JPS6017826A - Sealed line breaking device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an encapsulated line breaker, and particularly to an encapsulated line breaker that can be used repeatedly while maintaining high reliability.

[Prior art]

An example of a conventional line breaking device used in communication terminals is shown in Fig. 1 and explained below.
', 2' are communication lines, 3 is a protection device which is a subscriber protection device connected to this communication line 1.2, and this protection device 3 is discharged when an overvoltage is applied to communication fuses 4, 5. It is composed of a lightning arrester 6. Reference numeral 7 denotes a communication device which is a terminal device connected from this security device 3 via communication lines 1' and 2';
The overvoltage operating element Q-IJ-z, which is a constant voltage operating element connected to ', which becomes conductive when an overvoltage is applied, the communication circuit 9, the overvoltage operating elements B-3, 9-4, and the commercial power line disconnection device. It is constituted by power supply fuses 10.11. An overvoltage operating element 8-1.8-20 connected in series between the communication line 10.2' and an overvoltage operating element 8-3.8-4 connected in series between the tangential point and the power fuse 10.11. The connection points are interconnected. In addition, this terminal device has a power line 12 which is a commercial power supply line.
It is connected to a pole transformer 14 via 13. Note that N E1 + E2 indicates the earth, and RE 1 + RE 2
indicates ground resistance.

In the line breaking device configured in this way, when high voltage is applied to the communication lines 1 and 2 due to contact with a high-voltage power line, lightning surge, etc., the lightning arrester 6 is activated and the current is diverted to the ground E.
Discharge into l. At this time, when an overcurrent flows, the communication fuses 4 and 5 are blown, disconnecting the communication lines 1 and 2 from the communication device 7.

Further, when an overcurrent flows to the ground E1 due to the operation of the lightning arrester 6, if there is a grounding resistor REI, the potential of the communication line may not drop sufficiently due to this voltage drop. In this case, a branch of the surge current flows to the ground E2 of the pole transformer 14 via the overvoltage operating element 8-b8-2+8-3.8-4 and the power fuse 10.11, as shown by the two-dot chain line. Sometimes. Therefore, the power supply fuses 10 and 11 may blow out before the communication fuses 4 and 5. On the other hand, when overcurrent enters from the power supply line, each fuse blows in the opposite direction.

However, conventional line disconnection devices using fuses, such as and, have the disadvantage that once the fuse is blown, it must be replaced.

In particular, lightning surges occur frequently and many communication devices are affected at once, making maintenance complicated.

[Object and structure of the invention]

In view of the above points, the present invention was made to solve such problems and eliminate such drawbacks, and its purpose is to be able to be used repeatedly while maintaining high reliability and safety, and to It is an object of the present invention to provide an enclosed type line breaking device that can make the safety device economical and reduce maintenance costs.

In order to achieve such an object, the present invention has an on/off contact connected in series to the line, and when an overcurrent flows through the line, the line is deformed due to heat generation, and the on/off contact opens to cut off the line. The shape memory metal is sealed in one common housing.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

First, in order to explain embodiments and to facilitate understanding of the present invention, a shape memory metal, which is a main component of the present invention, will be described.

Shape-memory metals are metals that are molded at high temperatures, deformed at low temperatures, and when heated, return to the shape that was molded at high temperatures. A metal that exhibits this phenomenon is Tl −
Typical examples include N1 alloy and Cu-based alloy. As for the types of deformation, unidirectional shape memory metals recover their shape in one direction from low temperature side to high temperature side, and temperature cycles from high temperature side to low temperature side and from low temperature side to high temperature side. There are two-way shape-memory metals that spontaneously change shape.

In the present invention, both of these can be used, and Figures 10-2.3 and 4.6 show examples using the former unidirectional shape memory metal, and Figures 5.7, 8.9, Figure 10.11 shows an example using the latter bidirectional shape memory metal.

Now, the present invention is implemented as follows.

FIG. 2 is a block diagram showing an embodiment of an encapsulated line breaking device according to the present invention, in which a unidirectional shape memory metal is used as a substitute for the rabbit communication fuses 4 and 5 or the power supply fuses 10 and 11 in FIG. An example of the case of use is shown below.

FIG. 2(&) shows the overall configuration, and FIG. 2(b) l(e) shows state transitions for explaining the operation of FIG. 2(a).

In this FIG. 2, 15 is a breaking device, 16 is an on/off contact connected in series to the line, and 17-1.

17-2 is a unidirectional shape arrangement that deforms as shown in Figure 2 (b) above a certain temperature (transformation temperature), and after being deformed, maintains its shape as long as external force is applied even if the temperature is lowered. Memory metal (hereinafter abbreviated as shape memory metal), 18-1.18-
2 is an on/off contact 16 and a shape memory metal 17-1.17
19-1.19-2 is a magnetic material,
The gas is sealed inside the 20 magnets and the 21 housings 1B-1 and 18-2.

The inside of this flute body 18-1.18-2 is sealed with a vacuum or non-corrosive gas, and the shape memory metal 17-1. It is inserted into a current discharge path, and is deformed by heat generation when an overcurrent flows, opening the on/off contact 16 and interrupting the line.

Next, the operation of the embodiment shown in FIG. 2 will be explained with reference to FIG.

First, there was a lightning surge on the communication lines 1 and 2 shown in Figure 1.

When overvoltage enters due to contact with a high voltage line, the lightning arrester 6 discharges, and the overcurrent flows through the interrupter 15 shown in FIG.
It flows through the path of shape memory metal 17-2. Note that when the polarity is reversed, the flow flows through the shape memory metal 17-2, the on/off contact 16, and the shape memory metal 17-1.

When an overcurrent flows through this shape memory metal 17-1117-2, Joule heat is generated due to its specific resistance.
The temperature of the metal 17-1, 17-2 increases as shown in the following equation.

t=tO Here, C is the specific heat of shape memory metal 17-1117-2,
K constant, 1 is electric current, R is shape memory metal 17-1.1
7-2 resistance, Φ (T-To) is shape memory metal 17-1
+17-2 is the heat radiation energy per unit time when the temperature is T, and To is the ambient temperature. And the overcurrent, the current is to-
It is assumed that the current flows for tlO.

Now, when the temperature T exceeds the transformation temperature, the shape memory metal 17-1, 17-2 turns off the on-off contact 16 (open state). When the on/off contact 16 is turned off, the line is cut off.

After the overvoltage disappears, the state shown in FIG. 2(b) is maintained, but in order to restore this state, the magnet 20 is
) in the direction of ``A''. And this magnet 2
0 to the position shown in FIG. 2(c), the magnetic flux B passes through the on/off contact 16 as shown by the dashed arrow, so a force F acts between the contacts and the on/off contact 16 to restore. After restoration, move the magnet 20 to 10- in Fig. 2(b).
If it is moved in direction 1, it returns to the state shown in FIG. 2 (,).

Next, the characteristics of the on/off contact used in the device of the present invention and the casing will be explained.

First, the conditions required for an on/off contact are: ■ It must be able to repeatedly interrupt overvoltage and overcurrent (high energy).

■ Maintain low and stable contact resistance characteristics under normal conditions where no overcurrent flows.

It is.

Possible on/off contacts that meet these conditions include 1) those using solid metal, and 11) those using liquid metal, but in either case, on/off contacts are necessary to ensure reliability and safety. It is necessary to seal the off contact with the housing. The reason is explained below.

1) When solid metal is used for the on/off contact (Reason 1) When high energy is cut off, the contact wears out rapidly. As the contact wears out, the contact resistance characteristics deteriorate, so
For the on/off contact, it is desirable to use a metal that does not easily wear out.

Here, metals that are hard and have a high melting point have excellent side-load consumption characteristics, but such metals tend to form an insulating film on the surface in a corrosive atmosphere. In particular, the contact parts of the on/off contacts promote chemical reactions with the corrosive atmosphere due to sliding, so the insulating film tends to be thick and easily eroded. -For example, on
As the off contact, AgPd, AuPd, Mo
These materials are suitable because they are hard and do not wear out easily, but in the atmosphere they react with corrosive gases such as oxygen, sulfur, and chlorine, forming an insulating film. These coatings are often not destroyed when the contact force is small or when the flowing current is small, causing an increase in contact resistance and noise.

In order to solve this problem with the on/off contact, in the present invention, the on/off contact is placed in a housing, and the inside of the housing is evacuated or sealed with a non-corrosive gas.

In either case, the formation of an insulating film can be prevented, so
Contacts and L are made of high hardness, high melting point metals that easily corrode in the atmosphere.
- Can be used with. Examples of this non-corrosive gas include inert gases such as N2, )T, Ar, etc.
2. In addition to mixed gases of the above-mentioned gases such as Co + N2 and N2, even mixed gases such as N2 + 02 (a small amount) in which an oxidizing gas is added to an inert gas can cause O8
Because the concentration of is low, oxidation (corrosion) of contacts is not promoted,
In the present invention, gases that do not increase contact resistance are referred to as non-corrosive gases.

To give an example, at the A and Pd contacts, N2+o
g (i% or less), N2+02 (5%
In the following cases, the contact resistance does not increase, so they are called non-corrosive gases. In addition, in a three-gas mixture such as N2 + 02 + H2, which is an oxidizing gas and a reducing gas mixed in an inert gas, if the concentration of 02 and N2 is appropriate, the oxidation and reduction of the contact will be in equilibrium, so oxidation will be promoted. can be prevented. In this case as well, the contact resistance tends to increase, so it is called a non-corrosive gas. For example, Agpd +AuP
For d, N2 + 0z (20%) + H2 (100FP
In the case of M~1 section), the contact resistance does not increase.
Methods for attaching contacts to shape memory metal include crimping, welding, plating, vapor deposition, and sputtering.

This is done by ion implantation, etc.

(Reason 2) With solid on/off contacts, the contact area is small, so
The accuracy of the opposing positions of the on/off contacts has a large effect on the contact characteristics. Therefore, in order to obtain stable contact resistance characteristics, it is necessary to securely fix one side of the shape memory metal that moves the contacts. In the embodiment shown in FIG. 2, one end of the shape memory metal that moves one contact is fixed by the casing, and the other contact is also fixed by the casing.
The facing position accuracy of the contact points is good, and therefore the contact characteristics are also good.

(Reason 3) Line breaking devices may be used in all atmospheric and environmental conditions. However, the shape memory metal used in the present invention corrodes in a corrosive atmosphere, and its temperature deformation characteristics may change. For this reason, it is preferable to put it in a housing like the above-mentioned on/off contact, and either evacuate the inside or seal it with a non-corrosive gas.

(Reason 4) The line interrupting device according to the present invention may interrupt large voltages and large currents (high energy). In this case, the on/off contact may discharge and some or the entire contact may melt. Here, since this on/off contact is turned off by the force of deformation of the shape memory metal, the molten contact may be scattered by this force. This electrical discharge from the contacts or the scattering of molten metal is dangerous and may cause a fire.

However, in the device according to the present invention, the casing blocks fires caused by electrical discharge and prevents the contacts from scattering, and carbon dioxide, nitrogen gas, carbon tetrachloride, or the like is used as the flame extinguishing material.

Next, to explain the configuration of the housing, in FIG. The housing 18-2 may be made of metal. In the latter case, since the casing 18-2 acts as a heat sink, the shape memory metal generated by the overcurrent is cooled down in a short time after the overvoltage is removed. Therefore, recovery time can be shortened.

FIG. 3 is a configuration diagram showing another embodiment of the present invention, in which (a) shows the overall configuration, and (b) and (C) show state transitions to explain the operation. be.

In FIG. 3, the same reference numerals as in FIG. 2 indicate corresponding parts, 22 is a blocking device, 23 is a unidirectional shape memory metal (hereinafter abbreviated as shape memory metal), 24 is a magnetic material, and 25 is a unidirectional shape memory metal.
．． Reference numeral 26 denotes a movable contact and a fixed solid contact that constitute an on/off contact.

Next, the operation of the embodiment shown in FIG. 3 will be explained.

First, normally, the shape memory metal 23 is stretched by an external force, and the on/off contact formed by the movable contact 25 and the fixed solid contact 26 is in the on state. (See Figure 3(,)) Next, when an overcurrent flows through the shape memory metal 23 and the aforementioned transformation temperature is reached due to heat generation due to Joule heat, the shape memory metal 23 changes as shown in Figure 3(a). Due to the deformation, the on/off contacts from the movable contact 25 and the fixed solid contact 26 are turned off. At this time, since the shape memory metal 23 has a spring property in the deformable portion, the opening speed of the contact at the time of breaking is fast.

Therefore, it is possible to shorten the discharge time that occurs at the contact at the time of interruption.

Such interrupting characteristics are not only desirable for protecting the equipment, but also contribute to extending the life of the interrupter by reducing wear on the contacts of the interrupter. After the overvoltage is removed, the shape memory metal 23 maintains the shape shown in FIG. 3(b).

To restore the crack, use magnet 2 as shown in the arrow in Figure 3 Cb).
0, attracts the magnetic material 24, and then Fig. 3(e)
All you have to do is lower the magnet 20 as shown by the arrow and turn on the on/off contact.

FIG. 4 is a configuration diagram showing still another embodiment of the present invention, and is an example of a case where a spring is used as a biasing means to turn on the on/off contact in the present invention using a unidirectional shape W7 memory metal. This shows that. Therefore, Figure 4 (a) shows the overall configuration, and Figure 4 (b>, (c
) indicates the state transition used to explain the operation.

In FIG. 4, parts corresponding to the same reference numerals as in FIG. 3 are shown, 2711S1 is a shutoff device, and 28 is a spring.

Next, the operation of the embodiment shown in FIG. 4 will be explained.

First, normally, as shown in FIG. 4(a), the shape memory metal 23 is stretched by the contraction force of the spring 28, and the on-line contact formed by the movable contact 25 and the fixed solid contact 26 is expanded.
The off contact is in the on state.

Next, when an overcurrent flows through the shape memory metal 23, the shape memory metal 23 becomes high temperature and deforms as shown in Figure 4(b). The off contact turns off.

When this on/off contact is turned off, the shape memory metal 23 is cooled and becomes flexible, and expands due to the contraction force of the spring 28. Therefore, the on/off contact is turned on again. If the overvoltage has not gone away when the on/off contact is turned on, there is a possibility that the overcurrent will flow again, but since the overvoltage like a lightning surge only lasts a few milliseconds at most, the on/off contact will be restored. In many cases, the overvoltage has gone away and there is no problem.

FIG. 5 is a block diagram showing still another embodiment of the present invention, and shows an example in which a bidirectional shape memory metal is used as the shape memory metal. (a) shows the overall configuration, and (b) shows state transitions.

In this Fig. 5, the same reference numerals as in Fig. 3 indicate corresponding parts, 29 is a cutoff device, and 30 is a low-temperature part as shown in Fig. 5 (a).
It is in an elongated state as shown in Figure 5 (
It is deformed as shown in b), and when the temperature is lowered again, it becomes as shown in Fig. 5 (,
It is a bidirectional shape memory metal (hereinafter abbreviated as shape memory metal) that has the property of recovering to the state shown in ).

The operation of the shutoff device 29 constructed in this manner is the same as that of the embodiment shown in FIG. That is, when an overcurrent flows, the shape memory metal 30 becomes high temperature, and as shown in FIG. 5(b)
Due to the deformation as shown in FIG. 2, the on/off contact formed by the movable cross point 25 and the fixed solid contact 26 turns off. Then, when the current is interrupted, the shape memory metal 30 is cooled and stretches again, so that the on/off contact is turned on.

6 and 7 are configuration diagrams showing still other embodiments of the present invention, in which the fixed solid contact 26 of the on/off contact shown in FIGS. 4 and 5 is replaced with a liquid contact 31 such as mercury. This is an example of a case where Furthermore, this Figure 6,
In FIG. 7, the same parts as in FIG. 3 are given the same reference numerals, and their explanation will be omitted.

In the device of the present invention, which may interrupt large currents,
Deterioration of contact resistance characteristics due to contact wear is a problem, but
Liquid contacts have low contact consumption and good contact characteristics, so they are suitable for disconnecting devices used in electric and power lines.

Here, to explain the function of the housing, mercury is suitable as a liquid contact, but mercury easily oxidizes and evaporates in the atmosphere. The phenomenon of sagging also causes deterioration of contact characteristics.

Furthermore, when a large current is interrupted, the mercury at the contact portion may scatter due to the breaking force of the shape memory metal, which is dangerous. These disadvantages of mercury contacts are overcome by enclosing them in a housing 18 and sealing them. Since the prevention of mercury scattering during interruption is self-evident, the effect on contact characteristics will be explained. Shape memory metals are required to have kinetic properties that allow them to quickly open and close their on/off contacts at high temperatures. Therefore, if the shape is made to have spring properties at high temperatures, a certain length is required as shown in FIGS. 6 and 7. For this reason, the movable contact (solid contact) 25 provided at one end of the shape memory metal may not return to the position before separation at the time of recovery, resulting in positional deviation. However, in this embodiment, in which a mercury liquid contact 31 is used as a fixed contact and the interrupting device is used vertically as shown in FIGS. Therefore, the slight position of the movable advantage 25 does not have any adverse effect on the contact characteristics.

Next, we will explain the filling gas that prevents the noise of contacts and memory metals.As in the case of solid ON/OFF contacts, inert gases such as N2+Ar and CO2, ■21C
Cyclogenic gases such as O, mixed gases of these, mixed gases consisting of inert gases and trace amounts of oxidizing gases such as O2, mixed gases of three types consisting of inert gases, cyclic gases, and oxidizing gases, etc. can be used.

In particular, when I (2 gas) is sealed, the discharge duration when the contact is opened can be shortened, which has the advantage of improving the interrupting characteristics.In addition, as a movable contact, AgPd = A
uPd, Nl 1Mo, Ag-8t, etc. can be used.

FIG. 8 is a configuration diagram showing still another embodiment of the present invention.
This is an example of a case where it can be used as a substitute for the security device shown in the figure.

In this FIG. 8, the same reference numerals as in FIGS. 1 and 5 indicate corresponding parts, 32, 33 is a interrupting device, 34 is a conductor, 35 is an insulation coating, 361L, 36b is a constant voltage limiting element, 37a, 37b is a high current withstand fuse.

Next, the operation of the embodiment shown in FIG. 8 will be explained. Overvoltages that are applied to communication lines 1 and 2 without being switched include lightning surges and high-voltage line contact, but the former type of lightning surge occurs frequently and occurs on many lines at the same time, so its impact is large. . Therefore, the operation in response to this lightning surge will be explained first.

In FIG. 8(a), when an overvoltage is applied to the communication line 1, it is applied to the lightning arrester 6 via the shape memory metal 30 and the conducting wire 34. Then, the lightning arrester 6 is discharged. When this overcurrent flows through the shape memory metal 30, the shape memory metal 30 generates heat and deforms as shown in FIG. 8(b). The contact is turned off. Then, when the overvoltage and pressure disappear,
Since the lightning arrester 6 is restored, the overcurrent stops. When the overcurrent stops, the shape memory metal is cooled down by 30 mm, so Figure 8 (,)
As shown in FIG. 3, the line is automatically restored in order to turn on the on/off contact consisting of the movable extendable contact 25 and the fixed contact 26 again. The same applies when an overvoltage is applied to the communication line 2. Furthermore, it goes without saying that the liquid contact 31 shown in FIGS. 6 and 7 may be used as the fixed solid contact 26.

FIGS. 9(a) and 9(b) show the circuit of FIG. 8, and the dash-dotted arrow indicates the path of the two overcurrents.

Next, overvoltage application due to contact with a high voltage line will be explained. This overvoltage caused by contact with high-voltage lines differs from the aforementioned lightning surge in that it lasts for a long time. Therefore, in the state shown in FIG. 8(b), the shape memory metal 30
If an overcurrent flows through the conducting wire 34 and the lightning arrester 6 for a long period of time, these may melt. In order to prevent this, high current withstand fuses 37a and 37b, which do not blow out during lightning surges but blow out when overcurrent flows continuously, are shown in Figure 8 (a).
) may be inserted into the lines (communication lines 1 and 2).

However, contact with high-voltage lines is extremely rare, and it is unlikely that many lines will come into contact with each other at the same time. Therefore, even if the disconnection device cannot be used repeatedly due to melting, etc., it is not necessary to replace the disconnection device due to maintenance reasons. It's not a big problem. Rather, it is desirable that the current be blown out immediately when the current withstand capacity (current value x duration) exceeds a certain level.

As for the form of this fusing, 1) Conductor 34. The shape memory metal 30 is fused.

11) When the conductor 34 melts, the shape memory metal 30 loses its original shape restoring function, which bidirectional shape memory metal has, due to heat, and maintains the state shown in FIG. 8).

In either case, the communication line 1, the communication line 1', and the ground E are spatially separated from each other.

The melting of such a cutoff device is dangerous because it involves the scattering of melted fragments, but since the cutoff device according to the present invention has a casing, scattering is prevented and safe.

FIG. 10 is a block diagram showing still another embodiment of the present invention, and shows an example of a shutoff device used for the same purpose as the embodiment shown in FIG.

In FIG. 10, the same reference numerals as in FIG. 8 indicate corresponding parts, 38 is a conductor, and 39 is an insulating coating.

The difference from FIG. 8 is that in FIG. 8, the shape memory metal 3o is connected in series to the line (communication line 1).
If the resistance of the shape memory metal 30 is large, there will be a call loss in a communication line, and a power loss will occur if it is used in a power line.In contrast, in the embodiment shown in FIG.
Since they are connected in parallel to the line, there is no loss.

Next, the operation of the embodiment shown in FIG. 10 will be explained with reference to FIG. 11.

First, normally, current flows through a conductor (as shown in Figure 11(a)).
(conductor) 38. (See the arrow of the dashed-dotted line (a)) Next, when overvoltage is applied to the communication line 1, the lightning arrester 6
As shown in FIG. 11(b), the shape memory metal 30 generates a discharge.
As shown by the one-dot button line (b) arrow, an overcurrent flows, and the shape memory metal 30 is deformed as shown in FIG. 11(b). At this time, the conductor (conductor wire) 38 is the shape memory metal 3
0, the on/off contact consisting of the movable contact 25 and the liquid contact 31 is turned off. After the overcurrent has passed, the shape memory metal 3° stretches as shown in Figure 11 (,), so the conductor (conductor wire) 3
8 is also extended, and the on/off contact formed by the movable contact 25 and the liquid contact 31 is turned on.

Since the device of the embodiment shown in FIG. 10 has a small series resistance, it is suitable for communication lines with severe transmission loss and power lines with large current capacity.

〔Effect of the invention〕

As explained above, according to the present invention, overvoltage and voltage.

It quickly operates in response to overcurrent and cuts off the line, and after the overvoltage and overcurrent have subsided, the line can be reconnected with stable characteristics. In other words, it can be used repeatedly, making the security device more economical and reducing maintenance costs.It can also be used for both communication lines and power lines, so it has no practical effects. It is extremely large. In addition, since devices using bidirectional shape memory metal as the shape memory metal have an automatic recovery function, long-term suspension of operation is not allowed. It is extremely effective in that it is suitable for power lines.

[Brief explanation of drawings]

Figure 1 is a configuration diagram showing an example of a conventional line breaking device;
The figure is a block diagram showing one embodiment of an encapsulated line breaking device according to the present invention, FIG. 3 is a block diagram showing another embodiment of the present invention, and FIGS. 4, 5, 6, and 7. and FIG. 8 are block diagrams showing still other embodiments of the present invention, FIG. 9 is a circuit diagram for explaining the operation of the embodiment shown in FIG. 8, and FIG. 10 is a still another embodiment of the present invention. 11 is a configuration diagram showing the 10th
FIG. 3 is a circuit diagram for explaining the operation of the embodiment shown in the figure. 1.2...Communication line, 16...On/off contact, 17-1.17-2.23...Unidirectional shape memory metal, 18-1.18-2.18. ...Case, 21
... Gas, 25 ... Movable contact, 26 ... Fixed solid contact, 30 ... Bidirectional shape memory metal, 31
...Liquid contact.

Claims (4)

[Claims] (1) An on/off contact connected in series with the line is inserted into an overcurrent discharge path via the line, and when an overcurrent flows, it deforms due to heat generation and opens the on/off contact to cut off the line. What is claimed is: 1. An encapsulated line breaker comprising a shape memory metal and a shape memory metal encapsulated in a common housing. (2) The enclosed line breaking device according to claim 1, wherein the inside of the casing is sealed with a vacuum or a non-corrosive gas. (3) The enclosed type line breaking device according to claim 1 or 2, characterized in that a liquid contact is used for at least one of the on/off contacts. (4) The enclosed type line breaking device according to claim 1, 2, or 3, characterized in that a flame-extinguishing material is enclosed within the casing.