JPS5835826A - Circuit breaker - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low voltage circuit interrupter capable of selectively interrupting.

Conventional low-voltage circuit protection methods can be roughly divided into the following three methods.

That is, the first method selects all capacity and suspends, the second method deselects all capacity and suspends, and the third method cascades and suspends. In the first method of selecting full capacity and interrupting, if a short circuit occurs at point C on the load side of lower interrupter B in the single line diagram as shown in Figure i1, the corresponding lower interrupter B is selected and the interruption is interrupted. However, the interrupter A at the upper level is used as a closed circuit and continues to supply power to other healthy circuits.

In this case, the upper level interrupter A in the Hosenkyo pJIM shown in FIG.
As shown in the diagram, the lower interrupter B has a short-time trip characteristic, and the lower interrupter B has an instantaneous trip characteristic that operates with less current than the upper interrupter A, as shown in the figure, and is fully protected. In addition, both interrupters A and B must have the maximum short-circuit current of the circuit, and the protection coordination characteristics shown in Figure 3, the upper interrupter A and the lower interrupter B must have instantaneous trip characteristics. The lower interrupter B is designed to perform a trip operation with a smaller current than the upper interrupter A. If there is a short-circuit accident on the load side of the lower interrupter B, and a short-circuit current greater than or equal to the current SX that crosses the tripping characteristics of M and B, both circuit breakers A and B will simultaneously interrupt the operation. It was designed to do so. In this method, both interrupters A and B require an interrupting capacity greater than the maximum short-circuit current of the circuit. in this case,
Even if there is a short-circuit accident on the load side of the lower order interrupter B, if the upper order interrupter A is interrupted, the circuit that is supplied with power from the upper order interrupter A will be completely out of power. Furthermore, in the third method of cascading and interrupting, the upper level.

The protective coordination characteristics of each of the lower order interrupters A and H are the same as in the case of full capacitance non-selection and interrupt shown in Figure 3, but the lower order interrupter B has a smaller interrupt current than the maximum short circuit current of the circuit. It is possible to use a device with only a large capacity. Therefore, in this case, if a short circuit occurs on the load side of the lower interrupter B, the upper interrupter A and the lower interrupter B are simultaneously interrupted, and the arc energy at the time of interruption is absorbed by both interrupters A.
, B simultaneously share the load, and the lower level interrupter B compensates for the lack of interrupting capacity and performs the interrupt. In this case, it is generally necessary to use a current-limiting interrupter that limits and interrupts the current before the short-circuit current increases as the upper order interrupter A, and in the case of cascading and interrupting, the lower order interrupter B must be replaced.

In each of the above methods, the full capacity selection and interruption method is the most ideal from the point of view of circuit protection. In the case of other methods, ie, full capacity non-selective interruption, or cascade interruption, a small-capacity lid interrupter can be used, which is economical, but is not preferable because it results in a total power outage. By the way, when the full capacity is selected and the interrupt occurs, the upper interrupter cannot have an instantaneous trip characteristic, so it must withstand a large short-circuit current that flows until the circuit opens due to short-time trip operation. In other words, this upper-level interrupter requires a large short-time current capacity, which has the disadvantage of making the interrupter large in size and expensive.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a circuit that has a small current capacity for a short time, that is, is small in size, is inexpensive, and can select and interrupt all capacities. It is.

An embodiment of the present invention will be explained in detail below with reference to sectional views showing a closed circuit state shown in FIGS. 4 and 5. In FIGS. 4 and 5, 1 is a molded case, 2#i opening/closing operation handle, and S is an overcurrent side disconnection device unit provided inside the case 1. In this embodiment, the overcurrent side disconnection device unit is Therefore, instead of an instantaneous tripping device having an instantaneous tripping characteristic, a short-time tripping device having a short-time tripping characteristic is provided. The specific structure of this short-time closing device includes an electromagnetic type, a semiconductor type, etc., and since it is widely used at present and its contents are well known, the details thereof will be omitted. 4.degree. 4' is a fixed contact and a movable contact inserted into the main circuit. 5
is a U-shaped fixed conductor with a fixed contact 4g at one end, 6
is a movable arm with a movable contact at its tip. The fixed conductor 5 and the movable arm 6 are arranged in parallel and facing each other, and the fixed contact 4 and the movable contact 4' are provided at one end thereof, so that the directions of current flowing in the parallel portions are opposite to each other. 7
is a spring that elastically biases the movable arm 6t to rotate clockwise (arrow x) in the figure so as to apply contact pressure to each contact point 4, 4'. Reference numeral 8 denotes a latch, which engages with the locking pawl 3a of the tripping device 3.

Here, the other end of the movable arm 6 is rotatably supported on one end of a rotary link 9 via a pin 9af, and the other end of this rotary link 9 is rotatably supported on the case 1 by a fixed shaft 9b. I support you. One end of the first link 10 is attached to the pipe 79*, and the other end is connected to the second link 11 by means of a pin 101.
A is pivoted at one end. Further, the other end of the second link 11 is pivotally supported by the bottle l1m at approximately the center of the third link 12, and one end of the third link 12 is rotatably attached to the case 1 by the bottle 12*. It is pivoted. Then, the other end of this third link 12 is engaged with the latch 8, and the handle 2
A coil nozzle 13 is stretched between the pin 10m and the pin 10m.

With such a table configuration, when a short circuit current flows through the interrupter, the fixed conductor 5 and the movable arm 6 in FIG.
Then, the Kt flows flow in mutually opposite directions. At the same time, the trip device 3 connected in series to the main circuit is also energized by the main circuit current, causing the trip to occur for a short time! A signal is input to the elementary part so that it operates with a certain time delay. When the short-circuit current begins to flow, the movable arm 6 and the fixed conductor 5 instantly separate due to the electromagnetic repulsive force caused by the current flowing in parallel and opposite directions, and rotate to the position shown by the dashed-dotted line in Fig. 4. Due to this rapid opening action caused by electromagnetic force, the arc generated between the contacts and 4 and 4' is rapidly extended, resulting in a short-time trip energized by the short circuit current. This is because the device 3 is designed to operate with a time delay of 3 to 5 cycles.

It takes 3 to 5 cycles until the lock 8 and the locking claws 31 and 1 are disengaged. Therefore, the electromagnetic reaction force acting on the movable arm 6 changes depending on the magnitude of the current flowing during this time, so the opening and closing are repeated several times. When the short time trip device 3 operates and the locking pawl 3a is disengaged from the latch 8 after 3 to 5 cycles have elapsed, the coil spring 13 causes the rotation link 9 to close.
The suspension is completed by pulling up the table and placing it in the state shown in FIG.

On the other hand, if a short-circuit current is generated in the breaker at the lower level before the short-time tripping device operates and the circuit is interrupted, the electromagnetic reaction force applied to the movable arm 6 will completely disappear, so the movable arm 6 will The circuit enters the closed position shown in FIG. 4 (the position shown by the solid line), and is in a state where power supply can be continued.

Therefore, according to the above embodiment, when a thick short-circuit current flows, it is not necessary to maintain the contacts 4 and 4' in the closed position using large contact pressure from the spring 1 to prevent them from opening, and this makes the structure strong. Since there is no need to do so, a small and inexpensive interrupter can be used.

Traditionally, the current-limiting interrupt method has been widely used to increase the interrupting capacity of the interrupter, but such a current-limiting interrupt method allows the contacts to open instantly without any time delay when a short-circuit current flows. This is a contradictory condition to provide a short-time current capacity t so as to open a point between 3 to 5 cycles for selection and interruption, and it has not been possible to satisfy both t- at the same time.

However, according to the above embodiment, the instantaneous side has short-time trip characteristics by the short-time trip device, and a contact mechanism that opens the contacts due to electromagnetic repulsion to limit current, and when the current disappears, recloses and connects the power supply. Since the configuration combines the disconnection characteristics, the full capacity selection circuit can be maintained with a relatively small short-time current capacity.

As described in detail above, the present invention provides a movable arm that holds a movable contact parallel to a fixed conductor that holds a fixed contact and is biased elastically toward the closing direction, so that the arm is fixed against overcurrent.
Due to the electromagnetic reaction force acting between the four bodies and the movable arm, the above contacts are fully opened, and after a predetermined cycle, the circuit is opened by a short-time disconnection device, so even if the current capacity is small for a short time, the current capacity is full and interrupted. We can provide circuits and interrupters that can perform this.

[Brief explanation of drawings]

Figure 1 is a diagram showing an example of a single-line connection in a low-voltage circuit, Figure 2 is a selected and interrupted maintenance cooperation curve, Figure 3 is a non-selection and interruption maintenance cooperation curve, and Figures 4 and 5. The figures are cross-sectional views showing one embodiment of the present invention. Figure 4 shows a closed circuit state, and Figure 5 shows a closed circuit state. 1... Case, 2... Handle, 3... Short time trip device, Jm... Locking claw, 4.4'... Contact,
6...Fixed conductor, 6...Arm, r...Spring, 8
... Latch, ... Rotating link, 10.11.12.
··Link. Applicant's agent Patent attorney Takehiko Suzue Figure 2
Figure 3 → i Charging ix → i Denmaru Figure 4 Figure 5

Claims (1)

[Claims] A fixed conductor that holds a fixed contact at one end; a movable arm that holds a movable contact that contacts and separates from the fixed contact at one end and is arranged parallel to the fixed conductor; a pivot link that rotatably holds the end; and a spring that elastically biases the movable arm relative to the pivot link and applies contact pressure to the movable contact so as to elastically contact the fixed contact. , constitutes a toggle mechanism driven by the operation of the handle, and has one end connected to the pivot point of the movable arm and the rotation link, and is engaged with the locking claw of the short-time pullout device to be held in a predetermined position. a latch that is held and holds each of the contacts in a closed position via the link, and the contacts are opened by electromagnetic repulsion between the fixed conductor and the movable arm when the current exceeds a predetermined value. and circuit interrupter.