JP2001169460A - Surge current avoidance element and avoidance circuit thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surge current avoidance element and an avoidance circuit thereof, capable of controlling surge current in a back flow direction by restricting the conducting direction of an element mounted to avoid the surge current to one way, and preventing the surge current from flowing into an apparatus side even in the case of such surge current as exceeds such a conducting limit, or, whatever path the surge current comes in, preventing the surge current from flowing through a circuit in the apparatus for protecting the apparatus from the surge current. SOLUTION: This surge current avoidance element 1 is formed out of a surge current reacting part 11 and a semiconductor part 12. The surge current reacting part 11 reacts rapidly if surge current occurs to form an acceptance on the side of the avoidance element 1 before it flows into the apparatus. The semiconductor part 12 prevents surge current from a reverse direction. The surge current reacting part 11 is disposed on the side connected with the apparatus and the semiconductor part 12 is on the side of an earth line 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a surge current avoiding element for preventing a surge current such as lightning or static electricity from flowing to an electric device to damage a circuit, and a circuit for avoiding the surge current.

[0002]

2. Description of the Related Art It goes without saying that electricity is indispensable for modern society. Such electricity is damage to electrical equipment due to excessive surge current such as lightning or static electricity, or fire due to sparks or the like. As a primitive method of avoiding lightning damage, lightning rods should be installed at the highest point of the building and grounded so that lightning does not flow to electrical equipment inside the building when lightning strikes There are things that can prevent fires. Also, although it does not have as much energy as lightning,
In order to prevent static electricity generated from clothes or the like from several thousand volts to 10,000 volts or more from flowing into a circuit inside the electric device, a so-called ground wire for grounding an exterior energized portion of the device is connected.

However, in the case of a simple combination of the lightning rod and the ground, the lightning does not always strike the lightning rod, and it is not uncommon for lightning to strike the reinforcing bars inside the building. For this reason, it is not uncommon for an electrical device to be damaged by an excessive surge current due to lightning flowing through a power supply device of a building or an electrical device located near a wall. Assuming such a case, as an enhancement of the grounding means for each device described above, there is a device in which an element such as an arrestor or a varistor for releasing an arc current or the like is mounted inside the device.

[0004] Such arresters and the like worked effectively in the past, when circuits such as transistors and capacitors were used a long time ago. That is, since a transistor or a capacitor has a certain degree of resistance, a surge current such as an arc flows to the arrester side, thereby preventing damage to the device. However, with recent semiconductor technology,
As semiconductor circuits have become more integrated, the resistance of the circuits themselves has become very low, and such arresters have become useless. Therefore, more effective surge current prevention means is needed. As such a device, there is a "molybdenum arrester" disclosed in Japanese Patent Publication No. Hei 7-118361. This is an effective arrestor formed by utilizing the high conductivity and the oxide film forming property of molybdenum and the insulating property of molybdenum oxide.

[0005] It is certain that this molybdenum surge arrester has superior lightning arrester performance as compared with the conventional arrester, and the molybdenum surge arrester comes here by being connected between a commercial power supply and protective equipment and further grounded. It has been demonstrated that induced lightning can be avoided, and that it has a follow-current blocking performance that insulates commercial power after lightning. However, even when such an excellent lightning arrester is attached, there has been reported an example in which the device was damaged due to lightning arresters. In other words, although thunder was confirmed in the distance, there was no direct lightning strike in the building, but some equipment was damaged apparently due to surge current. The cause is, for example, a lightning strike from that point due to a lightning strike in the distant place, and the induced lightning does not pass through the main power supply equipped with a molybdenum lightning arrester, but flows into the equipment through a communication line etc., It is conceivable that lightning strikes nearby and a grounded surge current propagates through the ground and flows back through the ground wire. In other words, in the past, it was only necessary to avoid large surge currents from the main power supply.However, due to the reduction in resistance associated with the refinement of equipment and the development of communication networks, there are various surge current intrusion routes, The inventor has noticed that there is a problem that the device is damaged even if the surge current is not large.

[0006]

Therefore, the present inventors are concerned about the above-mentioned problems, and as a result of intensive studies, by limiting the conduction direction of the element to be mounted to avoid the surge current to one direction, the surge in the reverse flow direction is suppressed. Control the current, and
Even if the surge current exceeds such a conductivity limit, the surge current does not flow to the device side, that is, even if the surge current enters from any path, it is necessary to prevent the surge current from flowing to the circuit inside the device. It is an object of the present invention to provide a surge current avoidance element and a circuit for avoiding the surge current, which can prevent the device from surge current.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to a surge current avoiding element for conducting a current of a voltage higher than a predetermined value in response to a voltage of a certain value or more. It is provided to maintain the conductivity in one direction up to the voltage.

In addition, a surge current avoiding element is provided, which comprises a surge current responsive part which responds to a voltage higher than a certain value and conducts a current of a higher voltage, and a semiconductor part which is conductive in a certain direction. It is formed.

[0009] Further, at least two surge current responsive parts, which are surge current avoidance elements and respond to a voltage higher than a predetermined value and conduct a current of a higher voltage, are provided. The terminals connected to the reaction part are arranged so as to face each other with a gap therebetween so that the arc voltage from one terminal to the other terminal is higher than the arc voltage in the opposite direction.

[0010] In addition, at least three surge current responsive parts, which are surge current avoiding elements and which conduct a current of a higher voltage in response to a voltage of a certain value or more, are provided. The terminals connected to the reaction section are arranged facing each other with a gap therebetween, the first surge current reaction section is connected to a device or circuit to be protected, and the second and third surge current reaction sections are respectively connected to different ground wires. Connected, the distance between the terminal of the first surge current responsive part and the terminal of the second surge current responsive part is greater than the distance between the terminal of the second surge current responsive part and the terminal of the third surge current responsive part. It was done.

[0011] These surge current avoidance elements allow a surge current from one direction to flow and ground, but a surge current from an undesired direction not to flow or to another ground.

In the surge current avoidance circuit,
The other end of a first ground wire, one end of which is substantially grounded, is connected to one contact of a surge current avoiding element that conducts a current of a higher voltage in response to a voltage of a certain value or more. The other end of the circuit line, one end of which is connected to the protection device side, is connected to the other contact of the avoiding element, and a bypass line is provided between the first ground line and a second ground line separately provided therefrom. It is a thing.

Further, the other end of a ground wire, one end of which is substantially grounded, is connected to one contact of a surge current avoiding element which conducts a current of a higher voltage in response to a voltage higher than a certain value. A surge current avoiding circuit in which one end of the circuit line having one end connected to the protection device side is connected to the other contact of the avoiding element, wherein a bypass is provided between the ground line and the circuit line. An element or the like having semiconductor properties such that the conduction direction is from the ground line side to the circuit line side is disposed in the middle of the bypass line.

[0014] With these avoidance circuits, even if a surge current invades from any direction, it does not flow in the direction of the device to be protected, and the circuit in the device can be protected.

[0015]

According to the present invention, when a surge current enters a circuit connected to a device to be protected, the surge current always flows to the ground line and does not flow to the device, regardless of the direction from which the surge current flows. In order to prevent the surge current from flowing in the reverse direction, the avoidance element has a conduction direction limited, and in the case of a surge current in the reverse direction, the avoidance circuit controls the current to flow in another direction so as not to flow to the device side. .

Each of the detailed embodiments will be described in each embodiment. As the avoiding element, a surge current reacting portion having a property of reacting at a high speed to a constant voltage and being able to conduct a large amount of electricity is provided. And a semiconductor unit that controls the conduction direction by connecting in series. Further, the surge current reaction section and the terminals connected to the surge current reaction section as described above are respectively combined in a plurality, and the terminals are arranged facing each other with a gap therebetween, and the gap or arc performance of these terminals is given a characteristic so that the surge is suppressed. In some cases, the direction of arcing due to conduction of electric current is limited to determine the direction of conduction of the element itself.

The avoidance circuit will also be described in detail in each embodiment, but as a basic form, no matter which direction the surge current comes from, the surge element is mounted by the action of the attached element before flowing toward the device to be protected. It is designed to flow toward the ground. That is, when the surge current is from the power supply side, the surge current flows to the element having the property of avoiding the surge current having a high reaction speed, and is grounded. On the other hand, in the case of reverse flow from the ground line due to induced lightning, surge current flows through the bypass line to a separately provided second ground line such as the ground provided on the negative line on the power supply side. As a result, it is possible to completely prevent a surge current from flowing to the device side.

Also, for example, in a circuit for avoiding a surge current connected to an equipment frame or the like, a loop circuit is formed by using two elements, and a surge current due to static electricity or the like from the equipment frame is a first element. In the case of backflow from the ground due to induced lightning or the like, the second element immediately reacts and flows once toward the equipment frame.
Before reaching the frame, the first element reacts and grounds. In other words, the loop from the first element to the second element is constituted by a high reaction speed of the element and by making the relative value of the resistance value easily flow to the ground side. For example, when the surge current reaction unit is configured by using the above-described principle of the molybdenum surge arrester, the molybdenum surge arrester can change the corresponding surge current by increasing or decreasing the junction. Then, the resistance of the second element is increased,
By making the connection from the element to the first element as short as possible, it is possible to realize the above-described bidirectional surge current avoidance circuit.

[0019]

Embodiment 1 FIG. 1 is a schematic diagram showing a basic form of an avoidance element according to Embodiment 1. As shown in FIG. 1, as a first form of the avoidance element, when a surge current is generated in the attached circuit, it reacts at a high speed and a large receptacle is provided on the avoidance element 1 side before flowing to the device. A surge current reaction section 11 to be formed and a semiconductor section 12 capable of stopping a surge current from the opposite direction.
And As the surge current reaction section 11, a high-speed and highly-reliable one such as the molybdenum surge arrester described above is preferable. Further, the semiconductor section 12 is preferably made of silicon or germanium, not having a small capacity like a semiconductor integrated circuit, but having a larger capacity than a discrete system. These are connected in series to form the avoidance element of the present embodiment. In consideration of the reaction speed, the surge current reaction unit 11 is arranged on the side connected to the device, and the ground line 13 is connected. It is desirable to dispose the semiconductor unit 12 in the area.

Embodiment 2 FIG. 2 is a schematic diagram showing a basic form of an avoidance element according to Embodiment 2. As shown in FIG. 2, the avoidance element 2 of the second embodiment
Is composed of two surge current reaction sections 21 and 23 that conduct a current of a higher voltage in response to a voltage higher than a certain value, and their terminals 22 and 24 are arranged facing each other with a gap therebetween. ing. The arc voltage from one terminal 22 to the other terminal 24 is
23, which is equal to or lower than a certain voltage that is a condition for conduction to 23,
The arc current from the terminal 24 in the opposite direction to the terminal 22 is formed to be very high. As described above, means for increasing only the arc voltage in one direction is achieved by a combination of a material and a shape. Therefore, ground wire 2
In the case of a surge current in five directions, the surge current is grounded by the reaction of the respective surge current reaction units 21 and 23 and arc discharge. On the other hand, when the surge current is a reverse current flowing from the ground wire 25, no conduction occurs unless the current is extremely high.

Since the avoidance element 2 of this embodiment causes arc discharge, it can be used as a light bulb when used in combination with a high voltage generating means. That is, the avoidance element 2 is covered with a transparent material such as glass, and arc discharge is used as a light source instead of the conventional filament light emission. As a result, the lamp can be used as a display lamp for a circuit for avoiding a surge current described later, in which a high voltage may flow, and unlike a conventional filament, a semi-permanent light bulb that does not break due to a surge current flowing. Can be used as

Embodiment 3 FIG. 3 is a schematic diagram showing a basic form of an avoidance element according to Embodiment 3. As shown in FIG. 3, the avoidance element 3 according to the third embodiment includes three first to third surge current reaction units 31, 33, and 35 having the same configuration.
2, 34, 36 are arranged facing each other with a gap therebetween, and the terminal 34 and the terminal 36 are arranged close to each other.
The first surge current reaction unit 31 is connected to a device or a circuit to be protected, and the second and third surge current reaction units 3
3 and 35 are provided separately from ground wires 37 and 3
8 is connected. Therefore, when the surge current is from the device or the circuit side, the terminal 32 is connected to the terminal 34.
And an arc discharge is applied to the terminal 36 and grounded.
However, if the surge current is a reverse current flowing from the ground wire 37 or 38, the arc current is discharged only to the terminals adjacent to each other, and the terminal 32 is not discharged. There is no.

Fourth Embodiment FIG. 4 is a circuit diagram showing an example of a surge current avoiding circuit according to a fourth embodiment. As shown in FIG. 1, as a basic circuit, commercial power L1, L2 is drawn in through a breaker 41, and a device 42 to be protected is connected thereto, and wiring between the breaker 41 and the device 42 is provided. An avoidance device 5 for avoiding a surge current is connected to 43 by a circuit line 45, which is grounded via a first earth line 53. In this circuit, a bypass line 54 is provided between the first ground line 53 and a second ground line La provided for the commercial power L2.
5 are arranged. The avoidance device 5 is composed of the high-sensitivity avoidance elements 51 and 52 which have the directionality of conduction as described in the first or second embodiment.

When a surge current arrives from the supply system of the commercial power supplies L1 and L2, such as lightning, the avoidance elements 51 and 52 immediately react and react from the avoidance device 5 via the circuit line 45 to the first ground line. Although grounded from 53, the surge current is eliminated, the avoidance device 5 cuts off, and commercial power again flows to the device 42 as normal.

On the other hand, when an induced lightning strike due to a lightning strike or the like to the neighborhood occurs and tries to invade from the first ground line 53 through the ground, it does not flow to the avoidance device 5 but to the bypass line 54. And the second ground line L via the semiconductor element 55
Since it flows to a, damage to the device 42 can be prevented. When there is no surge current, the bypass line 54 is cut off by the semiconductor element 1.

The function of preventing the backflow by the combination of the avoidance device 5 and the semiconductor element 5 can be replaced by the avoidance element 3 shown in the third embodiment.

On the other hand, the equipment 42 has a ground wire 6 grounded via the circuit wire 64 and the avoidance element 61 on its exterior frame.
3 is connected, and the avoiding element 61 is the same as that of the first embodiment.
Alternatively, an avoidance element as shown in 2 is used, but is selected depending on the type of the device 42 and the like. Also, the ground wire 63
A bypass line 65 is provided between the bypass line 65 and the circuit line 64, and the bypass element 65 is disposed on the bypass line 65. The avoidance element 61 is for reacting the surge current, such as static electricity, to the ground wire 63 when the surge current such as static electricity is generated in the outer frame of the device 42 so as not to flow into the inside of the device 42. When a surge current as described in the fourth embodiment is transmitted from the ground wire 63 to the ground, the surge current is caused to flow backward. Therefore, each avoidance element has one-way conductivity,
The resistance value of the avoidance element 61 is smaller than the resistance value of the avoidance element 62. The contact point between the bypass line 65 and the circuit line 64 is provided very close to the avoidance element 61.

A conventional surge current generated on the device 42 side is grounded by the reaction of the avoiding element 61. On the other hand, a surge current from the ground wire 63 side such as induced lightning flows through the bypass line 65 due to the reaction of the avoiding element 62, but is directed to the device 42 side by the reaction of the avoiding element 61. Is grounded through the ground wire 63 without flowing.

In the circuit for avoiding surge current shown in the first or second embodiment, the element portion is a compact element circuit.
By using a product with these terminals outside, it is possible to easily attach it to a conventional device or circuit as long as the ground wire is already provided.

Fifth Embodiment In a fifth embodiment, an example of use of the avoidance element and the avoidance circuit described in each of the above embodiments is shown, and FIG. 5 is a block diagram showing the outline. The inventor pays attention to the damage caused by the induced lightning as described above, and in the present embodiment, the distribution board of the optical communication cable is shown. That is, FIG.
The optical cable 7 laid as shown in (1) is fixed by screwing the tension member 71, and each optical communication line 72 is branched and connected to the conversion hub 8. Commercial power L is drawn into the wiring board 70, a terminal (outlet) 74 is provided, and a power supply line 81 of the conversion hub 8 is connected.

Although the tension member 71 can be simply connected to a conventional ground wire, it is connected to a ground wire 73 via a bypass circuit 75 as a more reliable countermeasure against surge current. This has a structure similar to that of the avoidance elements 61 and 62 shown in the fourth embodiment. On the other hand, an avoidance circuit 85 is provided between the commercial circuit L and the terminal 74, and is connected to the ground line 73. As the avoidance circuit 85, a circuit using the avoidance element 3 shown in the third embodiment or a structure similar to that of the avoidance device 5 and the semiconductor element 55 described in the fourth embodiment can be applied.

The avoidance circuit shown in the fifth embodiment is very effective as a countermeasure against induced lightning of an optical communication cable, which has not been given much importance in the past. Induction lightning is optical cable 7
Is grounded to the ground wire 73 via the avoidance circuit 75. on the other hand,
The induced lightning induced from the commercial power L is grounded via the avoidance circuit 85. In addition, the backflow of the induced lightning through each ground wire is grounded by the function described in the fourth embodiment. Therefore, it can be said that the wiring board 70 is effective as a complete countermeasure against induced lightning including the conversion HUB 8.

Further, in the above-described distribution board for an optical cable, a conversion HUB and a HUB for an electric signal (not shown) are built in the distribution board to constitute one communication device. By doing so, not only the communication line becomes more compact, but also a surge current generated before reaching the terminal device can be effectively and reliably processed by such a communication device. In such a communication device, since an optical cable and commercial power can be laid through the same pipe, installation work is easy, and the hermeticity of the communication device itself can be enhanced. In addition to surge current, it is possible to take measures against water damage. The same applies to wireless LAN systems that have been diversified in recent years.
It is also possible to incorporate a system, attach a surge current avoidance circuit thereto, and configure the system to also handle surge current from the antenna.

[0034]

According to the present invention having the above-described structure, the following effects can be obtained. (1) The apparatus can be comprehensively protected by effectively responding not only to the conventionally considered induced lightning and static electricity from the power supply direction, but also to the induced lightning that can be said to be a backflow from the ground wire. (2) Since it can be applied to any form of wiring, an avoidance element and an avoidance circuit that can protect not only terminal equipment but also the entire network from surge current can be attached to existing wiring or laid a new wiring board. It can be easily applied in the form.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a basic form of an avoidance element according to a first embodiment.

FIG. 2 is a schematic diagram illustrating a basic form of an avoidance element according to a second embodiment.

FIG. 3 is a schematic diagram illustrating a basic form of an avoidance element according to a third embodiment.

FIG. 4 is a circuit diagram of an avoidance circuit according to a fourth embodiment.

FIG. 5 is a block diagram illustrating a usage example of an avoidance element or an avoidance circuit according to a fifth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Avoidance element 11 ... Surge current reaction part 12 ... Semiconductor part 13 ... Ground wire 2 ... Avoidance element 21 ... Surge current reaction part 22 ... Terminal 23 ... Surge current reaction part 24 ... Terminal 3 Avoiding element 31 First surge current responsive section 32 Terminal 33 Second surge current responsive section 34 Terminal 35 Third surge current responsive section 36 Terminal 37 Ground Wire 38 Ground wire 41 Breaker 42 Equipment 43 Wiring 45 Circuit wire 5 Avoidance device 51 Avoidance element 52 Avoidance element 53 First ground wire 54 Bypass Line 55 Semiconductor element 61 Avoidance element 62 Avoidance element 63 Ground line 64 Circuit line 65 Bypass line La Second ground line L1 Commercial power L2 Commercial power

Claims (15)

[Claims] 1. A surge current avoiding element for conducting a current of a voltage higher than a predetermined value in response to a voltage higher than a predetermined value. A surge current avoiding element characterized by maintaining the following. 2. A surge device comprising: a surge current responsive portion that conducts a current of a voltage higher than a predetermined value in response to a voltage higher than a predetermined value; and a semiconductor portion that is conductive in a predetermined direction. Current avoidance element. 3. At least two surge current responsive parts for conducting a current of a higher voltage in response to a voltage higher than a certain value are provided, and terminals connected to the respective surge current responsive parts are spaced from each other. A surge current avoiding element characterized in that an arc voltage from one terminal to the other terminal is higher than an arc voltage in the opposite direction. 4. At least three surge current responsive parts for conducting a current of a higher voltage in response to a voltage higher than a predetermined value are provided, and terminals connected to the respective surge current responsive parts are spaced from each other. And face to face, the first
The surge current responsive section is connected to a device or circuit to be protected, the second and third surge current responsive sections are respectively connected to different ground wires, and the terminal of the first surge current responsive section is connected to the second surge current responsive section. A surge current avoiding element, wherein a distance between the terminal of the surge current responsive portion and the terminal of the third surge current responsive portion is greater than a distance between the terminal of the second surge current responsive portion and the terminal of the third surge current responsive portion. 5. The surge current avoiding element according to claim 4, wherein the terminal of the second surge current responsive section and the terminal of the third surge current responsive section are arranged close to each other. 6. The other end of a first ground wire having one end substantially grounded to one contact of a surge current avoiding element for conducting a current of a higher voltage in response to a voltage higher than a certain value. Is connected to the other contact of the avoiding element, and the other end of the circuit wire having one end connected to the protection device side is connected to the other ground contact between the first ground wire and a second ground wire separately provided therefrom. A surge current avoidance circuit characterized in that a bypass line is provided in the circuit. 7. The surge current according to claim 6, wherein an element having a semiconductor property whose conduction direction is from the first ground line side to the second ground line side is disposed in the middle of the bypass line. Avoidance circuit. 8. The other end of a ground wire, one end of which is substantially grounded, is connected to one contact of a surge current avoiding element that conducts a current of a higher voltage in response to a voltage higher than a certain value. A surge current avoiding circuit in which one end of the circuit line having one end connected to the protection device side is connected to the other contact of the avoiding element, wherein a bypass is provided between the ground line and the circuit line. A circuit for avoiding a surge current, wherein a line is provided, and an element or the like having a semiconductor property whose conduction direction is from the ground line side to the circuit line side is disposed in the middle of the bypass line. 9. The circuit for avoiding a surge current according to claim 7, wherein the element having a semiconductor property is a semiconductor element. 10. A current conduction direction of a surge current avoiding element is from a circuit line side to a first ground line side, or a surge current avoiding element that maintains conductivity in this direction up to a limit voltage. The surge current avoidance circuit according to claim 6, wherein: 11. The surge device according to claim 7, wherein the device having semiconductor properties is a surge current avoiding device that conducts a current of a voltage higher than a certain value in response to the voltage. Current avoidance circuit. 12. The surge device according to claim 8, wherein the device having a semiconductor property is a surge current avoiding device that conducts a current of a voltage higher than a certain value in response to the voltage of a certain value or more. Current avoidance circuit. 13. The surge current avoiding circuit according to claim 6, wherein the second ground wire is connected to a ground wire provided on the power supply side. 14. The surge current avoiding circuit according to claim 8, wherein a contact point of the bypass line with the circuit line side is provided close to the surge current avoiding element. 15. The device according to claim 12, wherein a resistance value of the avoidance element provided between the circuit line and the ground line is lower than a resistance value of the avoidance element provided on the bypass line side. Surge current avoidance circuit.