JPH046057B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a circuit breaker, which is configured with two pairs of contacts per unit, and the movable contacts are one in common, or two movable contacts move together, and the first contact has one pair. A set of magnetic pieces is provided, and the second contact has a current limiting resistor connected in series between the power supply side terminal and the fixed contact, and when a short circuit interrupts a large current, the first contact with the magnetic piece opens, After that, the second current-limiting resistor is inserted.
The breaking capacity can be made nearly infinite by opening the movable contact after the current is transferred to the contact.

[Prior art]

Generally, a circuit breaker has a tripping mechanism that detects an overcurrent and automatically opens a movable contact. Conventionally, in this type of circuit breaker, the time required from when an overcurrent flows through the tripping element and the tripping mechanism begins to operate until the movable contact opens is relatively long due to mechanical limitations. It has been difficult to obtain a high breaking capacity because the circuit cannot be interrupted instantaneously, causing welding of contacts or burning of current-carrying parts. In addition, a part of the contact mechanism has been improved to generate electromagnetic repulsion between the fixed and movable contacts in the event of a short circuit and a large current, causing the movable contacts to separate, or a dead center spring is provided between both contacts to prevent overloading. There is one in which the spring is displaced by an electromagnetic repulsive force acting between both contacts when current is applied, thereby causing the movable contacts to separate. However, in the case of circuit breakers that utilize electromagnetic repulsion, the movable contact floats to a slightly open state near the lowest operating current value that causes electromagnetic repulsion, and a large current arc occurs, causing the movable and fixed contacts to float. The contacts will melt and become damaged. Further, the generated arc acts as a resistance component, reducing the circuit current, and as a result, both contacts come into contact, but there is a high risk that the melted contacts will fuse together. In such a circuit breaker, the minimum operating current value is relatively high, so in the event of an intermediate overcurrent fault, the overcurrent tripping mechanism cannot coordinate with the tripping characteristics of the overcurrent tripping mechanism. The shortcoming is that the instantaneous cut-off operation cannot be completed and the operation ends up being incomplete, resulting in the damage described above. Patent no.
No. 969677 (Patent Application Publication No. 1906, 1977), which is a movable contact rotatably mounted on a support body with a movable contact support body that rotates on the movable contact side by an automatic tripping mechanism. Furthermore, a set of magnetic pieces is provided on the movable contact and its support, so that normal breaking operation is performed in the event of an overcurrent, and an electromagnetic attractive force acts between the two magnetic pieces in the event of a short circuit and large current. The present invention provides a circuit breaker in which only the movable contact is instantaneously slightly opened, and at the same time, the movable contact is completely opened by an automatic tripping mechanism. However, in this case, even though the movable contact part is a part that opens and closes at all times, it has a complicated structure and increases weight, and the inertia when constantly opening and closing is large, which adversely affects the opening/closing speed and opening/closing performance. There were drawbacks such as the support portion being subject to wear and damage. There is also a method of current-limiting and breaking by combining a circuit breaker and a current-limiting resistor, but it requires a large installation space and
Furthermore, since a current limiting resistor is inserted in series with the contact portion, loss always occurs, resulting in disadvantages such as increased equipment and management costs.

[Purpose of the invention]

The present invention eliminates the above-mentioned drawbacks,
Rapidly cuts off the short-circuit current at the initial stage when it starts to flow,
It is an object of the present invention to provide a circuit breaker which performs so-called current-limiting circuit breaker, enables primary circuit breaker at a sufficiently low current value compared to the current value at which welding is likely to occur, and can make the circuit breaker nearly infinite in circuit breaker capacity.

[Structure of the invention]

The structure of the invention taken to achieve the above object is as follows. That is, in the present invention, a primary cutoff circuit and a secondary cutoff circuit are provided between a power supply terminal and a load side terminal, a movable fixed contact and a movable contact are arranged in the primary cutoff circuit, and the movable The fixed contact faces the movable contact and is pivotally mounted so as to be rotatable in the direction of separation from the movable contact, and a movable magnetic piece is attached to the movable fixed contact so as to be swingable. A magnetic piece forms a magnetic path that surrounds a part of the movable fixed contact, and the base has a fixed magnetic piece that electromagnetically attracts the magnetized movable magnetic piece when a short circuit current flows through the movable fixed contact. The magnetic piece is attached opposite to the movable magnetic piece, and the secondary breaking circuit is provided with a fixed contact and a movable contact opposite thereto, and the movable contact is attached to the movable magnetic piece of the primary breaking circuit. It is integrated with the contactor or is a separate body that operates together with the contactor, and a current limiting resistor is connected in series between the power supply side terminal and the fixed contactor.
In the event of a short circuit with a large current, the electromagnetic attraction force that acts between the movable and fixed magnetic pieces provided in the primary interrupting circuit instantly separates the movable fixed contact from the movable contact, and the secondary current-limiting resistor is inserted. This is a circuit breaker in which the current is transferred to the cutoff circuit, and after the current is limited by the current limiting resistor, the movable contacts of both cutoff circuits are driven to the open position by the operation of the overcurrent tripping mechanism. In this way, the breaking speeds of the movable fixed contact and the movable contact are synergized, the breaking distance is also increased, a current limiting effect is added, and the breaking capacity can be made nearly infinite.

【Example】

The present invention will be explained in more detail with reference to embodiments shown in the drawings. Reference numeral 1 is the base of the case body made of insulating material.
A mounting shaft 3 is rotatably pivoted approximately at the center. Reference numeral 2 denotes a movable contact, which includes a movable contact 2a and a movable contact 2b (disposed on the back side of the movable contact 2a in FIG. 1, and shown in FIG. 2).
It is composed of individual parts. The movable contact 2a and the movable contact 2b are fixed to the mounting shaft 3. The movable contactor 2 and an operating mechanism and a tripping mechanism (none of which are shown) using an external operating handle are connected by a mounting shaft 3, and this mounting shaft 3 allows the contactor to be turned on and off via the coupling mechanism. The operation is configured to be performed. Reference numeral 4 denotes a fixed contact, which is composed of a movable fixed contact 4a and a fixed contact 4b, which are provided to face the movable contact 2a and the movable contact 2b, respectively. The movable fixed contact 4a is rotatably mounted on a shaft 7a supported by a fixed magnetic piece 5 attached to the base 1. The fixed contact 4b is rotatably mounted on a shaft 7b supported by the fixed contact base 6. A repulsion spring (not shown) is mounted on the mounting shaft 3 and urges the movable contact 2 in a direction to separate from the fixed contact 4. A movable magnetic piece 9 shown in FIG. 7 is swingably attached to the movable fixed contact 4a by an attachment shaft 8. As shown in FIG. That is, the movable magnetic piece 9 has a "〓"-shaped bent part 9a formed at its upper part.
A movable fixed contact 4a is mounted so as to be located within a space 9d formed by the bent portion 9a. Further, a fixed magnetic piece 5 that cooperates with the movable magnetic piece 9 is attached to the base 1 so as to face each other. The fixed magnetic piece 5 has a flat portion 5f and engagement teeth 5d formed by cutting out a portion of the flat portion 5f. Plane part 5
f is disposed facing the lower open end 9e of the movable magnetic piece 9 with a required gap. The engaging tooth 5f is in contact with the side edge 9b of the movable magnetic piece 9 (see FIG. 9). A power supply side terminal seat 10 is formed on the base 1.
A current limiting resistor 12 is connected between the power supply terminal 11 fixed to the power supply side terminal seat 10 and the fixed contact 4b (see FIG. 2). A tripping element 13 (for example, consisting of an electromagnetic tripping coil with a time-limiting element) is installed on the base 1 to detect abnormal current such as overcurrent or short circuit current and operate the tripping mechanism. . Reference numeral 14 denotes a movable iron piece, which is configured to be attracted to the tripping element 13 at an appropriate time when an abnormal current occurs, thereby driving the drive lever 15 of the tripping mechanism to detach the latching mechanism. Reference numeral 16 denotes a terminal on the load side, which is fixed to a terminal seat 17 formed on the base 1, and is connected to the tripping element 1.
One end 18 of the excitation winding No. 3 is connected. Reference numeral 19 denotes a conducting wire connecting the movable contactor 2 and the other end of the excitation winding of the tripping element 13, and a flexible copper stranded wire or the like is used so as not to hinder the movement of the movable contactor 2. A reset lever 20 is fixed to the mounting shaft 3. The reset lever 20 is interposed between the movable contact 2 and the fixed contact 4, which are live parts, and between the movable magnetic piece 9 and the fixed magnetic piece 5, and is made entirely or partially of an insulating material. The base end of the fixed magnetic piece 5 (see FIG. 8) is extended to form a "" shaped frame portion 5a. Through holes 5b and 5c are provided in both side walls of the "" shaped frame portion 5a, through which the reset rod 21, which is longer than the both walls, is movably passed through. A collar 21a is provided between both side walls of the reset rod 21.
A return spring 22 is interposed between a and the side wall of the "" shaped frame part. Therefore, the reset rod 21 is
Normally, the left end 21b in FIG. 1 protrudes due to the biasing force of the return spring 22, and faces the tip 20a of the reset lever 20. Further, the right side of the reset rod 21 in the figure is arranged so that when the movable magnetic piece 9 is attracted to and engaged with the fixed magnetic piece 5 (see FIG. 5), the right end 21c of the reset rod faces the movable magnetic one-side edge 9b. ing. Note that the reset action is performed by driving and rotating the reset lever 20, which is driven when the movable contactor 2 is opened. An engagement mechanism is provided between the movable magnetic piece 9 and the fixed magnetic piece 5. That is, the fixed magnetic piece 5 is formed with engaging teeth 5d as shown in FIGS. 5 and 8, and when the movable magnetic piece 9 is attracted to the fixed magnetic piece 5, the movable magnetic piece 9 It is configured to be locked by engaging with an engagement groove 9c formed in a "U" shape. Below the movable fixed contact 4a and the fixed contact 4b, there is a biasing force in a direction that causes the movable fixed contact 4a and the fixed contact 4b to return to the contact position where they are rotated around their respective mounting shafts 7a and 7b. contact spring 23a,
23b is provided. The contact springs 23a, 23b are mounted between protrusions 4c, 4d formed on the movable fixed contact 4a and fixed contact 4b and spring guides 24a, 24b attached to the base 1. Contact springs 23a and 23b are movable fixed contacts 4
a. Pressure is applied to the fixed contact 4b in the direction of the movable contact, and when the movable contacts 2a and 2b are turned on, the movable fixed contact 4a and the fixed contact 4b are moved by the contact springs 23a and 23b. It is intended to give a wipe of contact by pressing against it some distance. A flexible conducting wire 25 is connected between the terminal 11 and the movable fixed contact 4a so as not to hinder the movement of the movable fixed contact 4a and the movable magnetic piece 9. Furthermore, a flexible conducting wire 26 is connected between the fixed contact base 6 and the fixed contact 4b so as not to hinder the movement of the fixed contact 4b. A stopper 27 is fixed to the base 1 and regulates the reference position of the movable contact 2 when the contact is opened, and 5e and 6a are formed from the fixed magnetic piece 5 and a part of the fixed contact base 6 and are movable when the contact is opened. Fixed contact 4
a, a stopper for regulating the position of the fixed contact 4b; The positions of the stoppers 5e and 6a are such that a slight gap is provided between the movable fixed contact 4a and the fixed contact 4b toward the movable contacts 2a and 2b from their contact reference position A, thereby preventing wiping when the contact is inserted. giving. Function The function of the circuit breaker according to this embodiment will be explained. (A) First, the manually operated tripping device will be explained with reference to FIGS. 1 to 3. Mounting shaft 3 is turned on by turning on the external operation handle.
When the movable contact 2 is driven, the fixed contact 4
, and further advances by the wipe amount G1' to reach the reference contact position A, resulting in the state shown in FIGS. 1 and 2. When the external operation handle is operated in the cutoff direction, the movable contact 2 is rotated by the mounting shaft 3 in the release direction to a predetermined position, separated from the fixed contact 4, and cuts off the electric circuit, resulting in the state shown in Fig. 3. Become. The separation distance G1 between the fixed and movable contacts at this time is set to an appropriate value required for a general circuit breaker. Further, at this time, a repulsion spring (not shown) acts to urge the movable contactor 2 in the opening direction and rapidly shut it off. When a current is generated in the closed state, that is, the state shown in FIGS. 1 and 2, the movable iron piece 14 is attracted by the operation of the tripping element 13, the drive lever 15 is driven, and the catch mechanism of the operating handle mechanism is tripped. As a result, the movable contactor 2 is opened, resulting in the state shown in FIG. 4, as in the case of operating the operating handle. (B) Next, the interrupting operation when a large current such as a short circuit current flows will be explained with reference to FIGS. 5 and 6. When a large current flows through the movable fixed contact 4a, a magnetic field is generated around the movable fixed contact 4a. The movable magnetic piece 9 surrounds the movable contact 4a,
The flat portion 5f of the fixed magnetic piece 5 faces the lower open end 9e with a required gap (shown in FIG. 8).
is arranged, the flat parts 5f of the movable magnetic piece 9 and the fixed magnetic piece 5 are magnetized, and the movable fixed contact 4
Form a magnetic path surrounding a. Due to the magnetization of the flat part 5f of the movable magnetic piece 9 and the fixed magnetic piece 5, an electromagnetic attraction force is generated between the movable magnetic piece 9 and the flat part 5f of the fixed magnetic piece 5, and as a result, the movable magnetic piece 9
rotates instantaneously in the direction of the fixed magnetic piece 5. Therefore, as shown in FIG. 5, the movable fixed contact 4a rapidly separates from the movable contact 2a, thereby performing a primary cutoff. In this case, since the contact spring 23a acts as a repulsion spring against the rotation of the movable contact 4a, the engagement groove 9 of the movable magnetic piece 9 is
The engaging teeth 5d of the fixed magnetic piece 5 are engaged with and locked by the movable fixed contact 4a, thereby preventing the movable fixed contact 4a from returning and increasing the separation distance G2 from the movable contact 2a.
is maintained. Up until now, electricity was being applied between the movable fixed contact 4a and the movable contact 2a, but after being disconnected as described above, the fixed contact is passed through the current limiting resistor 12 (see Figure 2). Movable contact 2 from 4b
Since current is passed between the contacts b, the large current is current limited by the current limiting resistor. On the other hand, a short circuit large current flows through the tripping element 13,
As a result, the tripping mechanism operates with a slight delay determined from the mechanism, and the movable contact 2 is driven in the opening direction. At this time, since the movable fixed contact 4a is locked to the fixed magnetic piece 5 via the movable magnetic piece 9 during the primary cutoff,
As shown in Fig. 6, the movable contact 2 opens more than the fixed contact 4 to perform secondary breaking, and as shown in Fig. 6, the maximum separation distance G3 between both the fixed and movable contacts is G3 = G1 + G2 becomes. At the time of this secondary cutoff, the reset lever 20 rotates counterclockwise in the figure at the same time as the movable contact 2 rotates, the tip 20a of the reset lever 20 pushes the reset rod 21, and the right end 21c of the reset rod pushes the movable magnetic one side. Push the edge 9b to release the engagement between the movable magnetic piece 9 and the fixed magnetic piece 5, and return the movable fixed contact 4a to the contact reference position A by the repulsive force of the contact spring 23a, maintaining the separation distance G1 (the first (See Figure 4). By the time the movable fixed contact 4a returns, arc extinguishing has already been completed, and by this return, preparations for re-insertion are completed. In general, the current value at which contacts tend to weld is:
For example, in a circuit breaker with a 50 ampere frame, the minimum operating current value of the attracting operation by both the movable and fixed magnetic pieces 9 and 5 is about 1500A to 2500A for silver oxide cadmium contacts and 2500A to 5000A for silver tungsten contacts. If the current value is kept below the current value at which welding is likely to occur, for example about 1500 A, welding of the contacts will not occur under any conditions. In this way, the circuit breaker according to this embodiment rapidly interrupts the short-circuit current at the initial stage when it starts to flow, and performs so-called current-limiting interrupting, so it is possible to perform primary interrupting at a sufficiently low current value compared to the current value that tends to cause welding. Yes, the above conditions can be fully satisfied. In addition, in the circuit breaker according to the present invention, for example, unlocking of the fixed contact that is locked at the time of the primary shutdown is not done automatically by driving the reset lever by the movable contact at the time of the secondary shutdown as described above. , a return device may be provided separately and the lock may be manually unlocked after the interruption is completed, and the locking device may be separately provided between the fixed contact and the base by various means, etc. It is not limited and various arbitrary changes are possible.

【Effect of the invention】

The present invention has the above configuration and has the following effects. (1) In the event of a short circuit with a large current, the movable fixed contact is instantly separated from the movable contact by the electromagnetic attraction force that acts between both the movable and fixed magnetic pieces provided in the primary cutoff circuit, thereby performing primary cutoff. Therefore, the current moves to the secondary interrupting circuit in which the current limiting resistor is inserted, and after being limited by the current limiting resistor, the movable contacts of both interrupting circuits are moved to the open position by the operation of the overcurrent tripping mechanism. Drive. In other words, at the time of primary shutoff, the lightweight movable fixed contact opens and closes independently of the movable contact handle mechanism, etc., so the shutoff operation can be performed instantly and reliably, and the current is sufficiently limited by the current limiting resistor. At the same time, since a sufficient tripping distance can be obtained by secondary interrupting, primary interrupting can be performed at a sufficiently low current value compared to the current value that tends to cause welding, and the interrupting capacity can be made nearly infinite. (2) Since the attraction operation by both the fixed and movable magnetic pieces is performed sensitively at sufficiently low current values, it is possible to completely prevent contact welding by suppressing the minimum operating current value below the current value that causes contact welding. can. (3) The movable contact does not come with a magnetic piece during regular opening/closing, making it lightweight and suitable for rapid opening/closing. Also, since no large impact or vibration is applied to the magnetic piece attached to the fixed contact, the supporting part of the magnetic piece, etc. Wear and damage can be prevented. (4) It has a built-in current limiting resistor, so there is no need to install a separate current limiting resistor, so the installation space is small, and each contact has two pairs of contacts, so the current limiting resistor is connected in parallel with the energizing contact. Since a resistor is included, the loss is almost zero at all times, which has various advantages such as reducing equipment and management costs.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, and FIG. Fig. 3 is a front view of the main part of the same embodiment showing the open state with the operation handle, Fig. 4 is a front view of the main part of the same embodiment showing the tripping state, and Fig. 5 is the same same embodiment in the primary shut-off state. Fig. 6 is a front view of the main part showing the secondary cut-off state, Fig. 7 shows a side view of the movable magnetic piece, b shows a front view, and Fig. 8 shows a of the fixed magnetic piece. FIG. 9 is a plan view, b is a front view, and FIG. 9 is a perspective view of a main part showing the arrangement relationship between a movable magnetic piece and a fixed magnetic piece. 2a, 2b: movable contact, 4a: movable fixed contact, 4b: fixed contact, 5: fixed magnetic piece, 9: movable magnetic piece, 12: current limiting resistor, 13: tripping element,
20: Reset lever, 21: Reset rod, 2
2: Return spring, 23a, 23b: Contact spring.

Claims (1)

[Scope of Claims] 1. A circuit breaker having an overcurrent tripping mechanism, wherein a primary breaking circuit and a secondary breaking circuit are provided between a power supply terminal and a load side terminal, and the primary breaking circuit includes a movable fixed contact. and a movable contact, the movable fixed contact facing the movable contact and pivotally connected to the movable contact so as to be rotatable in a direction in which it separates from the movable contact; The movable magnetic piece is swingably attached, and the movable magnetic piece forms a magnetic path that surrounds a part of the movable fixed contact. A fixed magnetic piece that electromagnetically attracts a movable magnetic piece that is magnetized is installed opposite to the movable magnetic piece, while a fixed contact and a movable contact opposite thereto are arranged in the secondary interrupting circuit. The movable contact is integrated with the movable contact of the primary breaking circuit or is a separate body that operates together with the movable contact, and a current limiting resistor is connected in series between the power supply side terminal and the fixed contact.
In the event of a short circuit with a large current, the electromagnetic attraction force that acts between the movable and fixed magnetic pieces provided in the primary interrupting circuit instantly separates the movable fixed contact from the movable contact, and the secondary current-limiting resistor is inserted. The current is moved to the cutoff circuit, and after the current is limited by the current limiting resistor, the movable contacts of both cutoff circuits are driven to the open position by the operation of the overcurrent tripping mechanism. circuit breaker.