JPH088036A - Discharge type surge absorbing device - Google Patents

Abstract

PURPOSE:To provide a discharge type surge absorbing device capable of accommodating for normal mode surge going and returning between lines and common type surge transmitted between each line and ground in spite of a single device, and which does not generate transverse surge. CONSTITUTION:A first discharge electrode 14 and a second discharge electrode 16 are faced on the inside of an airtight container 12 filled with discharge gas to form a first discharging gap 26 between both electrodes. A third discharge electrode 18 is faced to the first discharge electrode 14 and the second discharge electrode 16 to form a second discharging gap 28 between the first discharge electrode and the third discharge electrode 18 and a third discharging gap 30 between the second discharge electrode 16 and the third discharge electrode 18. The gap length of the second discharging gap 28 is made almost equal to the gap length of the third discharging gap 30, and the gap length of the first discharging gap 26 is made shorter than the gap length of the second discharging gap 28 and that of the third discharging gap 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge type surge absorbing element which absorbs a surge by utilizing a discharge phenomenon in a discharge gap enclosed in an airtight container, and more particularly to a communication line which is a single element. The present invention relates to a discharge type surge absorbing element capable of performing a surge absorbing measure between lines such as a line and between each line and a ground.

[0002]

2. Description of the Related Art Conventionally, a discharge type surge utilizing a discharge phenomenon in a discharge gap enclosed in an airtight container in order to protect an electronic circuit element or the like from a surge such as a transient abnormal voltage entering an electronic device or an induced lightning strike. An absorbing element is used. FIG. 3 shows an example thereof, and this discharge type surge absorbing element 60 has a pair of discharge electrodes 64, 64 with a predetermined distance from each other in an airtight container 62 made of an insulating material such as glass or ceramic. The discharge gaps 66 are formed between the discharge electrodes 64, 64 so as to be opposed to each other, and the airtight container 62 is penetrated through the tip ends of the lead terminals 68, 68 connected to the base ends of the discharge electrodes 64, 64. It is derived from the outside. In the airtight container 62, Ne, Ar,
A discharge gas mainly containing a rare gas such as Xe or He is filled. The discharge electrodes 64, 64 are cylindrical electrode bases 64 made of a conductive material having good discharge characteristics such as Ni or Fe.
Emitter layers 64b and 64b made of an emitter material such as barium oxide or lanthanum hexaboride are formed on the tip surfaces of a and 64a.

When a surge voltage higher than the rated voltage is applied to the discharge type surge absorbing element 60 via the lead terminals 68, 68, arc discharge is generated in the discharge gap 66 through glow discharge, and this arc discharge is generated. Surge absorption is realized through the large current of. The operating voltage (DC discharge starting voltage) of this discharge type surge absorbing element 60 follows Paschen's law,
It is defined by the gap length of the discharge gap 66, the composition of the enclosed discharge gas, the gas pressure, and the like.

FIG. 4 is a circuit diagram showing an example of use of the discharge type surge absorbing element 60. This is a communication line T, R and a power line L connected to a general facsimile electronic circuit 70.
Connect various elements to 1, L2 and ground line G to protect circuit 72
Is formed. That is, the fuse 74, the first discharge type surge absorbing element 60a, the common mode choke coils 76a and 76b, the bridge diode 78 are provided on the communication lines T and R sides, and the power switch 80 is provided on the power line L1 and L2 sides. ,
Fuse 82, varistor 84, resistors 86, 88, capacitor 90
Is connected. Further, a second discharge type surge absorbing element 60b is connected between the communication line R and the ground line G, and a third discharge type surge absorbing element 60c is connected between the power source line L1 and the ground line G.

However, the communication lines T and R and the power line L
When a surge or noise from the outside enters into the protection circuit 72 via 1 and L2, the discharge type surge absorbing element or the like operates to absorb these. For example, regarding the case where a surge is applied to the communication lines T and R, first, for a normal mode surge that reciprocates between the communication lines T and R, the first discharge type surge inserted between the lines is used. Absorption element
60a operates and absorbs this. Also, for a common mode surge conducted between the communication line T and the ground, the first discharge type surge absorbing element 60a and the second discharge type surge absorbing element 60b operate to escape to the ground, With respect to the common mode surge conducted between the line R and the ground, the second discharge type surge absorbing element 60b operates to let it escape to the ground. The first discharge type surge absorbing element 60a is generally selected to have a relatively low operating voltage (DC discharge starting voltage) of 300 to 500V. As the second surge absorbing element 60b, one having a relatively high operating voltage of 1000 to 1500 V is generally selected.

[0006]

As described above, conventionally,
It is necessary to use at least two discharge-type surge absorption elements in order to deal with both normal mode surges that reciprocate between the lines and common mode surges that conduct between each line and ground. It was an obstacle to cost reduction.

Further, the operating voltage of the first discharge type surge absorbing element 60a is 300V, and the second discharge type surge absorbing element 60b is
Assuming that the operating voltage is 1000 V, the first discharge type surge absorbing element 60a and the second surge absorbing element 60b are connected in series between the communication line T and the ground. Discharge start voltage is 300V + 1000V
However, since only the second discharge type surge absorbing element 60b is interposed between the communication line R and the ground, the discharge start voltage between R and G is 1000V. In this way, if there is a difference in the discharge start voltage (surge absorption voltage) between T-G and R-G, when a surge of the same phase and same potential enters both lines, there is a time difference in the start of surge absorption. As a result, a so-called lateral surge is generated, and there is a risk that it will conduct between the lines and enter the electronic circuit 70 side.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a normal mode surge reciprocating between lines and a space between each line and the ground even though the device is a single element. It is to realize a discharge type surge absorption element that can cope with a common mode surge that is conducted and that does not generate a lateral surge.

[0009]

In order to achieve the above object, a discharge type surge absorber according to the present invention has a first discharge electrode and a second discharge electrode in an airtight container filled with a discharge gas. The first discharge gap is formed between the two discharge electrodes, and the third discharge electrode is separated from the first discharge electrode and the second discharge electrode by a predetermined distance. And a second discharge gap is formed between the first discharge electrode and the third discharge electrode, and a third discharge gap is formed between the second discharge electrode and the third discharge electrode. The gap length of the second discharge gap and the gap length of the third discharge gap are set to be substantially the same.

The gap length of the first discharge gap is set to the second gap.
May be smaller than the gap length of the discharge gap and the gap length of the third discharge gap. In addition, for example, the discharge starting voltage in the first discharge gap is 300 to 500V,
The discharge start voltage in the discharge gap and the third discharge gap is set to 1000 to 1500V. The lead terminals connected to the first discharge electrode, the second discharge electrode, and the third discharge electrode are led out to the outside of the airtight container, and at least between the lead wires on the inner surface of the airtight container, the creeping discharge characteristic It is desirable to configure it to deposit a good dielectric material.

[0011]

The discharge start voltage of the discharge type surge absorbing element is defined by the gap length of the discharge gap when the composition and gas pressure of the discharge gas sealed in the airtight container are constant.
That is, since the gap length of the second discharge gap and the gap length of the third discharge gap are substantially equal to each other, the discharge starting voltages in the second discharge gap and the third discharge gap are also substantially equal to each other.
On the other hand, when the gap length of the first discharge gap is smaller than the gap length of the second discharge gap and the gap length of the third discharge gap, the discharge start voltage in the first discharge gap is set. Is
The value is smaller than the discharge start voltage in the second discharge gap and the third discharge gap.

Therefore, for example, if the first discharge electrode and the second discharge electrode are respectively connected to a pair of communication lines and the third discharge electrode is grounded, a first discharge gap is created between the lines. In addition to being connected, the second discharge gap and the third discharge gap are connected between each line and the ground, respectively, and a surge countermeasure is provided between the lines and between each line and the ground even though it is a single element. Is possible.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a discharge type surge absorber according to the present invention.
FIG. 11 is a partial cross-sectional view showing 10. This discharge type surge absorber
10 is an airtight container formed by fusing both openings of a glass tube.
A discharge gas mainly composed of a rare gas such as Xe, Ne, Ar, and He is provided in 12 and three columnar discharge electrodes (first discharge electrode).
14, a second discharge electrode 16, a third discharge electrode 18) and a lead terminal 20, which is connected to the base end of each discharge electrode.
22 and 24 are formed by penetrating the fusion-bonded portions 12a and 12b of the airtight container 12 and leading them to the outside.

The first discharge electrode 14, the second discharge electrode 16 and the third discharge electrode 18 are made of metal such as Ni and Fe having a good discharge characteristic and are formed into a cylindrical shape.
lanthanum hexaboride (LaB ₆ ) on the tip surface of a, 18a
And barium oxide (BaO), calcium oxide (Ca
O), magnesium oxide (MgO) and the like, and emitter layers 14b, 16b and 18b are deposited. In each discharge electrode,
The first discharge electrode 14 and the second discharge electrode 16 are arranged so as to be parallel to each other with a first discharge gap 26 therebetween. Further, the tip surface of the third discharge electrode 18 is separated from the tip surfaces of the first discharge electrode 14 and the second discharge electrode 16 by a second discharge gap 28 and a third discharge gap 30, respectively. Are arranged to face each other. The first discharge gap 26 is about 0.8 mm,
The second discharge gap 28 and the third discharge gap 30 are each set to about 3 mm.

A dielectric layer 32 having a good creeping discharge characteristic is deposited on the inner surface of the airtight container 12. This dielectric layer 32 is specifically made of barium oxide (BaO), nickel oxide (NiO), barium titanate (BaTiO ₃ ).
Etc. A single substance or a mixture of dielectric substances having a relatively high dielectric constant is vapor-deposited in layers on the inner surface of the airtight container 12. The lead terminals 20, 22 are connected by 20, the 24 by 24, and the 24, 22 by the dielectric layer 32.

As for the operating voltage (DC discharge starting voltage) of the discharge type surge absorbing element, the gap length of the discharge gap is appropriately set when the composition and gas pressure of the discharge gas sealed in the airtight container are the same. It can be adjusted by In this embodiment, the discharge starting voltage in the first discharge gap 26 is set to about 300 V, and the second discharge gap 28 and the third discharge gap are set.
The discharge starting voltage in 30 is set to about 1000V, respectively.

FIG. 2 is a circuit diagram showing an example of use of the discharge type surge absorbing element 10. This is similar to FIG. 4 above.
Facsimile electronic circuit 70 Protection circuit 72 inserted in front stage
The same components as those described above are designated by the same reference numerals, and the description thereof will be omitted. First, the first lead terminal 20 and the second lead terminal 22 of the discharge type surge absorber 10
Are connected to the communication lines T and R, respectively, and the third lead terminal 24 is connected to the ground line G. As a result, the first discharge gap 26 is inserted between the communication lines T and R, and
The discharge gap 28 is inserted between the communication line T and the ground, and the third discharge gap 30 is inserted between the communication line R and the ground.

The protection circuit 72 is connected to the communication line T,
When a normal mode surge reciprocating in R is applied, a discharge is generated in the first discharge gap 26 of the discharge type surge absorbing element 10 to absorb the surge. On the other hand, when a common mode surge is applied between the communication line T and the ground, a discharge is generated in the second discharge gap 28, and the surge is released to the ground. Furthermore, if a common mode surge is applied between the communication line R and ground,
A discharge is generated in the discharge gap 30 and the surge is released to the ground. As described above, since the gap lengths of the second discharge gap 28 and the third discharge gap 30 are substantially equal to each other, and the discharge start voltages of the two are set to be equal to each other, they are in phase with the communication lines T and R.・ Even if a common mode surge of the same potential is applied, lateral surge does not occur as a result of the surge absorption starting at the same time.

As described above, since the dielectric layer 32 connecting the lead terminals is formed on the inner surface of the airtight container 12, when a surge is applied between any of the lead terminals, first, On the surface of the dielectric layer 32, creeping corona discharge excellent in surge response is generated, and surge absorption is immediately started. The priming effect of electrons and ions emitted by this creeping corona discharge makes it possible to generate an arc discharge in the discharge gap between the discharge electrodes in an extremely short time.

[0020]

In the discharge type surge absorbing element according to the present invention, since the first discharge gap, the second discharge gap and the third discharge gap are enclosed in the airtight container, a single discharge gap is formed. Although it is an element, it is possible to apply a surge absorbing measure between the lines and between the lines and the ground, which simplifies the configuration and reduces the cost. Moreover, by making the gap lengths of the second discharge gap and the third discharge gap substantially the same, the discharge start voltage of the second discharge gap and the discharge start voltage of the third discharge gap are designed to be equal. Therefore, by connecting the first discharge electrode and the second discharge electrode to each line and grounding the third discharge electrode, the surge absorption voltage between each line and ground can be set to the same value. As a result, even if a surge having the same phase and the same potential is applied between each line and the ground, there is no time difference in the start of surge absorption, and therefore there is no risk of a lateral surge.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a discharge type surge absorbing element according to the present invention.

FIG. 2 is a circuit diagram showing an example of use of the discharge type surge absorber.

FIG. 3 is a partial cross-sectional view showing a conventional discharge type surge absorber.

FIG. 4 is a circuit diagram showing an example of use of a conventional discharge type surge absorber.

[Explanation of symbols]

 10 Discharge type surge absorbing element 12 Airtight container 14 First discharge electrode 16 Second discharge electrode 18 Third discharge electrode 20 Lead terminal of first discharge electrode 22 Lead terminal of second discharge electrode 24 Third discharge Electrode lead terminal 26 First discharge gap 28 Second discharge gap 30 Third discharge gap 32 Dielectric layer

Claims (4)

[Claims] 1. A first container is provided in an airtight container filled with a discharge gas.
A second discharge electrode and a second discharge electrode facing each other at a predetermined distance to form a first discharge gap between the two discharge electrodes and a third discharge electrode connected to the first discharge electrode and the second discharge electrode. A second discharge gap between the first discharge electrode and the third discharge electrode, and a third discharge electrode between the second discharge electrode and the third discharge electrode. The discharge type surge absorbing element is characterized in that the discharge length of the second discharge gap and the length of the third discharge gap are set to be substantially the same. 2. The gap length of the first discharge gap is smaller than the gap length of the second discharge gap and the gap length of the third discharge gap. Discharge type surge absorber. 3. The discharge start voltage in the first discharge gap is set to 300 to 500 V, and the discharge start voltage in the second discharge gap and the third discharge gap is set to 10.
The voltage is set to 00 to 1500 V, and
Alternatively, the discharge type surge absorbing element described in 2. 4. The lead terminals connected to the first discharge electrode, the second discharge electrode and the third discharge electrode are respectively led out of the airtight container, and at least between the lead wires on the inner surface of the airtight container. 4. A dielectric substance having a good creeping discharge characteristic is deposited.
5. The discharge type surge absorber according to any one of 1.