JP3571479B2 - Circuit breaker - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a circuit breaker capable of breaking a circuit even when an overcurrent flows to a load side, and particularly to a circuit breaker in which a high voltage is not generated in a member inside a housing.
[0002]
[Prior art]
A circuit breaker is a switch for automatically shutting off a circuit when a short circuit fault occurs in a transmission / distribution line, a substation bus or equipment, etc., and is also used for opening and closing the circuit in normal times. In particular, it is not preferable that an overcurrent flows to the load side, and it is necessary to surely shut off the circuit.
[0003]
As disclosed in Japanese Patent Application Laid-Open No. 61-151945 (JP-B-7-27750), a conventional circuit breaker has a movable contact block of a central pole provided with a switching mechanism provided at a central pole via a lower lever. (See FIG. 60). Further, the overcurrent trip device is provided for each pole and fixed to the conductor of each pole (FIGS. 16 and 20).
[0004]
[Problems to be solved by the invention]
In the above prior art, the opening / closing mechanism, the lower lever, and the overcurrent trip device were formed of metal. Therefore, the switching mechanism is charged to substantially the same potential as the movable contact block of the central pole, and the overcurrent trip device is charged to substantially the same potential as the conductor of each pole. Therefore, when the cover of the circuit breaker is unavoidably opened by adding or replacing an internal accessory device (original power is turned off), there is a problem that the charged portion is exposed and is dangerous.
[0005]
An object of the present invention is to provide a circuit breaker that eliminates the risk of electric shock and is excellent in safety.
[0006]
[Means for Solving the Problems]
The present invention, the power source electrically connected to the power supply side stationary conductor and the load side electrically connected to the load side stationary conductor and closing trip mechanism to the terminal on the power source side terminal are mechanically connected during ON operation a main circuit having a movable conductor which electrically connects the load side stationary conductor and the side stationary conductor, and the main circuit case for accommodating the main circuit, the on-off when the current of the main circuit exceeds a predetermined value tripping a tripping device to perform the interruption operation of the main circuit of mechanism the main circuit case is formed of an insulating material, the trip unit on the inside of the main circuit case, and said power supply side stationary A movable core disposed to form a magnetic circuit between the fixed core disposed near one of the conductor and the load-side fixed conductor and the fixed core outside the main circuit case; Operation of the core and the movable core A transmission mechanism for transmitting to the opening / closing trip mechanism, wherein the fixed core is formed in a substantially U shape, and surrounds the power-side fixed conductor or the load-side fixed conductor and has a substantially U shape. The circuit breaker is arranged such that a front end portion faces the outside of the main circuit case .
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described.
One embodiment of the circuit breaker of the present invention will be described with reference to FIGS.
1 is a cross-sectional view of a circuit breaker, FIG. 2 is a plan view of the circuit breaker, FIG. 3 is an explanatory diagram of an arrangement of a fixed core and a movable core, and FIG. 4 is an explanatory diagram of a magnetic circuit.
[0010]
The circuit breaker of the present embodiment is a three-pole circuit breaker. Each pole is electrically connected to the power-supply-side fixed contact stand 11 as a power-supply-side fixed conductor electrically connected to the power-supply-side terminal 11A and to the load-side terminal 17A. A load-side fixed contact table 17 as a load-side fixed conductor, which is electrically connected, is provided at a substantially point-symmetric position with respect to the rotation center of the movable contact table 14 as a rotatably held movable conductor, A main circuit is formed by the power-supply-side fixed contact stand 11, the load-side fixed contact stand 17, and the movable contact stand 14.
[0011]
The power supply side fixed contact base 11 has a power supply side fixed contact 12 at a position facing the power supply side movable contact 13, and the load side fixed contact base 17 has a load side fixed contact 16 at a position facing the load side movable contact 15. have.
[0012]
The movable contact stand 14 has a power supply side movable contact 13 and a load side movable contact 15 at point-symmetric positions with respect to the center of rotation.
[0013]
The movable contact stand 14 is mechanically connected to the opening / closing tripping mechanism 3 as an opening / closing tripping mechanism. When the opening / closing tripping mechanism 3 is turned on, the power-side fixed contact stand 11 and the load-side fixed contact stand 17 are moved. Is rotated to a position where the is electrically connected.
[0014]
This main circuit is housed in a main circuit case 2 formed of an insulator. When the main circuit is housed in the main circuit case 2, the power supply terminal 11A of the power supply fixed contact block 11 and the load terminal 17A of the load fixed contact block 17 protrude from the main circuit case 2. Is located in the main circuit case 2 and is electrically insulated from the outside.
[0015]
A holding member for rotatably holding the movable contact stand 14 in the main circuit case 2 is also formed of an insulating material, and a charged portion exposed when a voltage is applied to the main circuit includes a power supply terminal 11A and a load terminal. 17A part.
[0016]
In this embodiment, the main circuit case 2 and the holding member are formed of a thermosetting resin having strength such as polyester resin. In the main circuit case 2, a high-temperature and high-pressure arc gas is generated between the fixed contact and the movable contact on the power supply side and the load side at the time of interruption. Therefore, the main circuit case 2 and the holding member are required to withstand the high-temperature and high-pressure arc gas, and a polyester resin is used in consideration of the cost of the product. Note that any other resin, ceramic, or the like may be used as long as it is an insulating material that can withstand high-temperature and high-pressure arc gas.
[0017]
An arc chute (arc extinguishing device) is provided in the main circuit case 2 near the contacts of the power-supply-side fixed contact stand 11, the load-side fixed contact stand 17, and the movable contact stand 14 to attract and cool an arc generated at the time of interruption. . Further, in this embodiment, an arc discharge port for discharging the cooled arc gas is provided in the main circuit case 2.
[0018]
The main circuit case 2 is arranged in parallel for three poles, and the holding members are connected so that the movable contact blocks 14 of the respective poles can be opened and closed substantially simultaneously. In this embodiment, the opening / closing trip mechanism 3 is mounted on the upper portion of the main circuit case 2 outside the central pole, and is connected to a rotating arm of an insulator coaxially connected to the rotation axis of the holding member. As a result, the opening / closing trip mechanism 3 is provided on the outside 2 of the main circuit case and connected to the movable contact stand 14 via an insulator, so that even when a voltage is applied to the main circuit, the opening / closing trip mechanism 3 is provided. No voltage is applied to 3.
[0019]
Inside of a circuit breaker, such as an alarm switch, an auxiliary switch that outputs the status of the circuit breaker to the outside, a voltage trip device that trips according to an external signal, and an undervoltage trip device In this embodiment, when the attachment device is attached, the attachment device is attached adjacent to the opening / closing trip mechanism 3 at the poles on both sides of the center pole.
[0020]
The opening / closing trip mechanism section 3 is operated to manually turn on / off the main circuit by the operation handle 41, and when the current of the main circuit exceeds a predetermined value, the tripping device 5 cuts off the main circuit. Is
[0021]
The trip device 5 forms a magnetic circuit between the fixed core 51 disposed inside the main circuit case 2 near the load-side fixed contact block 17 and the fixed core 51 outside the main circuit case 2. And a transmission lever 53 as a transmission mechanism for transmitting the operation of the movable core 52 to the opening / closing tripping mechanism 3.
[0022]
The fixed core 51 is formed in a substantially U-shape as shown in FIG. 2, surrounds the conductor 171 of the load-side fixed contact stand 17, and has two U-shaped ends outside the main circuit case 2 (FIG. 2 in FIG. 2).
[0023]
In this embodiment, the fixed core 51 is provided on the load-side fixed contact base 17 so that the trip device 5 can be arranged at a position close to the latch portion 3a of the opening / closing trip mechanism 3, but the movable core 52 and the transmission lever 53 are provided. May be provided in the vicinity of the power-supply-side fixed contact stand 11.
[0024]
On the other hand, the movable core 52 is rotatably held at one end, and can form a substantially closed magnetic circuit together with the fixed core 51 at a position facing the fixed core 51 via the insulating layer of the main circuit case 2. It is arranged as follows.
[0025]
The movable core 52 is normally biased by a spring and held from the fixed core 51 via a predetermined gap. When the current of the main circuit increases and exceeds a set value (about 10 to about 20 times the rated current), the magnetic flux generated around the conductor 171 of the fixed contact stand 17 on the load side increases, and this conductor 171 The magnetic flux flowing through the fixed core 51 and the movable core 52 which are arranged so as to surround the core also increases.
[0026]
When the magnetic force due to this magnetic flux overcomes the force of the spring urging the movable core 52, the movable core 52 is attracted to the fixed core 51 and moves, and is finally fixed via the insulating layer of the main circuit case 2. A closed magnetic circuit is formed in contact with the core 51. The movable core 52 has a shape such as a U-shape or an I-shape that can form a magnetic circuit together with the fixed core 51.
[0027]
At the other end of the movable core 52, a transmission lever 53 is formed, and when the movable core 52 is sucked and moved (counterclockwise in FIGS. 1 and 3), it comes into contact with the latch 3a to rotate the latch 3a (FIG. 1). 4 in the clockwise direction in FIG. 4), and the main circuit is opened by the tripping operation of the opening / closing tripping mechanism 3. As a result, the open circuit is interrupted and a large overcurrent can be prevented from flowing to the load side.
[0028]
In this embodiment, since the movable core 52 is provided outside the insulating main circuit case 2, no voltage is applied to the movable core 52 even when the main circuit is energized. Thus, the movable core 52 and the transmission lever 53 of the trip device 5 are provided outside the main circuit case 2 and are electrically insulated from the main circuit, and serve as a non-charging portion.
[0029]
Therefore, in the present embodiment, the opening / closing tripping mechanism 3 and the tripping device 5 are insulated from the main circuit and become non-charging portions. For this reason, even when the cover of the circuit breaker is forced to be opened in a live state due to addition or replacement of the internal accessory device, the charged portion is not exposed, and a circuit breaker excellent in safety can be obtained.
[0030]
In this embodiment, a current transformer for detecting a current flowing through the main circuit is provided at a portion of the load-side fixed contact stand 17 of the main circuit from the main circuit case 2 to the load-side terminal 17A, and the output of the current transformer is The current is supplied to an overcurrent detection circuit provided above the current transformer.
[0031]
The overcurrent detection circuit generates an output based on a predetermined time limit characteristic in a range of about 1.1 times to about 20 times the rated current. The output of the overcurrent detection circuit is supplied to a magnetic trip device (not shown) that releases the movable core attracted by the permanent magnet by reverse excitation. As such a magnetic trip device, for example, one described in Japanese Patent Application No. 8-62449 can be used.
[0032]
When the movable core of the magnetic trip device is released, it comes into contact with the latch portion 3a to rotate the latch portion 3a (clockwise in FIGS. 1 and 4), and the main circuit is opened by the trip operation of the opening / closing trip mechanism portion 3. Open circuit. As a result, the open circuit is interrupted and the overcurrent can be prevented from flowing to the load side.
[0033]
The main circuit case 2, the opening / closing trip mechanism 3, the trip device 5, the current transformer, the overcurrent detection circuit, and the magnetic trip device are housed in a housing 6 having a main body case 61 and a main body cover 62. The knob portion of the operation handle 41 attached to the opening / closing trip mechanism 3, the power supply terminal 11 </ b> A, and the load terminal 17 </ b> A are exposed outside the housing 6.
[0034]
In the present embodiment, the movable contact and the fixed contact of the main circuit are housed in the main circuit case 2 made of an insulating material that can withstand high-temperature and high-pressure arc gas, so that the housing 6 has a necessary minimum strength. And an inexpensive thermoplastic resin may be used. As such a thermoplastic resin, nylon or the like can be used.
[0035]
In this embodiment, openable and closable covers are provided on both sides of the operation handle 41 on the front side of the housing 6 (on the side where the operation handle 41 is provided). And so on. In this embodiment, even when the cover is forced to be opened in a live state, the maintenance work of the internal accessory device can be performed safely without exposing the charged portion.
[0036]
Although the present embodiment describes a three-pole circuit breaker, the present invention is not limited to this, and the present invention is applied to a single-pole, two-pole, four-pole circuit breaker or, if necessary, five or more-pole circuit breakers. May be applied.
[0037]
Further, in the present embodiment, the main circuit is formed by the power-supply-side fixed contact stand 11, the load-side fixed contact stand 17, and the movable contact stand 14, but the power-supply-side fixed contact stand as used in the prior art and the load The main circuit formed by the movable contact block connected to the side may be housed in an insulating main circuit case to insulate the opening / closing trip mechanism and the trip device from the main circuit.
[0038]
In addition, the fixed core 51 may be formed in a U-shape, and the movable core 52 may be formed in a U-shape, or both the fixed core 51 and the movable core 52 may be formed in a U-shape. It may be provided in the unit.
[0039]
Since the magnetic circuit composed of the fixed core 51 and the movable core 52 is used and the inside and outside of the main circuit case 2 are electrically separated, when opening the main body cover 62 of the circuit breaker when working. , There is no high voltage member nearby, and it is possible to reduce the danger to the user.
[0040]
【The invention's effect】
According to the present invention, since the fixed core and the movable core are used, even when the user opens the main body cover and works when the circuit breaker is operated, a high voltage is applied to the members inside the housing. It does not occur and the danger to the user can be reduced.
[Brief description of the drawings]
FIG. 1 is a sectional view of an embodiment of a circuit breaker according to the present invention.
FIG. 2 is a plan view of one embodiment of the circuit breaker of the present invention.
FIG. 3 is an explanatory diagram illustrating an example of an arrangement of a fixed core and a movable core in the circuit breaker of the present invention.
FIG. 4 is an explanatory diagram of an example of a magnetic circuit in the circuit breaker of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Power supply side fixed contact stand 11A Power supply side terminal 12 Power supply side fixed contact 13 Power supply side movable contact 14 Movable contact stand 15 Load side movable contact 16 Load side fixed contact 17 Load side fixed contact stand 17A Load side terminal 171 Conductor 2 Main circuit case 3 Opening / closing trip mechanism 3a Latch portion 41 Operating handle 5 Tripping device 51 Fixed core 52 Movable core 53 Transmission lever 6 Housing 61 Main body case 62 Main body cover

Claims (1)

Wherein the power supply side stationary conductor at power-side terminal electrically connected to the power supply side stationary conductor mechanically connected to ON operation electrically connected to a load side stationary conductor and closing trip mechanism to the load terminal a main circuit having a movable conductor which electrically connects the load side stationary conductor, and the main circuit case for accommodating the main circuit, the opening and closing trip mechanism when the current of the main circuit exceeds a predetermined value tripping causes the shutoff operation of the main circuit and a device,
The main circuit case is formed of an insulating material, and the trip device is a fixed core disposed inside the main circuit case and near one of the power-side fixed conductor and the load-side fixed conductor. A movable core disposed outside the main circuit case and forming a magnetic circuit between the fixed core and the movable core, and a transmission mechanism for transmitting an operation of the movable core to the opening / closing trip mechanism. Has,
The fixed core is formed in a substantially U-shape, and is disposed so as to surround the power-supply-side fixed conductor or the load-side fixed conductor and to have both ends of the substantially U-shape facing the outside of the main circuit case. A circuit breaker characterized by that:

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