JPH0150079B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a lightning arrester earth fault preventer. More specifically, when a surge arrester malfunctions due to some reason and a leakage current occurs, in order to avoid accidents such as power outages due to the leakage, the ground fault circuit from the surge arrester is cut off and at the same time an indication that the surge arrester is malfunctioning is displayed. Concerning equipment for In order to prevent damage to distribution lines and distribution equipment due to lightning strikes or abnormal surges, lightning arresters are usually installed on distribution lines. However, if the arrester is damaged by lightning that exceeds its withstand capacity or deteriorates due to wind and rain, current may leak from the arrester, causing a ground fault and causing an accident such as a power outage. In order to prevent such accidents, it is desirable to equip the lightning arrester with a device that interrupts the ground fault circuit of the arrester when a ground fault current occurs. In Japan, the ungrounded type is normally used as a high-voltage distribution line system. The ground fault current that flows in this type of electrical line is extremely small (approximately 100 mA to 15 A) compared to the grounded type, and therefore, the conventional lightning arrester and ground fault preventer, which can also be applied to ungrounded types, uses the explosive energy of explosives. Many of them use an operation method that uses . Its structure and operating principle will be briefly explained with reference to FIGS. 1 and 2. A lightning arrester side terminal 8 is attached to the center of the upper surface of the inorganic insulating jacket 3, and a capsule chemical cylinder 7a is loaded inside a cylindrical resistor 5 that is electrically connected to a flange 8a provided below the terminal 8. The discharge gap 6 is formed between the upper surface and the flange 8a in parallel with the resistor. The lower part of the capsule chemical cylinder 7a containing the gunpowder 7 is sealed by a stopper 7b, and the lower end of the stopper 7b is connected to the ground terminal 9 provided so as to pass through the center of the bottom of the insulating cover 4. The cover 4 is fitted under the inorganic insulation sheath 3. While the lightning arrester 1 is operating normally, the resistor 5
Since the resistance value of is high, no current flows through the resistor 5,
The lightning current is discharged between the resistor 5 and the discharge gap 6 installed in parallel, and the lightning arrester and earth fault preventer do not operate. When an abnormality occurs in the lightning arrester, the leakage current flows through the resistor 5.
The flow causes the resistor to generate heat, which causes the internal pressure of the capsule to rise rapidly, causing the insulating jacket 3 to detach, disconnecting the lightning arrester circuit and at the same time indicating an abnormality in the lightning arrester. In this way, conventional earth fault preventers use explosives to operate with a minute current, and the explosive energy of the explosives is used as a thrust to separate the casing, that is, to disconnect the lightning arrester circuit. However, since it uses gunpowder, special care must be taken in terms of safety, there are significant restrictions on manufacturing and handling, and it is disadvantageous in terms of price. In view of the above-mentioned current situation, the inventors of the present invention have conducted extensive research to provide a ground fault preventer that can quickly interrupt a ground fault circuit by sensing minute currents without using explosives. A hot-melt adhesive is used to lock the constituent members, and the hot-melt adhesive is melted by the heat generated by the resistor due to the earth fault current, and the engagement between the constituent members is released. It has been discovered that two constituent members of a housing can be easily and safely separated in response to a minute electric current,
The invention has been completed. In other words, the present invention comprises: a housing consisting of two hollow bodies with one end open; two terminals disposed facing each other in the cavity of the housing; and spaced apart from the inner wall surface of the hollow bodies. a resistor provided and connecting both terminals; a pair of discharge electrodes forming a discharge gap inside the resistor in parallel with the resistor; an inner wall surface of the hollow body and the resistor; The present invention relates to a lightning arrester ground fault preventer comprising a hot melt adhesive that fills a part or all of a space to bond and fix two hollow bodies, and a separation promoter that applies a force to separate the two hollow bodies. Next, embodiments of the lightning arrester earth fault preventer of the present invention will be described in detail based on the drawings, but the present invention is not limited to such embodiments. FIG. 3a shows a schematic vertical sectional view of an embodiment of the earth fault preventer of the present invention, and FIG. 4 shows a partially exploded perspective view thereof. This embodiment basically consists of two cylindrical hollow body casings 11, 12 which are open at one end.
A housing 10 consisting of a lightning arrester side terminal 13, a grounding side terminal 14, a cylindrical resistor 15 connecting both terminals, and a discharge electrode 17 forming a discharge gap 16 inside the resistor 15 and in parallel therewith. ,1
8. Metal plate contact 19 for holding resistor 15
A spring 20 presses the ground terminal 14 against the ground terminal 14, and a hot melt adhesive 21 fills the space between the inner walls of the two casings 11 and 12 and the resistor 15. For assembly, attach the lightning arrester side terminal 13 to the casing 11.
is fixed, and in contact with the terminal 13, a resistor 15 having a discharge electrode 17 fitted to one end and a metal plate contact 19 fitted to the other end is fixed. The resistor 15 is preferably cylindrical in order to form a discharge space inside, but the resistor 15 is preferably cylindrical in shape so that the hot melt adhesive 21 does not fill the discharge space, such as a cylindrical inner casing (not shown). If it is provided inside the body, it may be rod-shaped. Resistor 15 is casing 1
It is fixed away from the inner wall of 1 to form a filling space for hot melt adhesive. A hole 22 is provided in the center of the bottom surface of the casing 12, and the ground terminal 14, on which the electrode 18 is integrally formed, is slidably inserted into the hole 22. A coil spring 20 is provided between the flange 23 of the terminal 14 and the bottom surface of the casing 12, and this spring is used as a separation promoter during separation. The casings 11 and 12 assembled as described above are aligned so that the electrode 18 penetrates the hole 24 in the center of the metal plate contact 19, and pushed against the spring 20 until the open ends of both casings come into contact. In this case, it is preferable that the periphery of the metal plate contact 19 is in slidable contact with the inner wall surface of the casing 12 or faces the inner wall surface of the casing 12 with a slight gap. Then, from the injection port 25, the casings 11, 12 and the resistor 1 are
Apply hot melt adhesive 2 to the space formed by 5.
1 is injected, and when the hot melt adhesive starts to overflow from the overflow hole 25a, the injection is stopped, and the casings 11 and 12 are adhesively fixed to assemble the earth fault preventer. In this operation, if the lightning arrester (not shown) is operating normally, only lightning current will not flow from the arrester, and if lightning current flows, the discharge gap 16 will be discharged to divert the lightning current to the ground. Entangle. If an abnormality occurs in the lightning arrester and a minute leakage current flows from the distribution line, no discharge occurs in the discharge gap 16, and the leakage current passes through the resistor 15 and causes a ground fault. At this time, the resistor 15 generates heat due to the leakage current, and melts the hot melt adhesive 21 bonding the casings 11 and 12 together. When the hot melt adhesive 21 melts, the flange 23 of the terminal 14 pushes against the metal plate contact 19 due to the force of the spring 20, separating the casing 12 from the casing 11, separating the terminal 14 from the contact 19, and interrupting the ground fault circuit. The casing 12 detached from the casing 11 hangs down,
Displays that an abnormality has occurred in the lightning arrester. The shape of the housing is not limited to cylindrical, but can also be box-shaped,
It may also be spherical. In addition, the inner surface of the housing
As shown in Figure b, it is also possible to form a shape that allows a space to be formed between the resistor and only the part filled with hot melt adhesive, in which case a smaller amount of adhesive is required and the housing can be downsized. The material only needs to be an insulator.
Although inorganic or organic insulators may be used, thermoplastic resins such as vinyl resins are preferred because they are easy to mold and are inexpensive. When using the cylindrical housing shown in Figures 1 and 2, the size is 32 mmφ in outer diameter and 41 mm in height, but the size can be increased by appropriately selecting resistors, springs, hot melt adhesive, etc. It is also possible to downsize. In addition, as a method of connecting the terminal to the lightning arrester, terminal 1
I mentioned the case where 3 is connected to a lightning arrester, but
Conversely, there is no problem even if the terminal 14 having the spring 20 is connected to the lightning arrester. The shape and material of the discharge electrode may be any conventionally used one. The hot melt adhesive may be appropriately selected depending on the magnitude of the ground leakage current expected in the event of a failure of the lightning arrester. Specific examples include Dumilan (modified ethylene-vinyl acetate copolymer, trade name of Takeda Pharmaceutical Co., Ltd.), Admer (modified polyolefin adhesive, trade name of Mitsui Petrochemical Industries, Ltd.),
Examples include Evaflex (modified product of ethylene-vinyl acetate copolymer, trade name of Mitsui Polychemical Co., Ltd.) and blends thereof with resins such as polyethylene, but are not limited to these. In the present invention, the gap between the casing and the resistor is made small, and only the joint between the two casings is tapered as shown in Figure 3b, so that the hot melt adhesive can easily enter. The type, position, etc. can be changed in various ways. Another embodiment of the earth fault preventer of the present invention will be described below, in which the same parts as in the embodiment shown in Figs. 3a to 4 are denoted by the same reference numerals, and the explanation thereof will be omitted. The embodiment shown in a schematic vertical cross-sectional view in FIG. 5 is designed to easily connect the casing 26 and the casing 27. A flange portion 28 is formed at the open end of the casing 26, and a metal plate is formed on the open end of the casing 26. Together with the contact 19, the open end of the casing 26 is closed. A predetermined number of through holes 29 are bored in the flange portion 28 . The same number of protrusions 30 as the through holes 29 are provided on the open end surface of the casing 27 . FIG. 6 shows a sectional view taken along the line A--A in FIG. 5. Assembly is performed by inserting the protrusion 30 into the through hole 29 and injecting the hot melt adhesive 21 from the injection port 25. The operation is similar to the embodiment shown in FIG. 3, in which the heat generated by the resistor 15 melts the hot melt adhesive, and the force of the spring 20 causes the casing 27 and the terminal 14 to separate. When constructed as in this embodiment, assembly is extremely simple. 7 and 8 show schematic longitudinal cross-sectional views of another embodiment of even more compact construction. In the embodiment shown in FIG. 7, a weight 31 is used instead of a spring as a separation promoter. The structure of the casing 32 is similar to that of the casing 11 of the embodiment shown in FIG. In this embodiment, the electrode 18 on the ground side terminal 14 side is formed integrally with the metal plate contact 34, but the electrode 18 may also be formed integrally with the terminal 14 as in the embodiment shown in FIG. good. Inside the other casing 33, only terminals are disposed on its bottom surface. A weight 31 is attached to the outside of the casing 33 to adjust separation of the casing 33. When the weight of the casing 33 is appropriately selected, the weight 31 becomes unnecessary. That is,
The isolated promoter in this example is the casing 3
It is the dead weight of 3. For assembly, the two casings are brought together so that the terminal 14 and the metal plate contact 34 come into close contact with each other, and the hot melt adhesive 21 is injected through the injection port 25. The operation is the same as the embodiment shown in FIGS. 3a and 5, except that instead of the spring, the weight 31 or the weight of the casing 33 acts as the separation promoter. The embodiment shown in FIG. 8 has the same internal structure of the housing as the embodiment shown in FIG. 7. In this embodiment, flanges 37 and 38 are provided around both closed ends of both casings 35 and 36, respectively.
A feature is that a spring 39 is provided so as to be engaged with these and wind the housing. Assembly and operation are the same as the embodiment shown in FIG. 7, except that instead of a weight, a spring 39 acts as a separate promoter. Note that the spring 39 may be attached after the housing is assembled. Although the earth fault preventer of the present invention has been described above in detail based on the drawings, the locations at which internal structures such as resistors and electrodes are separated are not limited to those embodiments, and may be designed in various ways. Can be changed. Furthermore, the earth fault preventer of the present invention may be installed between a power distribution line and a lightning arrester. In the lightning arrester earth fault preventer of the present invention, the sensitivity can be improved by appropriately selecting the type and size of the resistor, the type and amount of hot melt adhesive, the type and force of the separation promoter such as a spring and weight. The current and the time required for separation can be arbitrarily selected. For example, in the embodiment shown in FIG. 3a, a cylindrical carbon resistor of 8 kΩ is used as the resistor, and Dumilan D-219 (modified ethylene-vinyl acetate copolymer (softening point: 76
℃), a trade name of Takeda Pharmaceutical Co., Ltd.), an electric current test was conducted, and the results shown in Table 1 were obtained.

[Table] As a comparative example, measurements were also taken on a conventional ground fault preventer using explosives, and the results are also shown in Table 1. As is clear from Table 1, the earth fault preventer of the present invention disconnects more quickly with a smaller current. As described above, the earth fault preventer of the present invention does not use any dangerous substances such as explosives, so it is safe and can have a simple structure. Therefore, manufacturing constraints are significantly eased and it is suitable for mass production.
Handling and installation can also be performed safely and quickly. Furthermore, by appropriately selecting and combining components such as hot melt adhesives, the present invention can be applied to lightning arresters of any standard, from those with higher sensitivity to those with lower sensitivity than conventional ones. In addition, since one of the casings is kept hanging down after detachment, a malfunctioning lightning arrester can be easily discovered.

[Brief explanation of drawings]

Fig. 1 is a schematic vertical cross-sectional view of a conventional lightning arrester/ground fault preventer, Fig. 2 is a schematic circuit diagram of the ground fault preventer shown in Fig. 1, and Fig. 3a is an implementation of the lightning arrester/ground fault preventer of the present invention. FIG. 3b is a partial sectional view of another embodiment of the casing used in the present invention, FIG. 4 is a partially exploded perspective view of the embodiment shown in FIG. 3a, and FIG. 5 is a schematic longitudinal sectional view of the embodiment shown in FIG. FIG. 6 is a cross-sectional view taken along the line A-A in FIG. 5, and FIGS. 7 and 8 are schematic longitudinal sectional views of another embodiment of the earth fault preventer of the present invention, respectively. FIG. 3 is a schematic vertical cross-sectional view of an example. (Main symbols in the drawing), 1: Lightning arrester, 10: Housing, 11, 12, 26, 27, 32, 33,
35, 36: Casing, 13: Lightning arrester side terminal,
14: Ground side terminal, 15: Resistor, 16: Discharge gap, 17, 18: Discharge electrode, 20, 39:
Spring, 21: Hot melt adhesive, 31: Weight.

Claims (1)

[Scope of Claims] 1. A housing consisting of two hollow bodies with one end open, two terminals disposed facing each other in the cavity of the housing, and a space between them and the inner wall surface of the hollow body. a resistor provided with an opening and connecting both terminals; a pair of discharge electrodes forming a discharge gap inside the resistor in parallel with the resistor; and an inner wall surface of the hollow body and the resistor. A lightning arrester earth fault preventer comprising a hot melt adhesive that fills part or all of the space between the two hollow bodies and adhesively fixes the two hollow bodies, and a separation promoter that applies a force to separate the two hollow bodies. 2. The earth fault preventer according to claim 1, wherein the separation promoter is an elastic body. 3. The earth fault preventer according to claim 1, wherein the separation promoter is a weight.