that has an important effect on the low surge characteristic is, for example, in the case of a circular contact, in the order of [I] [M] [II] or [II] [M] [I] in the radial direction. It is changing in order.

In the case where current is interrupted by using a contact having such a configuration as a vacuum valve, when the two contacts that have been in contact during energization are separated from each other, the amount of the conductive component in the region constituting the contact is the largest. A large amount of ions are emitted from the first composition region [I] made of a material having a small amount of metal or metal particles evaporate and float between the alloy regions of both contacts, and an arc is led to this and the arc is introduced between the two alloy regions. Connected.

Thereafter, when the distribution of ions and metal particles existing between the two contacts is changed by the action of a magnetic field, the arc travels from the first composition region [I] to the intermediate region [M]. That is, the amount of the highly conductive component gradually increases from the first composition region [I] to the second composition region [II] through the intermediate region [M], so that the arc can be easily formed without stagnation. Transition. In this way, the arc is forcibly shifted toward the second composition region [II] by controlling the magnetic field. Then, after a lapse of time necessary for the low surge function to be satisfied, that is, for the arc to be connected between the two contacts, a transition is made to the second composition region [II] without Ag. The connection will be disconnected.

The first composition region [I] is made of a low-surge Ag-WC alloy. This Ag-WC alloy is an alloy having an excellent low surge function as described above. In the present invention, the Ag-WC alloy is made of Ag as a conductive material or a material having Ag as a main component and a part thereof replaced with Cu, and WC as an arc-resistant component.
Means an alloy consisting of And the high conductive material is 10
It is preferable that Ag of up to 50% by weight and the balance of the arc resistant component be WC. If the amount of the conductive component in [I] is less than 10% by weight, the cutting current value will not be sufficiently low,
Also, the dispersion is large, and the cutting tends to deteriorate with the passage of the number of times of opening and closing. On the other hand, if it exceeds 50% by weight, the cutting current value is high, which is not preferable.

The highly conductive material in the first composition region [I] is not limited to Ag, and even if it is made of Ag and Cu, the content of the highly conductive material is 10 to 50% by weight.
If the amount of Cu is within 40% of the amount of Ag, the amount of the conductive component in the intermediate region [M] is [II]>
As long as the range of [M]> [I] is satisfied, the arc spreads over the entire surface of the electrode and exhibits favorable breaking characteristics.

The second composition region [II] is made of a Cu—Cr-based alloy having a large current blocking property. This Cu-Cr-based alloy is an alloy having excellent large current interruption characteristics as described above. Here, the highly conductive material is 20 to 80% by weight of Cu,
It is preferable that the remaining arc-resistant material is made of Cr. If the amount of the conductive component in [II] is less than 20% by weight, it is difficult for the arc to sufficiently transfer from [M] to [II].
On the other hand, if it exceeds 80% by weight, the consumption of the portion [II] increases due to the arc.

The intermediate region [M] is located at an intermediate position between the first composition region [I] and the second composition region [II], and has an intermediate property between these [I] and [II]. Made of alloy. With such a configuration, the second composition region [I] from the first composition region [I] through the intermediate region [M].
The transition of the arc to [I] is performed smoothly.
As the constituent material of [M], the highly conductive material is A
Preferably, the arc-resistant material is made of g or / and Cu, and the arc-resistant material is made of Cr or / and WC. Therefore, specifically, as the constituent material of the intermediate region [M], Ag-WC, Cu-WC, Ag + Cu-WC, Ag
-Cr, Cu-Cr, Ag + Cu-Cr, Ag + Cu-
WC + Cr, Ag-WC + Cr and Cu-WC + Cr
There are combinations of
As long as the amount of the conductive component is in the range of [II]>[M]> [I], a preferable blocking performance is exhibited.

When WC + Cr is used as the arc-resistant material in the intermediate region [M], one end contacting the first composition region [I] moves from one end contacting the second composition region [II] to the other end contacting the second composition region [II]. Thus, the ratio of Cr / WC is changed stepwise or continuously from the amount of the arc resistant component in the first composition region [I] to the amount of the arc resistant component in the second composition region [II]. This is preferable because the arc smoothly transitions from [I] to [M] to [II].

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In one embodiment of the present invention, a contact is composed of Ag-WC as a first composition region [I], Cu-Cr as a second composition region [II], and an intermediate region [M] between them. The case will be described with reference to FIG. The difference from the conventional contact shown in FIG. 4 is that an intermediate region [M] is arranged between [I] and [II].

Next, the results of tests and evaluations on the low surge property and the large current breaking property of the contact according to the present invention will be described. In order to compare and contrast the low surge function and the large current breaking function of each contact, the same conditions were used for the contact pressure in a state where both contacts were in contact, the opening speed when moving away from this state, and the degree of vacuum.

The superiority of the low surge property can be evaluated by the magnitude of the current break required for the arc to be connected between the separated contacts, and the smaller this value is, the better the low surge property is. Becomes A of 44A through LC circuit
When a C current was applied, the voltage drop of the coaxial shunt inserted in series with the vacuum circuit breaker was measured with an oscilloscope, and the current break value was calculated.

The superiority or inferiority of the large current interruption can be evaluated by the magnitude of the current when the interruption is successful, that is, the maximum value of the current. The larger this value is, the more excellent the large current interruption is. After cleaning the contact surface by baking, voltage aging, etc., and keeping the conditions constant, the maximum value of the current at the cutoff limit was measured while increasing the current at 1 KA at 7.2 KV, 50 Hz, and the magnification relative to a predetermined standard value. Was calculated as the cutoff magnification.

The effects of the contact according to the present invention will be described with reference to Tables 1 and 2 showing the surge current value and the breaking ratio for each contact of Example 1 and Comparative Examples 1 and 2. Example 1 and Comparative Examples 1 and 2
In each case, 33Ag-WC of the low cutting material is used in (21) in FIG. 1, that is, the first composition region [I], and 50Cu-Cr of the high current blocking material is used in the second composition region [II], FIG. 1 used in (23). On the other hand, [I] [I
1], the amount of the conductive component Ag is 15 wt% (Comparative Example-1), 42 wt% (Example 1), and 75 wt% ( When evaluated as Comparative Example-2), when the amount of Ag in [M] was an intermediate amount between the conductive materials of [I] and [II],
The arc ignited in [I] spread to [II], and as a result of effectively utilizing the electrode area, excellent breaking performance was exhibited (Example-1). In contrast, the amount of Ag in [M] is 15
In the case of wt%, that is, when the amount of Ag (conductive material) in [I] was smaller than that in Comparative Example 1, the arc was [I].
And [M] tended to stick together, the electrode surface could not be used effectively, and the breaking characteristics were not sufficient (Comparative Example-
1). On the other hand, when the amount of Ag in [M] is 75 wt%, that is, when the amount of the conductive material (Cu) in [II] is larger (Comparative Example-2), the arc is at the boundary between [M] and [II]. In the area of [II], which has excellent breaking performance.
The ability of 0Cu-Cr could not be sufficiently exhibited, and the breaking characteristics were not sufficient (Comparative Example-2). From the above, the amount of the highly conductive material in the intermediate region [M] is [II]>[M]>
It must be within the range of [I].

Example 2, Comparative Examples 3 and 4 The case described above is based on the fact that Ag is used as the conductive component in the intermediate region [M].
Was described for Ag-WC using Cu, but the same tendency was obtained in Cu-WC using Cu as the conductive component.
That is, when the amount of Cu in [M] is an intermediate amount between the conductive components of [I] and [II], the arc ignited in [I] quickly spreads to [II], and the electrode surface As a result of the effective use of
2). On the other hand, when the amount of Cu in [M] is 20 wt%, that is, when the amount of Ag (conductive material) in [I] is smaller (Comparative Example-3), the arcs are [I] and [M]. ], And the breaking characteristics were not sufficient due to electrode damage due to arc concentration (Comparative Example-
3). On the other hand, when the amount of Cu in [M] is 70 wt%, that is, when the amount of Cu (conductive component) in [II] is larger (Comparative Example-4), the arc is at the boundary between [M] and [II]. In the area of [II], which has excellent breaking performance.
0 Cu-Cr was not able to exhibit its ability sufficiently, and it was not possible to obtain favorable breaking characteristics (Comparative Example-
4). From the above, the amount of the highly conductive material in the intermediate region [M] is:
[II]> as in the case of Ag described in Example 1 above.
It is desirable to be in the range of [M]> [I].

Embodiments 3 to 7 The contacts used in [M] are not limited to Ag-WC and Cu-WC as shown in Embodiments 1 and 2, but Ag-Cr, C
In the case of u-Cr (Examples 3 and 4), when the amount of the conductive component satisfies [II]>[M]> [I], preferable breaking performance was obtained. Similarly, the same effect was obtained when the conductive component of the contact used in [M] was Ag + Cu (Examples 5 to 5).
7). The same effect was obtained even when the arc resistance component was WC + Cr (Example-7).

Example -8 In Examples 1 to 7 and Comparative Examples 1 to 4, the first composition region [I] was described using an example of an Ag-WC alloy. However, the present invention is not limited to this. However, when the total amount is 29 wt%, the preferred shut-off characteristic is exhibited when the amount of the conductive component in the intermediate region [M] is in the range of [II]>[M]> [I] (implementation). Example-8). In this case, the arc spreads favorably over the entire electrode surface, as in the previous embodiment.

Examples 9 to 10 and Comparative Examples 7 to 8 As described above, the conductive component in the alloy is used as a condition for sufficiently exhibiting the breaking characteristics of the material of the second composition region [II] due to the presence of the intermediate region [M]. [II]>[M]>
It was found that [I] was necessary. On the other hand, the amount of the conductive component in the first composition region [I] is 4 wt% Ag.
In the case of, the cutting current value is not sufficiently low (improved),
In addition, the variation was large (Comparative Example-7),
wt% Ag (Example-9). Also, when the amount of the conductive component in [I] is 75 wt% Ag, the cutting current value is high, which is not preferable (Comparative Example- 9).
8). From these, in the vacuum valve of the present invention, the amount of the conductive component in the first composition region [I] is preferably 10 to 50 wt%. In particular, in the case of 4Ag-WC (Comparative Example-7), the cutting tends to deteriorate (the cutting current value increases) with the passage of the number of times of opening and closing.

Examples 11 to 13 and Comparative Examples 9 to 10 When the amount of the conductive component in the Cu—Cr alloy used in the second composition region [II] is 10 wt% Cu, the arc is sufficiently [M]. From [II] to 95 wt.
In the case of% Cu, the arc greatly consumes the portion [II].
Therefore, the amount of the conductive component in the second composition region [II] is preferably in the range of 20 to 80% by weight. As described above, the amount of the conductive component of [M] is [II]>[M]>
It is essential to be within the range of [I], and if it is within this range, the conductive component in [M] may be not a single component but a multi-component, particularly from [II] to [I]. It may change continuously or stepwise.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

As described above, the vacuum switch contact according to the present invention has at least two types of Ag-WC alloy regions having a low surge function and Cu-Cr alloy regions having a large current breaking function. And an alloy having an intermediate property between the two alloy regions, and the conductive component amount of the alloy is Cu-Cr based alloy region>
There is a boundary region in the range of the intermediate region> Ag-WC alloy region. For this reason, from the Ag-WC alloy region, Cu
-Forced arc transfer by controlling the magnetic field to the Cr-based alloy region is easily performed without stagnation, and the two contradictory requirements of a low surge function and a large current interruption function can be satisfied at the same time.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a contact for a vacuum switch of the present invention.

FIG. 2 shows a vacuum switch.

FIG. 3 is a partially enlarged view showing details around a movable electrode 8 in FIG. 2;

FIG. 4 is a view showing a conventional contact for a vacuum switch.

FIG. 5 is a diagram showing a coil electrode used in a vacuum switch.

FIG. 6 is a diagram showing a spiral electrode used in a vacuum switch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cut-off room 2 Insulating container 3a Sealing fitting 3b Sealing fitting 4a Metal lid 4b Metal lid 5 Conductive rod 6 Conductive rod 7 Fixed electrode 8 Movable electrode 9 Bellows 10 Arc shield 11 Arc shield 12 Brazing 13a Movable contact 13b Fixed contact 14 Brazing 21 First composition region [I] 22 Intermediate region [M] 23 Second composition region [II] 44 Coil electrode 45 Spiral electrode H Magnetic field

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Atsushi Yamamoto 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Fuchu Plant, Toshiba Corporation (56) References JP-A-63-266720 (JP, A) JP-A-63- 175308 (JP, A) JP-A-56-121228 (JP, A) JP-A-63-86835 (JP, A) JP-A-2-270232 (JP, A) JP-A 2-288033 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01H 33/66

Claims (6)

(57) [Claims] 1. A vacuum valve comprising a contact made of a highly conductive material and an arc-resistant material, wherein the contact has a first composition region [I] and a second composition region [2] having different compositions, respectively. II] and an intermediate region [M] interposed between the first composition region [I] and the second composition region [II], wherein the first composition region [I] has a low surge Ag- WC-based alloy, the second composition region [II] is composed of a large current blocking Cu-Cr-based alloy, and the intermediate region [M] is the first composition region [I] and the second composition region [ II], wherein the amount (% by weight) of the conductive component (M) is based on the amount (% by weight) of the conductive component in each of the regions. M]>
A vacuum valve, comprising: a contact in the range of [I]. 2. The first composition region [I] is composed of 10 to 50% by weight of a highly conductive material Ag and the remaining arc resistant material is WC. 2 conductive materials
2. The vacuum valve according to claim 1, further comprising a contact, wherein 0 to 80% by weight of Cu and the balance of the arc-resistant material are made of Cr. 3. The intermediate region [M] is made of a highly conductive material of A
The vacuum valve according to claim 1, further comprising a contact made of g or / and Cu, and wherein the arc-resistant material is made of Cr or / and WC. 4. The highly conductive material of the first composition region [I] is made of Ag and Cu, and the content of the highly conductive material is 1
The vacuum valve according to claim 1, further comprising a contact in a range of 0 to 50% by weight, and the amount of Cu is within 40% of the amount of Ag. 5. An arc-resistant component C in said intermediate area [M].
r + WC is such that the ratio of Cr / WC from one end contacting the first composition region [I] to the other end contacting the second composition region [II] is equal to that of the first composition region [I]. 5. The contact according to claim 1, wherein the contact resistance is changed stepwise or continuously from the arc resistance component amount to the arc resistance component amount of the second composition region [II]. The vacuum valve according to any one of the preceding claims. 6. The first composition region [I], the second composition region [II], and the intermediate region [M] are radially [II] [M] [I] from the center of the contact. 6. The vacuum valve according to any one of claims 1 to 5, further comprising a contact arranged in the order of [I], [M], and [II].