JPH0637559Y2 - Main circuit automatic disconnection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an automatic disconnecting device that surely opens a main circuit when a short circuit occurs inside a switch-built-in cabinet.

(Prior Art) As shown in FIG. 3, three switch cabinets (a), (b), and (c) are installed inside a normal power distribution tower 31. The switch cabinet (b) in which the current flows to the power supply (B) via the busbar 32 via the switch cabinet (b) and following the arrow in the figure.
Also, the so-called π feed is sent to the switch cabinet (c) leading to the consumer. If a short-circuit accident occurs inside the switch cabinet (a), the power supply from the power supply (A) is temporarily stopped and then this time the power supply (B).
However, the main circuit must be open in the switch cabinet (a) where the short-circuit accident occurred at this time.

This is because the switch cabinet (a) may be short-circuited again when the power source (B) supplies power. The same applies to the other switch cabinets (b) and (c).

Therefore, conventionally, in order to prevent such a re-short circuit, a device for controlling a switch using the supplied current is incorporated in each of the switch cabinets (a), (b), and (c).

(Problems to be solved by the invention) However, according to such a conventional control device, since the current supplied to the switch is used, the device itself fails and operates normally when an overcurrent flows. It may not work.

It is also conceivable to physically operate the handle of the switch manually to disconnect the main contact, but the movable contact may become stuck due to the arc and may not come out of the fixed contact. Cannot be released.

Therefore, the problem is how to have an electrical structure and to surely open the main circuit when a short circuit occurs.

(Means for Solving Problems) The present invention has been made in view of the above point, and in a cabinet with a built-in switch, a substantially cylindrical body is formed by a plurality of contact pieces. In the electric contact provided in the main circuit, the two contacts inserted from the openings at both ends are pressed by a spring arranged in the substantially central portion of the outer periphery of the contact piece, and in the center inner surface of each of the above-mentioned contact pieces, Providing a protrusion in contact with the outer periphery of one contact, the outer periphery of one contact due to the high temperature due to a short-circuit accident that occurred in the cabinet on the outer periphery of the end of the above-mentioned protrusion near the opening on one contact side of each of these contact pieces. A ring-shaped shape memory alloy that contracts toward each other is provided, and by the above-mentioned contraction, each contact piece rotates about the above-mentioned protrusion as a fulcrum, and the other contact and each contact piece are separated from each other. Contact piece and shape memory alloy The present invention aims to solve the problem by providing an automatic main circuit disconnecting device characterized by being configured.

(Operation) When an arc or the like occurs due to a short-circuit accident in the cabinet, the high temperature generated at that time causes the shape memory alloy to contract. By this contraction, the contact pieces contract to the outer circumference of one of the contacts, and each contact piece rotates around the protrusion of each contact piece as a fulcrum, and the contact of each contact piece to the other contact side is released.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.
As shown in FIG. 2 and FIG. 2, it is applied between the contact 3 of the power supply terminal 2 for control and the contact 4 of the main circuit in the cabinet 1 of the switch. A protrusion 6 is provided on the center inner surface of each of the contact pieces 5 formed into a substantially cylindrical body that is inserted, and the contact piece 5 is biased from the outside by a coil spring 7.

First, each contact piece 5 for electrically connecting the contacts 3 and 4 has a structure as if a substantially cylindrical body is divided into four in the axial direction, but each contact piece 5 in this embodiment has a projection 6 on the inner surface of the center, and A protrusion 8 is provided between the protrusion 6 and the tapered portion on the contact 4 side.

Then, each contact piece 5 having such a structure is made into a substantially cylindrical body, and the contacts 3 and 4 are inserted from both ends thereof. At this time, a spacer 9 having a collar body 9a is inserted inside the substantially cylindrical body. That is, the projection 6 on the inner surface of each contact piece 5 is applied to the lower side of the collar body 9a, and the spacer 9 is sandwiched by the projection 6.

On the other hand, the projection 8 is applied to the stepped portion formed on the contact 4 to sandwich the stepped portion. The coil spring 7 for pressurizing the contact piece 5 is formed in a ring shape and fitted on the outer side of the protrusion 6 of the contact piece 5.

As the shape memory alloy 10 in this embodiment, a shape similar to that of the coil spring 7 is used, which is near the opening on the contact 4 side and closer to the base of the contact 4 than the protrusion 8. It is fitted on the outer circumference of the contact piece 5.

Now, when the movable contact 12 is inserted into the fixed contact 11 at the main contact and the main circuit is closed via the conductor 14 to the bushing 13 communicating with the busbar, the inside of the cabinet 1 is closed. When a short circuit accident occurs in the main circuit of, the shape memory alloy 10 contracts toward the center of the contact 4 due to the high temperature generated at that time, but at this time, the protrusion 8 just serves as a fulcrum in the lever, and the shape memory alloy Assuming that the portion 10 is the force point and the end of the contact piece 5 in pressure contact with the contact 3 is the point of action, the end of the second end resists the pressure of the coil spring 7 due to the contraction of the shape memory alloy 10. A large opening is made in the direction of arrow A in the figure, and the pressure contact with the contact 3 is opened, and as a result, the main circuit is opened.

When the protrusion 8 of each contact piece 5 is a fulcrum, all the portions above it (the portion on the contact 3 side) are open, so the spacer 9 is sandwiched below the collar body 9a. 6 also releases the pinch. as a result,
The spacer 9 falls in the direction of arrow B in the figure, and this time the collar body
The outer periphery of 9a is pinched by the protrusion 6. The protrusion 6 is a collar body
By sandwiching 9a, the open state of the end of the contact piece 5 on the side of the contact 3 is maintained as it is, regardless of the contraction of the shape memory alloy 10.

Although the spacer 9 is provided in the above embodiment, the spacer 9 is not an essential requirement of the present invention. Similarly, the protrusion 6 is not an indispensable requirement. One end of each contact piece 5 contacts the contact point 3 and the protrusion 8 contacts the contact point 4 and the coil spring 7 is provided on the outer periphery of each contact piece 5 in the middle of these contact points. Is provided
The contact pieces 5 may be pressed against the contacts 3 and 4 by the coil spring 7.

(Effect of the Invention) According to the present invention, when a short circuit accident due to an arc or the like occurs in a cabinet with a built-in switch, the main circuit of the switch is open regardless of whether the main contact is open or closed. Can be opened, and re-short circuit can be reliably prevented.
Therefore, power can be immediately supplied from another power source, and so-called two-line butting can be temporarily used.

In addition, it is the ring-shaped shape memory alloy that is responsible for disconnecting the main circuit contacts and that is sensitive to abnormally high temperatures in the cabinet, without electrical circuits or equipment, and may malfunction or malfunction due to overcurrent. It does not occur and is highly reliable.

Moreover, in terms of the overall structure, it is possible to realize with simple technology by making a slight modification to the so-called tulip-type contact that is commonly used in the past and attaching a shape memory alloy. Is.

Moreover, even if the deformation operation of the shape memory alloy is small, the electric circuit is surely opened by the lever principle.

Although it is used inside the cabinet, it has almost the same structure and size as the tulip type contact used in the past as described above, so the space it occupies does not pose any problem and the structure of the cabinet It has no practical effect, and the practical effect of this invention is high.

[Brief description of drawings]

FIG. 1 is a partial front sectional view of a switch cabinet using the first embodiment, FIG. 2 is an enlarged sectional view of an essential part of the cabinet, and FIG. 3 is an explanatory view showing a relationship between a main circuit and a power supply. is there. In the figure, 1 is a switch cabinet, 3 and 4 are contacts, 5 are contact pieces, 6 and 8 are protrusions, 7 is a coil spring, 9 is a spacer, and 10 is a shape memory alloy.

Claims (1)

[Scope of utility model registration request] In a cabinet with a built-in switch, a plurality of contact pieces form a substantially tubular body, and two contacts inserted from openings of both ends of the tubular body are arranged at a substantially central portion of the outer periphery of the contact piece. In the electric contact provided in the main circuit, which is pressed by the spring, a protrusion is provided on the center inner surface of each of the above-mentioned contact pieces so as to contact the outer periphery of one of the contact pieces, and one contact side of each of these contact pieces A ring-shaped shape memory alloy that contracts toward the outer circumference of one contact due to the high temperature due to a short-circuit accident that occurred in the cabinet is provided on the outer periphery of the end near the opening of the The main circuit automatic disconnecting device characterized in that the contact piece is configured to rotate so that the other contact point and each contact piece are separated from each other by rotating around the above-mentioned protrusion as a fulcrum. .