JP6085441B2 - Circuit breaker contact - Google Patents

Description

  The present invention relates to an electrical contact used for a gas circuit breaker of an electric circuit.

  A circuit breaker used for a high-voltage, high-current circuit such as a large number of power transmission / distribution networks and power distribution networks generally has two pairs of electrical contacts (hereinafter also referred to as “contacts”). One pair is a main contact which is a main conductive path. The other pair is an arc contact that performs arc processing. The latter arc contact is used to perform an operation in which an arc is generated when the current is switched.

  When a large current is opened and closed, an arc is generated between the two electrical contacts that are opened and closed.

  In a device that opens and closes a large current, the current flows mainly through the main contact when conducting. When the current is interrupted (opening), the main contact is opened prior to the arc contact, and only the arc contact is energized. When the arc contact is opened in this state, an arc is generated between the arc contacts.

  When turning on (closing), connect the arc contact first, and then connect the main contact. In any operation, an arc is generated between the arc contacts.

  If the above-described interruption and closing procedures are performed, no arc is generated between the main contacts, and the arc is generated only between the arc contacts.

  By this mechanism, the main contact can select a material pursuing conductivity without considering the influence of the arc. On the other hand, the arc contact has a high arc resistance structure and material premised on replacement. However, arc contacts are not cheap. It is desired to extend the life of arc contacts.

An arc generated by opening and closing the arc contact takes time to extinguish. The leaving of the generated arc promotes the consumption of the arc contact. Therefore, it is necessary to extinguish (extinguish) the arc as soon as possible. A means for quickly extinguishing the arc is to blow an arc-extinguishing gas onto the arc. This arc-extinguishing gas is a gas that has a high arc-blocking ability and is stable at high temperatures. A large amount of sulfur hexafluoride SF ₆ is used. A circuit breaker that uses arc-extinguishing gas is called a gas circuit breaker.

  In FIG. 1, the schematic diagram of the arc contact part principal part of a general gas circuit breaker is shown. When the arc contact is interrupted, an arc is generated between the fixed-side arc contact 1 and the movable-side arc contact 2. On the other hand, the arc extinguishing gas 4 is stored in the buffer cylinder 3 in a compressed state. At the time of interruption, the arc extinguishing gas is released and blown between both arc contacts in accordance with the opening from the fixed side (left hand side) arc contact 1 of the movable side (right hand side) arc contact 2. After that, the arc disappears.

  The important point in this operation is to direct a large amount of arc-extinguishing gas to the arc and blow a sufficient amount accurately.

  The arc contact on the movable side has a shape generally called “tulip type”. Cited Document 1 and Patent Document 2 are examples of documents using a tulip arc contact. In any of the documents, the movable side arc contact is a tulip type arc contact.

  A schematic diagram of a tulip-shaped arc contact is shown in FIG. The tulip-shaped arc contact 2 has a cylindrical shape having a portion bulging inward near the tip (the portion closest to the fixed arc contact), and a plurality of slits 8 extending in the length direction from the tip in the length direction. It has a ripped shape. The torn tip is expressed as “terminal 7”. This shape makes it possible to open and close the arc contact in the radial direction by utilizing elastic deformation of the arc contact. This structure makes it possible to insert a cylindrical fixed-side arc contact in a state of being in close contact with the inner diameter side of the tulip-type contact (FIGS. 1 and 7 (I)).

  Making the movable-side arc contact a tulip type allows the arc contact 2 to be opened and closed in the radial direction. On the other hand, the arc-extinguishing gas is ejected from the buffer cylinder 3 toward the arc generating portion. At that time, a part of the arc extinguishing gas enters into the cylinder of the tulip contact through the slit 8 of the tulip contact (FIG. 2).

  For this reason, the flow rate of the arc extinguishing gas is lowered, and the spraying pressure on the arc generating portion is lowered. It delays arc extinguishing. The delay in arc extinguishment promotes wear due to evaporation of both arc contacts.

  By narrowing the slit width of the movable arc contact, it is possible to limit the movement of the arc extinguishing gas into the movable contact. Usually, the slit width is about 0.8 to 1.5 mm. By narrowing the width of the slit 8 (extremely 0 mm), the flow rate of the arc extinguishing gas into the movable side arc contact is reduced, and the time until the arc extinguishing is shortened. This measure is particularly effective when the contacts are opened.

  However, the tulip-shaped movable arc contact 2 has flexibility (can be opened and closed) in the radial direction as described above. At the moment of opening when the fixed-side arc contact 1 comes out of the movable-side arc contact 2, due to its flexibility, it is completely open (the movable-side arc contact and the fixed-side arc contact are not in contact at all). In contrast, the tip of the movable arc contact is squeezed (FIG. 6-2). At the time of opening, an arc is generated between both arc contacts, and the temperature of both contacts is increased. Therefore, the problem that the terminals 7 of adjacent movable arc contacts are welded to each other occurs. Usually, a material that hardly causes welding, such as a Cu-W composite material, is used for the tip portion of the movable arc contact. However, the temperature of Cu near the surface rises above the melting point. This welding is difficult to prevent even with a Cu-W composite material. Once welding occurs between adjacent terminals 7, the movable side arc contact does not open smoothly as shown in FIG. 7 (J) at the next closing, and the adhesion of both arc contacts is reduced. 7 (K), in the worst case both arc contacts collide and break. Therefore, the tulip arc contact of the prior art has a slit 8 having a width of about 0.8 to 1.5 mm between the terminals 7.

Patent Document 1 describes one of measures against the above-described present situation. Patent Document 1 discloses a technique for preventing the entry of arc-extinguishing gas by providing an insulating nozzle that protrudes from the movable-side arc contact at the timing of arc-extinguishing gas blowing in the tulip-shaped movable-side arc contact cylinder. doing. This means is considered to obtain a certain effect by adjusting the shape of the insulating nozzle and the protruding timing. However, this method requires an increase in the number of parts, which is not desirable in terms of manufacturing cost.

Japanese Patent Publication No. 07-9779 Japanese Patent Laid-Open No. 08-180772

An object of the present invention is to efficiently blow an arc-extinguishing gas toward an arc as compared with a conventional structure by changing the structure of a tulip-shaped arc contact. If this object is achieved, the replacement frequency of the arc contact can be reduced, which is advantageous in terms of cost.

  The present inventors have taken measures against the above problems.

  The inventors of the present invention have a tulip-shaped arc contact having a plurality of terminals branched by slits, and a protrusion extending in the length direction of the arc contact from each terminal toward the adjacent terminal. Was provided. It should be noted that the tulip-shaped arc contact may be fixed or movable depending on the structure of the circuit breaker. An arc contact that elastically deforms in the radial direction when the circuit breaker is opened and closed is called a “tulip-type contact”. A rod-shaped arc contact that is paired with the “tulip-shaped contact” and does not deform is referred to as a “bar-shaped contact”.

  As described above, the slit width of a normal tulip contact is about 0.8 to 1.5 mm. In the present invention, the base material of the contact is left in a protruding shape in a part of the slit portion of the normal tulip-type contact, and the adjacent terminal and the narrowed portion are provided. This narrow portion is the portion having the shortest distance from the adjacent terminal and is about 0.03 to 0.4 mm, more preferably 0.03 to 0.2 mm. The distance other than the protrusions may be about 0.8 to 1.5 mm, which is a normal slit width, and may be 0.5 to 3 mm.

  The reason why the protrusion is provided is to reduce the amount of the arc extinguishing gas that passes through the slit and enters the cylinder of the tulip contact when the circuit breaker is opened and closed. The arc extinguishing gas is supplied from a gas source such as a buffer cylinder.

  Due to the protrusions provided, the amount of arc-extinguishing gas passing through the slit between the terminals is significantly reduced. The decrease is used for extinguishing the arc generated between both arc contacts. That is, as compared with the conventional technique, a large proportion of the arc extinguishing gas can be concentrated on the arc generation portion.

  In order to realize this effect, the protrusion preferably extends over the entire length of the slit. This is because the arc extinguishing gas easily enters the tulip-shaped contact from there if the gap between the slit portions is wide.

  Examples of the shape of the protrusions are shown in FIGS. FIG. 5 is a schematic view of the terminal and the slit portion as seen from the cross-sectional direction. The cross section may be a simple arc-shaped protrusion, may have a clear step, or may have a continuously changing dimension. Further, the protrusion may extend only from one terminal with respect to the slit, or may extend from both sides. The protrusion may be configured by a straight line or a curved line. A combination of both may be used. The important point is the width of the narrowest part of the slit.

  In the case of providing a linear portion (for example, (C) 10 in FIG. 5) at the tip of the protrusion 6, the width is preferably 1 mm or less, more preferably 0.2 mm or less.

  As described above, when the gap between the terminals of the tulip contact is extremely narrow, there is a risk that adjacent terminals may be welded when the contacts are closed. When welding over a wide area, the slit portion remains welded during the next closing, and not only the opening and closing in the radial direction is not smooth, but also the adhesion of both arc contacts deteriorates (FIG. 7 (J ) (K)) In the worst case, there is a risk that the arc contact may be damaged due to the penetration of the rod-type contact.

  Therefore, when providing the linear part which may be welded, the front-end | tip part (contact surface with an adjacent terminal) with a possibility of welding has good 1 mm or less. If this width is 1 mm or less, even if adjacent terminals are welded, the welded portion is easily broken by the pressure of the bar-type contact at the time of opening (when the bar-type contact is inserted). A more desirable range is 0.2 mm or less.

  Both arc contacts are made of a composite material, for example a Cu-W composite material. This material is composed of an arc resistant component (in this case, tungsten W) that is difficult to melt and evaporate by arc heat at the time of opening and closing both contacts, and a low melting point metal (in this case, excellent in thermal conductivity, conductivity, and workability) It is a composite material with copper (Cu). In particular, the vicinity of the tips of both contacts where an arc is generated is made of such a composite material. The part far from the tip is made of a metal material such as Cu. In FIG. 1 and FIG. 2, the portion made of the composite material is generally colored.

Moreover, the countermeasure of the form which an insulator protrudes from the cylinder of a tulip-type contact as shown to prior art document 1 can amplify an effect more by making it compatible with the structure of this invention.

The arc contact of the circuit breaker of the present invention can concentrate the flow of an arc extinguishing gas such as SF ₆ blown against the arc at the switching pole of the circuit breaker on the arc generating part. In addition, new parts and devices associated therewith are unnecessary. Therefore, it is possible to suppress arc contact consumption. Furthermore, the amount of arc-extinguishing gas required can be reduced, and a buffer cylinder for storing the arc-extinguishing gas can be reduced in size. An economical circuit breaker is obtained.

Schematic diagram of general circuit breaker (when closed) Schematic diagram of a general circuit breaker (immediately after opening) An example of a tulip-type contact Schematic diagram of the tulip contact of the present invention Schematic diagram of the tulip contact of the present invention The some example of the projection part of a slit part. Schematic cross section of the tulip-shaped contact in the radial direction Schematic diagram of tulip-type contact at the time of opening Schematic diagram of a tulip-type contact immediately after opening Schematic view of the tulip-shaped contact as viewed from the rod contact side (H) At the time of opening (I) At the time of normal closing (J) The opening state in which a part of the terminal is welded (K) A part of the terminal is welded Closed state

  A schematic diagram of a tulip-shaped arc contact for a circuit breaker according to the present invention is shown in FIG. FIG. 4 is a schematic view of the tip side (bar-shaped contact 1 side) as viewed from the inner surface side of the tulip-shaped arc contact 2 shown in FIG. The viewpoint was seen from the left side of the dotted line section of FIG.

  The tulip-type contact 2 is basically cylindrical, and has a plurality of slits 8 in the length direction of the cylinder from the tip that is in contact with the rod-type contact 1. A portion divided by the slit 8 is referred to as a terminal 7. The plurality of terminals 7 are arranged in a circle, and each is separated by the slit 8. The portion where the slit 8 does not extend in the length direction maintains a cylindrical shape (11 in FIG. 3).

  Heat resistance and arc resistance are required at the tip of the arc contact (the contact portion of both contacts and the vicinity thereof). Therefore, in general, a material having excellent arc resistance such as a Cu—W composite material or a Cu—WC composite material is used for the tip portion and the vicinity of the arc contact. For other parts, Cu, Ag metal or alloy is used.

  The length of the slit in the tulip arc contact was 80 mm from the tip, and the maximum width was 1.2 mm.

  The detail of a slit part is shown to FIGS. 4-2 and sectional drawing 5 (C). In FIG. 5, the lower part of the drawing is the center of the arc contact. The cross section in the longitudinal direction of the contact has a slit portion 8 of 1.2 mm extending from the outer diameter side to the inner diameter side of the tulip-shaped contact, and has a protruding portion 6 that protrudes in a convex shape near the inner diameter side. Yes. The protrusion 6 extends from both of the adjacent terminals, and the narrowest gap is 0.2 mm.

  A structure having the protrusions over the entire length excluding the tip portions of all the slit portions 8 was adopted. The tip portion refers to a portion that comes into contact with the rod-type contact. As shown in FIG. 2, since the arc extinguishing gas 4 is blown out from the side surface of the tulip-type contact, the slit width at the tip hardly affects the flow of the arc extinguishing gas.

  The tulip type contact of the present invention described above was incorporated in the circuit breaker as a movable side arc contact. The main part of the circuit breaker has a structure shown in FIG. 1 in a closed state. In this state, the fixed-side arc contact 1 is inserted into the tip of the movable-side arc contact 2. A buffer cylinder 3 is disposed around the movable-side arc contact 2, and an arc-extinguishing gas 4 is blown toward the arc when the pole is opened. The arc extinguishing gas nozzle 5 is provided on the movable contact side in order to limit the arc extinguishing gas blowing direction and increase the arc extinguishing efficiency.

    The circuit breaker described above was tested by switching current.

  In the test, a current of 12 kV and 25 kA was cut off (opened) and connected (closed) five times. This is an example.

  The other conditions and structures are the same, and a sample using the tulip arc contact 2 in which the slit portion 8 does not have the protrusion 6 is used as a comparative example. The comparative example is a conventional circuit breaker.

  After the test, the bar arc contact and the tulip arc contact were removed from the testing machine. The consumed weights (before test-after test) of both removed contacts were compared. The consumption weight of the example was 4.2 (g) and remained at 70% of the consumption weight 6.0 (g) of the comparative example.

  This is presumed to be because the arc-extinguishing gas was accurately blown to the place where the arc occurred. In one comparative example, since a part of the arc extinguishing gas is directed to the inside of the cylinder through the slit portion of the tulip electrode, it is considered that the arc extinguishing is delayed and as a result, the contact is consumed.

  Next, other requirements were the same as in Example 1, and a test was performed in which only the shape of the protrusions in the slit portion of the tulip contact was changed.

  As shown in FIG. 5D, the shape of the protrusion has an obtuse triangular shape gradually raised from a portion close to the inner diameter side and a portion close to the outer diameter side. The raised portion extends from both adjacent terminals, and the narrowest gap is 0.05 mm.

When a test similar to the above test was performed, the consumption weight was further reduced by about 3% compared to Example 1. The portions corresponding to both vertices of the obtuse angle triangle were partially roughened along the slit length direction. This is considered to be a trace of adjacent terminals welded due to elastic deformation of the tulip-type contact at the time of opening. In the test, no increase in mechanical resistance was observed when the movable contact moved during opening and closing. Therefore, the welded portion is very small, and the welded portion is easily broken by the movement of the movable contact, and can be used without any problem.

1 Fixed side arc contact 2 Movable side arc contact (tulip type contact)
3 Buffer cylinder 4 Arc extinguishing gas (SF ₆ gas, etc.)
5 Arc-extinguishing gas nozzle 6 Protruding part, raised part 7 Terminal 8 Slit part 81 Deformed slit part immediately after opening 9 Welding between terminals 10 Straight line part of projecting tip

Claims (5)

This is a circuit breaker contact that is used for a gas circuit breaker and cuts off or connects the current by connecting / disconnecting a pair of bar contacts
A plurality of slit portions in the length direction of the cylinder in a cylindrical shape;
A plurality of terminal portions separated by the slit portion;
A contact for a circuit breaker having a protruding portion which is a portion having a small diameter in the diameter direction of a cylinder between adjacent terminal portions . The circuit breaker contact according to claim 1, wherein the protrusion is provided over the entire length excluding the contact tip of the slit portion. The closest distance between the protrusion and the adjacent terminal,
Alternatively, the circuit breaker contact according to any one of claims 1 and 2 , wherein any one of the closest distances between the protrusions of the terminals adjacent to the protrusions is 0.03 to 0.4 mm.   The width of the contact surface between the protrusion adjacent to the protrusion or the terminal adjacent to the protrusion is greater than 0 mm and equal to or less than 1 mm with respect to the diameter direction of the cylindrical shape. The circuit breaker contact according to any one of the above. Circuit breaker and the movable mold contact with breaker contacts according to any one of claims 1 to 4,
Gas circuit breaker having a breaker contact of the rod-like forming the breaker movable type contact pair.

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