JP2741654B2 - Discharge type surge absorbing element - Google Patents

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 for absorbing a surge by utilizing a discharge phenomenon in a discharge gap enclosed in an airtight container, and more particularly to a discharge type surge absorbing element capable of changing a discharge starting voltage. The present invention relates to a surge absorbing element.

[0002]

2. Description of the Related Art Conventionally, in order to protect electronic circuit elements and the like from surges such as transient abnormal voltage or induced lightning that enter an electronic device, a discharge type surge utilizing a discharge phenomenon in a discharge gap sealed in an airtight container. An absorbing element is used. FIG. 5 shows an example of this. In this discharge type surge absorbing element 60, the tip surfaces of a pair of discharge electrodes 64, 64 are separated by a predetermined distance in an airtight container 62 made of an insulating material such as glass or ceramic. The two discharge electrodes 64, 6
A discharge gap 66 is formed between the airtight container 6 and the distal end of the lead terminal 68 connected to the base end of each of the discharge electrodes 64.
2 and penetrate to the outside. The airtight container 62
The inside is filled with a discharge gas mainly composed of a rare gas such as Ne, Ar, Xe, and He. The discharge electrode 6
Reference numerals 4 and 64 denote an emitter material such as barium oxide (BaO) or lanthanum hexaboride (LaB ₆ ) on the surface of the tip of a cylindrical electrode substrate 64a made of a conductive material having good discharge characteristics such as Ni or Fe. The emitter layer 64b is formed.

When a surge is applied to the discharge type surge absorbing element 60 via the lead terminals 68, 68, an arc discharge is generated in the discharge gap 66 via a glow discharge, and a large current of the arc discharge is generated. Surge absorption is realized. The operating voltage (DC discharge starting voltage) of the discharge type surge absorbing element 60 is determined by the gap length of the discharge gap 66, the composition of the sealed discharge gas, the gas pressure, and the like according to Paschen's law.

[0004] As shown in FIG. 6, the discharge electrode surge absorbing element 60 is, for example, (in the figure L ₂₎ one of the pair of power supply lines L _1, L ₂ connected to the protected circuit 38 and the ground G Are connected through the lead terminals 68, 68. A varistor 40 is interposed between the power supply lines L ₁ and L ₂ , and a fuse 42 for interrupting overcurrent is connected in series to the power supply line L ₁ . When a normal mode surge that reciprocates between the power supply lines L ₁ and L ₂ is applied to the power supply lines L ₁ and L ₂ , the varistor 40 operates to absorb the surge. Further, when a common mode surge that is conducted between the power supply lines L ₁ , L ₂ and the ground G is applied, the discharge type surge absorbing element 60
Operates to escape this to the ground G.

[0005]

The operating voltage of the discharge type surge absorbing element 60 (DC discharge starting voltage).
Considering the voltage value of a general induced lightning surge (3000 V or less) which occurs as a natural phenomenon, the voltage should be set to about 300 to 500 V so that the surge can be reliably absorbed. However, in a withstand voltage test defined by the Electrical Appliance and Material Control Law, a power supply line L ₁ , L ₂ is short-circuited and an AC 1200 V (or AC) is applied between L ₁ , L ₂ -G.
Since an overvoltage of 1500 V) is applied for one minute, if a discharge type surge absorbing element having an operating voltage lower than this is connected, the element operates and a current flows due to the execution of the withstand voltage test. As a result, the test is rejected. For this reason, in the past, the discharge-type surge absorbing element 60 having a high operating voltage of 2400 to 3800 V had to be selected so as to never operate in the withstand voltage test. As a result, during the actual use of the protected circuit 38 after the withstand voltage test, 24
When a surge of less than 00 V is applied, the discharge type surge absorbing element 60 does not operate, and there is a risk that the protected circuit 38 cannot be effectively protected.

The present invention has been made in view of the above-mentioned conventional problems, and has provided a discharge type surge absorbing element capable of coping with both a withstand voltage test specified by the Electrical Appliance and Material Control Law and a general induced lightning surge. The purpose is to do.

[0007]

In order to achieve the above object, a discharge type surge absorbing element according to the present invention comprises a first discharge electrode and a second discharge electrode in an airtight container filled with a discharge gas. A first discharge gap having a discharge start voltage set to 300 to 500 V is formed between the two discharge electrodes at a predetermined distance from each other, and a third discharge electrode is arranged at a predetermined distance from the first discharge electrode. And a second discharge gap is formed between the two discharge electrodes, the gap length being longer than the first discharge gap and the discharge start voltage set at 2400 to 3800 V. Lead terminals connected to the second discharge electrode, the second discharge electrode and the third discharge electrode are respectively led out of the hermetic container, and the lead terminals of the second discharge electrode and the third
And an open / close switch having a movable iron piece and a fixed contact is connected between the lead terminal of the discharge electrode and the lead terminal of the discharge electrode.

In another discharge type surge absorbing element according to the present invention, a first discharge electrode and a second discharge electrode are opposed to each other at a predetermined distance in an airtight container filled with a discharge gas. A first discharge gap in which a discharge start voltage is set to 300 to 500 V is formed between the two discharge electrodes, and a third discharge electrode is disposed to face the first discharge electrode at a predetermined distance, and A second discharge gap having a gap length larger than the first discharge gap and having a discharge start voltage set at 2400 to 3800 V is formed between the discharge electrodes, and the first discharge electrode, the second discharge electrode, The lead terminals connected to the third discharge electrode are respectively led out of the hermetic container, and a first conductive member and a second conductive member are arranged on the outer surface of the hermetic container at a predetermined distance, and Lead terminal of first discharge electrode and first conductive portion And a conductive connecting member for connecting the lead terminal of the third discharge electrode and the second conductive member, and further connecting the first conductive member and the second conductive member to the outer surface of the hermetic container. Are detachably engaged. It is desirable to form a dielectric layer having excellent surface discharge characteristics at least between the lead terminals on the inner surface of the airtight container.

[0009]

The lead terminal of the second discharge electrode and the lead terminal of the third discharge electrode are kept open by turning off the open / close switch or removing the conductive connecting member. If a surge is conducted between the lead terminal and the lead terminal of the third discharge electrode, a discharge is generated in the second discharge gap formed between the first discharge electrode and the third discharge electrode, and the surge is absorbed. . On the other hand, the discharge starting voltage of the discharge type surge absorbing element increases in proportion to the gap length of the discharge gap when the composition and the pressure of the discharge gas sealed in the hermetic container are constant. After short-circuiting between the lead terminal of the discharge electrode and the lead terminal of the third discharge electrode outside the hermetic container, and conducting a surge between the lead terminal of the first discharge electrode and the lead end of the third discharge electrode, First
The second discharge electrode formed between the second discharge electrode and the second discharge electrode.
A discharge is generated in the first discharge gap having a smaller gap length than that of the first discharge gap, and the surge is absorbed.

Therefore, the first discharge gap and the second
The discharge starting voltage of the first discharge gap is set at 300 to 500 V, the discharge starting voltage of the second discharge gap is set at 2400 to 3800 V, If a voltage between the lead terminal of the second discharge electrode and the lead terminal of the third discharge electrode is opened outside the hermetic container when undergoing the withstand voltage test of the Control Law, an overvoltage of 1200 V (or 1500 V) can be obtained in the test. Is continuously applied, no discharge is generated not only in the first discharge gap but also in the second discharge gap, and no current flows, so that the test can be passed. On the other hand, after completion of the withstand voltage test, the lead terminal of the second discharge electrode and the lead terminal of the third discharge electrode are short-circuited by turning on the open / close switch or fitting a conductive connection member. 1
If a discharge is generated in the discharge gap, it is possible to reliably absorb a general induced lightning surge.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a partial sectional view showing a first discharge type surge absorbing element 10 according to the present invention. The first discharge type surge absorbing element 10 includes a discharge gas mainly composed of a rare gas such as Xe, Ne, Ar, and He in an airtight container 12 formed by fusing both ends of a glass tube. The columnar discharge electrodes (the first discharge electrode 14, the second discharge electrode 16, and the third discharge electrode 18) are sealed, and the lead terminals 20, 22, 24 connected to the base ends of the respective discharge electrodes. In an airtight container 1
2 through which the two fused portions 12a and 12b are penetrated and led to the outside.

First discharge electrode 14, second discharge electrode 16
And the third discharge electrode 18 is an electrode base 1 formed by processing a metal having good discharge characteristics, such as Ni or Fe, into a cylindrical shape.
Emitter layers 14b, 16b, 18b made of lanthanum hexaboride (LaB ₆ ), barium oxide (BaO), calcium oxide (CaO), magnesium oxide (M9O), etc. are deposited on the tip surfaces of 4a, 16a, 18a. Consisting of Among each discharge electrode, the first discharge electrode 14 and the second discharge electrode 1
6 are arranged in parallel with a first discharge gap 26 therebetween. Further, the third discharge electrode 18 is arranged such that the front end surface thereof faces the front end surfaces of the first discharge electrode 14 and the second discharge electrode 16 with a second discharge gap 28 therebetween. . The first discharge gap 26 is about 0.8 mm
And the second discharge gap 28 is set to about 6 mm.

On the inner surface of the hermetic container 12, a dielectric layer 29 having good creeping discharge characteristics is formed. Specifically, the dielectric layer 29 is made of barium oxide (BaO), nickel oxide (NiO), barium titanate (BaTiO).
₃ ) A simple substance or a mixture of dielectric substances having a relatively high dielectric constant, such as ₃ ), is formed on the inner surface of the hermetic container 12 in a layered manner. This dielectric layer 29 allows each of the lead terminals 20, 22, 2
Four are connected.

An open / close switch 30 is connected between the lead terminal 22 of the second discharge electrode 16 and the lead terminal 24 of the third discharge electrode 18 outside the hermetic container 12. The open / close switch 30 has a movable iron piece 30 a connected to the lead terminal 22 of the second discharge electrode 16 and a fixed contact 30 b connected to the lead terminal 24 of the third discharge electrode 18.

As shown in FIG. 2, the first discharge type surge absorbing element 10 is disposed on a substrate 34 in an electronic equipment housing 32. The wall 32a of the electronic device housing 32
Has a female threaded through hole 32b therein, and a screw 36 is inserted into the through hole 32b from outside the housing 32. And the open / close switch 30 is
The screw 36 is positioned so that the tip of the screw 36 just contacts the movable iron piece 30a. FIG. 3 is a circuit diagram showing a connection example of the first discharge type surge absorbing element 10. As shown, a pair of power supply lines L ₁ and L ₂ are connected to a protected circuit 38, and a varistor 4 is provided between the two lines L ₁ and L _2.
0 is interposed. Further, the power supply line L _1, a fuse 42 for interrupting an overcurrent are connected in series. Furthermore, the first discharge electrode 14 of the first discharge type surge absorbing element 10 is connected to the power line L ₂ through the lead terminal 20. A ground G is connected between the lead terminal 24 of the third discharge electrode 18 and the fixed contact 30b of the on / off switch 30.

2 and 3, since the on / off switch 30 is turned off, when a surge voltage higher than the rated voltage is applied to the first discharge type surge absorbing element 10, the first discharge electrode A discharge is generated in the second discharge gap 28 formed between the first discharge electrode 14 and the third discharge electrode 18, and the surge is released to the ground G. On the other hand, when the screw 36 is turned and its tip is inserted deep into the housing 32, the movable iron piece 30a comes into contact with the fixed contact 30b to turn on the on / off switch 30, and the second discharge electrode 16 Third
Is short-circuited, and as a result, the second discharge electrode 16 is also connected to the ground G. The discharge starting voltage of the discharge type surge absorbing element increases in proportion to the gap length of the discharge gap under the condition that the composition and pressure of the discharge gas sealed in the hermetic container are constant. Accordingly, when a surge is applied to the first discharge type surge absorbing element 10 in this state, the first discharge gap 26 has a smaller gap length than the second discharge gap 28, so that the first discharge gap 26 has a smaller length. A discharge is generated in the first discharge gap 26 formed between the discharge electrode 14 and the second discharge electrode 16, and the surge is released to the ground G.

By appropriately selecting the gap lengths of the first discharge gap 26 and the second discharge gap 28, the discharge starting voltage of the first discharge gap 26 is set to 300 to 500 V, and the second discharge gap 26 is set to the second discharge gap. The discharge starting voltage of the gap 28 is 2400
３3800V can be set. When a withstand voltage test according to the Electrical Appliance and Material Control Law is performed, the open / close switch 30
Is turned off, AC12 in the withstand voltage test is
When the voltage of 00V (or 1500V AC) is applied, the first discharge type surge absorbing element 10 does not operate,
The test does not fail because no current flows. On the other hand, after the withstand voltage test is completed, if the screw 36 is tightened to turn on the open / close switch 30 and then shipped,
Even when a normal surge is applied when the protected electronic device is used, a discharge is generated in the first discharge gap 26, and the surge is reliably absorbed. It should be noted that even if the screw tightening before shipment is forgotten and a discharge cannot be generated in the first discharge gap 26, a discharge can be generated in the second discharge gap 28. For at least 240
Applying a large voltage surge exceeding 0 V (or 3800 V) to the protected electronic device can be avoided.

As described above, since the dielectric layer 29 connecting the respective 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, a creeping corona discharge excellent in surge responsiveness is generated on the surface of the dielectric layer 29, and the surge absorption is immediately started. The priming effect of the electrons and ions emitted by the creeping corona discharge makes it possible to generate an arc discharge as a main discharge in a discharge gap between the discharge electrodes in a very short time.

FIG. 4 shows a second discharge type surge absorbing element 50 according to the present invention. In the second discharge type surge absorbing element 50, a first metal ring 52 as a conductive member is fitted on the outer periphery of the airtight container 12 and at a predetermined interval 54 from the first metal ring 52. A second metal ring 56 as a conductive member is fitted, and the lead terminal 22 of the second discharge electrode 16 and the first metal ring 52 are fitted.
And the lead terminal 2 of the third discharge electrode 18
4 and the second metal ring 56, and a conductive connection member 58 is fitted between the first metal ring 52 and the second metal ring 56. The conductive connecting member 58 is formed with a notch 5 having a predetermined size in a cylindrical metal ring.
Because of the provision of 8a, it can be detachably fitted from above the cylindrical airtight container 12. The width of the conductive connection member 58 is larger than the distance 54 between the first metal ring 52 and the second metal ring 56. The first metal ring 52 and the second metal ring 56 are electrically connected by the male connection member 58. The other configuration is substantially the same as that of the first discharge type surge absorbing element 10 described above.

The second discharge type surge absorbing element 50 also has
Like the above, the connecting lead terminals 20 of the first discharge electrode 14 to the power line L _2, the second metal ring 5
By connecting the ground G between the lead 6 and the lead terminal 24 of the third discharge electrode 18, the circuit configuration of FIG. 3 can be realized. When conducting a withstand voltage test according to the Electrical Appliance and Material Control Law, the conductive connection member 58 is removed and the second discharge electrode 1 is removed.
6 and the third discharge electrode 18 are kept open so that the second discharge type surge absorbing element 50 does not operate depending on the voltage applied in the withstand voltage test. On the other hand, if the conductive connection member 58 is fitted to short-circuit the second discharge electrode 16 and the third discharge electrode 18 after the withstand voltage test is completed, a normal surge occurs when the protected electronic device is used. Even if it is applied,
Discharge generation is realized in the first discharge gap 26, and surge is reliably absorbed. That is, in the second discharge type surge absorbing element 50, the first metal ring 5
2, the second metal ring 56, and the conductive connection member 58
Perform the same function as the open / close switch 30 in the first discharge type surge absorbing element 10 described above.

[0021]

According to the discharge type surge absorbing element of the present invention, the first discharge gap where the discharge starting voltage is set to 300 to 500 V and the second discharge gap where the discharge start voltage is set to 2400 to 3800 V are set. A discharge is generated inside the hermetic container, and by selecting ON / OFF of the open / close switch and attaching / detaching the conductive connection member to short-circuit / open between the second discharge electrode and the third discharge electrode outside the hermetic container. It is possible to switch between different gaps, so that it is possible to realize two types of high and low discharge inception voltages even with a single element, withstand voltage test specified in the Electrical Appliance and Material Control Law and general induced lightning surge Can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a schematic view showing an example of use of a first discharge type surge absorbing element.

FIG. 3 is a circuit diagram showing a usage example of the first discharge type surge absorbing element.

FIG. 4 is a schematic view showing a second discharge type surge absorbing element according to the present invention.

FIG. 5 is a sectional view showing a conventional discharge type surge absorbing element.

FIG. 6 is a circuit diagram showing a usage example of a conventional discharge type surge absorbing element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 1st discharge-type surge absorption element 12 Hermetic container 14 1st discharge electrode 16 2nd discharge electrode 18 3rd discharge electrode 20 Lead terminal of 1st discharge electrode 22 Lead terminal of 2nd discharge electrode 24th No. 3 discharge electrode lead terminal 26 First discharge gap 28 Second discharge gap 29 Dielectric layer 30 On / off switch 52 First metal ring (first conductive member) 56 Second metal ring (second conductive) Member) 58 conductive connecting member

Claims (3)

(57) [Claims] A first gas-tight container filled with a discharge gas contains a first gas.
And a second discharge electrode are arranged facing each other with a predetermined distance therebetween, and a discharge starting voltage of 300 to 500
V to form a first discharge gap set at
Discharge electrodes were disposed to face the first discharge electrode and the predetermined distance, rather the gap length than the first discharge gap in size between both the discharge electrodes, the discharge starting voltage 2400~3800V
Is formed, and the first discharge gap is set.
Connected to the electrode, the second discharge electrode and the third discharge electrode
The lead terminals are led out of the hermetic container and
Between the lead terminal of the electrode and the lead terminal of the third discharge electrode
Connected to an open / close switch equipped with a movable iron piece and fixed contacts
A discharge type surge absorbing element, characterized in that: 2. A first airtight container filled with a discharge gas.
Discharge electrode and second discharge electrode facing each other at a predetermined distance
And a discharge starting voltage of 300 to 500 between both discharge electrodes.
V to form a first discharge gap set at
At a predetermined distance from the first discharge electrode
Arranged opposite to each other and between the two discharge electrodes more than the first discharge gap.
Large gap length, discharge start voltage 2400-3800V
Is formed, and the first discharge gap is set.
Connected to the electrode, the second discharge electrode and the third discharge electrode
Lead terminals are led out of the airtight container and
A first conductive member and a second conductive member on the outer surface of the airtight container;
The second discharge electrode is disposed at a predetermined distance from the second discharge electrode.
Between the terminal and the first conductive member and between the third discharge electrode
Connect the lead terminal and the second conductive member respectively,
And a first conductive member and a second conductive portion on the outer surface of the hermetic container.
The conductive connection member that connects the members is detachably engaged.
And a discharge type surge absorbing element. 3. The discharge type surge absorbing element according to claim 1, wherein a dielectric layer having good surface discharge characteristics is formed at least between the lead terminals on the inner surface of the hermetic container.