JPS6077329A - Current limiting breaker - Google Patents

Abstract

(57) [Abstract] 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 current limiting circuit breaker in which a shape memory alloy whose movable side electrode is curved so as to generate an electric repulsion blade is connected thereto.

Conventional devices of this type include a line protection switch that responds to overcurrent using a shape memory alloy (hereinafter referred to as rSMEJ) shown in Fig.
No. 831).

In the figure, numeral 1 is an SME whose shape can be reversibly changed by temperature changes that occur at the martensitic transformation temperature, 2 is a contact, and 3 is an insulator.

Under normal current conditions, the contacts 2 are in contact with each other with a constant contact pressure as shown in Figure 1, allowing the current to flow.Here, when an overload current or short-circuit current
When flowing through SMEl, its temperature increases due to its own resistivity, and when it exceeds the martensitic temperature, the second
As shown in the figure, S M and E 1 are deformed and the contacts 2 are opened.

Furthermore, since the currents flowing through the left and right SMELs are in opposite directions, the repulsive force of the currents facilitates the opening of the contacts 2. This repulsive force is particularly strong at the end of a short-circuit current.

Therefore, the insulator 3 is placed at rC, as shown in FIG. 1, for insulation between the electrodes.

By the way, there is a problem when using SMEI as a compression plate to provide contact pressure as shown in Figure 1 - especially N, -T, and Cu alloy-based S in alloy-based SME.
Compared to ME, the force is weak in the low temperature region below the M3 point of the martensitic l-transformation initiation warm reaction, and in the high temperature region above the Af point plate, which is the temperature at which the martenzite structure disappears, conversely, it has a thicker can. Therefore, in the state shown in FIG. 1, the contact resistance of the contact portion 2 is large, and the SMEI operates due to the heat generated.

The present invention has been devised to overcome the drawbacks of the conventional devices, and its purpose is to increase the contact pressure and to increase the opening speed, especially at the time of short circuit current. It is an object of the present invention to provide a current limiting circuit breaker equipped with a thermal element made of a shape memory alloy that achieves two points.

The present invention will be specifically explained below.

FIG. 3 is a perspective view of one embodiment of the present invention.

The same reference numerals indicate the same or corresponding parts in all drawings.

Reference numeral 11 is a movable side electrode made of steel (Fe-C) and two parallel conductors, which are bent halfway into a semi-elliptical shape as shown in Figure 3. is the fixed electrode.

13 consists of a filamentous SME, and - all ends are the movable side electrode 11
A movable electrode 14 is attached to one end, and two movable electrodes 11σ) are connected to the central movable electrode 11.
It is isolated and traced. Note that 15 (- is a fixed electrode connected to the surface-determining side electrode 12.

The operation will now be explained. In the case of a steady current, the contact pressure of both the fixed electrode 15 and the movable electrode 140 is connected to the S M E 13 of the movable electrode 11. The elastic force is given by the elastic force of K near the U-shape (the part surrounded by the dotted line), and this elastic force is generally [σ larger than the elastic force of S M E]
So, the weak contact pressure in conventional means should be improved.

Next, when an overload current or short circuit current flows, S M
When the temperature of E 13 rises and exceeds the martensitic transformation temperature, as shown in Figure 4, S]\j E 13&'! 9
shape [to do]

In order to stop the short-circuit current, the movable electrode 11 and the SME
Electrode repulsive force is generated due to the formation of current paths that alternately flow in opposite directions between I3, which promotes the separation of both the fixed electrode 15 and the movable electrode 140, and causes the two contacts to separate at high speed. It will be done.

In addition, since the movable electrode 11 is a rigid body, that is, it is fixed, it is installed so that even if a short circuit current flows and an attractive force is generated between the two movable electrodes 11, there is no problem. . The two movable electrodes 11 are attracted to each other by attractive force,
Since the SME 13 will not be able to move if they are joined, this is prevented.

Note that the other end of the movable IIQ electrodes 11 combined into one and the other end of the fixed side electrode 12 (not shown) are each connected to a power terminal of a current limiting circuit breaker.

FIG. 5 is a perspective view of another embodiment of the invention.

This implementation consists of the movable side' electrode 11 and the S M E 1
3 can be said to be integrally formed by SMB.

Another embodiment of the present invention is shown in FIG.

In this embodiment, the SME 13 is formed of two parallel conductors, and the front side' electrode 11 passes between them.

The operations of these embodiments are similar to the embodiment shown in FIGS. 3 and 4 of Sagi.

Thus, according to the present invention, the overload current is caused by the deformation of the SME, and the short-circuit current is caused by the deformation of the SME and the repulsive force between the opposing parts of the U-shaped filament, which opens the contact, so that the opening speed increases. , and normal 1fft'! In some cases, the elasticity based on the U-shaped filament provides an ideal current-limiting cutoff that provides sufficient closing contact pressure at the contact point.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams of the conventional device when the electrodes are closed and opened, FIG. 3 is a perspective view of an embodiment of the present invention when the electrodes are closed, and FIG. 4 is an illustration of the electrodes when the electrodes are opened. Fig. 5 is a perspective view of the pond saw implementation 1+11 of the present invention when the pole is closed, and Fig. 6 is a perspective view of another embodiment of the invention when the pole is closed. be. ■, 13...Shape memory alloy (SME) 2...Contact 3...Insulator 11...Movable side electrode 12...Fixed side electrode 14...Movable electrode 15...Fixed 'electrode 1' , Applicant's agent Seihaku Inomata, Figure 1, House, 6

Claims (1)

[Claims] 1. A fixed electrode and a movable electrode are provided, and a linear shape memory alloy and a movable side electrode are connected in series to the movable electrode to form a U-shaped part in which current flows in opposite directions. When a current flows and the shape memory alloy exceeds the martensitic I-state starting temperature, the fixed electrode and the movable electrode are separated by the deformation of the shape memory alloy and the electrode repulsion force generated in the U-shaped portion. A current limiting circuit breaker characterized by being designed to open.