Spark gap assembly for overvoltage protection and surge arrester

Abstract

A spark gap assembly includes a first spark gap section and a second spark gap section electrically connected in series with the first spark gap section. The first spark gap includes a first spark gap and a first grading circuit electrically connected in parallel with the first spark gap. The second spark gap section includes a second spark gap and a second grading circuit electrically connected in parallel with the second spark gap.

Description

[0001] Related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 127,468, filed December 18, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The embodiments relate to spark gap assemblies for overvoltage protection and surge arresters. Summary of the Invention

[0004] A surge arrester provides a current path from a conductor to ground, protecting power systems and components from power surges caused by lightning, electrical switching events, and / or other factors. Surge arrester designs may include metal oxide varistor (MOV) stacks, highly nonlinear ceramic semiconductors that switch from an insulating state during normal operation to a conductive state during a surge. During a surge, the resistance of the MOV stack decreases, allowing the arrester to conduct the surge current to ground. Therefore, the voltage increase across the conductor during a surge can be limited to a level that will not damage the power system or components.

[0005] As described above, the MOV panel included in a surge arrester can protect equipment from short-duration power surges caused by lightning or electrical switching. However, the MOV panel of a surge arrester may not be effective in preventing sustained overvoltage conditions at typical line frequencies (such as 50-60 Hz). Sustained overvoltage can cause the arrester to overheat, which increases the conductivity of the MOV panel and thus increases power dissipation. As a result, the arrester may reach a critical temperature at which thermal runaway and short-circuit faults may occur within the arrester. Short-circuit faults within the arrester can lead to severe power arcing or accidental release of hot debris into the environment, posing a hazardous situation to nearby personnel and equipment.

[0006] A first aspect provides a spark gap assembly including a first spark gap section and a second spark gap section electrically connected in series with the first spark gap section. The first spark gap includes a first spark gap and a first step circuit electrically connected in parallel with the first spark gap. The second spark gap section includes a second spark gap and a second step circuit electrically connected in parallel with the second spark gap.

[0007] A second aspect provides a discharger including a spark gap assembly. The spark gap assembly includes a first spark gap section and a second spark gap section electrically connected in series with the first spark gap section. The first spark gap includes a first spark gap and a first step circuit electrically connected in parallel with the first spark gap. The second spark gap section includes a second spark gap and a second step circuit electrically connected in parallel with the second spark gap.

[0008] A third aspect provides an accessory device connected in series with a spark arrester and including a spark gap assembly. The spark gap assembly includes a first spark gap section and a second spark gap section connected in series with the first spark gap section. The first spark gap includes a first spark gap and a first staged circuit connected in parallel with the first spark gap. The second spark gap section includes a second spark gap and a second staged circuit connected in parallel with the second spark gap.

[0009] Other aspects of the invention will become apparent from consideration of the detailed description and accompanying drawings. Attached Figure Description

[0010] Figure 1 A schematic diagram of a discharger according to some embodiments is shown.

[0011] Figure 2 A schematic diagram of a discharger according to some embodiments is shown.

[0012] Figure 3 It shows Figure 1 An exemplary configuration of the discharger.

[0013] Figures 4A-4D It shows Figure 1 An exemplary configuration of the discharger.

[0014] Figures 5A-5C It shows Figure 2 An exemplary configuration of the discharger.

[0015] Figure 6 A schematic diagram of a discharger according to some embodiments is shown.

[0016] Figure 7 A schematic diagram of a discharger according to some embodiments is shown.

[0017] Figure 8 It shows Figure 7 An exemplary configuration of the discharger.

[0018] Figure 9 It shows Figure 8 The voltage-current characteristics of the discharger.

[0019] Figure 10An accessory device according to some embodiments is shown.

[0020] Figure 11 An accessory device according to some embodiments is shown. Detailed Implementation

[0021] Before detailing any embodiments, it should be understood that the embodiments are not limited in their application to the details of the configuration and arrangement of the components set forth in the following description or shown in the accompanying drawings. These embodiments can be practiced or carried out in various ways. Furthermore, it should be understood that the wording and terminology used herein are for descriptive purposes and should not be considered limiting. The terms “comprising,” “including,” or “having,” and variations thereof are used to mean including the items listed thereafter and their equivalents, as well as additional items. Unless otherwise specified or limited, the terms “installation,” “connection,” “support,” and “coupling,” and variations thereof are widely used and encompass both direct and indirect installation, connection, support, and coupling.

[0022] Additionally, it should be understood that embodiments may include hardware, software, and electronic components or modules, which, for the purposes of discussion, may be shown and described as if most components were implemented solely in hardware. However, those skilled in the art will recognize, based on this detailed description, that in at least one embodiment, the electronic aspects may be implemented in software (e.g., stored on a non-transitory computer-readable medium), which may be executed by one or more electronic processors such as microprocessors and / or application-specific integrated circuits (“ASICs”). Thus, it should be noted that multiple hardware and software-based devices and multiple different structural components may be utilized to implement embodiments. For example, “server,” “computing device,” “controller,” “processor,” etc., described in this specification may include one or more electronic processors, one or more computer-readable medium modules, one or more input / output interfaces, and various connectors (e.g., system buses) connecting these components.

[0023] Figure 1 A surge arrester, such as surge arrester 100, according to some embodiments of this application is illustrated. Surge arrester 100 includes a housing 105, a first stud 110 extending from the upper portion of the housing 105, and a second stud 115 extending from the lower portion of the housing 105. The first stud 110 electrically connects surge arrester 100 to a power system 120. The second stud 115 electrically connects surge arrester 100 to ground 125. The housing 105 may be made of any suitable material, such as, but not limited to, ceramic, glass, and / or nylon.

[0024] The surge discharger 100 also includes a spark gap assembly 130, which comprises a plurality of spark gap sections 135A-135N electrically connected in series with each other. For example, as Figure 1 As shown, at least two spark gap sections 135A and 135B are included in the spark gap assembly 130. However, the spark gap assembly 130 may include any desired number N spark gap sections 135A-135N. For example, Figure 2 An embodiment of a surge discharger 200 including a spark gap assembly 230 is shown. The spark gap assembly 230 includes three spark gap sections 135A-135C electrically connected in series with each other. In other embodiments, the spark gap assembly may include more than three spark gap sections, such as four, five, six or more spark gap sections.

[0025] Each spark gap segment 135 includes a corresponding spark gap 140 electrically connected in parallel with a corresponding grading circuit 145. Each grading circuit 145 may include one or more passive grading elements, such as resistors, capacitors, or inductors. For example, a first spark gap segment 135A includes a first spark gap 140A electrically connected in parallel with a first grading circuit 145A. Similarly, a second spark gap segment 135B includes a second spark gap 140B electrically connected in parallel with a second grading circuit 145B. As will be described in more detail below, the grading circuit 145 may include any number and / or combination of passive grading elements as desired.

[0026] The spacing or length between each spark gap 140 and the components included in the grading circuit 145 can be selected such that the spark over characteristics of the spark gap assembly 130 depend on the rate of change of voltage dV / dt across the spark gap assembly 130. For example, these spark gaps 140 can be graded such that the electric field within each spark gap 140A-140N is approximately equal while the power system 120 is operating at its normal operating frequency (e.g., 50-60Hz). That is, the corresponding grading circuit 145, electrically connected in parallel with the corresponding spark gap 140, can be designed such that when a surge occurs in the power system 120 at its normal operating frequency, the voltage across each spark gap 140A-140N is equal.

[0027] Furthermore, the spark gaps 140 can be graded to maximize the first spark discharge voltage of the spark gap assembly 130. The first spark discharge voltage is defined as the voltage across the spark gap assembly 130 at which a spark discharge will initially occur across one of the spark gaps 135 within the assembly. During a surge event, an increase in the rate of voltage change across the spark gap assembly 130 can lead to unequal potential drops across multiple spark gaps 140. Additionally, an increase in the rate of voltage change across the spark gaps 140 can reduce the first spark discharge voltage of the spark gap assembly 130.

[0028] When the first spark discharge event occurs, the voltage across spark gap assembly 130 may decrease. That is, when current spark discharges, or flows between the first of the spark gaps 140, the remaining voltage of spark gap assembly 130 is redistributed across the remaining spark gaps 140 that have not yet spark discharged. If the overvoltage condition persists, allowing continued surge energy input to spark gap assembly 130, additional spark discharge events may occur. For example, continued surge energy input could lead to additional spark discharge events, causing all gaps 140 in assembly 130 to spark discharge. In this case, the total impedance of spark gap assembly 130 will be significantly reduced.

[0029] Figure 3 An exemplary schematic diagram of a spark gap assembly 130 included in a surge discharger 100 is shown. As described above, the spark gap assembly 130 includes a first spark gap section 135A and a second spark gap section 135B connected in series. The first spark gap section 135A includes a first spark gap 140A connected in parallel with a first grading circuit 145A. In the illustrated embodiment, the first grading circuit 145A includes a resistor R1, thereby grading the first spark gap 140A by the resistor R1. Additionally, the second spark gap section 135B includes a second spark gap 140B connected in parallel with the second grading circuit 145B. In the illustrated embodiment, the second grading circuit 145B includes a capacitor C1, thereby grading the second spark gap 140B by the capacitor C1.

[0030] Voltage V1 represents the voltage drop across the first spark gap 140A. When voltage V1 is greater than or equal to the spark discharge voltage V140A of the first spark gap... S1 At this time, the spark discharge event occurs at the first spark gap 140A. Similarly, voltage V2 represents the voltage drop across the second spark gap 140B. When voltage V2 is greater than or equal to the spark discharge voltage V of the second spark gap 140B... S2 At that time, the spark discharge event will occur at the second spark gap 140B.

[0031] When constructing the spark gap assembly 130, the corresponding spacing between the first spark gap 140A and the second spark gap 140B can be selected to be equal or unequal. Additionally, the corresponding values ​​for resistor R1 and capacitor C1 can be selected such that when the power system 120 operates at its normal operating frequency f0, resistor R1 and capacitor C1 have nearly equal impedances Z. R1 and Z C1 The normal operating frequency f0 is typically 50-60Hz; however, different values ​​can be selected for f0 depending on the application of the gap component.

[0032] Equations 1 and 2 provided below define the relationships between various voltages within the spark gap assembly 130 when the power system 100 operates at its normal operating frequency f0. As defined in Equation 1, when a voltage is applied to the surge discharger 100 at its normal operating frequency f0, the first voltage V1 across the first spark gap 140A and the spark discharge voltage V of the first spark gap 140A... S1 The ratio is approximately equal to the voltage V2 across the second spark gap 140B and the spark discharge voltage V of the second spark gap 140B. S2 The ratio. Furthermore, as defined in Equation 2, when a voltage is applied to the surge discharger 100 at the normal operating frequency f0, the voltage V across the spark gap assembly 130... A It is approximately equal to the ratio of the voltage V1 across the first spark gap 140A to the voltage V2 across the second spark gap 140B.

[0033] Equation 1: Where f = f0

[0034] Equation 2: Where f = f0

[0035] By combining Equations 1 and 2 above, when a voltage is applied to the surge discharger 100 at the normal operating frequency f0, the first spark discharge voltage V of the spark gap assembly 130 is... AS1 This can be determined using Equation 3.

[0036] Equation 3:

[0037] During a surge event, either the first spark gap 140A or the second spark gap 140B can spark discharge first. The second spark discharge voltage V of the spark gap assembly 130 depends on which of the first spark gap 140A and the second spark gap 140B sparks discharges first. AS2 Will equal V S1 or V S2For example, if the first spark gap 140A performs a spark discharge before the second spark gap 140B, then the second spark discharge voltage V of the spark gap assembly 130... AS2 Will equal V S2 Conversely, if the second spark gap 140B performs a spark discharge before the first spark gap 140A, the second spark discharge voltage V of the spark gap assembly 130 will be higher. AS2 Will equal V S1 .

[0038] Reference Figure 3 The spark gap assembly 130 shown, when a surge event occurs at the normal operating frequency f0, experiences a significant increase in the rate of voltage change across the spark gap assembly 130 caused by the surge event, which increases the potential across the resistive spark gap 140A. That is, due to the impedance Z of capacitor C1... C1 Due to the frequency dependence, the voltage V1 across the first spark gap 140A increases. Therefore, the first spark discharge voltage V of the spark gap assembly 130 increases. AS1 Decrease, causing V AS1 The spark discharge voltage V is approximately equal to the first spark gap of 140A. S1 In addition, the second spark discharge voltage V of the spark gap assembly 130 AS2 Will equal V S2 .if Figure 3 The spark gap assembly 130 is configured such that the first spark gap 140A and the second spark gap 140B are equal in pitch. Then, when the power system 120 operates at its normal operating frequency f0, V AS1 and V AS2 It can be reduced to V AS1 The value is approximately 71%.

[0039] Figure 3 The exemplary spark gap assembly 130 shown and described above can help protect against sustained overvoltage conditions occurring at the normal operating frequency f0. Additionally, Figure 3 The exemplary spark gap assembly 130 shown and described above can help protect the power system 100 from fault conditions that cause DC voltage (e.g., f = 0) in the power system 100. In such a fault, the second spark gap 140B first spark discharges, where V AS1 ≈V S2 And V AS2 ≈V S1 .

[0040] It should be understood that, Figure 3 The illustrated embodiment of the spark gap assembly is merely an example and does not limit the spark gap assembly 130 to... Figure 3The configuration is shown. More specifically, the spark gap assembly 130 may include a spark gap 140, which is graded by any number and / or combination of passive components such as resistors, capacitors, and inductors. In other words, the grading circuit 145, which is electrically connected in parallel with a given spark gap 140, may include any number and / or combination of passive grading components as desired. Figures 4A-4D Several additional exemplary configurations of the spark gap assembly 130 are shown. These configurations are intended only as exemplary spark gap assembly configurations. Figures 4A-4D Many other configurations not shown can also be implemented.

[0041] exist Figures 4A-4D In the embodiment of the spark gap assembly 130 shown, the impedance of each stage circuit 145 can be selected such that the first spark discharge voltage V of the spark gap assembly 130 is... AS1 Frequency-dependent. Additionally, the impedance of each stage circuit 145 can be selected such that V... AS1 It is reduced by at least 25% under pulse (f>1kHz) or DC voltage (f=0Hz) conditions. Figures 4A-4D The use of a relatively more complex hierarchical circuit, as shown, offers advantages in limiting the power consumption of individual hierarchical elements (e.g., the resistors, capacitors, and inductors included in hierarchical circuit 145) during surge events. As an example, Figure 4A The voltage across capacitor C3 in the middle can be greater than Figure 3 The voltage V1 across capacitor C1 is much smaller. Therefore, it can be... Figures 4A-4D The tiered circuit 145 shown selects smaller and / or cheaper capacitors.

[0042] Figure 2 An embodiment of a surge discharger 200 including a spark gap assembly 230 is shown, the spark gap assembly 230 consisting of three spark gap sections 135A-135C connected in series. This is consistent with the description above and... Figure 1 , Figure 3 and Figures 4A-4D Similar to the illustrated embodiment, the surge arrester 200 includes a housing 105, a first stud 110 extending from the upper portion of the housing 105, and a second stud 115 extending from the lower portion of the housing 105. The first stud 110 electrically connects the surge arrester 200 to the power system 120. The second stud 115 electrically connects the surge arrester 200 to the ground 125. The housing 105 may be made of any suitable material, such as, but not limited to, ceramic, glass, and / or nylon.

[0043] The surge discharger 200 also includes a spark gap assembly 230 comprising three spark gap segments 135A-135C electrically connected in series with each other. Although shown as including only three spark gap segments, it should be understood that the spark gap assembly 230 may include any desired number N spark gap segments 135A-135N. Each spark gap segment 135 includes a spark gap 140 electrically connected in parallel with the grading circuit 145. For example, the first spark gap segment 135A includes a first spark gap 140A electrically connected in parallel with the first grading circuit 145A. Similarly, the second spark gap segment 135B includes a second spark gap 140B electrically connected in parallel with the second grading circuit 145A. Likewise, the third spark gap segment 135C includes a third spark gap 140C electrically connected in parallel with the third grading circuit 145C. The hierarchical circuits 145A-145C may include any number and / or combination of passive hierarchical components (e.g., resistors, capacitors, inductors, etc.) as required.

[0044] Figures 5A-5C An exemplary configuration of the spark gap assembly 230 is shown. Figures 5A-5C The configuration shown is intended merely as an exemplary configuration of the spark gap assembly 230. It should be understood that... Figures 5A-5C The illustrated configuration does not limit the spark gap assembly 230 in any way. Furthermore, any desired number and / or combination of passive grading elements may be included in the grading circuitry 145 of the spark gap assembly 230.

[0045] about Figure 5A The exemplary configuration of the spark gap assembly 230 shown has spark gaps 140A-140C having corresponding spark discharge voltages V. S11 V S12 and V S13 In other words, when the voltage V across the first spark gap 140A... 11 Greater than or equal to spark discharge voltage V S11 At this time, the first spark gap 240A will discharge. Similarly, when the voltage V across the second spark gap 140B... 12 Greater than or equal to spark discharge voltage V S12 At that time, the second spark gap 140B will discharge. Similarly, when the voltage V across the third spark gap 140C... 13 Greater than or equal to spark discharge voltage V S13 At that time, a spark discharge will occur in the third spark gap at 140°C. Figure 5A In the exemplary embodiment of the spark gap assembly 230 shown, Equations 4 and 5 provided below define the relationships between various voltages within the spark gap assembly 230 when a voltage is applied to the assembly 230 at the normal operating frequency f0.

[0046] Equation 4: Where f = f0

[0047] Equation 5: Where f >> f0

[0048] about Figure 5A The spark gap assembly 230 shown is such that a surge event induces a first spark discharge voltage V at both ends of the spark gap assembly 230. AS1 When a surge event occurs, the first of the spark gaps 145A-145C will spark discharge. When a surge event induces a second spark discharge voltage V across the spark gap assembly 230... AS2 At that time, two of the three spark gaps 145A-145C will spark discharge. When a surge event induces a third spark discharge voltage V across the spark gap assembly 230. AS3 At that time, all three spark gaps 145A-145C included in the spark gap assembly 230 will spark discharge.

[0049] Equation 6: Where f = f0

[0050] Equation 7: V AS1 >V AS2 >V AS3 …>V ASN , where f >> f0

[0051] The use of the third spark gap section 135C provides a greater reduction in spark discharge voltage as the operating frequency of the power system 120 increases, allowing for a sufficiently high rate of voltage change across the spark gap assembly 230, V AS1 V AS2 and V AS3 All can be reduced to V AS1 The value of (f=f0) is between 40-50%. When the spark gap assembly 230 is subjected to a surge, such as a lightning strike, all three gaps 140A-140C will sequentially spark discharge, causing the spark gap assembly voltage V to... A Can remain at V AS1 (f=f0) values ​​below 40-50%.

[0052] As described above, spark gap assemblies are not limited in their construction to include only two or three spark gap segments. In some embodiments, spark gap assemblies similar to spark gap assemblies 130 and 230 described above may include a plurality of N spark gap segments. In such embodiments, each of the N spark gap segments included in the spark gap assembly includes a corresponding spark gap and a hierarchical circuit electrically connected in parallel with the corresponding spark gap. Equations 8 and 9, provided below, define the relationships between various voltages within a spark gap assembly comprising a plurality of N spark gap segments.

[0053] As defined in Equation 8, the passive grading element included in the grading circuit of the spark gap assembly is selected such that when the spark gap assembly operates at its normal operating frequency f0, for all N spark gaps included in the spark gap assembly, the voltage V across a particular spark gap is [value missing]. N The corresponding spark discharge voltage V of this specific spark gap SN The ratios between them are approximately equal. For example, when the spark gap assembly operates at the normal operating frequency f0, the voltage V1 across the first spark gap and the spark discharge voltage V of the first spark gap are approximately equal. S1 The ratio is approximately equal to the voltage V across the Nth spark gap. N Spark discharge voltage V with the Nth spark gap SN The ratio.

[0054] Equation 8: Where f = f0

[0055] Equation 9: Where f >> f0

[0056] Equation 10: Where f = f0

[0057] Equation 11: V AS1 >V AS2 >V AS3 …>V ASN , where f >> f0

[0058] Additionally, passive grading elements are selected in the grading circuit of the spark gap assembly such that the spark discharge voltage V of each sequence of the spark gap assembly is... ASN (For example, V) AS1 V AS2 V AS3 ... V ASN The first spark discharge voltage V of the spark gap assembly is reduced during high-frequency surge events. That is, when the spark gap assembly is subjected to a high-frequency (e.g., >1kHz) surge event, the first spark discharge voltage V of the spark gap assembly is reduced. AS1 Greater than the second spark discharge voltage V AS2The second spark discharge voltage V AS2 Greater than the third spark discharge voltage V AS3 The third spark discharge voltage V AS3 Greater than the Nth spark discharge voltage V ASN In some embodiments, passive grading elements are selected such that the spark discharge voltage during high-frequency (e.g., f > 1 kHz) surge events is suppressed to less than 40% of the spark discharge voltage during surge events at normal operating frequencies (e.g., f = 50-60 Hz).

[0059] In some embodiments, such as the exemplary embodiments described above, the spark gap assembly may be the only active component included in the surge arrester. In such embodiments, the surge arrester is able to protect against surge events such as lightning or switching surges without requiring any metal oxide rheostat (MOV) discs or other nonlinear resistive components. In such embodiments, the passive grading elements included in the grading circuit of the spark gap assembly are protected from overvoltage loads by their respective spark gaps. Therefore, the surge arrester of this embodiment is unlikely to fail due to pulsed loads. Furthermore, the surge arrester of this embodiment is unlikely to experience thermal runaway failure because the corresponding impedances of the passive grading elements (e.g., resistors, capacitors, inductors, etc.) included in the grading circuit of the spark gap assembly are almost independent of temperature.

[0060] In some embodiments, the descriptions and / or [specifications] herein [are applicable]. Figure 1 The spark gap assemblies shown in Figure -5 (e.g., spark gap assembly 130, spark gap assembly 230, and spark gap assembly comprising N spark gap segments) can be implemented as a single component included in a surge arrester. The spark gap assembly can be electrically connected in series with one or more linear and / or nonlinear resistive elements, such as MOV discs, included in the surge arrester. In such embodiments, the MOV discs provide additional impedance to the surge arrester during a surge, causing each spark gap included in the spark gap assembly to spark discharge. Additionally, the MOV discs assist in resealing the spark gap assembly (e.g., clearing short-circuit faults) faster than spark gap assemblies without series electrical connection to the MOV discs that will be resealed. Furthermore, the MOV discs can assist in limiting the current through the surge arrester at the maximum continuous operating voltage (MCOV).

[0061] Figure 6 An exemplary embodiment of the surge discharger 300 is shown. The surge discharger 300 is similar in construction to the surge discharger 100 described herein; however, the surge discharger 300 additionally includes a stack of MOV disks or an MOV stack 305, which is electrically connected in series with the spark gap assembly 130. Similarly, Figure 7An exemplary embodiment of surge discharger 400 is shown. Surge discharger 400 is similar in construction to surge discharger 200 described herein; however, surge discharger 400 additionally includes an MOV stack 305 electrically connected in series with spark gap assembly 230. In some embodiments, the surge discharger includes an MOV stack electrically connected in series with a spark gap assembly comprising a plurality of N spark gap segments as described herein.

[0062] Figure 8 An exemplary schematic diagram of a surge discharger 400 is shown, which includes an MOV stack 305 electrically connected in series with a spark gap assembly 230. Figure 8 The configuration of the spark gap assembly 230 shown is similar to Figure 5A The configuration of the spark gap assembly 230 shown is the same. For example... Figure 8 As shown, the spark gap assembly 230 includes a first spark gap section 135A, a second spark gap section 135B, and a third spark gap section 135C. The first spark gap section 135A includes a first spark gap 140A, which is electrically connected in parallel with capacitor C8, or is graded by capacitor C8. The second spark gap section 135B includes a second spark gap 140B graded by a series combination of capacitor C7 and resistor R8. The third spark gap section 135C includes a third spark gap 140C graded by resistor R8.

[0063] When designing spark gap assemblies that are electrically connected in series with MOV stacks, the values ​​of the passive circuit elements (e.g., resistors, capacitors, inductors, etc.) included in the graded circuitry are selected such that the total impedance of the spark gap assembly increases after a surge. This increase in the total impedance of the spark gap assembly minimizes the time required to reseal each spark gap in the assembly and minimizes the duration of a dangerous arc. Therefore, surge arresters that include spark gap assemblies electrically connected in series with MOV stacks offer significant performance advantages when used in high fire hazard areas.

[0064] Figure 9 It shows Figure 8 A graph illustrating the exemplary voltage-current (VI) characteristics of the surge arrester 400 is shown. Specifically, Figure 9The VI characteristics of surge arrester 400 at various operating frequencies are shown in comparison with those of a standard MOV-based surge arrester (excluding spark gap assembly). In this example, surge arrester 400 is configured such that R8 = 150 kΩ, R9 = 75 kΩ, C7 = 17.7 nanofarads, and C8 = 17.7 nanofarads. Additionally, in this example, surge arrester 400 is configured such that the first spark gap 140A, the second spark gap 140B, and the third spark gap 140C each have a spark discharge voltage of 0.47 per unit, equivalent to the maximum continuous operating voltage of surge arrester 400.

[0065] exist Figure 9 In this context, the voltage of surge arrester 400 is expressed as a unit value of the surge arrester's maximum continuous operating voltage (PUMCOV). For example... Figure 9 As shown in the first curve 900, a conventional MOV-based surge arrester (excluding the spark gap assembly) has a protection voltage level of 2.4 PUMCOV at 10kA, regardless of the operating frequency of the conventional MOV-based surge arrester.

[0066] Conversely, the protection voltage level of the surge arrester 400 is frequency-dependent. For example... Figure 9 As shown in the second curve 905, when operating at a frequency of 60 Hz (f = f0), surge discharger 400 can withstand 2.75 PUMCOV without gap spark discharge. Furthermore, when operating at 60 Hz, surge discharger 400 can withstand a much larger overvoltage level compared to conventional MOV-based surge dischargers.

[0067] Figure 9 The third curve 910 in the figure represents the characteristics of surge arrester 400 under a lightning pulse, which is modeled as a 31 kHz pulse signal. Under the lightning pulse, surge arrester 400 does not exceed 2 P.U.MCOV before the spark gap assembly 230 fully spark discharges. Therefore, the spark gap assembly 230 does not interfere with the 2.4 P.U.MCOV protection level provided by conventional MOV-based arresters for a typical 10 kA lightning pulse current.

[0068] Curve 915 represents the characteristics of surge arrester 400 when subjected to a switching surge encountered on a high-voltage power line, which is modeled as a 165Hz signal. Under switching surge conditions, the maximum voltage across spark gap assembly 230 is encountered at the second spark discharge point, reaching a level of 2.05PU.

[0069] In some instances, it may be desirable to provide the protection offered by the spark gap assembly described herein to existing and / or new surge arresters that do not include their own spark gap assemblies. Therefore, in some embodiments, the protection described herein and / or... Figure 1-8 The spark gap assemblies shown (e.g., spark gap assembly 130, spark gap assembly 230, and spark gap assembly comprising N spark gap segments) may be included in an accessory device configured to be connected in series with a surge discharger that does not include its own spark gap assembly.

[0070] Figure 10 and Figure 11 An exemplary embodiment of a spark gap assembly accessory device 1000 is shown. The accessory device 1000 includes a housing 1005, a first stud 1010 extending from the upper portion of the housing 1005, and a lower stud 1015 extending from the lower portion of the housing 1005. The first stud 1010 electrically connects the accessory device 1000 to a surge arrester 1100, which does not include its own spark gap assembly. For example, the surge arrester 1100 may be a conventional MOV-based arrester that includes one or more resistive components (such as MOV stack 1105) but does not include a spark gap assembly. The second stud 1015 electrically connects the accessory device 1000 to ground 125. The housing 1005 of the accessory device 1000 may be made of any suitable material, such as, but not limited to, ceramic, glass, and / or nylon.

[0071] Figure 10 An embodiment of an accessory device 1000 is shown, which includes the spark gap assembly 130 described herein. Similarly, Figure 11 An exemplary embodiment of an accessory device including the spark gap assembly 230 described herein is shown. In some embodiments, the accessory device 1000 may include a spark gap assembly comprising a plurality of N spark gap segments described herein.

[0072] Therefore, among other things, this disclosure also provides a spark gap assembly included in a surge arrester. Various features and advantages of this application are set forth in the following claims.

Claims

1. A spark gap assembly, comprising The first spark gap section includes: First spark gap; and The first stage circuit is electrically connected in parallel with the first spark gap; and The second spark gap section is connected in series with the first spark gap section, and the second spark gap section includes: Second spark gap; and The second stage circuit is electrically connected in parallel with the second spark gap. The second spark gap section is configured to receive surge voltage from the power system, and the first spark gap section is configured to conduct surge current to the ground. Wherein, when the spark gap assembly operates at a first operating frequency, the first ratio of the voltage across the first spark gap to the spark discharge voltage of the first spark gap is approximately equal to the second ratio of the voltage across the second spark gap to the spark discharge voltage of the second spark gap, and wherein, when the spark gap assembly operates at a second operating frequency higher than the first operating frequency, the first ratio is greater than the second ratio.

2. The spark gap assembly according to claim 1, wherein, The spark gap assembly is electrically connected in series with a metal oxide rheostat (MOV).

3. The spark gap assembly according to claim 1, wherein, The first hierarchical circuit includes at least one selected from the group consisting of resistors, capacitors, and inductors; and The second hierarchical circuit includes at least one selected from the group consisting of resistors, capacitors, and inductors.

4. The spark gap assembly according to claim 1, wherein, The spark gap assembly is included in an accessory device that is electrically connected in series with the surge discharger.

5. The spark gap assembly according to claim 1, wherein, The spark gap assembly is included in the surge discharger.

6. The spark gap assembly according to claim 1, wherein, The first operating frequency is 60 Hz.

7. The spark gap assembly according to claim 1, further comprising: The third spark gap section is electrically connected in series with the first spark gap section and the second spark gap section. The third spark gap assembly includes: The third spark gap; and The third stage circuit is electrically connected in parallel with the third spark gap.

8. A discharger, comprising: Spark gap assembly, including: The first spark gap section includes: First spark gap; and A first staged circuit, which is electrically connected in parallel with the first spark gap; and The second spark gap section is connected in series with the first spark gap section, and the second spark gap section includes: Second spark gap; and The second stage circuit is electrically connected in parallel with the second spark gap. The second spark gap section is configured to receive surge voltage from the power system, and the first spark gap section is configured to conduct surge current to the ground. Wherein, when the spark gap assembly operates at a first operating frequency, the first ratio of the voltage across the first spark gap to the spark discharge voltage of the first spark gap is approximately equal to the second ratio of the voltage across the second spark gap to the spark discharge voltage of the second spark gap, and wherein, when the spark gap assembly operates at a second operating frequency higher than the first operating frequency, the first ratio is greater than the second ratio.

9. The discharger according to claim 8, further comprising: A metal oxide rheostat (MOV) is connected in series with the spark gap assembly.

10. The discharger according to claim 8, wherein, The first hierarchical circuit includes at least one selected from the group consisting of resistors, capacitors, and inductors; and The second hierarchical circuit includes at least one selected from the group consisting of resistors, capacitors, and inductors.

11. The discharger according to claim 8, wherein, The first operating frequency is 60 Hz.

12. The discharger according to claim 8, wherein, The spark gap assembly also includes: The third spark gap section is electrically connected in series with the first spark gap section and the second spark gap section. The third spark gap assembly includes: The third spark gap; and The third stage circuit is electrically connected in parallel with the third spark gap.

13. An accessory device electrically connected in series with a discharger, the accessory device comprising: Spark gap assembly, including: The first spark gap section includes: First spark gap; and The first stage circuit is electrically connected in parallel with the first spark gap; and The second spark gap section is connected in series with the first spark gap section, and the second spark gap section includes: Second spark gap; and The second stage circuit is electrically connected in parallel with the second spark gap. The second spark gap section is configured to receive surge voltage from the power system, and the first spark gap section is configured to conduct surge current to the ground. Wherein, when the spark gap assembly operates at a first operating frequency, the first ratio of the voltage across the first spark gap to the spark discharge voltage of the first spark gap is approximately equal to the second ratio of the voltage across the second spark gap to the spark discharge voltage of the second spark gap, and wherein, when the spark gap assembly operates at a second operating frequency higher than the first operating frequency, the first ratio is greater than the second ratio.

14. The accessory device according to claim 13, wherein, The discharger includes a metal oxide rheostat (MOV) disk.

15. The accessory device according to claim 13, wherein, The spark gap assembly also includes: The third spark gap section is electrically connected in series with the first spark gap section and the second spark gap section. The third spark gap assembly includes: The third spark gap; and The third stage circuit is electrically connected in parallel with the third spark gap.

16. The accessory device according to claim 13, wherein, The discharger does not include a spark gap.

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