JPS5848979B2 - circuit break - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In this invention, a movable contact and a fixed contact each having a contact point at their tip are arranged in parallel in a closed circuit state, and when a large current flows through these contacts, both contacts are connected. The present invention relates to a circuit breaker having a current-limiting mechanism that uses electromagnetic repulsion generated between contacts to separate a fixed contact from a movable contact without an overcurrent tripping device separating the movable contact.

In general, this type of circuit breaker exhibits sufficient performance for interrupting large currents such as short-circuit currents, but on the other hand, it is not suitable for interrupting relatively small currents where the circuit current gradually increases and an overcurrent condition occurs. Stable performance could not be obtained, and as a result, when the current was cut off, the contacts would weld, and this had to be removed.

An example of a conventional circuit breaker will be explained based on cross-sectional views shown in FIGS. 1 and 2.

FIG. 1 shows the circuit in a closed state, and a toggle mechanism 3 is connected to the handle 1 for opening/closing operation to open/close the movable contact 2. As shown in FIG.

When an abnormal current flows through the circuit while the contact is in a closed state, the claw 41 and the tripping lever 31 are disengaged by the action of the overcurrent tripping device 4, and the toggle mechanism 3 is automatically reversed to automatically open the contact. will be carried out.

Components such as the fixed contact 5, the power supply side terminal 6, the load side terminal 7, and the arc extinguishing device 8 are mounted inside a cover 9 and a case 10 made of an insulating material.

Here, the movable contact 2 and the fixed contact 5 have portions that are parallel to each other in order to generate electromagnetic repulsion between them.

FIG. 2 shows that the movable contact 2 is fixed before the opening operation of the movable contact 2 due to the reversal of the torge mechanism 3 accompanying the claw release action of the overcurrent tripping device 4. A state in which the fixed contact 5 is separated due to the electromagnetic repulsive force generated between both movable contacts is shown.

Movable contact 2 and fixed contact 5 with parallel parts due to arrangement
F=kI2- (1) (where k is a constant) holds between the magnitude of the current (2) flowing through the fixed contact 5 and the electromagnetic repulsive force F that the fixed contact 5 receives.

Therefore, in order to prevent the fixed contact 5 from separating in response to a current below a certain level, the tension spring 22 applies a clockwise rotational force to the fixed contact 5, thereby fixing the fixed contact 5 by electromagnetic repulsion. This prevents the contactor 5 from rotating counterclockwise about the shaft 11.

When the current exceeds the spring force f, the fixed contact 5 begins to separate, but in a state where equation (3) holds true, the contact force becomes 0 and the contact does not separate.

As described above, this circuit breaker has the disadvantage that there is always a region where the contact pressure is 0, and if the current is in this region, the contacts will weld.

In view of the above-mentioned drawbacks, this invention provides a contactor in which the contact pressure due to the current repulsion force increases as the current increases when the current is smaller than the current limit starting value, and the contact opens when the current exceeds the above-mentioned value. It is an object of the present invention to provide a circuit breaker equipped with a circuit breaker, thereby preventing contacts from welding when they are opened.

According to the present invention, the above-mentioned object is to provide a circuit breaker of the above-mentioned type, in which the fixed contact has a pin approximately in its center, and the pin is loosely fitted into a guide groove formed approximately vertically, and the contact This is achieved by providing a stopper below the end of the fixed contact and the opposite end of the fixed contact.

Embodiments of the present invention will be described below with reference to the drawings.

3 and 4 are sectional views of the contactor device portion of the circuit breaker according to the present invention, and FIGS. 5 to 8 are diagrams of its operating principle.

In addition, in FIGS. 3 and 4, the other components other than the fixed contact 12 are the same as the conventional ones shown in FIGS. 1 and 2.

The fixed contact 12 according to the present invention includes a fixed contact conductor 13,
It is composed of contacts 14 and pins 17.

The pin 17 is connected to a guide groove 16 provided approximately perpendicularly to the guide plate 15.
is inserted into.

The fixed contact conductor 13 is arranged substantially parallel to the movable contact 2 in a closed circuit state.

Further, the fixed contact conductor 13 is connected to the fixed contact 14 and the pin 1.
7 below, compression springs 18 and 1, respectively.
9 is pressed.

The operating principle will be explained below with reference to FIGS. 5 to 8.

Note that the part numbers in the figures correspond to FIGS. 3 and 4.

FIG. 5 shows a normal closed circuit condition.

In this state, due to the force of the compression springs 18 and 19, the fixed contact 12 is stabilized with the pin 17 fixed thereto hitting the top of the guide groove 16.
There is a suitable gap between the stopper 20 and the end 21 of the fixed contact 12 opposite to the contact 14 side.

Let the distance from the center of the pin 17 of the fixed contact 12 to the point of action of the compression spring 18 be l1, and the distance to the end 21 be l2, and the electromagnetic repulsion generated between the movable contact 2 and the fixed contact 12. Of the force, the force received by the l1 portion is F1,l
If the force received by the two parts is F2, then F1=kII12, F2=k2I1'' for a current ■1 below a certain current Im, and a compression spring is used to prevent the fixed contact 12 from moving due to these electromagnetic repulsion forces. The force f1 of 18 and the force f2 of compression spring 19 are determined.

Further, the dimensional relationship between l1 and l2 is determined so that the moment of the fixed contactor 12 about the pin 17 satisfies F1l1-f1l1<F2A2.

Under such conditions, when the current is less than Im, the fixed contact 12 receives a clockwise rotational force about the pin 17 in FIG. 5 due to electromagnetic repulsion.

That is, the contact force increases due to electromagnetic repulsion, and its magnitude increases in proportion to the square of the magnitude of the current.

When the magnitude of the circuit current exceeds Im, the fixed contact 12
The electromagnetic repulsive force F applied to the whole is the force f of the compression spring 19
2, the fixed contact 12 is large enough to rotate the entire fixed contact 12 in the clockwise direction using the contact 14 as a fulcrum, and the fixed contact 1
2 is moved to the position shown in FIG. 6 where the end 21 hits the stopper 20.

If the circuit current decreases in this state, the fixed contact 12 returns to the state shown in FIG. 5, ie, FIG. 3, by the force of the compression spring 19.

Next, when the circuit current increases further and reaches the current limit starting current IA, the fixed contact 12 uses the portion of its end 21 that hits the stopper 20 as a fulcrum to overcome the forces f1 and f2 of the compression springs 18 and 19. Rotate counterclockwise.

At this time, the pin 17 quickly moves along the guide groove 16 to the position shown in FIG.

The arc resistance generated by the opened contact 14 in this state limits the circuit current, and then the overcurrent tripping device 4, which has already started operating, is released, causing the toggle mechanism 3 to reverse and move. Opening is performed by the contactor 2, and circuit breaking is completed.

When the circuit is cut off, the electromagnetic repulsive force acting on the fixed contact 12 disappears, and the fixed contact 12 automatically returns to the state shown in FIGS. 7 to 8 due to the force of the springs 18 and 19.

As described above, according to the present invention, the contact pressure increases as the circuit current increases when the circuit current is smaller than the current limit starting current value, and when the circuit current exceeds that value, the contact pressure is quickly opened. It is possible to obtain a circuit breaker with

[Brief explanation of drawings]

1 and 2 are side sectional views showing a conventional circuit breaker in a closed state and an open state, respectively, and FIGS. 3 and 4 respectively show a contact device section in a circuit breaker according to the present invention. A side sectional view showing a closed circuit state and an open circuit state,
FIGS. 5 to 8 are schematic configuration diagrams for explaining the operating principle of the contact device section of the circuit breaker according to the present invention. 2: Movable contact, 12: Fixed contact, 13: Fixed contact conductor, 14: Contact, 15: Bearing, 16: Guide groove, 17
: Pin, 18, 19: Compression spring, 20: Stopper, 21: End of fixed contact.

Claims (1)

[Claims] 1. A movable contact and a fixed contact, each having a contact point at the tip, are placed in parallel in a closed circuit state, and the electromagnetic repulsion force generated between both contacts is used when a large current flows through these contacts. In a circuit breaker that has a current-limiting mechanism that separates the fixed contact from the movable contact without having an overcurrent tripping device open the movable contact, the fixed contact has a pin approximately in the center. The pin is loosely fitted into a guide groove formed approximately perpendicular to the movable contact, and is pressed toward the movable contact by springs approximately below the contact and the pin, and is a fixed contact. A circuit breaker characterized in that a stopper is provided below the end of the terminal opposite to the contact point.