JPH04359609A - Abnormal heating detector for electric cable - Google Patents

Abstract

PURPOSE:To provide an abnormal heating detector for an electric cable, which can detect the abnormal temperature rise of an electric cable and continuously indicate the history of this abnormal heating. CONSTITUTION:If abnormal heating of an electric cable 1 occurs, a pin consisting of shape memory alloy is heated and recovers to the memorized linear shape instantaneously. Thereupon, the connection of a metal fitting 3 is released, and since the biasing force of recovering rectilinearly is exerted on an indicator 2, a pin 4 is drawn out of the hole of a metal fitting 3 and comes off the electric cable 1 of the indicator 2. In this case, the indicator 2 is detained in the vicinity of the electric cable 1 since it is coupled to the electric cable 1 by a proper retaining means.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an abnormal heat generation detection device for electric cables that detects and indicates abnormal heat generation when an electric cable such as an insulated wire or a power cable that has an insulation coating generates abnormal heat. The present invention relates to an abnormal heat generation detection device for electric cables that uses an electric cable to perform an indicating operation in the event of abnormal heat generation.

0002

2. Description of the Related Art Electrical cables coated with insulation have a permissible temperature set depending on the type of electrical insulation material, and are used within this permissible temperature range.

Conventionally, when inspecting whether abnormal heat generation or overheating exceeding an allowable temperature has occurred in such an electric cable, the temperature of the electric cable is measured and it is determined whether the measured temperature is within the above-mentioned allowable temperature range. We are investigating whether The temperature of the electric cable is measured by applying a thermometer or a temperature sensor of a temperature measuring instrument to the surface of the electric insulating material covering the electric cable.

0004

[Problem to be Solved by the Invention] However, since the current flowing through an electric cable varies significantly depending on the load condition, it is rare that the surface temperature of the electric insulating material (cable temperature) is at its highest temperature at the time of measurement. be. For this reason, there is a problem in that even if the electric cable has experienced an abnormal heat generation temperature exceeding the allowable temperature in the past, it cannot be confirmed during measurement. That is,
Although it is necessary to understand the thermal history of abnormal heat generation or overheating exceeding the allowable temperature in electric cables, conventional technology cannot detect this.

[0005] The present invention has been made in view of the above problems, and is a method for detecting an abnormal temperature rise in an electric cable, which can reliably detect an abnormal temperature rise in the electric cable and continuously display the history of abnormal heat generation. The purpose is to provide a fever detection device.

[0006]

[Means for Solving the Problems] An abnormal heat generation detection device for an electric cable according to the present invention includes a marking member that can be elastically deformed to surround the electric cable, and a marking member that can surround the electric cable at a normal temperature. a shape memory alloy member that assumes a first position in which the abutting ends are locked in order to hold the indicator member in the state, and a shape memory alloy member that assumes a second position in which the butt ends are released from the lock due to heat generated during abnormal heat generation; and a holding means for connecting and holding the indicating member to the electric cable.

[0007]

[Operation] In the present invention, the shape memory alloy member maintains the first posture in which it locks the abutting end of the indicator member under the normal temperature of the abnormal heat generation detection device. As a result, the indicator member is elastically deformed and fixed in a state surrounding the electric cable. On the other hand, when abnormal heat generation occurs in the electric cable, the heat is transferred to the shape memory alloy, and the shape memory alloy member returns to the second position in which the butt end of the indicator member is released from the lock. . Then, the indicator member is released from being surrounded by the electric cable and deforms due to its elastic force. Therefore, the occurrence of abnormal heat generation in the electric cable is clearly indicated by the deformation of the indicator member, and this can be easily confirmed by visual inspection or the like. Further, since the indicator member is connected to the electric cable by a suitable holding means, it is held at a position near the electric cable.

Therefore, according to the present invention, abnormal heat generation in an electric cable can be detected and the history of abnormal heat generation can be continuously displayed even after a period of time has passed since the detection. For this reason,
The presence or absence of abnormal heat generation in electric cables can be investigated at any time. In addition, the shape memory alloy member only needs to be able to maintain the state in which the indicator member surrounds the electric cable, and it can be made into a small structure such as a pin, so its heat capacity can be made extremely small. can do. Therefore, even in the event of a small-scale abnormal heat generation in which the temperature rise of the electric cable is relatively low or the temperature rise time is relatively short, the pins will restore to their memorized shape, so such small-scale abnormal heat generation is reliable. can be detected. Furthermore, since the device of the present invention utilizes the heat generated by the electric cable, it does not require a special energy source to heat the shape memory alloy member, and as described above, the device is simple in structure, so it can be used with pins, etc. It can be used repeatedly by reattaching the shape memory alloy member,
It is also easy to apply to existing electric cables.

[0009] In the present invention, the holding means for the indicating member includes a fixing member attached to the electric cable, and a flexible filament or an elastic member that interconnects the fixing member and the indicating member. It is preferable to configure the following. The flexible filament has appropriate flexibility. For this reason,
When the holding means is constituted by the fixing member and the flexible filament, the marking member that is no longer surrounded by the electric cable is held in a state where it hangs below the electric cable due to its own weight; There will be a clear indication that there has been an abnormal fever. Meanwhile, the elastic member is installed so that the indicator member is urged away from the electric cable. Thereby, the indicator member that has been released from the state of surrounding the electric cable can be moved away from the electric cable in any direction outside the electric cable. That is, by arranging the elastic member at an appropriate position on the outer circumference of the electric cable, the indicating member can be moved upward, downward, to the left, or to the right from the outer circumference of the electric cable, regardless of the direction of gravity. They can be spaced apart in any direction, such as a direction. Therefore, in this case, depending on the position of the electric cable to which the device of the present invention is attached, the indicator member can be kept at a position where it can be easily confirmed, and the indication that abnormal heat generation has occurred becomes even clearer.

0010

Embodiments Next, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an abnormal heat generation detection device for an electric cable according to a first embodiment of the present invention. In addition,
The device of this embodiment is provided around an electric cable (insulated power cable) 1, and this electric cable 1 has a conductor 1b.
, an outer sheath 1a that insulates the conductor 1b, and a conductor 1b.
and a spacer 1c interposed between the outer cover 1a and the outer cover 1a.

As shown in FIG. 1, the sign body 2 made of a coil spring or the like having elastic force has a linear shape (indicated by a broken line in the figure) when no external force is applied. A pair of metal fittings 3 for connection are attached to both ends of the sign body 2, and the metal fittings 3 are provided with holes (not shown) that are connected when the pair is formed.

The pin 4 made of shape memory alloy has a linear shape (indicated by a broken line in the figure) memorized, and when the temperature reaches a predetermined transformation temperature or higher, the memorized shape is restored. . This pin 5 is attached to the sign body 2 in the following manner. First, the sign body 2 is wound around the electric cable 1 against its elastic force. At this time,
The metal fittings 3 are butted together so that the holes are connected. After inserting the straight pin 4 into the connecting holes of the pair of metal fittings 3, both end portions protruding from the metal fittings 3 are bent in a direction perpendicular to the two ends. As a result, the pair of metal fittings 3 are connected to each other via the pin 4, and the sign body 2 is locked so as to surround the electric cable 1. Note that the sign body 2 and the electric cable 1 are connected to each other by appropriate holding means (not shown).

In the abnormal heat generation detection device for an electric cable constructed as described above, when abnormal heat generation occurs in the electric cable 1, the surface temperature of the jacket 1a rises and the pin 4 is heated. When the temperature of the pin 4 reaches or exceeds the transformation temperature of the shape memory alloy constituting it due to this heat, the pin 4
instantaneously restores its memory shape, that is, the linear shape shown by the broken line in FIG. Then, the connection of the metal fitting 3 is released, and since a biasing force is acting on the sign body 2 to restore it to a straight line, the pin 4 comes out of the hole of the metal fitting 3, and the electric cable of the sign body 2 is removed. The state of encirclement is released. In this case, the sign body 2 is connected to the electric cable 1 by a suitable holding means, so that it is held near the electric cable 1.

Therefore, according to this embodiment, since the state in which the sign body 2 surrounds the electric cable is released and returns to a straight line, abnormal heat generation in the electric cable 1 can be detected by the shape of the sign body 2, and this can be detected. This can be confirmed visually. In addition, even if time passes after abnormal fever is detected,
Since the state of the indicator 2 does not change and the history of abnormal heat generation can be continuously displayed, the presence or absence of abnormal heat generation in the electric cable 1 can be easily investigated at any time. Furthermore, since the pin 4 made of shape memory alloy can be relatively small, its heat capacity is small. Therefore, even if the rise in the surface temperature of the electric cable 1 is relatively small or the temperature rise time is relatively short, the heat is easily transmitted to the entire pin 4, so even if the scale of abnormal heat generation is small, it can be reliably Can be detected.

FIG. 2 is a side view showing an abnormal heat generation detection device for an electric cable according to a second embodiment of the present invention, and FIG. 3 is a sectional view taken along line A--A in FIG. 2. In FIGS. 2 and 3, the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed explanations of those parts will be omitted. Further, it is assumed that the electric cable 1 is laid horizontally.

The fixture 6 is attached around the electric cable 1 so as to wrap around the electric cable 1 from below. The fixture 6 includes a clamp member 6a that is wrapped around the electric cable 1, and a fastening member 6b that fixes the clamp member 6a around the electric cable 1. The flexible filament 7 interconnects the approximate center of the fixture 6 and the approximate center of the sign 2. The flexible filament 7 has a predetermined length and can be made of a flexible material such as a braided wire, chain, or string. Thus, the sign body 2 is held near the electric cable 1 by the holding means 5 consisting of the fixture 6 and the flexible filament 7, and surrounds the electric cable 1 from below.

In this embodiment, when the surrounding state of the sign body 2 is released due to abnormal heat generation of the electric cable 1, the sign body 2 tries to fall below the electric cable 1 due to its own weight. Falling is prevented by the fixture 6 and the flexible strands 7. For this reason, the sign body 2 is
And as shown by the broken line in FIG. 3, it is held in a hanging state below the fixture 6. Thereby, the occurrence of abnormal heat generation in the electric cable 1 is indicated, and this indication can be easily confirmed at any time. In addition, since the sign body 2 can be surrounded again around the electric cable 1,
Can be used repeatedly.

FIG. 4 is a side view showing an abnormal heat generation detection device for electric cables according to a third embodiment of the present invention, and FIG.
6 is a side view showing an abnormal heat generation detection device for an electric cable according to the fourth embodiment of the present invention, and FIG. 7 is a sectional view taken along line -B.
is a sectional view taken along the line CC. Note that in FIGS. 4 to 7, the same parts as in FIGS. 1 to 3 are denoted by the same reference numerals, and detailed explanations of those parts will be omitted.

First, as shown in FIGS. 4 and 5, in the third embodiment, the fixture 6 is attached around the electric cable 1 so as to hold the circumferential surface of the electric cable 1 from above. . The elastic member 8 interconnects the approximate center of the fixture 6 and the approximate center of the sign 2. This elastic member 8 has an appropriate elastic force, and urges the sign body 2 in a direction away from the electric cable 1. In this way, the holding means 5 for the sign 2 is constituted by the attachment 6 and the elastic member 8. In this case, the sign body 2 is wrapped around the electric cable 1 from above the electric cable 1 and the sign body 2 is wrapped around the electric cable 1 from above.
When the shape memory alloy pins 4 are inserted and locked into the metal fittings 3 at both ends of the sign body 2, the sign body 2 surrounds the electric cable 1, and the elastic member 8 is brought into close contact with the electric cable 1. It is arranged like this. And electric cable 1
When the pin 4 is restored to a straight line due to abnormal heat generation and the surrounding state of the sign body 2 is released, the sign body 2 is moved by the urging force of the elastic member 8 as shown by the broken line in FIGS. 4 and 5. like,
It is held in a state in which it is sprung up above the electric cable 1. Furthermore, according to this embodiment, by arranging the elastic member 8 at any position in the outer circumferential direction of the electric cable 1, the direction in which the sign bodies 2 are separated can be set regardless of the direction in which gravity acts. .

On the other hand, as shown in FIGS. 6 and 7, in the fourth embodiment, the holding means 5 of the sign 2 is attached to a mounting tool 6.
and a connecting member 9. This connecting member 9
is arranged above the electric cable 1 so as to connect the approximate center of the fixture 6 and the approximate center of the sign body 2 to each other and to be in close contact with the electric cable 1. Furthermore, unlike the elastic member 8, the connecting member 9 does not have elastic force, so it will not deform even if the state of enclosing the sign body 2 is released. Therefore, the sign body 2, which is no longer surrounded by the electric cable 1, is held in contact with the upper part of the electric cable 1, as shown by broken lines in FIGS. 6 and 7.

As described above, in the present invention, the indicator member (indicator body 2) released from the surrounding state is not limited to one that is separated from the electric cable.

FIG. 8 is a schematic diagram showing the device of this embodiment actually attached to an electric cable (insulated power cable). Electrical cables 1 launched from a plurality of cable heads 10 are converged at portions spaced from the cable heads 10 by appropriate lengths. Then, at the rising part 11 between the convergence part and the cable head 10, the holding means 5 is appropriately attached around the electric cable 1 to surround the sign body 2. In this case, it is preferable to use the apparatuses of the above embodiments depending on the installation direction of the electric cable 1, ease of inspection, etc.

[0024]

As explained above, according to the present invention, by locking the abutting ends of the elastic indicator member with the shape memory alloy member, the indicator member is held in a state surrounding the electric cable. However, since the shape memory alloy member is transformed using the heat generated when the electric cable generates abnormal heat to release the surrounding state of the indicator member, abnormal heat generation of the electric cable can be detected based on the state of the indicator member. can. In this case, the shape memory alloy member can have a small structure and its heat capacity can be reduced, so even small-scale abnormal heat generation can be reliably detected. Further, since the indicator member is held near the electric cable by a suitable holding means, the history of abnormal heat generation can be continuously displayed, and this can be easily investigated at any time.

The device of the present invention does not require a special energy source and has a simple structure, so it can be easily applied to existing electric cables and has the advantage of being able to be used repeatedly. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an abnormal heat generation detection device for an electric cable according to a first embodiment of the present invention.

FIG. 2 is a side view showing an abnormal heat generation detection device for an electric cable according to a second embodiment of the present invention.

FIG. 3 is a sectional view taken along line AA in FIG. 2;

FIG. 4 is a side view showing an abnormal heat generation detection device for an electric cable according to a third embodiment of the present invention.

FIG. 5 is a sectional view taken along line BB in FIG. 4;

FIG. 6 is a side view showing an abnormal heat generation detection device for an electric cable according to a fourth embodiment of the present invention.

FIG. 7 is a sectional view taken along line CC in FIG. 6;

FIG. 8 is a schematic diagram showing a case where the device of this embodiment is actually attached to an electric cable.

[Explanation of symbols]

1; Electric cable 1a; Outer covering 1b; conductor 1c; Spacer 2; Sign body 3; Metal fittings 4; pin 5; Holding means 6; Attachment 6a; Clamp member 6b; Fastening member 7; flexible striatum 8; Elastic member 9; Connecting member 10; Cable head 11; Start-up part

Claims (3)

[Claims] 1. A marking member capable of elastically deforming to surround an electric cable, and abutting ends thereof are locked to hold the marking member in a state surrounding the electric cable at normal temperatures. a shape memory alloy member that takes a first attitude and takes a second attitude that releases the locking of the abutting end due to heat generated when abnormal heat generation occurs; and a holding means that connects and holds the indicator member to the electric cable. A device for detecting abnormal heat generation in electric cables. 2. The electric cable according to claim 1, wherein the holding means includes a fixing member attached to the electric cable, and a flexible filament that interconnects the fixing member and the indicating member. Abnormal heat generation detection device for electric cables as described. 3. The holding means includes a fixing member attached to the electric cable, and an elastic member that interconnects the fixing member and the indicating member and urges the indicating member away from the electric cable. The abnormal heat generation detection device for an electric cable according to claim 1, further comprising a heat generating member.