JP2000164080A - Switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switch with the whole device size made small by constructing small the contact part as one constituent part of the switch. SOLUTION: A switch is composed of a pair of stationary contacting pieces 4 provided at one end with an opening for insertion of movable contacting piece and held in such a condition as being energized in the closing direction to each other and a movable contacting piece 1 whose forefront makes contacting and separation while it is inserted into and drawn out of the opening of the stationary contacting pieces 4 interlocking with a drive shaft 22, wherein a pair of aux. electrodes 3 whose other ends are connected with the stationary contacting pieces 4 are parallel installed in positions ahead of the forefront of the stationary contacting pieces 4 and on the sides of the moving locus surface of the movable contacting piece 1. A current limiting element 9 is connected between the aux. electrodes 3 and stationary contacting pieces 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch, and more particularly to a switch capable of reducing the melting of metal at a fixed contact caused by an arc generated when a circuit is turned on and off.

[0002]

2. Description of the Related Art Conventionally, a drive shaft is rotationally driven, and a movable contact for each phase, which is fixed and supported on the drive shaft, is connected to and detached from each fixed contact, so that a circuit can be turned on and off.
In a switch that opens, in order to protect the main contact, a heat-resistant metal such as tungsten is brazed and reinforced to the switching contact to reduce melting by an arc. As another method, an auxiliary contact is provided at a position in front of the movable contact of the main contact, and when closing, the auxiliary contact is closed before the main contact. By opening the auxiliary contact, an arc is generated and extinguished on the auxiliary contact side to protect the main contact.

[0003]

However, in the above-mentioned measures for brazing and reinforcing a heat-resistant metal to a fixed contact, when the heat-resistant metal is brazed and reinforced, only the movable contact can be brazed and reinforced. Melting could not be reduced. For this reason, there is a problem that it is not possible to cope with opening / closing accompanied by a large arc capacity, and it is difficult to obtain a sufficient number of service times of the switching contacts. Also, if an auxiliary contact is provided in addition to the main contact to precede and extinguish an arc, the contact portion becomes large and a complicated open / close contact configuration is required, or a separate open / close drive device is required. It was disadvantageous in terms of cost.

[0004] On the other hand, regarding the environment in which these switches are installed, for example, when installing a high-voltage cabinet for an underground line on the road, dimensions of the cabinet may be limited due to restrictions of the ordinance or the like. Therefore, it is necessary to reduce the size of the entire switch including the contact portion. As described above, there has been an increasing demand for downsizing of switches installed in high-voltage cabinets for underground cables. Accordingly, it is an object of the present invention to provide a switch which can reduce the size of a contact portion in a component of the switch to greatly contribute to downsizing of the entire device.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention according to claim 1 is provided with an opening for inserting a movable contact at one end, and is provided in a state where the openings are pressed and urged in the closing direction. In a switch comprising a pair of fixed contacts held and a movable contact whose tip is connected to and detached from an opening of the fixed contact in conjunction with a drive shaft, a front of the tip of the fixed contact is provided. A pair of auxiliary electrodes each having an end connected to a fixed contact is disposed in parallel on both sides of the movement trajectory surface of the movable contact.

According to a second aspect of the present invention, in the first aspect, a current limiting element is connected between the auxiliary electrode and the fixed contact.

A third aspect of the present invention is characterized in that, in the first or second aspect of the present invention, the outer box of the switch has a sealed structure and is filled with an insulating gas.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing the inside of the switch according to the first embodiment of the present invention. In the figure, 2
1 is an outer box, 1 is a movable contact, 2 is a support bracket, 3 is an auxiliary electrode, 4 is a fixed contact, 22 is a drive shaft, 23, 24
Is a conductor, and 25 is a bushing. Further, SF ₆ gas is sealed in the outer box 21 as an insulating gas. This switch is provided with two circuit contacts. When the drive shaft 22 is driven to rotate, the movable contact 1 pivotally supported by the support fitting 2 rotates, and the tip of the movable contact 1 is fixed to the fixed contact 4. The contact can be turned on and off by being freely connected and detached.

FIG. 2 is an enlarged view showing the contact portion shown in FIG. 1 and a right side view thereof. As shown in the figure, the pair of fixed contacts 4A and 4B are formed with a convex portion on the inside of the distal end so as to face each other to form an opening portion 26, and the portion near the lower end thereof is formed on both sides of the fixed support fitting 5 on both sides. Tighten the bolts and nuts 12 via the holding plate 8 and the fixing spring 7 so as to sandwich them, and similarly tighten the bolts and nuts 11 via the holding plate 8 and the holding spring 6 so that the upper ends are inside each other. Biased in the direction. The center surfaces of the fixed contacts 4A and 4B held opposite to each other coincide with the movement trajectory surface 27 when the movable contact 1 is closed and opened.

When the movable contact 1 descends from above the locus surface 27 when the contacts are turned on, the blade at the tip of the movable contact 1 comes into contact with the opening 26, and the fixed contacts 4A and 4B are moved. The contact is turned on by entering the opening while pushing and expanding to both sides. Further, a pair of auxiliary electrodes 3A, 3B made of a copper alloy round bar subjected to electric field relaxation are arranged in parallel and symmetrical positions slightly above the upper ends of the fixed contacts 4A, 4B. I have. One end of each of the auxiliary electrodes 3A and 3B is fixed to the fixed support 5 by a mounting plate 13 made of a conductor.

Thus, the movable contact 1 and the fixed contact 4
By arranging auxiliary electrodes 3A and 3B electrically connected to fixed contacts 4A and 4B between A and 4B, the magnitude of the electric field relatively changes due to the positional relationship between the three. That is, when the contacts are opened, the movable contact 1
When they are separated from A and 4B, immediately after they are separated, they are extremely close to each other, so that a stronger electric field is generated on the fixed contacts 4A and 4B side than on the auxiliary electrodes 3A and 3B. However, as the separation proceeds, the electric field on the fixed contacts 4A and 4B side weakens, and the electric field on the auxiliary electrodes 3A and 3B side relatively increases.

That is, when the contacts are opened, the movable contact 1 is separated from the fixed contacts 4A and 4B, and an arc 31 is generated once.
It moves quickly from the fixed contacts 4A, 4B to the auxiliary electrodes 3A, 3B, becomes an arc 32 and disappears. As a result, the wear of the fixed contacts 4A and 4B due to the arc is significantly reduced.

In this embodiment, the auxiliary electrodes 3A,
Since 3B has a circular cross section that is extremely effective for electric field relaxation and uses a copper alloy, the generation of metal vapor due to arc energy is suppressed, and the arc is quickly extinguished.
In the present embodiment, the operation and effect are the same when the fixed contacts 4A and 4B are on the power supply side and the movable contact 1 is on the load side, or when the connection is reversed.

FIG. 3 shows that the movable contact 1 is a fixed contact 4A,
4 is an electric field map model showing a transition of an electric field distribution at a moment when the electric field is separated from 4B. FIG. A shows the state immediately after the separation, and FIG. The values in the figure indicate the strength of the electric field,
As the movable contact moves over time,
It is shown that the portion having the strongest electric field moves from the fixed contacts 4A, 4B to the auxiliary electrodes 3A, 3B.

FIG. 4 is a diagram showing a contact portion of the second embodiment. This embodiment differs from the first embodiment in FIG. 2 in that the mounting plate 10 supporting one end of each of the auxiliary electrodes 3A and 3B is made of an insulating material, and the other ends of the auxiliary electrodes 3A and 3B and the fixed support 5 are connected to each other. Is connected to the current limiting element 9 made of a non-linear resistor or the like. The configuration of the other parts is the first in FIG.
Therefore, common portions are denoted by the same reference numerals and description thereof is omitted. In this embodiment, the auxiliary electrode 3
By connecting the current limiting element 9 to the A, 3B side, the arc extinguishing timing after the generated arc moves to the auxiliary electrodes 3A, 3B is advanced. Thus, damage to the movable contact 1 and the auxiliary electrodes 3A and 3B due to the arc can be reduced correspondingly.

The contact portions of both embodiments shown in FIGS. 2 and 4, respectively, are housed in an outer box 21 having a sealed structure and filled with SF ₆ gas as shown in FIG. . The sealing pressure at this time was confirmed to be sufficient at about 0.02 MPa · G in the 22 kV interruption test, partly because the arc resistance was improved by providing the auxiliary electrodes 3A and 3B. As described above, the outer box 21 is reduced by the low filling pressure.
Can be simplified. Note that both embodiments described above
It is needless to say that the present invention is not limited to the switch of the type in which the movable contact 1 is rotationally driven, but may be applied to the switch of the type in which the movable contact 1 is linearly driven to be inserted into and detached from the fixed contact 4. .

[0017]

As described above, according to the present invention, the auxiliary electrodes are disposed on both front sides of the fixed contact so that the arc generated at the time of opening the contact is immediately moved to the auxiliary electrode. The characteristics are improved. Further, by connecting a current limiting element between the auxiliary electrode and the fixed contact, and further sealing the insulating gas, the arc resistance is further improved. In addition, by adopting these configurations, the size and simplification of the contact section and the phase-to-phase dimension are reduced, and the size and cost of the switch itself are reduced, as compared with a conventional switch with auxiliary contacts. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the inside of a switch according to a first embodiment of the present invention.

FIG. 2 is an enlarged view showing a contact portion of FIG. 1 taken out and a right side view thereof.

FIG. 3 is an electric field map model showing a transition of an electric field distribution at a moment when the movable contact of FIG. 2 is separated from a fixed contact.

FIG. 4 is an enlarged view showing a contact portion according to a second embodiment and a right side view thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Movable contact 2 Supporting bracket 3, 3A, 3B Auxiliary electrode 4, 4A, 4B Fixed contact 5 Fixed supporting bracket 6 Nipping spring 7 Fixed spring 8 Suppression plate 9 Current limiting element 10 Mounting plate 11, 12 Bolt / nut 13 Mounting plate 21 Outer case 22 Drive shaft 23, 24 Conductor 25 Bushing 26 Opening 27 Movement trajectory plane 31, 32 Arc

Continued on the front page (72) Inventor Toshihiko Miyazaki 1-7-1, Yurakucho, Chiyoda-ku, Tokyo Toko Electric Co., Ltd. (72) Inventor Masanori Matsuoka 1-7-1, Yurakucho, Chiyoda-ku, Tokyo Toko Electric Co., Ltd. In-house F-term (reference) 5G027 AA30 CA09

Claims (3)

[Claims] 1. A pair of fixed contacts held at a state where one end is formed with an opening for inserting a movable contact and pressed and urged in a closing direction. A switch comprising: a movable contact that is inserted into and removed from an opening of the fixed contact; and a fixed contact having an end on both sides of a moving trajectory surface of the movable contact in front of a tip of the fixed contact. A pair of auxiliary electrodes connected in parallel to each other are arranged in parallel. 2. The switch according to claim 1, wherein a current limiting element is connected between the auxiliary electrode and the fixed contact. 3. The switch according to claim 1, wherein an outer box of the switch is hermetically sealed and an insulating gas is sealed therein.