JP4090948B2 - Circuit breaker - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
According to the present invention, a fixed contact is provided at one end and the other end is connected to a circuit conductor on the power source side, and one end is disposed to face one end of the first fixed contact. A fixed contact similar to the above-described fixed contact is provided, and a second fixed contact having the other end connected to the load-side circuit conductor, and a movable contact contacting and separating from the pair of fixed contacts. More particularly, the present invention relates to a current limiting means for limiting an arc generated when a large current is interrupted in a circuit breaker configured to open and close an electric circuit of each pole by separating and connecting elements.
[0002]
[Prior art]
In the conventional circuit breaker, the electric circuit of each pole is opened and closed by separating and connecting a flat movable contact made of a magnetic material with respect to a pair of fixed contacts forming the electric circuit. is there. (For example, refer to Patent Document 1).
In addition, a substantially U-shaped magnetic body is arranged on the back side (anti-fixed contact side) of the movable contact, and the opening side of the magnetic body is opposed to the closed movable contact through a gap so that the movable contact can move. When a large current such as a short-circuit current flows through the contactor, the movable contactor is driven to open against the contact spring by the attractive force generated between it and the magnetic body based on the magnetic flux of the large current, thereby opening the contact It is designed to increase speed. (For example, refer to Patent Document 2).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-22942 (FIG. 1)
[0004]
[Patent Document 2]
Japanese Patent No. 2965025 (pages 2 and 3, FIG. 1)
[0005]
[Problems to be solved by the invention]
In the conventional circuit breaker, a substantially U-shaped magnetic body is arranged on the back side of the movable contact, and the movable contact is opposed to the opening of the magnetic body through a gap so that a large current flows to the movable contact. When the current flows, the movable contact is driven to open by the attractive force generated between the magnetic body and the magnetic material based on the magnetic flux of the large current. According to this configuration, although the opening speed of the movable contact is increased, the attractive force acting on the movable contact is abruptly reduced as the short-circuit current is attenuated. Accordingly, since the movable contact is pushed back to the fixed contact by the drag of the contact spring, the interruption performance is deteriorated. In particular, in the case of a high voltage circuit, there is a problem that the current is interrupted and then re-ignited.
[0006]
The present invention has been made to solve the above-described problems. When a large current such as a short-circuit current flows, the attraction generated between the substantially U-shaped magnetic body based on the current. Force the movable contact to open rapidly, and even if the short-circuit current is attenuated, the movable contact is held in an attractive state so that the current is reliably interrupted and re-ignited even in the case of a high-voltage circuit. To obtain a circuit breaker without a gap.
[0007]
[Means for Solving the Problems]
In the circuit breaker according to the present invention, a fixed contact is provided at one end and the other end is connected to a circuit conductor on the power supply side, and one end faces one end of the first fixed contact. A fixed contact similar to the above-mentioned fixed contact, the other fixed end of which is connected to the load-side circuit conductor, and a magnetic material formed on both ends of the fixed contact. A movable contact provided with a movable contact oppositely, an opening / closing mechanism connected to the movable contact to contact the movable contact with the first second fixed contact via a contact spring, and the movable In the circuit breaker having a pair of arc extinguishing chambers disposed near both ends of the contact and each extinguishing an arc generated when the movable contact is separated from the fixed contact , Arc extinction of the stationary contact and the second stationary contact In a position close to the back surface of the movable contactor which releases arc commutation unit or arc runner and the opening formed in the vicinity, the pair so that the current due to the arc can be commutated via the arc commutation unit or arc runner An arc commutation conductor straddling between the arc extinguishing chambers, a part in contact with the lower surface of the arc commutation conductor, and a part extending toward the movable contact at both sides of the arc commutation conductor. And an end face of the extending portion is used as a magnetic pole face, and a yoke adapted to be magnetized by a current flowing through the arc commutation conductor, wherein the movable contact is separated from the fixed contact. Sometimes, the yoke is magnetized by the current flowing through the arc commutation conductor, and the movable contact is attracted to the magnetic pole surface.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
1 shows a closed state in a circuit breaker according to Embodiment 1 of the present invention, in which a is a plan view, b is a side view, and FIG. 2 is a perspective view showing the main part of FIG.
1 and 2, a substantially U-shaped fixed contact 1 made of a conductor and a substantially L-shaped fixed contact 2 are arranged at predetermined intervals on the electric circuit, and fixed to each fixed contact. Contact 3 is attached.
[0009]
A strip-shaped movable contact 4 whose both ends are bent in a substantially U shape with respect to the fixed contact 1 and the fixed contact 2 has a pair of movable contacts 5 that come into contact with the fixed contacts 3, and is shown in FIG. In this state, the contact spring 6 is pressed against the fixed contacts 1 and 2 to bridge the fixed contacts 1 and 2. The movable contact 4 is connected to an opening / closing mechanism (not shown) via a cross bar 7 and is opened / closed by this opening / closing mechanism, but the contact spring 6 is closed by the movable contact 4 to the fixed contacts 1 and 2. When this occurs, it acts to generate a preset contact pressure.
[0010]
The fixed contact 1 is connected to the power supply side terminal via a circuit conductor (not shown), and the fixed contact 2 is connected to the load side terminal via an overcurrent tripping device and a circuit conductor (not shown). An arc extinguishing chamber 8 for extinguishing an arc generated when the movable contact 4 is separated from the stationary contacts 1 and 2 is disposed at both ends of the movable contact 4. A plurality of grids 9 made of U-shaped magnetic plates are disposed in the arc extinguishing chamber 8, supported by a pair of left and right insulating side walls 10, and an arc between the fixed contact 3 and the movable contact 5. If this happens, it is stretched and cooled.
[0011]
Further, the arc extinguishing chamber 8 is provided with an arc commutation conductor 11 across the arc extinguishing chambers 8. The arc commutation conductor 11 is formed of a good conductor such as copper, brass, or iron, for example, and an arc generated between the fixed contact 3 and the movable contact 5 is commutated. The arc generated between the fixed contact 3 of the fixed contact 1 and the movable contact 5 of the movable contact 4 will be described. This arc generated between the fixed contact 3 and the movable contact 5 is the arc extinguishing chamber 8. Is extended by. If this arc is generated by a large current such as a short-circuit current, the stretched arc is commutated from the fixed contact 3 to the arc commutation portion 1a formed at the tip of the fixed contact 1, The movable contact 5 commutates to the tip 11a of the arc commutation conductor 11. Similarly, an arc generated between the fixed contact 3 of the fixed contact 2 and the movable contact 5 of the movable contact 4 is also extended by the arc extinguishing chamber 8, and the arc runner 2a from the fixed contact 3 of the fixed contact 2 is extended. And commutates from the movable contact 5 to the tip 11b of the arc commutation conductor 11. In this way, the commutated current flows through the arc commutation conductor 11 while the arc continues.
[0012]
The arc commutation conductor 11 is provided with a yoke 12 (described later). The yoke 12 is magnetized by a current flowing through the arc commutation conductor 11 so that the movable contact 4 is opened from the fixed contacts 1 and 2. Aspirate to maintain. The yoke 12 is provided on the arc commutation conductor 11 so that a magnetic pole face 12a is formed at the U-shaped opening end and is magnetized by a current flowing through the arc commutation conductor 11. The magnetic pole surface 12a is provided with an impact absorbing member 12b such as a urethane resin molded product in order to absorb an impact when the movable contact 4 is adsorbed. The shock absorbing member 12b may be provided on the back surface (the surface that contacts the magnetic pole surface 12a) 4a of the movable contact 4. The arc commutation conductor plate 11 is also configured to hold one end of the contact spring 6.
[0013]
Next, the operation of the circuit breaker configured as described above in Embodiment 1 of the present invention will be described. FIG. 3 shows a state in which the circuit breaker of FIG. 1 is opened by manual operation when it is in a normal energized state. That is, in FIG. 1, a normal current flows to the fixed contact 2 through the fixed contact 1, the fixed contact 3, the movable contact 5, the movable contact 4, the movable contact 5, and the fixed contact 3. At this time, the movable contact 4 is pushed down in the direction of arrow A via the crossbar 7 by the operation of a manual opening / closing mechanism (not shown), and the movable contact 4 compresses the contact spring 6 as shown in FIG. Then, the movable contact 4 is separated from the fixed contacts 1 and 2. A slight arc is generated by this separation, but the movable contact 4 is not attracted to the yoke 12 because the current value is smaller than the short-circuit current.
[0014]
When the energized state exceeds a predetermined rated current and becomes an overcurrent, the movable contact 4 is moved through the crossbar 7 by the operation of an opening / closing mechanism (not shown) by the overcurrent tripping device. The movable contact 4 is pushed down in the A direction, and the movable contact 4 is separated from the fixed contacts 1 and 2 as shown in FIG. A slightly large arc is generated at the time of the opening, but the opening state is maintained by the operation of the opening / closing mechanism, and the arc is extinguished due to the action of the arc-extinguishing chamber 8 and is re-ignited. Does not occur.
[0015]
FIG. 4 shows a state in which the circuit breaker of FIG. 1 is opened by a large current such as a short circuit current. In the figure, when a large current such as a short-circuit current flows to the fixed contact 2 via the fixed contact 1, the fixed contact 3, the movable contact 5, the movable contact 4, the movable contact 5, and the fixed contact 3, The electromagnetic repulsive force acts between the parallel conductors of the stationary contacts 1 and 2 and the movable contact 4 prior to the operation of the opening / closing mechanism by the overcurrent tripping device, and the movable contact 4 opens against the contact spring 6. At this time, an arc is generated between the contacts 3 and 5.
[0016]
The arc generated between the contacts 3 and 5 due to a large current is extended by the arc extinguishing chamber 8 and is transferred from the fixed contact 3 to the arc commutation portion 1a formed at the tip of the fixed contact 1 as described above. From the movable contact 5, it commutates to the tip 11 a of the arc commutation conductor 11. Similarly, an arc generated between the fixed contact 3 of the fixed contact 2 and the movable contact 5 of the movable contact 4 is also extended by the arc extinguishing chamber 8, and the arc runner 2a from the fixed contact 3 of the fixed contact 2 is extended. And commutates from the movable contact 5 to the tip 11b of the arc commutation conductor 11. In this way, while the arc continues, the commutated current flows through the arc commutation conductor 11, and the movable contact 4 is adsorbed by the magnetization of the yoke 12 provided on the arc commutation conductor 11. . Therefore, the arc extinguishing chamber 8 works in a state where the current flowing through the movable contact 4 is attenuated due to commutation, and during this time, the tripping device and the opening / closing mechanism are operated to maintain the open state of the movable contact 4. The phenomenon of re-ignition is suppressed. In addition, since the arc is extinguished without the current flowing through the movable contact 4, damage to the movable contact 4 due to a large current can be suppressed. Moreover, the breaking speed of the movable contact 4 is fast, and the interruption performance is improved. Moreover, since the impact when it is attracted to the attracting surface 12a is buffered by the impact absorbing member 12b, the impact sound can be reduced and the deformation of the movable contact 4 due to the impact can be prevented. In addition, since the re-ignition phenomenon is suppressed, it is possible to reduce the wear of the fixed contact 3 and the movable contact 5 while being excellent in the breaking performance in the case of a high voltage electric circuit.
[0017]
Although the above embodiment has been described with respect to a single pole, the same applies to a plurality of poles used in a three-phase electric circuit.
[0018]
In the above embodiment, the yoke 12 and the arc commutation plate 11 are formed as separate members, but may be formed integrally with a magnetic material such as iron.
[0019]
Embodiment 2. FIG.
5 shows an open circuit state of a circuit breaker according to Embodiment 2 of the present invention, where a is a plan view, b is a side view, and FIG. 6 is an exploded perspective view showing an enlarged main part of FIG. is there.
In the figure, an iron core 13, which is a cylindrical magnetic body, is erected on a yoke 12, and a commutation coil portion 21 c of an arc commutation conductor 21 is wound around the outer periphery of the iron core 13. In the case of this embodiment, the commutation coil portion 21c is wound in two layers. The movable contact 4 is provided with a fitting insertion hole 4b, and the cross bar 7 is provided with a sliding hole 7a. The iron core 13 is fitted into the fitting insertion hole 4b and the sliding hole 7a, so that the movable contact 4 and the cross bar are inserted. 7 is slidably held in the vertical direction while being urged by the contact spring 6.
[0020]
In the circuit breaker according to the second embodiment of the present invention configured as described above, a large current such as a short circuit current has a fixed contact 1, a fixed contact 3, a movable contact 5, a movable contact 4, a movable contact 5, and a fixed contact. When flowing through the contact 3 to the fixed contact 2, this current causes an electromagnetic repulsion between the parallel contacts of the fixed contacts 1, 2 and the movable contact 4, and the movable contact 4 resists the contact spring 6. At this time, an arc is generated between the contacts 3 and 5.
[0021]
The arc generated between the contacts 3 and 5 is commutated to the tip portions 21 a and 21 b of the arc commutation conductor 21 by the action of the arc extinguishing chamber 8. These operations are the same as those in the first embodiment. And since the attraction | suction force of the yoke 12 becomes strong with the electric current which flows into the commutation coil part 21c of the arc commutation conductor 21, the function of the arc commutation conductor 21 becomes remarkable rather than the circuit breaker of Embodiment 1. FIG.
[0022]
【The invention's effect】
As described above, the present invention has a portion that is in contact with the lower surface of the arc commutation conductor and a portion that extends toward the movable contact at both sides of the arc commutation conductor. with the end face is a pole face, provided with a yoke adapted to be magnetized by a current flowing through the arc commutation conductor, when the movable contactor is separated from the fixed contacts, flowing through the arc commutation conductor Since the yoke is magnetized by the electric current and the movable contact is attracted to the magnetic pole surface, the following effects can be obtained.
[0023]
When interrupting a large current such as a short-circuit current, a movable contact separated from the fixed contact is attracted to the yoke magnetic pole surface by the yoke magnetized by the current flowing through the arc commutation conductor. The breaking speed of the child is fast and the breaking performance is improved. Therefore, problems such as re-ignition are suppressed even in the case of a high-voltage circuit.
[0024]
Since the arc is extinguished without a large current flowing through the movable contact, damage to the movable contact due to the large current can be suppressed.
[0025]
Since the shock when sucked on the suction surface of the yoke is buffered, the impact sound can be reduced and the deformation of the movable contact due to the shock can be prevented.
[Brief description of the drawings]
FIG. 1 shows a closed state of a circuit breaker according to Embodiment 1 of the present invention, in which a is a plan view and b is a side view.
FIG. 2 is an enlarged perspective view showing a main part of FIG.
FIG. 3 is a side view showing a state where the circuit breaker of FIG. 1 cuts off a normal current.
4 is a side view showing a state in which the circuit breaker of FIG. 1 is opened by a large current such as a short-circuit current. FIG.
FIGS. 5A and 5B show an open circuit state of a circuit breaker according to Embodiment 2 of the present invention, in which a is a plan view and b is a side view.
6 is an enlarged perspective view showing a main part of FIG. 5. FIG.
[Explanation of symbols]
1, 2 fixed contact, 3 fixed contact, 4 movable contact, 4a back surface, 4b fitting insertion hole, 5 movable contact, 6 contact spring, 8 arc extinguishing chamber, 11 arc commutation conductor, 12 yoke, 12a magnetic pole surface, 12b Shock absorbing member, 13 iron core, 21 arc commutation conductor, 21c commutation coil.

Claims (6)

A first fixed contact provided with a fixed contact at one end and the other end connected to a circuit conductor on the power source side, and one end disposed opposite to one end of the first fixed contact and the fixed contact; A second fixed contact having the same fixed contact and the other end connected to the load-side circuit conductor, and a movable contact formed with a magnetic material at both ends and facing the fixed contact. A contactor, an opening / closing mechanism connected to the movable contactor and contacting / disconnecting the movable contactor to the first second fixed contactor via a contact spring, and disposed close to both ends of the movable contactor In the circuit breaker having a pair of arc extinguishing chambers for extinguishing arcs generated when the movable contact is separated from the fixed contact, the first fixed contact and the second fixed contact Arc commutation section or arc formed near the arc extinguishing chamber Kuran'na and in a position close to the back surface of the movable contactor that separated the open, current due to the arc is straddled between the pair of arc extinguishing chamber so that it can be commutated via the arc commutation unit or arc runner An arc commutation conductor , a portion in contact with the lower surface of the arc commutation conductor, and a portion extending toward the movable contact at both sides of the arc commutation conductor, and an end surface of the extending portion is with the magnetic pole surface, comprising a yoke adapted to be magnetized by a current flowing through the arc commutation conductor, the current flowing through the arc commutation conductor when the movable contactor is separated open from the fixed contacts A circuit breaker characterized in that the yoke is magnetized and the movable contact is attracted to its magnetic pole surface. 2. The circuit breaker according to claim 1, wherein the arc commutation conductor and the yoke are integrally formed using a magnetic material. 2. The circuit breaker according to claim 1, wherein the arc commutation conductor is wound around an iron core standing on the yoke. 4. The circuit breaker according to claim 3, wherein an iron core insertion hole is provided in the movable contact, and an iron core standing on the yoke is inserted into the iron core insertion hole when the movable contact is separated. . 5. The shock absorbing member for absorbing an impact when the movable contact is attracted to the magnetic pole surface of the yoke is disposed on the magnetic pole surface of the yoke or the back surface of the movable contact. Circuit breaker according to item. 6. The circuit breaker according to claim 5, wherein the shock absorbing member is formed of a urethane resin molded product.

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