JPH0371526A - Gas-blast circuit-braker for electric power - Google Patents

Abstract

PURPOSE:To reduce damage to an electrode for electrification due to the arc generated at the time of communication by forming a base metal part in double layers, and by forming the periphery thereof out of a metal of low resistivity such as copper, while forming the center part thereof out of a metal of high rigidity such as iron. CONSTITUTION:By forming a base metal part of a fixed arc electrode 7 in double layers, resistance values of a fixed support 9 through a fixed arc electrode 7, a moving arc electrode 11, to a buffer cylinder 14 are rendered not to be so large compared with those of the fixed support 9, a fixed finger 6, to a moving electrode 10, and the buffer cylinder 14, whereby potential difference generated by the communication of current while the current is shut off by a gas-blast circuit-braker, is reduced. The generation of arc during the commutation of current from an electrode for electrification to the arc electrode can thus be suppressed, and damage to the electrode for electrification due to the arc can be reduced thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a power circuit breaker with an improved support structure for a fixed arc electrode.

(Prior Art) As the demand for electric power increases, efforts are being made to increase the capacity of gas circuit breakers used in power plants and substations. In particular, circuit breakers used in high-voltage systems are required to have large conducting currents and breaking currents.

Figure 3 shows the structure of the gas circuit breaker. The gas circuit breaker 1 has an arc extinguishing chamber 3 housed in a container 2 filled with insulating gas.

The arc extinguishing chamber 3 includes a fixed part 4 and a movable part 5 which are arranged opposite to each other. The fixed part 4 includes a fixed finger 6 through which current is normally applied, a fixed arc electrode 7, a fixed shield 8, and a fixed support 9 that supports these. The movable part 5 is composed of a movable electrode 10 to which a normal current is applied, a movable arc electrode 11°, an insulated nozzle 12, an operating rod 13, and a buffer cylinder 14. Further, in order to support the movable part 5, a supporting insulating cylinder 15. There is a movable support 16 and a buffer cylinder 14 and a pumper piston 17 which forms a compression chamber. The fixed part 4 is connected to the movable support 16 through a normal insulating tube 18. The insulating tube 18 may be an insulating rod or a capacitor.

When the current value to be applied is large, gas circuit breakers generally
It has two types of electrodes: a fixed finger 6 and a movable electrode 10 that are current-carrying electrodes, and a fixed arc electrode 7 and a movable arc electrode 11 that are current-blocking electrodes. The gas circuit breaker l is now in a closed state, that is, in a current-carrying state. The current passes through the conductor 19, the fixed support 9, the fixed finger 6,
Movable electrode 10, buffer cylinder 14, movable support 16
through conductor 20.

When the gas circuit breaker 1 interrupts a fault current or the like, an operating mechanism (not shown) pulls the operating rod 13 in the direction of the arrow in FIG. 4, and the movable part 5 moves in the direction of the arrow.

Then, as shown in FIG. 4, first, the fixed finger 6 and the movable electrode 10 are separated. Then, the movable electrode 10 and the buffer cylinder 14 pass through the fixed support 9 and the fixed finger 6.
Since the fixed arc electrode 7 and the movable arc electrode 11 have not yet separated, the current that was flowing changes its flow path from the fixed support 9 to the fixed arc electrode 7, the movable arc electrode 11, and the buffer cylinder 14. , that is, commutation occurs.

Then, as shown in FIG. 5, the movable part 5 further moves in the direction of the arrow, and the fixed arc electrode 7 and the movable arc electrode 11 are separated, so that an arc 21 is formed between the fixed arc electrode 7 and the movable arc electrode 11. Occur. As the buffer cylinder 14 moves, the gas compressed by the buffer cylinder 14 and the buffer piston 1 is blown against the generated arc 21 through the insulating nozzle i2.

The arc 21 is cooled and extinguished, and the current interruption is completed. FIG. 6 shows the open state of the circuit breaker 1 after the current has been cut off.

(Problems to be Solved by the Invention) As shown in FIG. 7, the tip of the fixed arc electrode 7 is made of an arc-resistant metal 22 that can withstand a high-temperature arc 21. Since the arc-resistant metal 22 is very expensive, the alloy portion 23 other than the tip where the arc 21 does not occur is made of a metal different from the arc-resistant metal. When the current interrupted by the circuit breaker is large, the amount and pressure of gas blown onto the arc 21 generated between the fixed arc electrode 7 and the movable arc electrode 11 is increased to extinguish the arc 21. Therefore, the arc 21 is sometimes agitated by this gas and distorted as shown in FIG.

If the arc 2 contacts the fixed support 9 at this time,
Since the fixed support 9 is generally not made of metal that can withstand high-temperature arcs, there is a risk that the fixed support 9 will melt due to the heat of the arc and the fixed part 4 will break, making it impossible to interrupt the current. In order to avoid this situation, the distance between the tip of the fixed arc electrode 7 where the arc 21 is generated and the fixed support 9 that fixes the fixed arc electrode 7 is made as long as possible.
The generated arc 21 is prevented from coming into contact with the fixed support 9. As a result, the fixed arc electrode 7 becomes long.

When the fixed arc electrode 7 becomes long, the alloy part 23 is made of a highly rigid metal such as iron so that the fixed arc electrode 7 itself does not bend under its own weight. However, the resistivity of iron is
Since it is higher than copper or aluminum and has a long length, the resistance value of the fixed support 9 is higher than that of the fixed support 9, the fixed finger 6, the movable electrode 10, and the buffer cylinder 14.
The resistance value from the fixed arc electrode 7 to the movable arc electrode 11 to the buffer cylinder 14 becomes extremely large,
I end up.

As a result, during the above-mentioned commutation during the current interruption process, the potential difference due to the commutation becomes large, making it difficult for the commutation to proceed smoothly.
When the fixed finger 6 and the movable electrode 10 are separated, a small amount of arc is generated. This arc has a fixed current at the arc electrode 7.
, the arc immediately disappears by commutation to the movable arc electrode 11, but this arc may roughen the surfaces of the fixed finger 6 and the movable electrode 10, melt some of them due to the heat of the arc, or cause the plating surface to disappear. This will reduce the current carrying performance of the circuit breaker.

However, if the alloy part 23 is made of a material such as copper, which has a low resistivity, the longer the electrode is, the more it will flex compared to steel, which has high rigidity. Mechanical problems such as galling of the poles occur.

An object of the present invention is to reduce the resistance of the fixed arc electrode of a gas circuit breaker without reducing its rigidity so much that the current from one energizing electrode to the arc electrode is reduced during the process of the gas circuit breaker interrupting current. An object of the present invention is to provide a gas circuit breaker capable of minimizing damage to a current-carrying electrode due to an arc occurring during commutation of a gas.

[Structure of the invention]

(Means for Solving the Problems) The power gas circuit breaker of the present invention has a fixed arc electrode made of an arc-resistant metal at its tip with a two-layer alloy part, and the outer periphery is made of a material such as copper having low resistivity. It is characterized by its core being made of highly rigid metal such as iron.

(Function) In the present invention, the alloy part of the fixed arc electrode has a two-layer structure, so that the resistance value of the entire base metal part can be lowered by the metal of the outer peripheral part, and even if the ffi pole is lengthened. The metal in the center allows it to maintain its rigidity. Therefore, even if the fixed arc electrode is lengthened to a predetermined length determined by the breaking performance, the breaking performance of the circuit breaker will not deteriorate.
The difference in resistance between the current-carrying electrode and the arc electrode can be reduced, and as a result, the generation of arcs that occur when current is commutated from the current-carrying electrode to the arc electrode can be suppressed as much as possible. Minimize the damage.

(Example) The present invention will be described below with reference to an example shown in FIGS. 1 and 2. In FIGS. 1 and 2, the same reference numerals as in FIGS. 3 to 7 indicate the same parts, so a description thereof will be omitted.6 The electric power gas circuit breaker of the present invention has a support structure for a fixed arc electrode. It is characterized by improved. That is, in FIG. 1, the base metal part of the fixed arc electrode 7 has a two-layer structure, with an outer peripheral part 31 made of copper and a central part 32 made of iron. The outer peripheral part 31 and the central part 32 have an integral structure.

The tip of the fixed arc electrode 7 is an arc-resistant metal 22, and the arc-resistant metal 22, outer peripheral portion 31, and center portion 32 are each fixed by brazing or the like.

The fixed arc electrode 7 and the fixed support 9 are attached to the center part 32.
The end is threaded and fixed to the fixed support 9 with a nut 33. The end of the outer circumferential portion 31 comes into contact with the fixed support 9 to ensure electricity supply.

Next, the operation of the power gas circuit breaker of the present invention configured as described above will be explained. Fixed support when the gas circuit breaker interrupts the current9. The current flowing through the fixed finger 6, the movable electrode 10, and the buffer cylinder 14 changes its flow from the fixed support 9, passes through the fixed arc electrode 7, the movable arc electrode 11, and then flows into the buffer cylinder 14, that is, it is commutated. At this time, the alloy part of the fixed arc jt electrode 7 has a two-layer structure in which the outer peripheral part 31 is made of copper and the center part 32 is made of iron, so the resistance value of the alloy part of the conventional fixed arc electrode 7 is different from that of the alloy part of the conventional fixed arc electrode 7. Compared to this, the value is lower, and the potential difference caused by the commutation of current is lowered, and as a result, it is possible to suppress the generation of an arc that occurs when the current is commutated from the current-carrying electrode to the arc electrode.

In order to compare the resistance values of the alloy parts of all the fixed arc electrodes 7, the distance from the mounting surface of the metal part with the fixed support 9 to the mounting surface with the arc-resistant metal 22 was measured. (□□□) The area of the two base metal parts 23 is S, (air). In the case of the present invention, the diameter of the center portion 32 is assumed to be 80% of the diameter of the alloy portion for comparison.

The resistivity of iron is 14.5 μΩ, and that of copper is 1.72 μΩ. The resistance value Ra when the base metal part is entirely made of iron is obtained by assuming that the resistance value of the central part 32 of the present invention is R1, and the resistance value of the outer peripheral part 31 is R2, and that these are in parallel. If the resistance value in this case is Rb, then the present invention can reduce the resistance value to about 28%.

In this way, by simply setting the diameter of the center part 32 of the base metal part to 80% and surrounding it with the outer peripheral part 31, the resistance value can be reduced by 3.
It can be reduced to 0% or less. Since the part attached to the fixed support 9 is the highly rigid center part 32, the attachment of the fixed arc electrode 7 may become loose due to the vibration of the gas circuit breaker, or the fixed arc electrode 7 may bend too much and the movable arc electrode There is no worry that galling will occur on the electrode due to sliding with the electrode.

Naturally, if the diameter of the center portion 32 is further reduced and the ratio of the outer peripheral portion 31 is further increased, the resistance value will further decrease. However, since the rigidity of the fixed arc electrode 7 also decreases and the mechanical problem described above increases, the diameter of the center portion 32 is reduced to 5.
It can only be reduced to around 0%.

In this way, by making the base metal part of the fixed arc electrode 7 have a two-layer structure, the resistance value from the fixed support 9 to the buffer cylinder 14 via the fixed arc electrode 7 and the movable arc electrode 11 is controlled by the fixed support 9 and the fixed finger. After 6, the movable type t
Jjxo does not need to be increased compared to the resistance value up to the buffer cylinder 14, so the potential difference caused by current commutation when the gas circuit breaker interrupts the current becomes lower. As a result, it is possible to suppress the generation of arcs that occur when current is commutated from the current-carrying electrode to the arc electrode, and it is possible to reduce damage to the current-carrying electrode caused by the arc.

Next, in another embodiment of the present invention shown in FIG. 2, the base metal part of the fixed arc electrode 7 has the same two-layer structure as described above, but
It has a structure in which the center part 35 and the arc-resistant metal 36 are screwed together, and the arc-resistant metal 36 and the outer peripheral part 37 and the arc-resistant metal 36 are further brazed to the center part 35, respectively. For this reason, since the structure is such that the outer peripheral part 37 is mechanically sandwiched between the center part 35 and the arc-resistant metal 36, even if the brazing is defective, the fixed arc electrode 7 will be damaged due to vibrations of the gas circuit breaker, etc. A safer fixed arc electrode that will not be damaged can be made, and a safer gas circuit breaker can be provided.

〔Effect of the invention〕

As described above, in the present invention, the base metal part of the fixed arc electrode has a two-layer structure, so that the resistance value of the path from the fixed support to the fixed arc electrode, the movable arc electrode, and the buffer cylinder can be adjusted to the fixed support, Compared to the resistance value of the path from the fixed finger to the movable electrode and buffer cylinder, it does not need to change much, so the potential difference caused by current commutation when the gas circuit breaker interrupts the current can be lowered. As a result, it has become possible to suppress the generation of arcs that occur when current is commutated from the current-carrying electrode to the arc electrode, so that damage to the current-carrying electrode caused by the arc can be reduced.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a cut-off part showing one embodiment of a power gas circuit breaker of the present invention, FIG. 2 is a cross-sectional view of a cut-off part showing another embodiment of the present invention, and FIGS. 3 to 6 7 is a cross-sectional view showing the process of a power gas circuit breaker from a closed state to an open state, and FIG. 7 is a cross-sectional view showing the structure of a fixed arc electrode of a conventional gas circuit breaker. 1... Gas circuit breaker 3... Arc extinguishing chamber 4... Fixed part 5... Movable part 6... Fixed finger
7... Fixed arc electrode 8... Fixed side shield 9
...Fixed support 10...Movable electrode 11...
Movable arc electrode 12... Insulated nozzle 14... Buffer cylinder 17... Pasofa biston 21
...Arc 22...Creating arc metal 23...Base metal part 31...Metal on the outer periphery of the base metal part 32...Metal at the center of the base metal part

Claims (1)

[Claims] (1) A fixed electrode section consisting of a current-carrying finger and a rod-shaped fixed arc electrode in a container filled with arc-extinguishing gas, and a movable electrode section consisting of a movable current-carrying electrode and a hollow cylindrical movable arc electrode. and arranged so as to be movable relative to each other, and further equipped with a gas blowing mechanism that blows an insulating gas flow onto an arc generated between the fixed arc electrode and the movable arc electrode when both electrode parts are opened. In the device, the tip of the fixed arc electrode is made of an arc-resistant metal, and the rest of the base metal is made of a metal with high rigidity at the center, and the surrounding area is made of a metal with higher conductivity than the center. A power gas circuit breaker characterized by having a two-layer structure.