JP3645774B2 - Current-limiting circuit breaker - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a current limiting interrupting device that interrupts a short circuit current of an electric power system while limiting the current.
[0002]
[Prior art]
When a short circuit accident occurs in the power system, a large short circuit current flows. This short-circuit current causes a large electromagnetic force and a pressure increase in the sealed space, thereby damaging the power equipment and causing a voltage drop in the system. In order to reduce these, when a short circuit accident occurs in the power system, the current level itself is suppressed by some means before the current level reaches the first peak value, that is, the current is limited, and this current limiting is cut off. It is hoped that.
[0003]
As the interruption device having the current limiting function in this way, a device using arc travel, a device using a semiconductor, a device using superconductivity, and the like are considered.
[0004]
Among these, the main part of a typical current-limiting circuit breaker using arc travel is configured as shown in FIG.
[0005]
That is, in the figure, 1 indicates a main circuit breaker. The main circuit breaker 1 includes a pair of contacts 2a and 2b that can be brought into contact with and separated from each other. In the figure, a broken line indicates a state where the contacts 2a and 2b are in contact with each other (closed state), and a solid line indicates a state where the contacts 2a and 2b are separated from each other (blocked state).
[0006]
These contactors 2a and 2b can perform a very fast disconnection operation, for example, about 2 milliseconds, from the time when the disconnection command is given to the time when the contacts 2a and 2b move to the disconnection position for the entire stroke. It is configured. These contacts 2a and 2b are connected to terminals 3a and 3b through conductors, respectively. At least one of the terminals 3a and 3b is connected to an auxiliary circuit breaker (not shown).
[0007]
Between the contacts 2a, 2b of the main circuit breaker 1, the arc generated between the contacts 2a, 2b when the contacts 2a, 2b perform a breaking operation (opening operation) is guided and traveled. Further, a current-limiting resistance element 4 that is released from a local short-circuit state due to an arc and recovers to the original resistance value between both ends is connected in parallel. The current limiting resistance element 4 is formed by radially and meandering strips made of iron or stainless steel with reference to the positions of the contacts 2a and 2b. The resistance value between both ends is set to a value that can limit the peak value of the short-circuit current to about 1 / several tens of times under the most severe short-circuit conditions.
[0008]
The current limiting interrupter configured as described above operates as follows when a short-circuit accident is encountered while being inserted in the power system.
[0009]
That is, when a short circuit accident occurs when the contacts 2a and 2b are in the on state, an accident detection system (not shown) detects the occurrence of the short circuit accident based on the current level of the system, the current increase rate, etc., and the detection signal is shown in the figure. Do not give to the drive. When the detection signal is given, the driving device gives a cutoff command to the main circuit breaker 1. As described above, the main circuit breaker 1 performs a very fast breaking operation of about 2 milliseconds from when the breaking command is given until the movable contact moves to the full stroke for the full stroke. Therefore, the time from when the short circuit accident occurs until the main circuit breaker 1 completes the opening operation is about 3 milliseconds, that is, at the time before the first peak value of the short circuit current arrives. The opening operation of the device 1 is completed.
[0010]
When the contacts 2a and 2b of the main circuit breaker 1 perform the opening operation, an arc is generated between the contacts 2a and 2b. This arc is guided and moved into a meandering space formed by the current limiting resistor 4 under the influence of electromagnetic force associated with the shape of the current path composed of the terminals 3a to 2a to 2b to 3b. The That is, arc spots formed at both ends of the generated arc are guided and traveled on the inner surfaces of both ends of the current limiting resistor 4 in a direction away from both ends. As a result, the current flowing between the terminals 3a and 3b starts to commutate to the current limiting resistance element 4.
[0011]
The generated arc finally travels in a meandering space formed by the current limiting resistor 4 as indicated by A in FIG. 5A, and the current limiting resistor 4 is locally moved during this period. Eventually disappears while short-circuiting. For this reason, the current-limiting resistance element 4 is released from the local short-circuit state due to the arc A, and recovers to the original resistance value between both ends when the arc A disappears. Therefore, the current flowing between the terminals 3a and 3b flows through the current limiting resistance element 4 restored to the original resistance value between both ends.
[0012]
The current limiting resistor 4 has a large resistance value. For this reason, as shown in FIG. 5B, the state is the same as when the large resistor B is connected in series between the terminals 3a and 3b, and the current flowing through the system is suppressed to a sufficiently small value. A flow condition is realized. This current limiting current is finally interrupted by an auxiliary circuit breaker (not shown).
[0013]
In FIG. 6, the occurrence of a short-circuit accident is detected, and the terminal for the elapsed time when the main circuit breaker 1 is opened in accordance with this detection and commutated to the current limiting resistance element 4 using arc travel is shown. The change in inter-voltage and terminal current is shown by a solid line. As can be seen from this figure, the main circuit breaker 1 opens and commutates to the current-limiting resistor element 4 at a time far before the time when the first peak value of the short-circuit current arrives, whereby the short-circuit current is used for current-limiting purposes. The value decreases to a value determined by the resistance value of the resistance element 4.
[0014]
However, the conventional current limiting type interrupting device configured as described above has the following problems.
[0015]
That is, when the contacts 2a and 2b of the main circuit breaker 1 are opened when a short-circuit accident occurs, an arc is first generated between the parts of the contacts 2a and 2b that are actually in contact. The arc spot of this arc finally moves to the current-limiting resistance element 4 while passing through the adjacent part from the above part as the arc moves under the influence of electromagnetic force.
[0016]
Here, the contacts 2a and 2b are usually made of copper having a low resistivity in order to reduce the voltage drop under the applied state or to reduce the contact resistance. When an arc is generated between the contacts 2a and 2b, the surface of the contacts 2a and 2b is heated to 1000 ° C. or more by heat generated by the arc. Copper forming the contacts 2a and 2b has a relatively low melting point of about 1000 ° C. For this reason, copper is melted at the surface portions of the contacts 2a and 2b, and the melted copper scatters in the traveling direction of the arc as the arc travels and adheres to the surface of the current limiting resistance element 4. The adhered copper material forms protrusions on the surface of the current limiting resistance element 4. When the short-circuit current is repeatedly interrupted, the protrusion on the surface of the current limiting resistor 4 becomes large, and the presence of this protrusion prevents smooth travel of the arc spot. As shown by the broken line in FIG. The accompanying arc retraction phenomenon (reverse phenomenon) occurs, and the current-limiting characteristics are greatly reduced. As a result, if repeated interruptions as defined in the standard are performed, the current limit will fail and the interruption will be impossible in severe cases. There was a thing.
[0017]
[Problems to be solved by the invention]
As described above, in the conventional current-limiting type circuit breaker using the traveling of the arc, the metal constituting the contact of the main circuit breaker is melted in a large amount by the heating by the arc, and this melt is used for current limiting. Due to the adhesion to the surface of the resistance element, the current limiting characteristic is lowered, and this causes a problem that the number of times that the short-circuit current can be interrupted is small, that is, the life is short.
[0018]
Therefore, the present invention can suppress a large amount of metal that constitutes the contact of the main circuit breaker by heating with an arc and can prevent the current-limiting characteristics from being deteriorated due to the influence of the molten and scattered metal. Accordingly, it is an object of the present invention to provide a current limiting interrupting device capable of improving the number of times that a short-circuit current can be repeatedly interrupted.
[0019]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a main circuit breaker having a stationary contact and a movable contact and a parallel connection to the main circuit breaker, and the main circuit breaker performs an opening operation. The current-limiting resistor that guides and runs the arc generated between the stationary contact and the movable contact of the main circuit breaker and finally recovers to the original resistance value between both ends by being released from the local short-circuit state by the arc. In the current limiting type circuit breaker comprising the element and an auxiliary circuit breaker that interrupts the current commutated to the current limiting resistance element,
The main circuit breaker extends from a portion adjacent to a portion of the stationary contact that is actually in contact with each other to generate arc spots of arcs generated between the stationary contact and the movable contact at both ends of the current limiting resistance element. An arc-resistant guide member made of an alloy of copper and tungsten for guiding and traveling toward the upper surface, and an alloy of silver and cadmium on the upper surface of the fixed contact that contacts the movable contact A low-resistance metal layer, and a cover provided so as to cover both edges of the arc-resistant guide member, and restricts the travel position of the arc spot to the center of the arc-resistant guide member. An insulating cover made of a tetrafluoroethylene material is provided.
[0021]
In the current limiting type breaking device according to the present invention, the arc spots of the arc generated between the contacts extending from the portions adjacent to the actual contact portions of the respective contacts are guided toward both ends of the current limiting resistance element. Since the arc-resistant guide member that travels is provided, if an arc is generated between the actual contact parts of each contactor during the opening operation of the main circuit breaker, the arc spot of this arc is resistant to the arc in a very short time. Transition to arc guide member.
[0022]
Therefore, it is possible to sufficiently shorten the time during which the actual contact portion of each contact is exposed to the arc, and to reduce the amount of metal that is melted and scattered from this portion. Moreover, since the arc resistant guide member represented by the tungsten alloy has a melting point of 2000 ° C. or higher, it is essentially hardly melted and scattered even when exposed to an arc.
[0023]
As a result, when the main circuit breaker is opened in response to a short-circuit accident, the amount of metal that scatters to the current limiting resistor side can be suppressed, and the metal that scatters and shifts can suppress the amount of current limiting resistor element. The formation of protrusions on the surface can be suppressed. Accordingly, it is possible to suppress a decrease in the current limiting characteristic caused by the protrusion, and to improve the number of times that the short-circuit current can be repeatedly interrupted.
[0024]
Furthermore, in the current limiting form blocking device according to the present invention, since an insulating cover for regulating the running position of the A Kusupotto the center of arc resistance guide members, the arc spot on the side surface of the arc resistance guide members It is possible to suppress the occurrence of arc spot running failure (stagnation) and arc retreat phenomenon caused by the formation.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the invention will be described with reference to the drawings.
[0026]
FIG. 1 shows a schematic configuration of a current limiting interrupter according to an embodiment of the present invention.
[0027]
In the figure, reference numerals 11a and 11b denote terminals. A main circuit breaker 12 and an auxiliary circuit breaker 13 are connected in series between these terminals 11a and 11b.
[0028]
The main circuit breaker 12 supports a pair of fixed contacts 14a and 14b provided with contact surfaces positioned on the same plane and spaced apart from each other, and the fixed contacts 14a and 14b. The conductors 15a and 15b, the movable contact 16 that is disposed so as to be able to contact and separate from the contact surfaces of the fixed contacts 14a and 14b and selectively short-circuit the fixed contacts 14a and 14b, and the movable contact 16 Movable auxiliary conductors 17a and 17b arranged on both sides of the center and facing the fixed contacts 14a and 14a at a distance of approximately the movable stroke of the movable contact 16, and the movable auxiliary Flexible conductors 18a and 18b for connecting the conductors 17a and 17b to the movable contact 16, and between the fixed contact 14a and the movable auxiliary conductor 17a and between the fixed contact 14b and the movable auxiliary conductor 1 Current limiting resistance element 19a connected in parallel between is b, and 19b, and the movable contact 16 is composed of a opening drive unit 20 for quick opening operation.
[0029]
The fixed contacts 14a and 14b are configured to represent the fixed contact 14a as a representative in FIG. That is, the fixed contact 14a (14b) is made of a copper material and has a boat-shaped cross section. The fixed contact 14a (14b) has a so-called outer bottom surface directed toward the movable contact 16 and projects perpendicularly from the tip of the conductor 15a (15b). Thus, the so-called stern side is attached to the tip of the conductor 15a (15b). One end side of the current limiting resistor 19a (19b) is connected to the back side of the fixed contact 14a (14b).
[0030]
A region facing the movable contact 16 on the so-called outer surface of the bottom of the fixed contact 14a (14b) is made of a silver / cadmium alloy layer or the like for the purpose of sufficiently reducing the contact resistance with the movable contact 16 at the time of loading. The low resistance metal layer 21 is formed by plating or brazing of an alloy plate. A thin plate of copper / tungsten alloy is formed in a region from the position adjacent to the low resistance metal layer 21 on the so-called outer surface of the bottom of the fixed contact 14a (14b) to the current limiting resistor 19a (19b) via the so-called tip. An arc-resistant guide member 22 made of (for example, copper 3.5 to tungsten 6.5 and 3 mm in thickness) or the like is fixed by brazing or the like.
[0031]
On both sides of the arc-resistant guide member 22 in the width direction, the exposed portion of the arc-resistant guide member 22 is limited to a central region between a position adjacent to the low-resistance metal layer 21 and a predetermined distance from the arc resistance. Insulating covers 23a and 23b made of, for example, tetrafluoroethylene are provided to restrict the position to the central region. In FIG. 2, reference numeral 24 denotes an insulating support material.
[0032]
On the other hand, the movable side auxiliary conductors 17a and 17b are configured to represent the movable side auxiliary conductor 17a in FIG. That is, the movable side auxiliary conductor 17a (17b) is formed of a copper material. At the tip of the movable side auxiliary conductor 17a (17b) facing the fixed contact 14a (14b), a hook-shaped portion 25 is formed in a relationship corresponding to the tip shape of the fixed contact 14a (14b). The other end side of the current limiting resistor 19a (19b) is connected to the back side of the shed portion 25.
[0033]
In a region from the surface position of the shed portion 25 facing the fixed contact 14a (14b) to the current limiting resistor 19a (19b), a thin plate of copper / tungsten alloy (for example, copper 3.5 to tungsten 6.5) is used. The exposed portion of the arc-resistant guide member 26 is limited to the central region on both sides in the width direction of the arc-resistant guide member 26 in which the arc-resistant guide member 26 having a thickness of 3 mm) is fixed by brazing or the like. In addition, insulating covers 27a and 27b made of, for example, tetrafluoroethylene (however, the insulating cover 27b is not shown) are provided to restrict the travel position of the arc spot to the central region. In FIG. 2, reference numeral 28 denotes an insulating support material.
[0034]
The current limiting resistance elements 19a and 19b have one opening between the fixed contact 14a and the movable auxiliary conductor 17a, and the other opening between the fixed contact 14b and the movable auxiliary conductor 17b. Strips made of iron or stainless steel are radially arranged in a meandering manner in front of these openings. The total resistance value between both ends is set to a value that can limit the peak value of the short-circuit current to about a few to a few tens of times under the most severe short-circuit conditions.
[0035]
Here, when one opening is formed between the fixed contact 14a and the movable auxiliary conductor 17a and the other opening is formed between the fixed contact 14b and the movable auxiliary conductor 17b, the current limiting resistance element 19a 19b, the distances from the openings of the portions 29a, 29b, 30a, 30b facing each of the openings and the distance between the portions do not hinder the running of the arc. It is set to a value that can prevent the reversal of.
[0036]
The contact opening drive device 20 releases the electric charge stored in the capacitor, for example, at a stroke when the interruption command is given, and uses the released energy to the movable contact 16 to cut off very quickly, for example, about 2 milliseconds. It is comprised so that operation | movement may be performed.
[0037]
As the auxiliary circuit breaker 13, a breaker capacity determined by the combined resistance of the current limiting resistor elements 19a and 19b, that is, a breaker capacity sufficiently smaller than the short-circuit capacity of the system is used.
[0038]
An accident detector 31 is provided between the auxiliary circuit breaker 13 and the terminal 11a to detect a short circuit accident based on the current level of the system, the current increase rate, and the like. When a short circuit accident occurs, this accident detector 31 detects this accident within, for example, 1 millisecond, and simultaneously with the detection, gives a breaking command S1 to the opening drive device 20 and, for example, after 20 milliseconds from the detection, the auxiliary circuit breaker. 13 is provided with a shutoff command S2.
[0039]
In actual use, the main circuit breaker 12 is installed in an insulating gas typified by SF6 gas.
[0040]
The current limiting principle of the current limiting interrupter configured in this way is almost the same as the conventional one.
[0041]
That is, as shown in FIG. 4A, when a short circuit accident occurs in the system with the movable contact 16 inserted, the accident detector 31 causes the short circuit accident based on the current level of the system, the current increase rate, etc. Is detected, and a blocking command S1 is given to the opening driving device 20 based on this.
[0042]
When the blocking command S1 is given, the opening driving device 20 causes the movable contact 16 to perform a blocking operation. This shut-off operation is very fast, about 2 milliseconds from the time when the shut-off command S1 is given. Therefore, the time from when the short-circuit accident occurs until the movable contact 16 finishes the opening operation is about 3 milliseconds, that is, the movable contact at a time far before the time when the first peak value of the short-circuit current arrives. The opening operation of the child 16 ends.
[0043]
When the movable contact 16 performs an opening operation, an arc is first generated between the movable contact 16 and the low resistance metal layer 21 of the fixed contacts 14a and 14b. This arc is affected by the electromagnetic force associated with the shape of the current path composed of the conductor 15a to the fixed contact 14a to the movable contact 16 to the fixed contact 14b to the conductor 15b. As a result, the arc spot moves between the fixed contact 14a and the movable auxiliary conductor 17a and between the fixed contact 14b and the movable auxiliary conductor 17b.
[0044]
The arc spot and the arc A connected to the arc spot are guided by arc-resistant guide members 22 and 26 provided on the fixed contacts 14a and 14b and the movable auxiliary conductors 17a and 17b, respectively, as shown in FIG. As shown, it is guided to travel into a serpentine space formed by the current-limiting resistance elements 19a and 19b.
[0045]
The arc A guided into the serpentine space in this way eventually disappears while locally short-circuiting the current limiting resistance elements 19a and 19b. For this reason, the current-limiting resistance elements 19a and 19b are released from the local short-circuit state due to the arc A, and are restored to the original resistance values at both ends when the arc A disappears. Therefore, the current flowing between the conductors 15a and 15b flows in series through the current limiting resistance elements 19a and 19b restored to the original resistance value between both ends.
[0046]
Since the current limiting resistance elements 19a and 19b have a large resistance value, the current flowing through the system is suppressed to a sufficiently small value, and a current limiting state is realized here. This current limiting current is finally interrupted by the auxiliary circuit breaker 13, and the function as a current limiting interrupting device is exhibited.
[0047]
In the current limiting type interrupting device according to this example, arc spots of arcs generated between the contacts extending from the portions adjacent to the actual contact portions of the respective contacts are formed at both ends of the current limiting resistance elements 19a and 19b. Since the arc-resistant guide members 22 and 26 for guiding and traveling are provided, if an arc is generated between the actual contact portions of the respective contacts in accordance with the opening operation of the main circuit breaker 12, the arc of the arc is generated. The spot can be transferred to the arc-resistant guide members 22 and 26 in a very short time.
[0048]
Therefore, it is possible to sufficiently shorten the time during which the actual contact portion of each contact is exposed to the arc, and to reduce the amount of metal that is melted and scattered from this portion. Further, since the arc resistant guide members 22 and 26 typified by a tungsten alloy have a melting point of 2000 ° C. or higher, they are essentially hardly melted and scattered even when exposed to an arc.
[0049]
As a result, when the main circuit breaker 12 performs an opening operation in response to a short circuit accident, the amount of metal scattered and transferred to the current limiting resistance elements 19a and 19b can be suppressed, and the amount of metal that is scattered and transferred is limited. It is possible to suppress the formation of protrusions on the surfaces of the diverting resistance elements 19a and 19b. Therefore, it is possible to suppress a decrease in the current limiting characteristic caused by the protrusion, and to improve the number of times that the short-circuit current can be repeatedly interrupted, in other words, to improve the life.
[0050]
Further, in the current limiting type interrupting device according to this example, the insulating covers 23a, 23b and 27a, 27b for restricting the arc spot traveling position to the central portion on the arc resistant guide members 22, 26 are provided. It is possible to suppress the occurrence of arc spot running failure (stagnation) and arc retreat phenomenon caused by the formation of the spots on the side surfaces of the arc-resistant guide members 22 and 26.
[0051]
In the above example, the current limiting resistor elements are arranged symmetrically with the switching part of the main circuit breaker 12 as the center. However, the present invention can be applied to a structure in which the current limiting resistor elements are arranged only on one side. it can. As the auxiliary circuit breaker 13, an easy-to-handle oil circuit breaker may be used. Furthermore, the material constituting the current limiting resistance element is not limited to iron or stainless steel.
[0052]
【The invention's effect】
As described above, according to the present invention, it is possible to suppress a decrease in current limiting characteristics caused by interruption of a short-circuit current, and to improve the number of times that the short-circuit current can be repeatedly interrupted.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a current limiting interrupter according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a main part of the interrupter locally taken out. FIG. FIG. 4B is a view taken in the direction of the arrow along the line XX in FIG. 4B, and FIG. 4B is a cross-sectional view taken along the line YY in FIG. FIG. 5A is a schematic configuration diagram of a main part of a conventional current limiting interrupter, and FIG. 5B is an equivalent circuit diagram when a current limiting operation is performed. FIG. Of change in voltage and current between terminals when a current limiting operation is performed
A ... Arcs 11a, 11b ... Terminal 12 ... Main circuit breaker 13 ... Auxiliary circuit breakers 14a, 14b ... Fixed contacts 15a, 15b ... Conductor 16 ... Movable contacts 17a, 17b ... Movable side auxiliary conductors 19a, 19b ... Current limiting resistance Element 20 ... Opening drive device 21 ... Low resistance metal layers 22, 26 ... Arc resistant guide members 23a, 23b, 27a, 27b ... Insulation cover

Claims (1)

A main circuit breaker having a stationary contactor and a movable contactor, and a main contactor connected in parallel to the main circuit breaker, and when the main circuit breaker performs opening operation, the fixed contactor and the movable contact of the main circuit breaker The arc generated between the children is guided and traveled, and finally the current-limiting resistance element that is released from the local short-circuit state due to the arc and recovers to the original resistance value between both ends, and commutated to this current-limiting resistance element In a current limiting interrupter comprising an auxiliary circuit breaker for interrupting current,
The main circuit breaker extends from a portion adjacent to a portion of the stationary contact that is actually in contact with each other to generate arc spots of arcs generated between the stationary contact and the movable contact at both ends of the current limiting resistance element. An arc-resistant guide member made of an alloy of copper and tungsten for guiding and traveling toward the upper surface, and an alloy of silver and cadmium on the upper surface of the fixed contact that contacts the movable contact A low-resistance metal layer, and a cover provided so as to cover both edges of the arc-resistant guide member, and restricts the travel position of the arc spot to the center of the arc-resistant guide member. A current-limiting circuit breaker comprising an insulating cover made of a tetrafluoroethylene material .

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