JPH0381919A - Gas insulation switch - Google Patents

Abstract

PURPOSE:To secure a high reliability of breaking performance and insulation performance by providing an arc resistant metal at a main contact opening point for an opening time and a range around it, and energizing conductor parts for contact parts except for the arc resistant metal in a complete closure condition. CONSTITUTION:For opening operation, a main contact is opened at its opening point Q, when load current at the main contact moves to the arc contact side to produce a main contact arc at the opening point Q because a resistance 33 is connected in series with a fixed side arc contact 29 to set the impedance at the part. The opening point Q is positioned at the center of an arc resistant metal 34, 35 both on the finger 25 side and the movable contact 17 side, so damage is slight if the arc is produced. By further opening after this, arc contacts 28, 29 gets apart from each other, and because the load current is reduced by the resistance 33, breaking current is small, and breaking can be achieved easily and in a short arc time.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention relates to a gas insulated switchgear used in power generation and substations, which has the responsibility of switching a current equal to or higher than the load current. This field relates to insulated switches, and particularly to techniques for improving current switching performance and equipment reliability.

(Prior Art) Gas-insulated switchgears have been widely used in recent years as switchgears for high-voltage circuits used in power generation and substations.

This gas-insulated switchgear houses various devices such as busbars, circuit breakers, disconnectors, and other auxiliary equipment in a grounded metal container.
S is inert, nonflammable, odorless, harmless, and has excellent insulation performance.
It is filled with F6 gas under pressure and used as a switching device for a high-pressure circuit. Such a gas insulated switchgear is arranged and configured according to a single line diagram of a switchgear in a power generation and substation. FIG. 4 is a single line diagram showing an example of a double bus type gas insulated switchgear.

In Fig. 4, a circuit breaker 3 is connected to the line side and bank side of the main bus 1.2, and bus disconnectors 4 and 5 are connected between the main bus 1.2 and the circuit breaker, respectively. has been done. The line-side circuit breaker 3 further includes a line disconnector 6.
is connected to the bushing 8 through the bank side circuit breaker 3.
is connected to the transformer 9 via the bank disconnector 7. Note that 10.11 in the figure is a tie disconnector.

In this circuit, the circuit breaker 3 is responsible for switching on and off the fault current, and the bus disconnector 4-5 is responsible for switching the so-called loop current, which switches the load current without stopping the line. have been given the responsibility to do so. In this way, a switch that interrupts a large current equivalent to or higher than the load current is
In addition to the main contact for passing the load current under normal closed circuit conditions, it has an arc contact to reduce damage to the main contact due to arcing that occurs when the circuit is opened. Arc-resistant metals such as copper tungsten are used.

As an example of such a switch, the structure of a disconnector used as a busbar disconnector and responsible for switching loop current is shown in FIG.

In FIG. 5, SF6 gas 1 is contained in the metal container 12.
3 is filled under pressure, and a fixed side contact portion 15 and a movable side contact portion 16 supported by an insulating spacer 14 are arranged to face each other. A movable contact 17 is disposed coaxially within the movable contact portion 16, and opens and closes the fixed contact portion 15 and the movable contact portion 16 by reciprocating in the axial direction. . An arc contact 18 is provided inside the movable contactor 17 to commutate the current and perform arcing and interrupting when the current is interrupted. Further, the movable contactor 17 is connected to an insulating rod 19, and a link 20
, a lever 21, and a main shaft 22, and are configured to be opened and closed by an operating device 23 installed outside the disconnector.

In such a disconnector of FIG. 5, when the current is opened, the interrupting current is commutated to the arc contact 18 at the same time as the main contact (movable contact 17) is opened, and then the arc contact 18 is opened. An arc is generated at this point and is eventually cut off.

Details of the contact portion of such a disconnector are shown in FIG. In this case, FIG. 6 shows a completely closed circuit state.

In FIG. 6, the movable contact 17 and the fixed conductor 24 of the fixed contact portion 15 are electrically connected via fingers 25, and the movable contact 17 and the fixed conductor 24 of the fixed contact portion 15 are electrically connected to each other through fingers 25. The contact load is obtained by a spring 26 attached to the finger 25. Further, a shield 27 is provided around the outer periphery of the finger 25. An arc contact, designated 18 in FIG. 5, is arranged inside the main contact thus constructed. That is, a movable arc contact 28 fixed to the movable contact 17 and a fixed arc contact 29 fixed to the fixed conductor 24 are provided inside the main contact, and these arc contacts 28.
The tip of 29 is made of arc-resistant metal 3 such as copper tungsten.
0.31 is provided.

When the disconnector configured as described above is opened, the sixth
From the state shown in the figure, the movable contactor 17 moves at high speed in the opening direction in the upper part of the figure, and first, the main contact opens. The state at this time is shown in FIG. Assuming point P in Figure 7 as the main contact opening point,
The main contacts open, and immediately thereafter the current that was flowing through the fingers 25 is transferred to the still-contact arcing contacts 28.
It is commutated between 29 and 29 hours. As the movable contact 17 further moves in the opening direction, the arc contacts 28 and 29 are eventually separated, and an arc 32 is formed between the arc contacts 28 and two arc-resistant metals 30 and 31, as shown in FIG. occurs. When the movable contact 17 moves further in the opening direction at high speed, the arc 32 is extended and at the same time is cooled by the surrounding SF6 gas, and is finally cut off.

Conventionally, high current switches of about 200 OA class generally have the above-mentioned contact structure, but as the capacity of gas insulated switchgears continues to increase, the load current has increased from 200 OA class to 400 OA and 800 OA. If the load current reaches a higher level, the load current will be interrupted by a significantly larger amount. If you try to interrupt such a large current with the above-mentioned switch, it will be difficult to smoothly transfer the current from the main contact to the arc contact when the main contact opens, and the main contact opening point (second When opened at point P in Figure 7, a voltage equal to the product of the impedance on the arc contact side and the commutation current is generated between the main contacts, and this increases as the load current increases, causing an arc to occur at point P. I come to do it. That is, at the moment of commutation to the arc contact,
An arc will occur between the main contacts, that is, at point P between the movable contact 17 and the finger 25. The main contacts carry the load current, so they are usually made of highly conductive materials such as copper or aluminum, but these materials are extremely susceptible to arcs and will be damaged by main contact arcs. . If the opening/closing operation is performed in a damaged state, the rough damaged part will slide on the healthy part and roughen the surface as well. As a result, the main contact contact point (point A in FIG. 6) in a completely open state is also damaged, resulting in a decrease in load current carrying performance. In addition, the damaged area is melted and solidified by the arc and is very rough, so when it slides during opening and closing operations, a larger amount of sliding metal powder than normally expected is generated, and these metal powders , scattering in the disconnector and depositing on the insulating spacer 14 shown in FIG.
There is also a risk that the insulation performance will deteriorate. Furthermore, due to the deterioration of current conduction performance and insulation performance as described above, the life of the switch is shortened, and there is also the problem that maintenance and inspection must be performed frequently.

On the other hand, when the load current of the switch becomes large, as shown in Fig. 6, simply providing arc contacts 28 and 29 results in poor breaking performance and long arc time. This accelerates the wear and tear of the metal particles, causing metal powder to scatter inside the aroma container, further increasing the risk of deterioration of insulation performance. In some cases, the load current may exceed the limit of interrupting performance and interrupting may become impossible. In order to prevent such inconveniences and improve the breaking performance, a technique has been adopted in which a resistor is inserted in series with the arc contact portion to reduce the breaking current against a large load current. An example of a disconnector having such a configuration is shown in FIGS. 9 and 10. In FIGS. 9 and 10, a resistor 33 is connected in series to the two fixed arc contacts. Here, considering the loop current switching responsibility of 8000 A, the recovery voltage is about 300 V, so the impedance of the circuit is about 38 mΩ. If this current is reduced to about 2000 A when commutated to the arc contact, an impedance of about 150 mΩ is required as the impedance of the entire circuit, which is approximately 10 mΩ as a resistor.
Corresponds to 0 mΩ.

By inserting such a resistor, a significant improvement in breaking performance can be expected, but as a result of the extremely large impedance of the arc contact circuit, the main contact firing during commutation as described above becomes inevitable. Otherwise, the degree of damage will be very large.

(Problems to be Solved by the Invention) Gas-insulated switchgears have now become indispensable as equipment constituting electric power systems, and the social mission of increasing their capacity is also increasing. It is important to ensure the performance and reliability of switches that are responsible for switching current, which is a part of the important functions in gas-insulated switchgear. There is also a strong demand for a longer period. On the other hand, as mentioned above, in conventional switches, even if a resistor is inserted into the arcing contact to improve breaking performance, the main contact inevitably arcs when a large current is interrupted. There is a high risk of deterioration of current carrying performance and insulation performance due to damage caused by arcing.

The present invention was proposed to solve the problems of the prior art, and its purpose is to
Even if an arc occurs at the main contact, the damage to the main contact can be suppressed to very slight damage, thereby providing high interrupting performance while maintaining the initial current carrying performance, and improving the insulation performance of the equipment. An object of the present invention is to provide an excellent gas insulated switch that can ensure reliability.

[Structure of the Invention] (Means for Solving the Problems) A gas insulated switch according to the present invention includes a main contact and an arc contact, in which the arc contact is opened after the main contact is opened. At the same time, an arc-resistant metal is provided at the tips of the contacts on both sides that make up the main contact, and each arc-resistant metal is placed in a range that covers the main contact breaking point and its surroundings when the main contact is opened. , and is characterized in that it is disposed in a range where it does not come into contact with the opposing contact in a completely closed state.

Further, it is also possible to connect a resistor in series to one of the arc contacts constituting the arc contact.

(Function) In the gas insulated switch of the present invention having the above-described configuration, even if an arc occurs at the main contact when the main contact is opened, the arc-resistant metal is provided in the arc-igniting part. Damage caused by arcs can be significantly reduced.

In this case, the electrical conductivity of the arc-resistant metal is lower than that of the material that makes up the main contact body, but in a fully closed circuit state, the highly conductive material that makes up the main contact body, rather than the arc-resistant metal, is the contact point. Therefore, the original current carrying performance can be ensured. On the contrary, in the present invention, as described above, damage caused by arcing can be significantly reduced, so even after repeated interruptions, the initial current carrying performance can be maintained for a long period of time. Since the amount of sliding metal powder generated can be significantly reduced, reliability in terms of insulation performance can be ensured.

Furthermore, if a resistor is connected to the arcing contact, the impedance will increase and it will be impossible to avoid the main contact from firing. However, as mentioned above, since the arcing part of the main contact is provided with an arc-resistant metal, the current carrying performance will be improved. In addition to maintaining reliability in terms of insulation performance, the connected resistor can reduce the interrupting current and improve the interrupting performance.

(Embodiment) An embodiment in which the present invention is applied to a disconnector will be specifically described below with reference to FIGS. 1 to 3.

In this case, FIG. 1 shows a completely closed circuit state, FIG. 2 shows a state at the moment when the main contact opens and closes, and FIG. 3 shows an arcing state at the arc contact. Note that the same parts as those in the prior art shown in FIGS. 4 to 10 are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 1, the movable contact 17 and the finger 25
The tip of the arc-resistant metal 34 such as copper tungsten is
．． 35 are provided respectively.

In this case, as shown in FIG. 2, the arc-resistant metals 34 and 35 are provided in a range that covers the main contact separation point (point Q) and its surroundings when the contacts are opened. In addition, in the completely closed circuit state shown in FIG. 1, the load current I flows through the contact point (point B) between the finger 25 and the movable contact 17, but the material of the contact point portion during normal energization is The movable contact 17 or the finger 25 is made of the original material, ie, a highly conductive material such as copper or aluminum, instead of arc metal. Therefore, the current carrying performance of the load current is equivalent to that of a conventional switch. Furthermore, a resistor 33 is connected in series to the two fixed side arc contacts.

When a circuit opening operation is performed on a contact configured in this way, the main contact opens at its opening point Q, as shown in Figure 2, and the load current flowing through the main contact at this time is caused by an arc. The current tries to commutate to the contact side, but since the resistor 33 is connected in series to the fixed arc contact 29 and the impedance of this part is large, the main contact is switched at the break point (point Q). Causes an arc. In this case, the break point (Q point) is located at the center of the arc-resistant metal 34.35 on both the finger 25 side and the movable contact 17 side, so even if an arc occurs, the damage will be extremely high. It is kept to a minor extent. Also,
When damage occurs in an arc-resistant metal such as copper tungsten, the damage only causes extremely minute dents, so there is little concern that the damage will spread and cause further damage to healthy parts. After this, when the contact is further opened, the arc contact 2
8.29, and an arc 32 occurs, but in this case, the load current is reduced by the resistor 33, so the breaking current is small, and the arc is broken easily and in a short time. It is possible to do so.

As described above, in this embodiment, by using an arc-resistant metal at the opening point of the main contact, a resistor is installed at the arc contact in order to prevent the main contact from firing when interrupting a large current, or to improve current interrupting performance. Even if main contact firing occurs unavoidably due to the insertion of can be secured.

In addition, in conventional switches, as mentioned above, sliding metal powder is generated due to contact roughness due to main contact firing, or metal powder is generated due to prolonged arc time due to insufficient breaking performance. However, in this example, in this example,
Even if the main contact fires, the contact surface will not be roughened, so the generation of sliding metal powder can be almost completely eliminated, and by inserting a resistor, the breaking performance can be improved and the arcing time can be shortened. The amount of metal powder scattered by the arc can be significantly reduced, ensuring reliability in terms of insulation performance.

Note that the present invention is similarly applicable to a disconnector in which a resistor is not provided at the arc contact. Moreover, it is applicable not only to disconnectors but also to general switches used in power systems, such as circuit breakers.

[Effects of the Invention] As explained above, in the present invention, an arc-resistant metal is provided in the main contact breaking point and the area surrounding it when the contact is opened, and in a completely closed state, a metal other than the arc-resistant metal is provided. By configuring the conductor part to conduct electricity as a contact part, even if an arc occurs at the main contact when the main contact is opened, damage to the main contact part can be suppressed to extremely slight damage. Therefore, it is possible to provide an excellent gas insulated switch that can ensure high breaking performance, current carrying performance, and insulation performance, and can maintain these initial performances over a long period of time.

In addition, the large capacity, high performance, and long lifespan of such switches make it possible to extend maintenance and inspection periods in the operation of electric power systems, and greatly contribute to fulfilling the social responsibility of supplying large amounts of current. I can contribute.

[Brief explanation of drawings]

1 to 3 are cross-sectional views showing one embodiment of the contact portion of a disconnector to which the present invention is applied, and FIG. 1 shows a completely closed state,
FIG. 2 shows the main contact opening, and FIG. 3 shows the arc contact firing. Fig. 4 is a single line diagram showing an example of a gas insulated switchgear, Fig. 5 is a sectional view showing an example of a conventional disconnector, and Figs. 6 to 8 show the contact portion of the disconnector shown in Fig. 5. These are cross-sectional views, with FIG. 6 showing the fully closed circuit state, FIG. 7 showing the main contact when it is open, and FIG. 8 showing the arc contact when it is firing. FIG. 9 is a cross-sectional view showing an example of a conventional disconnector in which a resistor is provided at the arc contact, and FIG. 10 is a cross-sectional view showing the contact portion (completely closed state) of the disconnector shown in FIG. 9. 1.2... Main busbar, 3... Circuit breaker, 4, 5... Disconnector for busbar, 6... Disconnector for line, 7... Disconnector for bank, 8... Bushing , 9... transformer, 10
．． 11...Tie disconnector. 12... Metal container, 13... SF6 gas, 14.
...Insulating spacer, 15...Fixed side contact part, 16...
- Movable side contact part, 17... Movable contact, 18... Arc contact, 19... Insulating rod, 20... Link,
21... Lever 22... Main shaft, 23... Operating device. 24... Fixed side conductor, 25... Finger, 26...
...Spring, 27...Shield, 28...Movable side arc contactor, 2...Fixed side arc contactor, 30.31
, 34.35... Arc-resistant metal, 32... Arc,
33...Resistor.

Claims (2)

[Claims] (1) In addition to the main contacts for carrying constant load current,
In a gas-insulated switch having an arc contact that generates and extinguishes an arc when interrupting a current equivalent to the load current at the time of opening, the arc contact is opened after the main contact is opened. At the same time, arc-resistant metals are provided at the tips of the contacts on both sides that make up the main contact, and each arc-resistant metal is placed in a range that covers the main contact opening point and its surroundings when the contacts are opened.
A gas insulated switch characterized in that the switch is disposed in a range where it does not come into contact with an opposing contact in a completely closed circuit state. (2) The gas insulated switchgear according to claim 1, characterized in that a resistor is connected in series to one of the arc contacts constituting the arc contact.