JPS6324309B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to connections in electrical circuits such as busbars, electrical wires used for trunk lines, bare conductors, or bus ducts that transmit relatively large amounts of power, and particularly relates to connections in electrical circuits such as busbars, trunk lines, bare conductors, or bus ducts that transmit relatively large amounts of power. The present invention relates to a connection part that makes it possible to detect abnormal heat generation due to Joule heat.

In electrical connections such as electric wires, bare conductors, or bus ducts, where electrical connections are made using the tightening force of bolts, insufficient tightening or loosening of the bolts can increase contact resistance and cause Joule heat. Needless to say, this Joule heat is harmful to electrical continuity between conductors.

Conventionally, in order to detect such harmful heat generation as soon as possible and prevent burnouts and power outage accidents, the color changes when a certain temperature is reached, and this color change allows supervisors to detect abnormal heating conditions. There are some that use temperature-indicating materials. Such temperature-indicating materials have been widely used in the past because they can be provided to connecting parts by simple means such as coating them as paint or pasting them as labels.

However, thermochemical materials change color due to thermochemical reactions, so during long-term use, they may not change color even if a certain temperature is reached, or conversely, they may change color even before a certain temperature is reached. In addition, when installed on electrical circuits installed outdoors, they often deteriorate due to the effects of ultraviolet rays, etc., which not only prevents the intended purpose from being achieved, but also causes problems that may cause unnecessary concern. Ta.

The present invention utilizes shape recovery, that is, return to its original shape, of a metal having a shape memory effect at a transformation temperature to allow a supervisor to visually observe an abnormal heat generation state, thereby solving the above-mentioned problems. The purpose is to provide a functional electrical circuit connection.

The above-mentioned metals with shape memory effect have the common property that they undergo thermoelastic martensitic phase transformation, and that the phase on the high temperature side of this phase transformation is an ordered lattice, and the metals have a temperature lower than the transformation temperature. When a metal that has been deformed by temperature is heated above the transformation temperature, it returns to its original shape from the deformed state.

Metals with this shape memory effect are, for example, Ti
-Ni alloy, Au-Cd alloy, and Cu-Zn-Al alloy are known. It is also known that the transformation temperature can be set to various values by changing the alloy composition. Therefore, if such a transformation is set at a temperature close to the temperature caused by the harmful heat generated in the electrical connection, the shape can be restored by the abnormal heat generation.

The present invention utilizes such a metal having a shape memory effect, and its gist is that a metal member having a shape memory effect is placed in the vicinity of or in a case covering an electrical conductor connected by bolting or the like. One end of the metal member is fixed, and a danger sign is placed on the other end of the metal member so that it cannot be seen from the monitoring side by deformation of the metal member, and the danger sign is displayed when the metal member returns to its shape at the transformation temperature. A connection part of an electrical circuit having an abnormal heat generation detection function is characterized in that the indicator is configured to be exposed to the monitoring side.

This will be explained below with reference to the drawings.

FIGS. 1 and 2 show the connecting portion of the flat conductors 1, 1', and since these are normally installed at a high place, monitoring is performed by looking upward from the bottom. Then, the ends of conductors 1 and 1' are overlapped,
The bolts 2, 2, 2, 2 pass through this overlapping part and are connected by tightening with nuts 3, 3, 3, 3, and on the overlapping part of one conductor 1,
Metal member 4 made into a rod shape and having a shape memory effect
One end of the metal member 4 is fixed with a holding fitting 5 or the like, and a display plate 6 is attached to the other end of the metal member 4.

The display board 6 has a red display on the bottom surface and a blue display on the top surface without deforming the metal member 4, and as shown in FIG.
The cable is twisted 180 degrees and installed with the red display 7 of the display board 6 facing upward.

Fig. 2 shows an abnormal heat generation state in which the metal member 4, which continues to be heated by the Joule heat generated in the overlapped portion, has been twisted by 180 degrees (Fig. 1).
However, when it is heated to a temperature higher than the transformation temperature, it tries to return to its original shape and rotates 180 degrees in the opposite direction.As a result, the display board 6 is reversed. The blue display 8 indicating normality, which was displayed on the side), is now exposed on the upper side, and the red display 7 indicating danger is exposed on the lower side, that is, on the monitoring side, thereby informing the supervisor of abnormal heating conditions.

3 and 4 show a plurality of flat conductors 11, 11, 11 as described above in a metal case 12.
This figure shows a bus duct housed inside the bus duct, and in this case, monitoring is performed by looking upward from the bottom of the bus duct, as described above. However, the conductor 11,1
On the upper surface of the connection cover 13 that covers the bolted connections of 1 and 11 and connects the case 12, one end of a flat metal member 14 having a shape memory effect is fixed with a presser metal fitting 15. As shown in FIG. 3, the other end of the metal member 14 is bent 180 degrees inward so as not to protrude from the side of the cover 13, and a red symbol indicating danger is displayed on the upper surface of the bent opening side. 16 and install it. Figure 4 illustrates a situation where abnormal heat generation occurs at the connection part of conductors 11, 11, 11.
The cover 13 heated by the radiant heat also heats the metal member 14, and the metal member 14, which has been heated above the transformation temperature, is bent 180 degrees in an attempt to return to its original shape. As the metal member 14 reverses and returns to its shape, the tip of the metal member 14 extends and protrudes to the side of the cover 13, and the red display 16 is exposed on the lower side, thereby notifying the supervisor of the abnormal heating state. ing.

As is clear from the above explanation, the connection part of the electric circuit according to the present invention uses a metal having a shape memory effect that causes a change in the state of the metallographic structure, that is, a return to its original shape at a transformation temperature, to provide a danger sign. Since the system is operated using the same technology, its characteristics do not change over time, and even if abnormal heat generation occurs during long-term use, it operates extremely accurately and reliably indicates danger, thereby preventing accidents from occurring. It has become something that can be prevented.

Prior to the present invention, we investigated the use of so-called bimetals, which are made by laminating metals with different thermal expansions, as thermally responsive elements for danger signs. This made it difficult to ensure accurate danger markings. In contrast, the present invention uses a metal that has a shape memory effect that causes a sudden change in shape when it reaches a predetermined temperature, so it is possible to clearly distinguish and display the normal temperature state and the abnormal heat generation temperature state. Since the metal does not require delicate adjustments and can be produced in large quantities, it can be applied as an inexpensive temperature sensing mechanism, and provides a highly reliable connection for this type of electrical circuit.

In addition, in the present invention, the metal member having a shape memory effect used in the present invention returns to its original shape by heating the deformed member above the transformation temperature, but no further change in shape occurs. There are directional types and bidirectional types, which repeat deformation and shape recovery after reaching the transformation temperature, and both can be used. In addition to the above-mentioned coloring, danger markings on metal parts may include text such as "normal" or "normal".
Means such as "safety", "danger", and "caution" may be adopted.

Furthermore, in addition to the above-mentioned twisting and bending, means such as tension and compression can also be applied to deform the metal member so that the danger sign is hidden from view from the monitoring side in preparation for abnormal heat generation, and these methods alone can also be applied. A plurality of deformation means may be combined.

Furthermore, the electric circuit to which the present invention is applied can also be applied to electric wires other than those described in the embodiments described above, such as those in which the terminals and intermediate connections of the electric wires are housed in a joint box. In addition to bolt tightening, the connection part itself can also be applied to electrical connections that utilize the elastic force of clips, which tend to generate joule heat due to increased contact resistance.

[Brief explanation of the drawing]

Figures 1 and 2 show an example of the connecting part of the electric circuit according to the present invention. Figure 1 is a perspective view showing the connecting part before abnormal heat generation occurs, and Figure 2 shows a situation where abnormal heat generation occurs. FIG. Third
Figures 4 and 4 show other embodiments of the connection section of the electric circuit according to the present invention, and FIG. 3 is a perspective view showing the connection section before abnormal heat generation occurs, and FIG. 4 shows the connection section in a situation where abnormal heat generation occurs. FIG. 1, 1', 11: flat conductor, 4, 14: metal member having shape memory effect, 7, 16: danger sign, 12: case, 13: case connection cover.

Claims (1)

[Claims] 1. Fixing one end of a metal member with a shape memory effect to a case that covers or near the electrical conductor connected by bolting, etc.
A danger mark is placed on the other end of the metal member so that it cannot be seen from the monitoring side due to the deformation of the metal member, and the danger mark is exposed to the monitoring side when the metal member returns to its shape at the transformation temperature. What is claimed is: 1. A connection part of an electric circuit having an abnormal heat generation detection function, characterized in that the connection part is configured as follows.