Surge protection device and gas-filled discharge tube

Abstract

In this surge protection device comprising at least one gas-filled discharge tube, a gap with a non-short-circuited carbon trigger in the at least one gas-filled discharge tube having the non-short-circuited carbon trigger and a gap with a short-circuited carbon trigger in the at least one gas-filled discharge tube having the short-circuited carbon trigger are connected to each other in series.

Description

Surge protection device and gas-filled discharge tube

[0001] The present invention relates to a surge protection device and a gas-filled discharge tube provided with a gas-filled discharge tube having a carbon trigger structure.

[0002] The gas-filled discharge tube (GDT) is a well-known component as a low-voltage surge protection device component, as its requirements and test circuits are defined in JIS C5381-311 (IEC 61643-311).

[0003] Patent Document 1 describes a gas-filled discharge tube provided with a carbon trigger structure for causing initial electron emission due to electric field concentration in a ceramic cylinder in order to improve the response characteristics of surge protection.

[0004] Patent Document 2 describes a DC protection device in which gaps are connected in series in multiple stages in order to increase the arc voltage and make it applicable to the power supply voltage.

[0005] Japanese Patent No. 3299584, Japanese Unexamined Patent Publication No. 52-016648

[0006] According to the prior art as described in Patent Documents 1 and 2, there has been a problem that the operating voltage (shock wave discharge start voltage) when a lightning surge enters becomes higher by the number of multiple gaps, and the response speed to the lightning surge decreases.

[0007] Therefore, an object of the present invention is to provide a surge protection device and a gas-filled discharge tube that can be applied to a desired power supply voltage by increasing the arc voltage and can also increase the response speed to a lightning surge.

[0008] According to the present invention, there is provided a surge protection device including at least one gas-filled discharge tube, in which a gap with a non-short-circuit carbon trigger in at least one gas-filled discharge tube having a non-short-circuit carbon trigger and a gap with a short-circuit carbon trigger in at least one gas-filled discharge tube having a short-circuit carbon trigger are connected in series with each other.

[0009] A short-circuit carbon-triggered gap is provided, and this short-circuit carbon-triggered gap is connected in series with a non-short-circuit carbon-triggered gap. The short-circuit carbon-triggered gap has a faster response speed because it does not have the delay time due to initial electron emission, which is the dominant factor in discharge delay in the discharge phenomenon, and as a result, the response speed as a surge protection device is faster. The discharge delay when a lightning surge is applied depends on the statistical delay until the initial electrons appear inside the gas-filled discharge tube and the formation delay until the avalanche phenomenon occurs, which allows a sufficient current to flow after the initial electrons appear, but the statistical delay is considered to be particularly dominant. In the short-circuit carbon-triggered gap, the response speed is faster because it does not have the delay time due to initial electron emission, which is this statistical delay.

[0010] Preferably, the gas-filled discharge tube is composed of a plurality of gas-filled discharge tubes, each having at least one gas-filled discharge tube connected in series with the others, and at least one of the plurality of gas-filled discharge tubes has a non-short-circuit carbon-triggered gap, while the remaining gas-filled discharge tubes have short-circuit carbon-triggered gaps. Since the gas-filled discharge tube with the short-circuit carbon-triggered gap and the gas-filled discharge tube with the non-short-circuit carbon-triggered gap are connected in series, the response speed is faster by the amount of the short-circuit carbon-triggered gap, for reasons such as the absence of a delay time due to initial electron emission.

[0011] Preferably, at least one gas-filled discharge tube consists of a single gas-filled discharge tube, and the single gas-filled discharge tube comprises a non-short-circuit carbon-triggered gap and a short-circuit carbon-triggered gap connected in series with each other. Because the short-circuit carbon-triggered gap and the non-short-circuit carbon-triggered gap are connected in series, the response speed is faster by the amount of the short-circuit carbon-triggered gap, for reasons such as the absence of a delay time due to initial electron emission.

[0012] In this case, it is more preferable that the single gas-filled discharge tube comprises an insulating structure, a plurality of insulating cylinders formed in the insulating structure, a pair of electrodes provided at both ends of each of the plurality of insulating cylinders, a gap with a non-short-circuit carbon trigger formed on the inner wall of some of the plurality of insulating cylinders and having a non-short-circuit carbon trigger that does not short-circuit the pair of electrodes, and a gap with a short-circuit carbon trigger formed on the inner wall of the remaining insulating cylinders and having a short-circuit carbon trigger that short-circuits the pair of electrodes.

[0013] It is also preferable that multiple insulating cylinders are arranged in parallel within the insulating structure while being connected in series with each other, or that multiple insulating cylinders are arranged in series while being connected in series with each other.

[0014] According to the present invention, a gas-filled discharge tube is provided which has a short-circuit carbon trigger gap with a short-circuit carbon trigger.

[0015] A short-circuit carbon-triggered gap eliminates the delay time caused by initial electron emission, which is the dominant factor in discharge delay in the discharge phenomenon. Therefore, if a short-circuit carbon-triggered gap is provided in a gas-filled discharge tube, the response speed will be faster.

[0016] The device further includes a non-short-circuit carbon-triggered gap with a non-short-circuit carbon trigger, and it is preferable that the non-short-circuit carbon-triggered gap and the short-circuit carbon-triggered gap are connected in series with each other. Because the short-circuit carbon-triggered gap and the non-short-circuit carbon-triggered gap are connected in series, the response speed is faster by the amount of the short-circuit carbon-triggered gap, for reasons such as the absence of a delay time due to initial electron emission.

[0017] According to the present invention, by connecting a short-circuit carbon-triggered gap in series with a non-short-circuit carbon-triggered gap, the response speed is increased because there is no delay time due to initial electron emission in the short-circuit carbon-triggered gap.

[0018] This is a schematic front view showing the overall configuration of a gas-filled discharge tube as one embodiment of the surge protection device of the present invention. This is a perspective view of the gas-filled discharge tube shown in Figure 1, where (A) is a perspective view seen from diagonally above and (B) is a perspective view seen from diagonally below. This is a plan view showing the schematic configuration of the gas-filled discharge tube shown in Figure 1. This is a cross-sectional view of Figure 3, where (A) is a cross-sectional view along line A-A in Figure 3, (B) is a cross-sectional view along line B-B in Figure 3, and (C) is a cross-sectional view along line C-C in Figure 3. This is an axial cross-sectional view showing an electrode coaxially fixed to the insulating cylindrical body of the gas-filled discharge tube shown in Figure 1. This is a plan view showing an example of the configuration of a short-circuit carbon trigger for the gas-filled discharge tube shown in Figure 1. This is a plan view showing an example of the configuration of a non-short-circuit carbon trigger for the gas-filled discharge tube shown in Figure 1. This is a schematic cross-sectional view showing the overall configuration of a gas-filled discharge tube with a different configuration as another embodiment of the surge protection device of the present invention. This is a schematic cross-sectional view showing the overall configuration of Sample 1 in Examples 1 and 2 of the present invention. This is a schematic cross-sectional view showing the overall configuration of Sample 2 in Examples 1 and 2 of the present invention. This is a characteristic diagram showing an example of the current waveform and voltage waveform of a gas-filled discharge tube in Embodiment 1 of the present invention. This is a characteristic diagram showing another example of the current waveform and voltage waveform of a gas-filled discharge tube in Embodiment 1 of the present invention. This is a cross-sectional view schematically showing the overall configuration of Samples 3 to 5 in Embodiment 3 of the present invention.

[0019] Figure 1 schematically shows the overall configuration of a gas-filled discharge tube in a front view as one embodiment of the surge protection device of the present invention, and Figure 2 shows the configuration of this gas-filled discharge tube viewed from diagonally above and diagonally below. Note that the arrow ARW in Figure 2 represents the direction of the front view in Figure 1. Figure 3 shows the schematic configuration of this gas-filled discharge tube in a plan view, and in Figure 4, (A) shows the cross section of the section along line A-A in Figure 3, (B) shows the cross section of the section along line B-B, and (C) shows the cross section of the section along line C-C. Figure 5 shows electrodes coaxially fixed to the insulating cylindrical body of this gas-filled discharge tube.

[0020] This embodiment is an example in which the surge protection device of the present invention is realized with a single gas-filled discharge tube, but the surge protection device of the present invention may be composed of a plurality of gas-filled discharge tubes connected in series with each other. In that case, some of the plurality of gas-filled discharge tubes (for example, one or two gas-filled discharge tubes) are composed of gas-filled discharge tubes equipped with a non-short-circuit carbon-triggered gap, and the remaining gas-filled discharge tubes of the plurality of gas-filled discharge tubes are composed of gas-filled discharge tubes equipped with a short-circuit carbon-triggered gap, and these gas-filled discharge tubes are electrically connected in series with each other.

[0021] As shown in Figures 1 to 4, the gas-filled discharge tube 10 constituting the surge protection device of this embodiment comprises an insulating structure 11 formed to have a flat, substantially rectangular parallelepiped outer shape, a plurality of insulating cylindrical bodies 12a to 12i (nine in this embodiment, arranged in 3 rows and 3 columns) formed to penetrate vertically between the upper and lower surfaces of the insulating structure 11 and arranged in parallel with each other, upper end electrodes 13a to 13i fixed coaxially to the upper ends of the insulating cylindrical bodies 12a to 12i, and lower end electrodes fixed coaxially to the lower ends of the insulating cylindrical bodies 12a to 12i. The device comprises electrodes 14a to 14i, a connecting wire 15a connecting lower electrodes 14a and 14b, a connecting wire 15b connecting upper electrodes 13b and 13c, a connecting wire 15c connecting lower electrodes 14c and 14d, a connecting wire 15d connecting upper electrodes 13d and 13e, a connecting wire 15e connecting lower electrodes 14e and 14f, a connecting wire 15f connecting upper electrodes 13f and 13g, a connecting wire 15g connecting lower electrodes 14g and 14h, and a connecting wire 15h connecting upper electrodes 13h and 13i.

[0022] The insulating structure 11, which has insulating cylindrical bodies 12a to 12i, is made of a ceramic material such as alumina, the upper electrodes 13a to 13i and the lower electrodes 14a to 14i are made of iron-nickel alloy, iron-nickel-cobalt alloy, or oxygen-free copper, and the connecting wires 15a to 15h are made of copper, brass, or phosphor bronze. The insulating cylindrical bodies 12a to 12i and the upper electrodes 13a to 13i and lower electrodes 14a to 14i are firmly joined to each other with a binder such as silver solder, the inside of the insulating cylindrical bodies 12a to 12i is sealed, and a gas containing an inert gas such as argon gas is sealed inside.

[0023] In the gas-filled discharge tube 10 of this embodiment, nine insulating cylindrical bodies 12a to 12i are provided with opposing upper electrodes 13a to 13i and lower electrodes 14a to 14i, thereby forming nine gaps between the upper electrodes 13a to 13i and the lower electrodes 14a to 14i, and these gaps are electrically connected in series with each other by connecting wires 15a to 15h.

[0024] Each of the upper electrodes 13a to 13i and lower electrodes 14a to 14i, for example, the upper electrode 13a, is composed of a disc-shaped electrode base 13a1 and a cylindrical electrode projection 13a2 that protrudes from the plane of the electrode base 13a1, as shown in Figure 5. The electrode projection 13a2 is coaxially inserted into the upper end of the insulating cylinder 12a and firmly fixed with a binder such as silver solder. However, a gap is formed between the inner surface of the insulating cylinder 12a and the outer surface of the electrode projection 13a2. The dimensions of the insulating structure 11, insulating cylindrical bodies 12a to 12i, upper electrodes 13a to 13i, and lower electrodes 14a to 14i are merely examples, but the upper and lower surfaces of the insulating structure 11 are approximately 24 mm x 24 mm and the height is approximately 4.5 mm, the inner diameter of each of the insulating cylindrical bodies 12a to 12i is approximately 4 mm, and the upper electrodes 13a to 13i and lower electrodes 14a to 14i each have an electrode base diameter of approximately 6 mm, a thickness of approximately 0.8 mm, an electrode projection diameter of approximately 3.8 mm, and a thickness of approximately 2 mm.

[0025] As shown in Figure 4, short-circuit carbon triggers 16a, 16b, and 16d-16i are formed on the inner walls of the insulating cylinders 12a, 12b, and 12d-12i, and a non-short-circuit carbon trigger 16c is formed on the inner wall of the insulating cylinder 12c. The short-circuit carbon triggers 16a, 16b, and 16d-16i are formed to electrically contact and short-circuit conductive metallized portions 17a, 17b, and 17d-17i (see Figure 6) formed at the upper ends of the insulating cylinders 12a, 12b, and 12d-12i, and conductive metallized portions 18a, 18b, and 18d-18i (see Figure 6) formed at the lower ends. The non-short-circuit carbon trigger 16c is formed such that it is electrically non-short-circuited to both the conductive metallized portion 17c (see Figure 7) formed at the upper end of the insulating cylindrical body 12c and the conductive metallized portion 18c (see Figure 7) formed at the lower end. The metallized portions 17a to 17i are electrically connected to the upper end electrodes 13a to 13i, and the metallized portions 18a to 18i are electrically connected to the lower end electrodes 14a to 14i. A short-circuit carbon-triggered gap is formed by insulating cylindrical bodies 12a, 12b, and 12d-12i, upper end electrodes 13a, 13b, and 13d-13i and lower end electrodes 14a, 14b, and 14d-14i, and short-circuit carbon triggers 16a, 16b, and 16d-16i. A non-short-circuit carbon-triggered gap is formed by insulating cylindrical body 12c, upper end electrode 13c and lower end electrode 14c, and non-short-circuit carbon trigger 16c.

[0026] Next, the functions and operations of short-circuit carbon triggers and non-short-circuit carbon triggers will be explained. In a gap with a non-short-circuit carbon trigger, when one end of the carbon trigger is electrically coupled to the electrode, the electric field strength at the tip of the other end increases, causing initial electron emission. When initial electron emission occurs, electrons flow along the surface of the carbon trigger at the start of discharge, emitting even more electrons and ultraviolet light, and an electron avalanche occurs due to the high electric field of the discharge gap. At the start of discharge, initial electron emission occurs, and this discharge delay reduces the response speed. The discharge delay when a lightning surge is applied depends on the statistical delay until the initial electrons appear inside the gas-filled discharge tube and the formation delay from the appearance of the initial electrons until a state is reached where sufficient current can flow and the avalanche phenomenon occurs, but the former statistical delay is particularly large. Therefore, in a gap with a non-short-circuit carbon trigger where initial electron emission occurs, the discharge delay is large and the response speed decreases. On the other hand, in a gap with a short-circuit carbon trigger, the response speed is faster because there is no delay time due to initial electron emission, which is the dominant factor in the discharge delay in the discharge phenomenon.

[0027] Figure 6 shows an example of the configuration of a short-circuit carbon trigger for this gas-filled discharge tube with the inner wall of the insulating cylinder unfolded.

[0028] As shown in Figure 6(A), the inner wall of the insulating cylinder 12a1 is provided with a plurality (four) of short-circuit carbon triggers 16a1 that extend parallel to each other in the vertical direction, at equal intervals. These short-circuit carbon triggers 16a1 are designed to electrically contact and short-circuit both the metallized portion 17a1 formed at the upper end and the metallized portion 18a1 formed at the lower end of the inner wall of the insulating cylinder 12a1. Each short-circuit carbon trigger 16a1 is mainly made of graphite (carbon) and is formed by drawing lines using a pencil (mechanical pencil) lead with a diameter of about 0.3 to 1.0 mm. The resistance value of the short-circuit carbon triggers 16a1 is several hundred ohms to several MΩ. The number and spacing of the short-circuit carbon triggers 16a1 are selected depending on the size of the gas-filled discharge tube, etc., and are not limited to the illustrated example. While this short-circuit carbon trigger was illustrated using the example of drawing a line with a pencil (mechanical pencil) lead, another method is to print with a non-volatile organic material (e.g., oil or fat) and then decompose it at high temperature in the absence of oxygen, forming the carbon from the remaining residue. The method of formation is not limited to carbon.

[0029] As shown in Figure 6(B), multiple (two) short-circuit carbon triggers 16a2 extending parallel to each other in the vertical direction are provided at equal intervals on the inner wall of the insulating cylinder 12a2. These short-circuit carbon triggers 16a2 are formed to electrically contact and short-circuit both the metallized portion 17a2 formed at the upper end and the metallized portion 18a2 formed at the lower end of the inner wall of the insulating cylinder 12a2. Each short-circuit carbon trigger 16a2 is mainly made of graphite (carbon) and is formed by drawing lines using a pencil (mechanical pencil) lead with a diameter of about 0.3 to 1.0 mm. The resistance value of the short-circuit carbon triggers 16a2 is several hundred ohms to several MΩ. The number and spacing of the short-circuit carbon triggers 16a2 are selected depending on the size of the gas-filled discharge tube, etc., and are not limited to the illustrated example. While this short-circuit carbon trigger was illustrated using the example of drawing a line with a pencil (mechanical pencil) lead, another method is to print with a non-volatile organic material (e.g., oil or fat) and then decompose it at high temperature in the absence of oxygen, forming the carbon from the remaining residue. The method of formation is not limited to carbon.

[0030] Figure 7 shows an example of a non-short-circuit carbon trigger configuration for a gas-filled discharge tube with the inner wall of the insulating cylinder unfolded.

[0031] As shown in Figure 7(A), the inner wall of the insulating cylinder 12c1 is provided with a plurality (four) of non-short-circuit carbon triggers 16c1 that extend parallel to each other in the vertical direction, at equal intervals. These non-short-circuit carbon triggers 16c1 are formed to be electrically non-contact with both the metallized portion 17c1 formed at the upper end and the metallized portion 18c1 formed at the lower end of the inner wall of the insulating cylinder 12c1. Each non-short-circuit carbon trigger 16c1 is mainly made of graphite (carbon) and is formed by drawing lines using a pencil (mechanical pencil) lead with a diameter of about 0.3 to 1.0 mm. The number and spacing of the non-short-circuit carbon triggers 16c1 are selected depending on the size of the gas-filled discharge tube, etc., and are not limited to the illustrated example. While this short-circuit carbon trigger was illustrated using the example of drawing a line with a pencil (mechanical pencil) lead, another method is to print with a non-volatile organic material (e.g., oil or fat) and then decompose it at high temperature in the absence of oxygen, forming the carbon from the remaining residue. The method of formation is not limited to carbon.

[0032] As shown in Figure 7(B), the inner wall of the insulating cylinder 12c2 is provided with a plurality (four) of non-short-circuit carbon triggers 16c2 extending parallel to each other in the vertical direction, at equal intervals. These non-short-circuit carbon triggers 16c2 are formed so as not to be electrically in contact with either the metallized portion 17c2 formed at the upper end of the inner wall of the insulating cylinder 12c1 or the metallized portion 18c2 formed at the lower end. Each non-short-circuit carbon trigger 16c2 is mainly made of graphite (carbon) and is formed by drawing lines using a pencil (mechanical pencil) lead with a diameter of about 0.3 to 1.0 mm. The number and spacing of the non-short-circuit carbon triggers 16c2 are selected depending on the size of the gas-filled discharge tube, etc., and are not limited to the illustrated example. While this short-circuit carbon trigger was illustrated using the example of drawing a line with a pencil (mechanical pencil) lead, another method is to print with a non-volatile organic material (e.g., oil or fat) and then decompose it at high temperature in the absence of oxygen, forming the carbon from the remaining residue. The method of formation is not limited to carbon.

[0033] As shown in Figure 7(C), the inner wall of the insulating cylinder 12c3 is provided with a plurality (2) of non-short-circuit carbon triggers 16c3 that extend parallel to each other in an oblique direction with respect to the vertical direction. These non-short-circuit carbon triggers 16c3 are formed to be electrically non-contact with both the metallized portion 17c3 formed at the upper end and the metallized portion 18c3 formed at the lower end of the inner wall of the insulating cylinder 12c3. Each non-short-circuit carbon trigger 16c3 is mainly made of graphite (carbon) and is formed by drawing lines using a pencil (mechanical pencil) lead with a diameter of about 0.3 to 1.0 mm. The number and spacing of the non-short-circuit carbon triggers 16c3 are selected depending on the size of the gas-filled discharge tube, etc., and are not limited to the illustrated example. While this short-circuit carbon trigger was illustrated using the example of drawing a line with a pencil (mechanical pencil) lead, another method is to print with a non-volatile organic material (e.g., oil or fat) and then decompose it at high temperature in the absence of oxygen, forming the carbon from the remaining residue. The method of formation is not limited to carbon.

[0034] As shown in Figure 7(D), the inner wall of the insulating cylinder 12c4 is provided with multiple (two) non-short-circuit carbon triggers 16c4 arranged in an X shape at an intersection. These non-short-circuit carbon triggers 16c4 are formed to be electrically non-contact with both the metallized portion 17c4 formed at the upper end and the metallized portion 18c4 formed at the lower end of the inner wall of the insulating cylinder 12c4. Each non-short-circuit carbon trigger 16c4 is mainly made of graphite (carbon) and is formed by drawing lines using a pencil (mechanical pencil) lead with a diameter of about 0.3 to 1.0 mm. The number and spacing of the non-short-circuit carbon triggers 16c4 are selected depending on the size of the gas-filled discharge tube, etc., and are not limited to the illustrated example. Although this short-circuit carbon trigger is shown as being formed by drawing lines using a pencil (mechanical pencil) lead, another method is to print with a non-volatile organic material (e.g., oil or fat) and form it with carbon remaining as a residue by high-temperature decomposition in the absence of oxygen. The method of formation is not limited as long as it is made of carbon.

[0035] As shown in Figure 7(E), the inner wall of the insulating cylinder 12c5 is provided with a plurality (four) of non-short-circuit carbon triggers 16c5 that extend parallel to each other in the vertical direction, at equal intervals. These non-short-circuit carbon triggers 16c5 are formed so as not to be electrically in contact with either the metallized portion 17c5 formed at the upper end of the inner wall of the insulating cylinder 12c5 or the metallized portion 18c5 formed at the lower end. A horizontal bar is formed in the portion that is electrically in contact with the metallized portion 17c5 or the metallized portion 18c5 to ensure that contact is secure. Each non-short-circuit carbon trigger 16c5 is mainly made of graphite (carbon) and is formed by drawing lines using a pencil (mechanical pencil) lead with a diameter of about 0.3 to 1.0 mm. The number and spacing of the non-short-circuit carbon triggers 16c5 are selected depending on the size of the gas-filled discharge tube, etc., and are not limited to the illustrated example. While this short-circuit carbon trigger was illustrated using the example of drawing a line with a pencil (mechanical pencil) lead, another method is to print with a non-volatile organic material (e.g., oil or fat) and then decompose it at high temperature in the absence of oxygen, forming the carbon from the remaining residue. The method of formation is not limited to carbon.

[0036] As described above, in this embodiment, one non-short-circuit carbon-triggered gap and eight short-circuit carbon-triggered gaps are electrically connected in series with each other. As a result, (1) by providing short-circuit carbon-triggered gaps, the response speed to lightning surges can be increased because there is no delay time due to initial electron emission, which is the dominant factor in discharge delay; (2) by connecting gaps in multiple stages, the total arc voltage can be increased to (arc voltage) × (number of gaps) and applied to the desired power supply voltage; and (3) by connecting gaps in multiple stages, the arc voltage can be increased and follow current can be interrupted. In a gas-filled discharge tube, if a power supply voltage is applied after it has been activated by a lightning surge, there is a possibility of follow current generation. That is, if the current is several hundred mA to 1A or more, the discharge becomes an arc state and a low voltage (around 15 to 25V) is maintained, so the follow current does not stop and continues. While increasing the number of gaps can raise the total arc voltage and thus interrupt the follow current, conventional technology uses multiple non-short-circuit carbon-triggered gaps, which increases the operating voltage (especially the shock wave discharge initiation voltage), delaying the discharge initiation and reducing the lightning protection effect. In this embodiment, however, one non-short-circuit carbon-triggered gap and eight short-circuit carbon-triggered gaps are electrically connected in series with each other, so the delay time due to initial electron emission occurs in only one gap, thus eliminating the problem of delayed discharge initiation.

[0037] Furthermore, by providing a non-short-circuit carbon-triggered gap, insulation can be maintained when lightning surges are not present. The lightning surge activation voltage of this non-short-circuit carbon-triggered gap depends on the speed of the lightning surge, but is usually around 500V to 1200V. By connecting a non-short-circuit carbon-triggered gap and a short-circuit carbon-triggered gap in series, the arc voltage when discharging in the gap can be brought close to the commercial voltage of AC 100Vrms or AC 200Vrms, thereby blocking the follow current.

[0038] When installing a short-circuit protection device, which consists of a gas-filled discharge tube with a short-circuit carbon trigger and a gas-filled discharge tube with a non-short-circuit carbon trigger connected in series to a commercial power supply, for example, it is desirable that the AC discharge initiation voltage of the non-short-circuit carbon trigger does not discharge at the commercial power supply voltage. This is because, when the short-circuit carbon trigger is not undergoing discharge, it acts as a single resistor. Therefore, the gas-filled discharge tube with the non-short-circuit carbon trigger connected in series with this resistor may discharge at the commercial power supply voltage, potentially causing adverse effects on the power supply.

[0039] In this embodiment, one non-short-circuit carbon-triggered gap and eight short-circuit carbon-triggered gaps are electrically connected in series with each other. However, the number of non-short-circuit carbon-triggered gaps and the number of short-circuit carbon-triggered gaps in the present invention are not limited to this. However, due to the response speed, it is desirable that the number of non-short-circuit carbon-triggered gaps be at least one, and possibly two to three.

[0040] Figure 8 schematically shows the overall configuration of a gas-filled discharge tube with a different configuration, as another embodiment of the surge protection device of the present invention.

[0041] As shown in Figure 8, the gas-filled discharge tube 110 constituting the surge protection device of this embodiment comprises a plurality (nine in this embodiment) of insulating cylindrical bodies 112a to 112i arranged in series with respect to each other in the vertical direction between the upper and lower surfaces of a structure formed to have a vertically elongated rod-shaped outer shape, and electrically connected in series; upper end electrodes 113a to 113i fixed coaxially to the upper ends of the insulating cylindrical bodies 112a to 112i, respectively; and lower end electrodes 114a to 114i fixed coaxially to the lower ends of the insulating cylindrical bodies 112a to 112i, respectively. The upper electrode 113a is electrically connected to the external connecting conductor 115a, the lower electrode 114a and the upper electrode 113b are electrically connected by the connecting conductor 115b, the lower electrode 114b and the upper electrode 113c are electrically connected by the connecting conductor 115c, the lower electrode 114c and the upper electrode 113d are electrically connected by the connecting conductor 115d, and the lower electrode 114d and the upper electrode 113e are electrically connected by the connecting conductor 115e. The lower electrode 114e and the upper electrode 113f are electrically connected by a connecting conductor 115f, the lower electrode 114f and the upper electrode 113g are electrically connected by a connecting conductor 115g, the lower electrode 114g and the upper electrode 113h are electrically connected by a connecting conductor 115h, the lower electrode 114h and the upper electrode 113i are electrically connected by a connecting conductor 115i, and the lower electrode 114i is electrically connected to an external connecting conductor 115j.

[0042] The insulating structure 111, which has insulating cylindrical bodies 112a to 112i, is made of a ceramic material such as alumina, and the upper electrodes 113a to 113i and lower electrodes 114a to 114i and connecting conductors 115a to 115j are made of copper-nickel alloy or iron-nickel alloy. The insulating cylindrical bodies 112a to 112i and the connecting conductors 115a to 115j are firmly joined to each other with a binder such as silver solder, and the connecting conductors 115a to 115j and the upper electrodes 113a to 113i and lower electrodes 114a to 114i are also firmly joined to each other with a binder such as silver solder. The insulating cylindrical bodies 112a to 112i are sealed inside and contain a gas containing an inert gas such as argon gas.

[0043] In the gas-filled discharge tube 110 of the present embodiment, upper electrodes 113a to 113i and lower electrodes 114a to 114i facing each other are provided in nine insulating cylindrical bodies 112a to 112i. Nine gaps are respectively formed between these upper electrodes 113a to 113i and lower electrodes 114a to 114i, and these are electrically connected in series to each other by connection conductors 115b to 115i. Each of the upper electrodes 113a to 113i and lower electrodes 114a to 114i is composed of a cylindrical electrode protrusion, and this electrode protrusion is inserted into the upper end portion within the insulating cylindrical body and fixed coaxially with this insulating cylindrical body. A gap is formed between the inner surface of the insulating cylindrical body and the outer peripheral surface of the electrode protrusion. The dimensions of the insulating cylindrical bodies 112a to 112i, upper electrodes 113a to 113i, and lower electrodes 114a to 114i in the present embodiment are substantially the same as those in the embodiments of FIGS. 1 to 4, and thus the description thereof is omitted.

[0044] Short-circuit carbon triggers are formed on the inner walls of the insulating cylindrical bodies 112a to 112h, and non-short-circuit carbon triggers are formed on the inner wall of the insulating cylindrical body 112i. The configurations, functions, and operations of the short-circuit carbon triggers and non-short-circuit carbon triggers are substantially the same as those in the embodiments of FIGS. 1 to 4, and thus the description thereof is omitted. In the present embodiment, short-circuit carbon trigger-equipped gaps are respectively constituted by the insulating cylindrical bodies 112a to 112h, upper electrodes 113a to 113h, and lower electrodes 114a to 114h, and the short-circuit carbon triggers, and a non-short-circuit carbon trigger-equipped gap is constituted by the insulating cylindrical body 112i, upper electrode 113i, lower electrode 114i, and the non-short-circuit carbon trigger.

[0045] As described above, in this embodiment, one non-short-circuit carbon-triggered gap and eight short-circuit carbon-triggered gaps are electrically connected in series with each other. As a result, (1) by providing short-circuit carbon-triggered gaps, the response speed to lightning surges can be increased because there is no delay time due to initial electron emission, which is the dominant factor in discharge delay; (2) by connecting gaps in multiple stages, the total arc voltage can be increased to (arc voltage) × (number of gaps) and applied to the desired power supply voltage; and (3) by connecting gaps in multiple stages, the arc voltage can be increased and follow current can be interrupted. In a gas-filled discharge tube, if a power supply voltage is applied after it has been activated by a lightning surge, there is a possibility of follow current generation. That is, if the current is several hundred mA to 1A or more, the discharge becomes an arc state and a low voltage (around 15 to 25V) is maintained, so the follow current does not stop and continues. While increasing the number of gaps can raise the total arc voltage and thus interrupt the follow current, conventional technology uses multiple non-short-circuit carbon-triggered gaps, which increases the operating voltage (especially the shock wave discharge initiation voltage), delaying the discharge initiation and reducing the lightning protection effect. In this embodiment, however, one non-short-circuit carbon-triggered gap and eight short-circuit carbon-triggered gaps are electrically connected in series with each other, so the delay time due to initial electron emission occurs in only one gap, thus eliminating the problem of delayed discharge initiation.

[0046] Furthermore, by providing a non-short-circuit carbon-triggered gap, insulation can be maintained when lightning surges are not present. The lightning surge activation voltage of this non-short-circuit carbon-triggered gap depends on the speed of the lightning surge, but is usually around 500V to 1200V. By connecting a non-short-circuit carbon-triggered gap and a short-circuit carbon-triggered gap in series, the arc voltage when discharging in the gap can be brought close to the commercial voltage of AC 100Vrms or AC 200Vrms, thereby blocking the follow current.

[0047] When installing a short - circuit protection device in which a gas - filled discharge tube with a short - circuit carbon trigger and a gas - filled discharge tube with a non - short - circuit carbon trigger are connected in series to a power supply unit, for example, to a commercial power supply, it is desirable that the AC discharge start voltage of the non - short - circuit carbon trigger does not discharge at the commercial power supply voltage to be installed. The reason is that since the short - circuit carbon trigger acts as a resistor when no internal discharge phenomenon occurs, the gas - filled discharge tube with a non - short - circuit carbon trigger connected in series to this resistor may discharge at the commercial power supply voltage, which may have an adverse effect on the corresponding power supply.

[0048] In the embodiments described above, non - short - circuit carbon triggers and short - circuit carbon triggers are provided on the inner wall of the insulating cylinder of the gas - filled discharge tube. However, these non - short - circuit carbon triggers and short - circuit carbon triggers in the present invention are not limited to being formed on the inner wall of the cylinder of the gas - filled discharge tube, and may be formed in any part within the cylinder space. Also, the shape and formation method of the carbon trigger are not limited to the method of drawing a linear carbon trigger using the core of a pencil (sharp pencil) as shown in the present invention. For example, a planar carbon trigger can be printed with a non - volatile organic substance (such as grease) and pyrolyzed at high temperature in a state without oxygen to form carbon remaining as a residue. Any shape and formation method may be used as long as the same function can be obtained.

[0049] (Example 1) As Example 1, an operation confirmation test of a surge protection device in which eight gaps with short - circuit carbon triggers and one gap with a non - short - circuit carbon trigger are electrically connected in series was conducted. For the test, a surge protection device composed of Samples 1 and 2 was used, which were formed by connecting in series eight gas - filled discharge tubes each having a single gap with a short - circuit carbon trigger and one gas - filled discharge tube having a single gap with a non - short - circuit carbon trigger. In Sample 2, the eight gas - filled discharge tubes with gaps with short - circuit carbon triggers have the same configuration as in the case of Sample 1, but the configuration of the one gas - filled discharge tube with a gap with a non - short - circuit carbon trigger is different from that in the case of Sample 1. Specifically, the gap length of the gap with a non - short - circuit carbon trigger is different.

[0050] Figure 9 shows a schematic overview of the overall configuration of Sample 1, and Figure 10 shows a schematic overview of the overall configuration of Sample 2.

[0051] As shown in Figure 9, Sample 1 consists of a gas-filled discharge tube with eight short-circuit carbon-triggered gaps and a gas-filled discharge tube with one non-short-circuit carbon-triggered gap connected in series thereto. The gas-filled discharge tube with eight short-circuit carbon-triggered gaps comprises eight insulating cylindrical bodies 212a to 212h arranged in series with respect to each other in the vertical direction between the upper and lower surfaces of a structure formed to have a vertically elongated rod-shaped outer shape, and electrically connected in series thereto, along with upper end electrodes 213a to 213h coaxially fixed to the upper ends of the insulating cylindrical bodies 212a to 212h, lower end electrodes 214a to 214h coaxially fixed to the lower ends of the insulating cylindrical bodies 212a to 212h, and connecting conductors 215b to 215h and connecting conductors 215a and 215i. A gas-filled discharge tube with a single non-short-circuit carbon-triggered gap comprises an insulating cylinder 212i, an upper electrode 213i coaxially fixed to the upper end of the insulating cylinder 212i, a lower electrode 214i coaxially fixed to the lower end of the insulating cylinder 212i, and connecting conductors 215j and 215k. Sodium silicate was used as the electrode coating agent. The insulating cylinders 212a to 212h are sealed internally and contain argon gas and 5% hydrogen gas at a gas pressure of 5.6 kPa at 680°C. The insulating cylinder 212i is also sealed internally and contains argon gas and 5% hydrogen gas at a gas pressure of 75 kPa at 680°C. The dimensions of each insulating cylinder 212a to 212h are as follows: inner diameter 4.4 mm, axial length 2.5 mm; insulating cylinder 212i is as follows: inner diameter 4.4 mm, axial length 5.0 mm; upper electrodes 213a to 213i and lower electrodes 214a to 214i are as follows: electrode base diameter 6.0 mm, thickness 1.0 mm, electrode projection diameter 4.1 mm, thickness 0.8 mm. The gap length is 0.9 mm between upper electrodes 213a to 213h and lower electrodes 214a to 214h, and 3.4 mm between upper electrode 213i and lower electrode 214i.

[0052] As shown in Figure 10, Sample 2 consists of a gas-filled discharge tube with eight short-circuit carbon-triggered gaps and a gas-filled discharge tube with one non-short-circuit carbon-triggered gap connected in series thereto. The gas-filled discharge tube with eight short-circuit carbon-triggered gaps comprises eight insulating cylindrical bodies 212a to 212h arranged in series with respect to each other in the vertical direction between the upper and lower surfaces of a structure formed to have a vertically elongated rod-shaped outer shape, and electrically connected in series thereto, along with upper end electrodes 213a to 213h coaxially fixed to the upper ends of the insulating cylindrical bodies 212a to 212h, lower end electrodes 214a to 214h coaxially fixed to the lower ends of the insulating cylindrical bodies 212a to 212h, and connecting conductors 215b to 215h and connecting conductors 215a and 215i. A gas-filled discharge tube with a single non-short-circuit carbon-triggered gap comprises an insulating cylinder 212i', an upper electrode 213i' coaxially fixed to the upper end of the insulating cylinder 212i', a lower electrode 214i' coaxially fixed to the lower end of the insulating cylinder 212i', and connecting conductors 215j' and 215k'. Sodium silicate was used as the electrode coating agent. The insulating cylinders 212a to 212i' are sealed internally, and argon gas and 5% hydrogen gas are sealed inside at a gas pressure of 5.6 kPa at 680°C. The dimensions of each insulating cylindrical body 212a to 212i' are as follows: inner diameter 4.4 mm, axial length 2.5 mm; upper electrodes 213a to 213i' and lower electrodes 214a to 214i' each have a base diameter of 6.0 mm, a thickness of 1.0 mm, a projection diameter of 4.1 mm, and a thickness of 0.8 mm. The gap length between the upper electrodes 213a to 213i' and lower electrodes 214a to 214i' is 0.9 mm.

[0053] For samples 1 and 2, the presence or absence of follow-through and arc voltage were measured when a lightning surge was applied while a power supply voltage of AC 200 Vrms (peak voltage: 282 V) was applied from an AC power supply circuit (resistance approximately 10 Ω, current approximately 20 A). The equipment used for measurement was a Tektronix digital oscilloscope (model MDO3024) and a Tektronix voltage probe (model P5100) to measure the surge voltage, and a Tektronix digital oscilloscope (model MDO3024), a Tektronix voltage probe (model P5100), and a Pearson current transformer (model 4997) for current measurement to measure the arc voltage. The surge voltage was 1.5 kV (1.2 / 50 μs) and was applied in phase with the AC power supply voltage. The total arc voltage for sample 1 was approximately 145 V, and the total arc voltage for sample 2 was approximately 135 V. The power supply voltage was 282V × sin15° = 73V when the surge application phase was 15°, 282V × sin30° = 141V when the surge application phase was 30°, and 282V × sin90° = 282V when the surge application phase was 90°. These test results are shown in Table 1.

[0054] Table 1 shows that in Sample 1, when the phase of the applied lightning surge was 15° relative to the AC power supply voltage, the follow current was interrupted because the total arc voltage (approximately 145V) was higher than the power supply voltage (73V). When the phase of the applied lightning surge was 30°, the follow current was interrupted because the total arc voltage (approximately 145V) was higher than the power supply voltage (141V). On the other hand, when the phase of the applied lightning surge was 90°, a follow current occurred because the total arc voltage (145V) was lower than the power supply voltage (282V), but it was interrupted within half a cycle. Therefore, it was found that follow current can be suppressed if the total arc voltage is approximately 51% or more of the power supply voltage (peak value) (= 145V / 282V).

[0055] On the other hand, as shown in Table 1, in Sample 2, when the phase of the applied lightning surge was 15° relative to the AC power supply voltage, the total arc voltage (approximately 135V) was higher than the power supply voltage (73V), so the follow current was interrupted. When the phase of the applied lightning surge was 30°, the total arc voltage (approximately 135V) was lower than the power supply voltage (141V), so a follow current occurred, but it was interrupted within half a cycle. Therefore, if the total arc voltage is approximately 96% or more of the power supply voltage (peak value) (= 135V / 141V), the follow current can be suppressed. When the phase of the applied lightning surge was 90°, the total arc voltage (approximately 135V) was lower than the power supply voltage (282V), so a follow current occurred, but it was interrupted within half a cycle. Therefore, it was found that if the total arc voltage is approximately 48% or more of the power supply voltage (peak value) (= 135V / 282V), the follow current can be suppressed.

[0056] Figure 11 shows the voltage waveform (200V / div) and current waveform (20A / div) for Sample 1 when the surge application phase relative to the AC power supply voltage is 30° over time (4ms / div), and Figure 12 shows the voltage waveform (200V / div) and current waveform (20A / div) for Sample 1 when the surge application phase relative to the AC power supply voltage is 90° over time (4ms / div).

[0057] As shown in Figure 11, when the surge application phase relative to the AC power supply voltage was 30°, the total arc voltage (approximately 145V) was higher than the power supply voltage (141V), so the follow current was interrupted. Also, as shown in Figure 12, when the surge application phase relative to the AC power supply voltage was 90°, the total arc voltage (145V) was lower than the power supply voltage (282V), so a follow current was generated, but it was interrupted within 1 / 2 cycle.

[0058] (Example 2) In Example 2, the discharge voltage (impulse discharge initiation voltage) was measured when an impulse voltage of approximately 1.5 kV (1.2 / 50 μs) was applied to samples 1 and 2 prepared in Example 1. The equipment used for measurement was the same as in Example 1. As a result, the impulse discharge initiation voltage for sample 1 was 1380 V, and the impulse discharge initiation voltage for sample 2 was 1060 V.

[0059] (Example 3) As Example 3, a surge protection device consisting of Sample 3, in which one gas-filled discharge tube having a single short-circuit carbon-triggered gap and one gas-filled discharge tube having a single non-short-circuit carbon-triggered gap are connected in series; a surge protection device consisting of Sample 4, in which two gas-filled discharge tubes having a single short-circuit carbon-triggered gap and one gas-filled discharge tube having a single non-short-circuit carbon-triggered gap are connected in series; and a surge protection device consisting of Sample 5, in which three gas-filled discharge tubes implementing a single short-circuit carbon-triggered gap and one gas-filled discharge tube having a single non-short-circuit carbon-triggered gap are connected in series, was used to test whether follow-currents occurred after a surge was applied. Specifically, the presence or absence of follow-currents due to continued discharge was observed when the power supply voltage at the time of surge application was the same as AC275Vrms.

[0060] Figure 13 shows a schematic overview of the overall configuration of samples 3 to 5.

[0061] As shown in Figure 13(A), Sample 3 consists of a gas-filled discharge tube with one short-circuit carbon-triggered gap and a gas-filled discharge tube with one non-short-circuit carbon-triggered gap connected in series thereto. The gas-filled discharge tube with one short-circuit carbon-triggered gap comprises an insulating cylindrical body 212h formed to have a vertically elongated rod-shaped outer shape, an upper end electrode 213h coaxially fixed to the upper end of the insulating cylindrical body 212h, a lower end electrode 214h coaxially fixed to the lower end of the insulating cylindrical body 212h, and connecting conductors 215h and 215i. The gas-filled discharge tube with one non-short-circuit carbon-triggered gap comprises an insulating cylindrical body 212i, an upper end electrode 213i coaxially fixed to the upper end of the insulating cylindrical body 212i, a lower end electrode 214i coaxially fixed to the lower end of the insulating cylindrical body 212i, and connecting conductors 215j and 215k. Sodium silicate was used as the electrode coating agent. The insulating cylinders 212h and 212i were sealed internally and contained argon gas and 5% hydrogen gas. The dimensions and gas pressure of Sample 3 were the same as those of a portion of Sample 1.

[0062] As shown in Figure 13(B), Sample 4 consists of a gas-filled discharge tube with two short-circuit carbon-triggered gaps and a gas-filled discharge tube with one non-short-circuit carbon-triggered gap connected in series thereto. The gas-filled discharge tube with two short-circuit carbon-triggered gaps comprises two insulating cylindrical bodies 212g and 212h arranged in series vertically between the upper and lower surfaces of a structure formed to have a vertically elongated rod-shaped outer shape, and electrically connected in series; upper end electrodes 213g and 213h fixed coaxially to the upper ends of the insulating cylindrical bodies 212g and 212h, respectively; lower end electrodes 214g and 214h fixed coaxially to the lower ends of the insulating cylindrical bodies 212g and 212h, respectively; and connecting conductors 215g and 215i. A gas-filled discharge tube with a single non-short-circuit carbon-triggered gap comprises an insulating cylinder 212i, an upper electrode 213i coaxially fixed to the upper end of the insulating cylinder 212i, a lower electrode 214i coaxially fixed to the lower end of the insulating cylinder 212i, and connecting conductors 215j and 215k. Sodium silicate was used as the electrode coating agent. The insulating cylinders 212g to 212i are sealed internally and filled with argon gas and 5% hydrogen gas. The dimensions and gas pressure of Sample 4 are the same as those of a portion of Sample 1.

[0063] As shown in Figure 13(C), Sample 5 consists of a gas-filled discharge tube with three short-circuit carbon-triggered gaps and a gas-filled discharge tube with one non-short-circuit carbon-triggered gap connected in series thereto. The gas-filled discharge tube with three short-circuit carbon-triggered gaps comprises three insulating cylindrical bodies 212f to 212h arranged in series vertically between the upper and lower surfaces of a structure formed to have a vertically elongated rod-shaped outer shape, and electrically connected in series; upper end electrodes 213f to 213h fixed coaxially to the upper ends of the insulating cylindrical bodies 212f to 212h, respectively; lower end electrodes 214f ​​to 214h fixed coaxially to the lower ends of the insulating cylindrical bodies 212f to 212h, respectively; and connecting conductors 215f and 215i. A gas-filled discharge tube with a single non-short-circuit carbon-triggered gap comprises an insulating cylinder 212i, an upper electrode 213i coaxially fixed to the upper end of the insulating cylinder 212i, a lower electrode 214i coaxially fixed to the lower end of the insulating cylinder 212i, and connecting conductors 215j and 215k. Sodium silicate was used as the electrode coating agent. The insulating cylinders 212f to 212i are sealed internally and filled with argon gas and 5% hydrogen gas. The dimensions and gas pressure of Sample 5 are the same as those of a portion of Sample 1.

[0064] For samples 3 to 5, the presence or absence of follow current and the arc voltage were measured when a lightning surge was applied while a power supply voltage of AC 275 Vrms was applied from an AC power supply circuit (resistance approximately 10 Ω, current approximately 20 A). The equipment used for the measurements was the same as in Example 1. The observation results are shown in Table 2.

[0065] Table 2 shows that in Sample 3, which used two gaps (one short-circuit carbon-triggered gap and one non-short-circuit carbon-triggered gap), follow-current continued to occur. In Sample 4, which used three gaps (two short-circuit carbon-triggered gaps and one non-short-circuit carbon-triggered gap), follow-current occurred but was interrupted within half a cycle. In Sample 5, which used four gaps (three short-circuit carbon-triggered gaps and one non-short-circuit carbon-triggered gap), follow-current occurred but was interrupted within half a cycle, indicating good follow-current interruption. Therefore, it was found that follow-current could not be interrupted with two gaps, but could be interrupted with three or more gaps. Note that when used in an actual DC power supply, the power supply voltage must be lower than the total arc voltage.

[0066] From the above examples 1 to 3, the following points were confirmed: (A) To safely interrupt the follow current, if the total arc voltage is approximately 48-51% or more of the power supply voltage (peak value), the follow current can be interrupted (according to experimental results, a total arc voltage of 145V was able to interrupt AC 200V (peak voltage: 282V)). (B) The device operated at low voltages of 1380V and 1060V when an impulse was applied (impulse discharge initiation voltage). Generally, a surge protection device can be used effectively if this impulse discharge initiation voltage is 1500V or less. (C) A surge protection device with three or more gaps connected in series has the potential to interrupt the follow current.

[0067] The embodiments and examples described above are illustrative and not limiting, and the present invention can be implemented in various other forms of modification and alteration. Accordingly, the scope of the present invention is defined solely by the claims and their equivalents.

[0068] This invention can be applied to any type of surge protection device having a gas-filled discharge tube.

[0069] 10, 110 Gas-filled discharge tube 11 Insulating structure 12a-12i, 12a1, 12a2, 12c1, 12c2, 12c3, 12c4, 12c5, 112a-112i, 212a-212i Insulating cylinder 13a-13i, 113a-113i, 213a-212i Upper electrode 13a1 Electrode base 13a2 Electrode protrusion 14a-14i, 114a-114i, 214a-214i Lower electrode 15a-15h Connecting wire 16a, 16b, 16d-16i, 16a1, 16a2 Short-circuit carbon trigger 16c, 16c1, 16c2, 16c3, 16c4, 16c5 Non-short-circuit carbon trigger 17a-17i, 17a1, 17a2, 17c1, 17c2, 17c3, 17c4, 17c5, 18a-18i, 18a1, 18a2, 18c1, 18c2, 18c3, 18c4, 18c5 Metallized section 115a-115j, 215a-215k Connecting conductor

Claims

1. A surge protection device comprising at least one gas-filled discharge tube, characterized in that a gap with a non-short-circuit carbon trigger in at least one gas-filled discharge tube having a non-short-circuit carbon trigger and a gap with a short-circuit carbon trigger in at least one gas-filled discharge tube having a short-circuit carbon trigger are connected in series with each other.

2. The surge protection device according to claim 1, characterized in that the at least one gas-filled discharge tube is composed of a plurality of gas-filled discharge tubes connected in series with each other, at least one of the plurality of gas-filled discharge tubes is provided with the non-short-circuit carbon-triggered gap, and the remaining gas-filled discharge tubes of the plurality of gas-filled discharge tubes are provided with the short-circuit carbon-triggered gap.

3. The surge protection device according to claim 1, characterized in that the at least one gas-filled discharge tube is composed of a single gas-filled discharge tube, and the single gas-filled discharge tube comprises a non-short-circuit carbon-triggered gap and a short-circuit carbon-triggered gap connected in series with each other.

4. The surge protection device according to claim 3, characterized in that the single gas-filled discharge tube comprises an insulating structure, a plurality of insulating cylindrical bodies formed in the insulating structure, a pair of electrodes provided at both ends of each of the plurality of insulating cylindrical bodies, a gap with a non-short-circuit carbon trigger formed on the inner wall of some of the plurality of insulating cylindrical bodies and having a non-short-circuit carbon trigger that does not short-circuit the pair of electrodes, and a gap with a short-circuit carbon trigger formed on the inner wall of the remaining insulating cylindrical bodies of the plurality of insulating cylindrical bodies and having a short-circuit carbon trigger that short-circuits the pair of electrodes.

5. The surge protection device according to claim 4, characterized in that the plurality of insulating cylindrical bodies are arranged in parallel within the insulating structure in a state in which they are connected in series with each other.

6. The surge protection device according to claim 4, characterized in that the plurality of insulating cylindrical bodies are arranged in series with each other connected in series.

7. A gas-filled discharge tube characterized by having a short-circuit carbon trigger gap with a short-circuit carbon trigger.

8. The gas-filled discharge tube according to claim 7, further comprising a gap with a non-short-circuit carbon trigger having a non-short-circuit carbon trigger, wherein the gap with the non-short-circuit carbon trigger and the gap with the short-circuit carbon trigger are connected in series with each other.

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