JPS59169024A - Circuit breaker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a circuit breaker capable of selective interruption and current limiting for use in the protection of low voltage circuits.

[Technical background of the invention]

Conventionally, for the protection of low voltage circuits, Figures 1 (,) to (d)
A current-limiting type circuit breaker as shown in is used.

Figure 1 (,) shows a closed circuit state. In the figure, 1 is an insulating case, inside which are a breaker main body (hereinafter referred to as the interruption part) 2 and a current-limiting breaker part (hereinafter referred to as the current-limiting part). It consists of 3 parts (abbreviated as ``part''). Further, a power supply side terminal 4 is led out from the insulating case 1 on the side of the interruption part 3, and a load side terminal 5 is led out from the current limiting part 2.

In the current limiting section 3, a load side fixed conductor 6 having a load side terminal 5 formed at one end has a current limiting section surface contact 7 at the other end.
is provided. Further, one end portion of a movable contact 9 is rotatably attached to a support conductor 8 provided upside down on the insulating case 2-1 by a rotating shaft 10. A current-limiting line movable contact 11 is provided at the other end of the movable contact 9. Also, a spring 12 is attached to the movable contact 9.
is attached to apply contact pressure to the current-limiting line movable contact 11.

Next, the breaker 2 will be explained. The power supply side fixed conductor 13 having the power supply side terminal 4 formed at one end thereof has an interrupted wire fixed contact 14 at the other end thereof. Further, one end of a fixed conductor 15 is electrically connected to the supporting conductor 8 in the current limiting section 3, which has an instantaneous tripping current-operating time characteristic shown in characteristic A1 in FIG. An overcurrent trip device 16 using an electromagnet or the like is installed.

Furthermore, one end of a flexible conductor 17 is connected to the other end of the fixed conductor 15, and the other end is connected to a movable center portion of one end of a rotatable and interrupted wire movable contact 18. Further, the other end of the movable contact 18 is provided with the breaker fixed contact 14.
Correspondingly, a movable contact 19 of the interruption part is provided. Note that 20 is a handle for manual on/off operation in the breaker section 2.

The current-carrying path of the circuit breaker described above is a series circuit between the breaker section 2 and the current limiter section 3, and the current limiter section 3
The load-side fixed conductor 6 and the current-limiting part movable contact 9 form parallel conductors and are configured to exert electromagnetic repulsion.

In the above-described circuit breaker, when a large short-circuit current flows, the short-circuit current flows in opposite directions to the parallel conductor consisting of the load-side fixed conductor 6 and the current-limiting part movable contact 9 in the current-limiting part 3. This generates an electromagnetic repulsion force, and the current limiter fixed contact 7 and the current limiter movable contact 11 (hereinafter referred to as the current limiter contact 7
11) is opened as shown in FIG. 1(b).

At this time, an arc is generated between the current limiter contacts 7 and 11,
Begin current limiting. Furthermore, at the same time, in the breaker section 2, the overcurrent tripping device 16 is also energized by the short circuit current flowing through the fixed conductor 15 and starts operating. In this case, since there is a mechanical time delay in the mechanical part (not shown), the breaker fixed contact 14 of the breaker 2 is closed as shown in FIG. 1(b).
, the breaker movable contact 19 (hereinafter referred to as the breaker line contact 1)
4 p 19) maintains a closed circuit state transiently. However, the interruption line contacts 14 and 19 of the breaker 2 are immediately opened as shown in FIG. 1(C). At this time, the electromagnetic repulsion force disappears in the current limiting section 3 due to the completion of the interruption, and the current limiting line contacts 7 and 1, which were open, are returned by the spring 12, as shown in FIG. 1(d). , the circuit closes again.

[Problems with background technology]

By the way, in the circuit interrupter as described above, the current is limited and interrupted by the arc resistance, so the breaking capacity can be increased, but the circuit is folded and interrupted. Therefore, in a low-voltage circuit where two circuit breakers are installed on the upper side (power supply system side) and lower side (load system side), the circuit breaker installed on the lower side with characteristic B1 in Figure 2 will be interrupted. If a short-circuit accident occurs on the load side of the equipment, the circuit breaker installed on the upper side with characteristic A1 in Figure 2 will have instantaneous trip characteristics as shown in Figure 2. Therefore, the characteristics of characteristic A1 and characteristic B1 intersect,
Both circuit breakers shut off at the same time, leading to an expansion of the power outage area.
It has the disadvantage that so-called selective cutoff is not performed. As described above, when the current limiting section 3 performs current limiting and cutting off, the interruption capacity is increased, but selective cutting is not performed, and it is generally difficult to satisfy these requirements at the same time. Also,
In response to the recent demand for an increase in breaking capacity, the circuit interrupter described above has a slow rate of change in resistance of the arc resistance for current-limiting interruption, and has no effective function to achieve a large required breaking capacity. It was something I didn't have.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and its object is to provide a circuit breaker having a simple structure, having high current limiting and interrupting performance, and capable of selectively interrupting the current.

6- [Summary of the Invention] In the circuit breaker according to the present invention, a resistor is connected in parallel between the contacts of the current-limiting part in the current-limiting part, and when a short circuit n current flows, the current-limiting part contact is subjected to an electromagnetic repulsion force. an electromagnet that opens the current-limiting part contact, limits and commutates the short-circuit current by an arc resistance caused by the opening, and is further excited by the current commutated to the resistor to maintain the open state of the current-limiting part contact, In order to strengthen the electromagnetic repulsive force, among the magnetic iron plates attached to the back surfaces of parallel conductors consisting of a fixed conductor and a movable contact in the current limiting section, a magnetic iron plate attached to the back of the movable contact is used to increase the electromagnet's movable force. The above object is achieved by providing a short-time operation type overcurrent force release device in the breaker main body, which also serves as the iron core.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. Third
Figures (a) to (J) are configuration diagrams showing one embodiment of the circuit breaker according to the present invention, and Figure 3 (,) shows the closed circuit state,
Figure 3 (C) (f) (h) shows the change in the state of the mechanism due to an overcurrent accident, and Figure 3 (b) (d) (e) ω)
(1) shows a change in the state of the electric circuit due to an overcurrent accident.

In Fig. 3 (,), 21 is an insulating case, and inside this, the interrupter main body (hereinafter abbreviated as the interrupter) 2
2 and a current limiting/interrupting part (hereinafter abbreviated as current limiting part) 23. Further, a load side terminal 24 is led out from the breaker part 22 side of the insulating case 2, and a power supply side terminal 25 is led out from the current limiting part 23. In the current limiting section 23,
A power supply side conductor 2 with a current side terminal 25 formed at one end thereof
6 is provided with a current-limiting part surface contact 27 at an intermediate portion, one end of a current-limiting resistor 28 is connected to the other end, and a magnetic iron plate 29 is arranged on the back surface. Also, the insulation case 21
One end of a current limiter movable contact 31 is rotatably attached to a middle portion of the supporting conductor 30 which is provided upside down.

On the other hand, a breaker fixed conductor, which will be described later, is supported and connected to one end of the support conductor 30, and furthermore, to the other end of the support conductor 30,
One end of the current limiting wire fixed conductor 33 is connected. The support conductor 30 and the current limiting movable contact 31 are engaged with each other by a spring 34 to generate a braking force during movement and a contact pressure when closing the contact. Further, a movable iron core 35 whose cross-sectional configuration is shown in FIG. 4 is attached to an intermediate portion of the current limiter movable contact 31, and a current limiter movable contact 36 is provided at the other end. Further, a fixed iron core 37 whose cross-sectional configuration is shown in FIG. 4 is provided at an intermediate portion of the current-limiting wire fixed conductor 33 in correspondence with the movable iron core 35. In addition, the fixed iron core 37 mentioned above
is configured as an electromagnet that is excited and generates electromagnetic force when current flows through the current limiting wire fixed conductor 33. Furthermore, the other end of the resistor 28 is connected to the other end of the current limiting wire fixed conductor 33.

Next, the interruption portion 22 will be described. In the breaker section 22, an overcurrent tripping device 39 is installed on a load-side conductor 38, at one end of which the load-side terminal 24 is provided. This overcurrent tripping device 39 differs from the conventional one in that it does not have a temporary tripping characteristic, but has the characteristics shown in FIG. 5 so that it operates with a time delay of several cycles when a short circuit current flows. It has short-circuit characteristics as shown by A2. Further, one end of a flexible conductor 40 is connected to the other end of the load side conductor 38,
Further, the other end of the flexible conductor 40 is connected to one end of a movable cut-off contact 41 provided so as to be rotatable, where the center of rotation is located. And this breaker movable contact 41
A breaker movable contact 42 is provided at the other end. Further, as described above, the interrupted part fixed conductor 43 is attached and connected to the base side of the support conductor 30 provided upside down on the insulating case 21, and the interrupted part fixed conductor 43 is connected to the interrupted part fixed conductor 43, corresponding to the breaking part movable contact 42. A fixed contact 44 is provided. In addition, 45 in the figure is a handle for on-off operation.

Further, the movable iron core 35 has a substantially U-shape as shown in FIG. 4, and is attached so as to surround the current limiter movable contact 3. The fixed iron core 37 also has a substantially U-shape and is attached so as to surround the current limiting wire fixed conductor 33. moreover,
A substantially U-shaped magnetic iron plate 29 is located at a position facing the movable iron core 10-35.
is attached so as to surround the current side conductor 26.

Next, the operation of the circuit breaker configured as described above will be explained with reference to FIGS. 3(,) to (i). Now, a short circuit accident has occurred on the load side, and the short circuit current i shown in Figure 6
It is estimated that l has flowed. At the initial stage, Figure 3 (a)
As shown in (b), the breaker movable contact 42, the breaker fixed contact 44 (hereinafter referred to as the breaker contact 42, 44), the current limiter surface contact 27, the current limiter movable contact 36 (hereinafter referred to as the current limiter) Contacts 27 and 36) remain closed to form a current-carrying path. Next, as shown in FIG. 3(e)t(d), an electromagnetic repulsion force is generated between the power supply side terminal conductor 26 and the current limiter movable contact 31, so that the current limiter contact 27.36
is opened and an arc is generated. in this case,
As shown in FIG. 4, a magnetic iron plate 29 and a movable iron core 35 are attached to the power supply side conductor 26 and the current limiter movable contact 31, which form parallel conductors, at positions facing each other. Therefore, the mutually generated magnetic flux density increases, and the electromagnetic repulsion is strengthened. Therefore, the contacts open rapidly and the arc resistance increases rapidly, which limits the current flow. Also, at this time, the current limiting part fixed conductor 33
A current begins to flow through the resistor 28, which excites the fixed core 37 forming an electromagnet, attracts the movable core 35, and promotes the opening/disengaging operation of the current limiter movable contact 31.

Then, the breaker contacts 42 and 44 are still closed, forming a current-carrying path. As more time passes, Figure 3 (e
) e As shown in (d), when the current-limiting line contacts 21.36 are completely opened, the arc is extinguished, and the short-circuit current flows through the current-limiting part fixed conductor 33 and the resistor 28 to the breaker part 22. Electricity is applied, and at this time, the excitation of the fixed core 37 is maximum, and the movable core 35 maintains an attracted state. At this time, the limited current shown in FIG. 6 continues to flow through the resistor 28, and after time t1, the current is completely commutated by the resistor 28 as shown in FIG.
, ), resulting in a current I3.

Thereafter, the breaker contacts 42, 44 have the characteristic A2 of FIG.
The overcurrent tripping device 39 having the short time characteristic shown in FIG. The excitation is reduced, and due to the action of the spring 34, the current limiting line contact 2
7.36 moves to closing operation. And the interruption part contact 4
When the current is completely cut off by 2.44, the fixed iron core 37 is de-energized, and as shown in Fig. 3 (h) and (1), the current-limiting line contact #, 36 is closed, and the breaker is closed. Contacts 42 and 44 open completely, completing the disconnection.

Next, selective breaker using this circuit breaker will be explained with reference to FIG. In FIG. 7, the characteristic A! in FIG. 5! , that is, a low voltage circuit is assumed in which an upper circuit breaker α having a short time limit characteristic and a lower circuit breaker β having a characteristic Bu in FIG. That is, if a short-circuit accident occurs on the load side of the circuit breaker β on the lower side of this low voltage circuit, the circuit breaker β on the lower side operates instantaneously, as shown in characteristic B2 in Fig. 5. , the current becomes zero before the overcurrent trip device 39 of the circuit breaker α on the upper side operates. That is, the lower circuit interrupter β completes the interruption, the upper circuit interrupter α opens the current limiting line contact 27.36, the breaker contact 42.44 remains closed, and the scheduled time is reached. The current-limiting line contacts 27 and 36 are also closed.

According to the above, the circuit interrupter with short-time operating characteristics 11 enables selective cut-off and prevents expansion of the power outage range of the low-voltage circuit.

In addition, if a short circuit occurs between the upper circuit interrupter α and the lower circuit interrupter β, the current limiting line contact 27
．． After the opening of 36, the current is commutated to the resistor 28, and the limited current flows for a certain period of time, and the short time limit 4 release device 39 of the interruption section is operated, and the interruption section contact 42! , 44 are opened and the shutoff is completed.

14- [Effects of the Invention] As described above, the overcurrent trip device is provided with a short time 4 trip characteristic that operates with a time delay of several cycles,
In addition, a resistor is connected between the contacts of the current-limiting part, and an electromagnet is installed in the current-limiting line movable contact and the current-limiting line fixed conductor provided with the current-limiting part movable contact, and is excited by the current commutated to the resistor. At the back of the center part of the power supply side conductor of the current limiting section,
Since a magnetic iron plate is arranged opposite to the electromagnet to enhance the electromagnetic repulsion of the electromagnet, the structure is simple, and the electromagnetic repulsion that opens the current limiter contacts is increased. A circuit interrupter with extremely good current limiting performance and capable of current limiting and selective interruption can be provided.

2 is a diagram showing the current vs. operating time characteristics of a conventional circuit breaker, and FIGS. 3 (#L) to (1) are configuration diagrams showing an embodiment of the circuit breaker according to the present invention. Fig. 4 is a partial cross-sectional structural diagram of Fig. 3, Fig. 5 is a diagram showing the characteristics of current versus operating time of the circuit breaker according to the present invention, and Fig. 6 explains the operation of the circuit breaker according to the present invention. Figure for, No. 7
The figure is a diagram for explaining selection and interruption.

2I... Insulating case, 22... Breaking part, 23...
・Current limiter, 24... Power supply side terminal, 25... Load side terminal, 26... Load side terminal conductor, 27... Current limiter surface contact, 28... Resistor, 2" 9...Magnetic iron plate, 3o
...Support conductor, 31...Current limiter movable arm, 32.
...Rotating shaft, 33... Current limiting wire fixed conductor, 34... Spring, 35... Movable iron core, 36... Current limiting part movable contact,
37... Fixed iron core, 38... Current side terminal conductor, 39
...Overcurrent trip device, 40...Flexible body, 4
DESCRIPTION OF SYMBOLS 1... Breaking part movable arm, 42... Breaking part movable contact, 43... Breaking part fixed conductor, 44... Breaking part fixed contact, 45... Handle.

Applicant's agent: Patent attorney Suzue Takehiko 13 Figure 4 Figure 6 ! Figure 5 Figure 7 1 　　　Vd 28t - dimension 27 11 cho d ー　Ll　“ 1　　　　ゝToku11

Claims (1)

[Scope of Claims] A circuit breaker main body having a short time-limited eddy flow force release device that performs a tripping operation after a scheduled time delay when a large current flows, and a circuit breaker body provided with a fixed contact of a current-limiting circuit breaker. A sinking interrupted line fixed conductor and a current-limiting breaker movable contact are provided, and the current-limiting breaker movable contact and the current-limiting breaker fixed contact are opposite to the current-limiting breaker fixed conductor in a closed circuit state. a current-limiting interrupting part movable contact forming a parallel conductor together with the current-limiting interrupting part fixed conductor so as to form an energizing path in the direction; a resistor connected in parallel to the parallel conductor; and a current flowing through the resistor. When the electromagnet is excited, a large current flows through the movable iron core provided in the current limiting section movable contact and the parallel conductor portion so as to attract the current limiting section movable contact in a direction of opening. and a magnetic iron plate provided on the current-limiting breaker fixed conductor so that an electromagnetic repulsion force is generated between the movable iron core and the movable iron core when