JPH04233119A - Switch - Google Patents

Abstract

PURPOSE:To provide a slit arc-extinguishing system switch excellent in a high- voltage breaking performance without imparing a cut-off current performance. CONSTITUTION:In a switch having a stopper 6 for defining the maximum rotational position of a movable contact maker 1 in the opening state so as to prevent the further rotation of the movable contact maker 1, a slit plate 8 made of an insulating member is located to the location where the movable contact maker 1 bounds upon hitting on the stopper 6, such that the movable contact 1 and the fixed contact 4 are put on both sides almost in parallel with the locus of the movable contact 1 from the closing state to the opening state.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch, and more particularly to a circuit breaker for low voltage wiring using a slit arc extinguishing method.

0002

2. Description of the Related Art Conventionally, circuit breakers using the slit arc extinguishing method have been disclosed in Japanese Utility Model Application No. 124744/1982 and Japanese Utility Model Publication No. 33317/1983. The basic structure of the slit arc extinguisher in these circuit breakers is shown in FIG. FIG. 3 shows the circuit breaker in an open state (open state). In the figure, 1 is a movable contact, 2 is a rotation center provided on the movable contact 1, and 3 is a center of rotation provided on the movable contact 1. A movable contact 4 is a fixed contact that comes into contact with and separates from the movable contact 3 by rotating the movable contact around the rotation center 2, and 5 is a fixed contact to which the fixed contact 4 is fixed. 6 is a stopper for stopping the rotation of the movable contact 1, and 7 is a terminal portion connected to the fixed contact 5. Reference numeral 8 denotes a slot plate made of an insulator, which is installed almost parallel to the locus of rotation of the movable contact 1 so as to sandwich the movable contact 3 and the fixed contact 4, and 9 denotes the arc-extinguishing part, mechanism part, etc. (not shown). Moreover, FIG. 4 is a sectional view taken along the line AA in FIG. 3.

Next, the operation will be explained. When the rated power is being supplied from the power supply to the load via the fixed contact 5, fixed contact 4, movable contact 3, and movable contact 1 (closed state), the movable contact 3 is pressed against the fixed contact 4 with a specified contact pressure. When a short-circuit accident occurs in the circuit on the load side of the circuit breaker and a large current flows to the circuit breaker, the movable contact 1 is rotated by the mechanism, and the movable contact 3 and fixed contact 4 are opened. . However, in the case of a short circuit accident, a current several times to several tens of times the rated current will pass through the contact surface between the movable contact 3 and fixed contact 4, so electromagnetic repulsion at the contact surface between the movable contact 3 and fixed contact 4 will occur. Normally, the force exceeds the contact pressure of the movable contact 3, and the movable contact 1 rotates without waiting for the mechanism to operate. When the movable contact 3 and the fixed contact 4 are separated, an arc is generated between the contacts 3 and 4. Since the generated arc is sandwiched between the slit plates 8, the cross-sectional area cannot be increased in that direction, and the arc resistance increases. Furthermore, since the arc is in contact with the slit plate 8, the arc energy is absorbed by the slit plate 8, which lowers the temperature of the arc, which also increases the arc resistance. Furthermore, the pressure generated by the arc becomes a force that pushes up the movable contact 1 by the slot plate 8, leading to a significant improvement in the rotational speed of the movable contact 1. This means an increase in arc length,
This also increases arc resistance. The effect of increasing arc resistance due to these slit plates 8 is called the slit effect. Since the arc resistance increases in this way, current limiting can be easily performed to reduce the current during a short circuit. However,
Since the surfaces 8a and 8b of the slotted plate 8 are exposed to the arc, the surface resistance is greatly reduced. This is due to the adhesion of fine metal powder melted and vaporized by the moving contact 1, movable contact 3, fixed contact 4, etc. to the surfaces 8a and 8b of the slot plate 8, and the Possible causes include carbonization due to the high heat of the arc. As a result, when the movable contact 1 is in the open state, the insulation between the movable contact 3 and the fixed contact 4 is almost the same as the gap length d between the movable contact 3 and the slot plate 8 shown in FIG.
It is maintained only by Therefore, even if the movable contact 1 moves slightly sideways at the current zero point during current interruption, the movable contact 3 and the surface 8a of the slot plate 8 or 8
b will come into contact with each other, and the insulation resistance between the movable contact 3 and the fixed contact 4 will drop sharply, greatly increasing the risk of failure and re-ignition. In addition, even if the movable contact 1 does not shake, the movable contact and the surface 8a of the slot plate 8 may be affected by the melt caused by the arc.
, 8b may come into contact with each other. As a result, it is said that the high-voltage interrupting performance of the narrow-gap type switch is insufficient.

[0004] In order to eliminate this drawback, for example, Japanese Utility Model Publication No. 11875/1982 and Japanese Patent Application Laid-open No. 208522/1983 have been proposed.
There was a configuration of a slit arc extinguishing section as shown in the publication. The basic configuration of these slit arc extinguishing parts is shown in FIGS. 5 and 6. FIG. 6 is a cross-sectional view taken along line AA in FIG. This configuration is characterized in that the movable contact 1 and the movable contact 3 come out from the gap space created by the gap plate 8 when the movable contact 1 is in the open state. The other parts are the same as those shown in FIG. 3, so their explanation will be omitted.

Next, the operation of the slit arc extinguishing section having this configuration will be explained. When a large current flows, such as in the event of a short-circuit accident, an arc is generated between the contacts 3 and 4, and the arc resistance is increased by the slit plate 8, as described above. Similarly, the surface resistance of the surfaces 8a and 8b of the slot plate 8 is reduced by the arc. However, when the movable contact 1 is in the open state, the movable contact 1 and the movable contact 3 come out from within the slit space, so the insulation distance between the movable contact 3 and the slit plate 8 at this time is With the gap length d shown in FIG. 6, the movable contact 3 and the slot plate 8 will not come into contact even if the movable contact 1 moves laterally or even if there is a small amount of melted material. That is, by reducing the height h of the slot plate 8 and taking the gap length d,
A sufficient insulation distance is provided between the movable contact 3 and the fixed contact 4 at the current zero point during current interruption, and the risk of failure re-ignition is greatly reduced, resulting in a switch with excellent high voltage interruption performance.

[0006]

[Problems to be Solved by the Invention] The conventional switch is constructed as described above, and as pointed out in the above-mentioned Japanese Utility Model Publication No. 11875/1987, the height h of the slot plate 8 is reduced. If the movable contact 1 and the movable contact 3 in the open state are allowed to protrude from the gap space more than necessary, the gap effect will be reduced. Furthermore, if the height h of the slit plate 8 is increased to increase the slit effect, the gap length d becomes shorter as described above, and the high voltage interrupting performance deteriorates. Therefore, in fact, the above Jikosho 6
When applying the method disclosed in Japanese Patent No. 1-11875 to a narrow arc extinguishing chamber, the problem was how large the gap length d should be.

The present invention was made to solve the above-mentioned problems, and provides a slit arc extinguishing method that can make maximum use of the slit effect without deteriorating the high voltage interrupting performance due to the slit plate. The purpose is to obtain a switch.

[0008]

[Means for Solving the Problems] The switch according to the present invention moves a slit plate made of an insulating member approximately along the trajectory of the movable contact from the closed state to the open state until the movable contact hits a stopper and bounces back. A movable contact and a fixed contact are arranged in parallel and sandwiched from both sides.

[0009]

[Function] In the switch of the present invention, even if the movable contact hits the stopper and bounces back when a large current is interrupted, it does not enter the slit space formed by the slit plate, and the contact between the movable contact and the slit plate is prevented. It is possible to completely prevent deterioration of high voltage interrupting performance due to the slit plate. Furthermore, the height of the slit plate is the maximum height that does not adversely affect the high voltage interrupting performance, and the slit effect continues for a long period of time, so excellent current limiting performance is exhibited.

0010

[Example] Example 1. An embodiment of the present invention will be described below with reference to the drawings. Figure 1
2 is a side view of a switch according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line A-A in FIG. 1. In the figure, 1
2 is a rotation center provided on the movable contact 1, and 3 is a movable contact fixed to the movable contact 1. In addition, the broken line indicates the position of the movable contact 1 at the time of opening,
The solid line indicates the position of the movable contact 1 that hit the stopper and bounced back. 4 is a fixed contact that comes into contact with and separates from the movable contact 3 as the movable contact 1 rotates about the rotation center 2; 5 is a fixed contact to which the fixed contact 4 is fixed. 6 is a stopper that stops the rotation of the movable contact 1; 8 is a slit plate made of an insulator installed almost parallel to the locus of the rotation of the movable contact 1 so as to sandwich the movable contact 3 and the fixed contact 4; As shown in the figure, the height is set at a position where the movable contact 1 hits the stopper 6 and bounces back, that is, at a height at which the movable contact 1 drawn by the solid line does not enter the narrow gap. Reference numeral 9 denotes a case that houses an arc extinguishing section, a mechanism section, etc. (not shown). Moreover, FIG. 2 is a sectional view taken along the line AA in FIG. 1.

Next, the operation will be explained. As described above, when a large current flows due to a short circuit or the like, the movable contact 1 rotates without waiting for the mechanical parts to move. This is due to electromagnetic repulsion at the contact surfaces of contacts 3 and 4, or a structure in which a part of fixed contact 5 passes a current antiparallel to the current flowing through movable contact 1, as shown in this embodiment. This is because the electromagnetic force acting between these antiparallel currents overcomes the contact pressure of the movable contact 3. Contacts 3 and 4 open,
The slit effect acting on the generated arc is the same as that described in the conventional example, and will therefore be omitted. While the movable contact 3 is in the slit space, the rotational speed of the movable contact 1 increases due to the pressure generated by the arc, as described above. Moreover, the electromagnetic force applied to the movable contact 1 by the current path of the fixed contact 5 described above also contributes to this increase in rotation speed. According to the law of conservation of angular momentum, the movable contact 1 coming out of the gap space collides with the stopper 6 while retaining most of the angular momentum about the rotation center 2 obtained within the gap space. Stopper 6
The movable contact 1 that collides with the movable contact 1 cannot come to rest instantaneously, but always bounces back to a certain position, the position shown by the solid line in FIG. FIG. 2 shows this state. Thereafter, the movable contact 1 will vibrate between this position and the stopper 6. The height h of the slit plate 8 in this invention is such that the upper end thereof is set at a height up to the position where the movable contact 1 bounces back, so that the movable contact 1 that has once left the slit space returns to the slit space. It never enters. Therefore, by setting the height h of the slit plate 8 in this way, contact between the movable contact 1 and the slit plate 8 at the current zero point can be prevented, and the deterioration of the high voltage interrupting performance due to the slit plate 8 can be prevented. Completely preventable. Moreover, in the above configuration, the height of the slot plate is the maximum height that does not adversely affect the high voltage interrupting performance. Therefore,
The movable contact 1 stays in the slit space for a long time, and the slit effect persists for a long period of time, so excellent current limiting performance is exhibited. The slit effect disappears after the movable contact 1 leaves the slit space, but at this time the passing current has already exceeded its peak, so the slit effect for current limiting is not necessary and there is no problem. For example, according to experiments conducted by the inventors, the average opening speed of the movable contact is 5 m/s at a breaking current of 12 KA, and the opening distance at the position where the movable contact hits the stopper and rebounds (the upper end of the slot plate) is 17 mm. The time it takes for the passing current to reach its peak is 3.4 ms, and the movable contact moves out of the gap space after the passing current reaches its peak.

0012

As described above, according to the present invention, the slit plate is connected to the movable contact almost parallel to the trajectory of the movable contact from the closed state to the open state until the movable contact hits the stopper and rebounds. Since the fixed contacts are arranged so as to be sandwiched from both sides, it is possible to obtain a slit arc extinguishing type switch which does not impair current limiting performance and has excellent high voltage interrupting performance.

[Brief explanation of the drawing]

FIG. 1 is a side view of a switch showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA in FIG. 1;

FIG. 3 is a side view of a conventional switch.

FIG. 4 is a sectional view taken along line AA in FIG. 3;

FIG. 5 is a side view of another conventional switch.

6 is a sectional view taken along line AA in FIG. 5. FIG.

[Explanation of symbols]

1 Movable contact 2 Center of rotation 3. Movable contact 4 Fixed contact 5 Fixed contact 6 Stopper 8 Slit plate

Claims (1)

[Claims] Claim 1: A movable contact having a rotation center and having a movable contact fixed to one end, and a fixed contact having a fixed contact fixed to one end, which can come into contact with and separate from the movable contact by rotation of the movable contact. and a stopper that defines a maximum rotational position of the movable contact in an open state and prevents further rotation of the movable contact, the movable contact hits the stopper and bounces back. position, approximately parallel to the trajectory of the movable contact from the closed state to the open state,
A switch characterized in that a slit plate made of an insulating member is provided so as to sandwich the movable contact and the fixed contact from both sides.