Lightning arrester deterioration evaluation method

Abstract

To provide a lightning arrester deterioration evaluation method capable of evaluating the degree of deterioration of the entire lightning arrester by using a simple approach of applying a DC current to the lightning arrester.SOLUTION: A lightning arrester deterioration evaluation method according to the present invention is a deterioration evaluation method for a lightning arrester in which a plurality of zinc oxide elements are laminated. The method for evaluating the deterioration of a lightning arrester includes a reference current value determination step for determining a reference current value, a connection step for connecting the lightning arrester to a device capable of flowing a DC current, and a measurement step for applying a DC current at the reference current value and measuring a voltage at that time. According to this aspect, the degree of deterioration of the lightning arrester can be easily assessed. Therefore, the performance of the lightning arrester can always be ensured.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for evaluating deterioration of a lightning arrester, and more particularly to a method for evaluating the degree of deterioration of a lightning arrester. [Background technology]

[0002] A lightning arrester is a device that protects electric power equipment in power generation, transformation, transmission, and distribution systems, consumer equipment that receives power, wired communication lines, antenna systems, communication equipment, etc., from transient abnormally high voltages caused by lightning, etc., and is one of the so-called surge protection devices. This type of arrester has a nonlinear current-voltage characteristic that shows low resistance to surge voltages and high resistance to normal ground voltages. The typical structure of this type of arrester is a stack of multiple zinc oxide elements, the main component of which is zinc oxide (ZnO), and an insulating outer covering such as an elastic polymer is attached to the outer surface of the stack.

[0003] FIG. 4 shows the configuration of a lightning arrester using the above-mentioned zinc oxide element and the equivalent circuit of the lightning arrester. In Patent Document 1, the zinc oxide element (current limiting element) constituting the lightning arrester is forcibly deteriorated in multiple stages, and the resistive current and V of each current limiting element measured at that time are measured. 10μA The degree of deterioration of the current limiting element inside the surge arrester is evaluated based on the relationship between V 10μA indicates the voltage drop when 10 μA DC is passed through the current limiting element. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2005-257391 A Summary of the Invention [Problem to be solved by the invention]

[0005] It is believed that a lightning arrester deteriorates with each lightning strike. If the degree of deterioration of the arrester becomes severe, i.e., if the arrester becomes defective, the voltage value for a given DC current value will drop and the arrester will no longer be able to protect against lightning, causing accidents in the power system and other places, as well as causing external abnormalities such as damage to the external insulating housing. Currently, defective arresters are discovered by relying on the abnormalities in appearance and are replaced with good ones.

[0006] As mentioned above, since lightning arresters deteriorate every time they are struck by lightning, there are some that are not judged to be defective, but are close to being defective. In this case, there is a problem that the lightning arrester will no longer perform its original role as a lightning arrester. In order to prevent this, it is necessary to evaluate the deterioration state of the lightning arrester before it becomes defective. As a countermeasure to such a situation, an operation is carried out in which lightning arresters are replaced with new ones in conjunction with related construction work, but there is a problem that lightning arresters that are equivalent to new ones and have not been struck by lightning and lightning arresters that have not yet deteriorated are also discarded, resulting in losses. In order to prevent this, it is necessary to be able to evaluate the deterioration state.

[0007] Patent Document 1 discloses a method of passing a direct current through a zinc oxide element that constitutes a lightning arrester, thereby deteriorating the zinc oxide element and evaluating the degree of deterioration of the lightning arrester. However, this method is based on the premise that the lightning arrester is used by applying a commercial frequency alternating current voltage of 1 pu (pu indicates a multiple of the applied voltage, with the continuous operating voltage being 1 pu) or more, and there is a problem in that it is not possible to know the degree of deterioration of a lightning arrester that is used without applying this voltage.

[0008] In view of the above circumstances, the present invention aims to provide a lightning arrester deterioration evaluation method that is a simple method of applying a direct current to a lightning arrester yet is capable of evaluating the degree of deterioration of the entire lightning arrester. [Means for solving the problem]

[0009] The lightning arrester deterioration evaluation method of the first invention is a lightning arrester deterioration evaluation method for a lightning arrester including a laminate of multiple zinc oxide elements, and is characterized by including a reference current value determination step of determining a reference current value, a connection step of connecting the lightning arrester to a device capable of passing a direct current, and a measurement step of applying a direct current at the reference current value and measuring the voltage at that time. The lightning arrester deterioration evaluation method of the second invention is characterized in that, in the reference current value determination step, a DC voltage is applied to a test lightning arrester in which some of the plurality of zinc oxide elements have been replaced with degraded zinc oxide elements, so as to achieve a predetermined current, and the reference current value is determined by comparing it with a case in which all of the plurality of zinc oxide elements are normal zinc oxide elements. A third aspect of the present invention relates to a method for evaluating deterioration of a lightning arrester according to the second aspect of the present invention, and is characterized in that, in the reference current value determining step, the DC voltage is imposed by a lightning impulse generator. The lightning arrester deterioration evaluation method of the fourth invention is characterized in that, in the second invention, the deteriorated zinc oxide element has a voltage value when a direct current of 1 mA is applied thereto is equal to or lower than a predetermined value. The lightning arrester deterioration evaluation method of the fifth invention is characterized in that, in the first invention, the reference current value determination process includes a first process of designating one of the zinc oxide elements as a degraded zinc oxide element, and a second process of designating two or more of the zinc oxide elements as degraded zinc oxide elements. The method for evaluating deterioration of a lightning arrester according to a sixth aspect of the present invention is characterized in that, in the first aspect of the present invention, the reference current value is 1 mA. Effect of the Invention

[0010] According to the first aspect of the present invention, the resistance leakage current can be used as a reference by applying a DC current of a reference current value to the lightning arrester, so that the degree of deterioration of the lightning arrester can be easily grasped. This makes it possible to always ensure the performance of the lightning arrester. According to the second invention, by determining a reference current value using a test lightning arrester in which some of the multiple zinc oxide elements have been replaced with degraded zinc oxide elements, the reference current value can be determined under conditions similar to that of an arrester in which some of the zinc oxide elements have been degraded due to a lightning strike. According to the third aspect of the present invention, a DC voltage is applied by a lightning impulse generator, thereby making it possible to more closely resemble deterioration caused by a lightning strike. According to the fourth invention, by using a zinc oxide element whose voltage value when 1 mA of DC is applied is equal to or lower than a predetermined value as the deteriorated zinc oxide element, it is possible to more closely resemble deterioration due to lightning. According to the fifth invention, the reference current value determination process includes a first step of replacing one of the zinc oxide elements with a degraded zinc oxide element and applying a DC voltage, and a second step of replacing two or more of the zinc oxide elements with degraded zinc oxide elements and applying a DC voltage, so that the reference current value can be determined based on the degraded state of one zinc oxide element. According to the sixth aspect of the present invention, the reference current value is 1 mA, which makes it easy to determine the degree of deterioration. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a flow diagram of a method for evaluating deterioration of a lightning arrester according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of a zinc oxide element used in the reference current value determination step of the arrester deterioration evaluation method of FIG. 1. [Diagram 3] 2 is a graph showing values ​​of DC voltages applied to a test surge arrester in the surge arrester deterioration evaluation method of FIG. 1. [Figure 4] 2A is a schematic diagram of a lightning arrester evaluated by the lightning arrester deterioration evaluation method of Fig. 1. (B) is an equivalent circuit diagram of the lightning arrester evaluated by the lightning arrester deterioration evaluation method of Fig. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Next, an embodiment of the present invention will be described with reference to the drawings. However, the embodiment shown below is an example of a method for evaluating deterioration of a lightning arrester to embody the technical concept of the present invention, and the present invention does not limit the method for evaluating deterioration of a lightning arrester to the following. Note that the size or positional relationship of the members shown in each drawing may be exaggerated for clarity of explanation.

[0013] The lightning arrester deterioration evaluation method of the present invention is a lightning arrester deterioration evaluation method for a lightning arrester including a laminate of multiple zinc oxide elements, and includes a reference current value determination step of determining a reference current value, a connection step of connecting the lightning arrester to a device capable of passing a direct current, and a measurement step of applying a direct current at the reference current value and measuring the voltage at that time.

[0014] In this embodiment, the resistance leakage current can be used as a reference by applying a DC current of a reference current value to the arrester, so that the degree of deterioration of the arrester can be easily grasped, and the performance of the arrester can be always ensured.

[0015] In addition, in the lightning arrester deterioration evaluation method according to the present invention, in the reference current value determination step, a DC voltage is applied to a test lightning arrester in which some of the zinc oxide elements have been replaced with deteriorated zinc oxide elements so as to obtain a predetermined current, and the reference current value is determined by comparing the test lightning arrester with all of the zinc oxide elements being normal zinc oxide elements. With this aspect, the reference current value can be determined in a state similar to that of an arrester in which some of the zinc oxide elements have been deteriorated due to a lightning strike.

[0016] In the lightning arrester deterioration evaluation method according to the present invention, in the reference current value determination step, the DC voltage is applied by a lightning impulse generator. With this aspect, the DC voltage is applied by a lightning impulse generator, so that deterioration caused by a lightning strike can be more similar.

[0017] In addition, in the method for evaluating deterioration of a lightning arrester according to the present invention, the deteriorated zinc oxide element has a voltage value equal to or lower than a predetermined value when a direct current of 1 mA is applied. This embodiment makes it possible to more closely resemble deterioration caused by lightning.

[0018] In addition, in the lightning arrester deterioration evaluation method according to the present invention, the reference current value determination step includes a first step of replacing one of the zinc oxide elements with a deteriorated zinc oxide element and applying a DC voltage, and a second step of replacing two or more of the zinc oxide elements with deteriorated zinc oxide elements and applying a DC voltage. With this embodiment, the reference current value can be obtained based on the deteriorated state of one zinc oxide element.

[0019] In the method for evaluating deterioration of a lightning arrester according to the present invention, the reference current value is 1 mA, which makes it easy to determine the degree of deterioration.

[0020] (Embodiment) Fig. 1 shows a flow diagram of a method for evaluating deterioration of an arrester according to an embodiment of the present invention. As shown in Fig. 1, the method for evaluating deterioration of an arrester according to this embodiment is directed to an arrester 10 (see Fig. 4(A)) including a laminate of a plurality of zinc oxide elements 11. The method for evaluating deterioration of an arrester according to this embodiment includes a reference current value determination step 01 (hereinafter referred to as S01), a connection step S02, and a measurement step S03. Each step will be described below.

[0021] (Reference current value determination process) A person who implements the method for evaluating deterioration of an arrester determines a reference current value to be used in the subsequent measurement step in the step of determining a reference current value in S01. As shown in Fig. 4(A), an arrester 10, which is the subject of the method for evaluating deterioration of an arrester of this embodiment, has a shape with a long axis extending from the top to the bottom on the paper surface of Fig. 4(A). A plurality of zinc oxide elements 11 are stacked inside the arrester in the axial direction, and an insulating outer cover 12 is attached to the outer periphery of the stack. The resistance value between the top and bottom of the arrester 10 is nonlinear due to the properties of the zinc oxide elements 11, which are its constituent elements.

[0022] Fig. 2 shows a schematic diagram of a laminate of zinc oxide elements 11 constituting the lightning arrester 10. Fig. 2(A) shows a first laminate 11a constituting the first test lightning arrester, and Fig. 2(B) shows a second laminate 11b constituting the second test lightning arrester.

[0023] A laminate in which a plurality of zinc oxide elements 11 (for example, 10 in FIG. 2) are stacked in the axial direction is used in a commonly used lightning arrester 10. These zinc oxide elements 11 are inspected one by one before being assembled into the lightning arrester 10, and normal zinc oxide elements 20 that meet predetermined standards are stacked and used in the lightning arrester 10.

[0024] In this embodiment, in the reference current value determination process, a DC voltage is applied to a test lightning arrester in which some of the multiple zinc oxide elements 11 have been replaced with degraded zinc oxide elements, so that a predetermined current is obtained, and the reference current value is determined by comparing it with the case in which all of the multiple zinc oxide elements are normal zinc oxide elements.

[0025] In the first stack 11a shown in Fig. 2(A), of the ten zinc oxide elements 11 stacked in the axial direction, nine are normal zinc oxide elements 20 and one is a deteriorated zinc oxide element 21. In the second stack 11b shown in Fig. 2(B), of the ten zinc oxide elements 11 stacked in the axial direction, eight are normal zinc oxide elements 20 and two are deteriorated zinc oxide elements 21. For example, to perform 10% deterioration management, as shown in Fig. 2, the voltage value when a direct current of 1 mA is applied to the first stack 11a having ten stacked zinc oxide elements 11 and one deteriorated zinc oxide element 21 is used as the deterioration specified value.

[0026] 3 is a graph showing the value of the DC voltage applied to the test arrester in the arrester deterioration evaluation method. The horizontal axis of this graph shows the number of deteriorated zinc oxide elements 21 included in the zinc oxide element 11 constituting the arrester 10, and the vertical axis shows the value of the DC voltage when a predetermined DC current is passed through it.

[0027] First, the practitioner of the lightning arrester deterioration evaluation method measures the voltage values ​​that a normal lightning arrester 10 can have when DC currents of 1 mA, 0.1 mA, and 0.01 mA are applied to a lightning arrester 10 consisting only of normal zinc oxide elements 20. In FIG. 3, when a DC current of 1 mA is applied, the voltage value has a specific range. The section represented by the topmost band of dots in FIG. 3 is the voltage value when 1 mA is applied. The next section represented by the second band of dots from the top is the voltage value when 0.1 mA is applied. And the bottommost band of dots is the voltage value when 0.01 mA is applied. The reason why the normal voltage value of the lightning arrester 10 differs depending on the value of the applied DC current is due to the characteristics of the zinc oxide elements 11 inside the lightning arrester 10.

[0028] The intervals shown by the stripe dots in FIG. 3 are determined by applying a current of 1 mA, for example, to the lightning arrester 10 composed of only a predetermined number of normal zinc oxide elements 20, and measuring the voltage value at that time. The method of determination is not particularly limited. For example, the 3σ interval (a range of ±3σ from the average value) of the voltage value can be the interval shown by the stripe dots, or the interval between the maximum value and the minimum value can be the interval shown by the stripe dots. That is, when the 3σ interval method is adopted, the lower threshold voltage value is a value 3σ lower than the average value, and when the maximum / minimum method is adopted, the minimum value of the measured voltage value is the lower threshold voltage value.

[0029] Next, the practitioner of the lightning arrester deterioration evaluation method replaces one normal zinc oxide element 20 in the lightning arrester 10 with a deteriorated zinc oxide element 21 and applies each DC current (first step). In Fig. 3, the voltage value at 1 mA is represented by the symbol ◯, the voltage value at 0.1 mA by △, and the voltage value at 0.01 mA by □. Next, the practitioner replaces another one of the normal zinc oxide elements 20 in the lightning arrester 10 with the deteriorated zinc oxide element 21, for a total of two, and applies each DC current (one of the second steps). Finally, the practitioner replaces another one of the normal zinc oxide elements 20 in the lightning arrester 10 with the deteriorated zinc oxide element 21, for a total of three, and applies each DC current (one of the second steps).

[0030] As shown in FIG. 3, in all cases where a DC current of 1 mA, 0.1 mA, or 0.01 mA is applied, the DC voltage value decreases as the number of deteriorated zinc oxide elements 21 replaced increases. However, when comparing the difference with the section representing the voltage value when only normal zinc oxide elements 20 are used, it can be seen that in the case of 1 mA, a difference occurs even when the number of deteriorated zinc oxide elements 21 is one, but in the cases of 0.1 mA and 0.01 mA, it can be seen that there is almost no difference when the number of deteriorated zinc oxide elements 21 is one. As such, in this embodiment, the reference current value is determined by applying a DC voltage to the test arrester replaced with the deteriorated zinc oxide element 21 so as to obtain a predetermined current.

[0031] By determining the reference current value using a test arrester in which some of the zinc oxide elements 11 have been replaced with deteriorated zinc oxide elements 21, it is possible to determine the reference current value in a state similar to that of an arrester in which some parts have deteriorated due to a lightning strike. In addition, by applying a direct current at the reference current value to the arrester 10, the resistive leakage current can be used as the reference, so that the degree of deterioration of the arrester 10 can be easily grasped. This makes it possible to always ensure the performance of the arrester 10.

[0032] In addition, it is preferable that the deteriorated zinc oxide element 21 is imposed on, for example, the normal zinc oxide element 20 by a lightning impulse generator. For example, the lightning impulse generator is a device capable of generating an impulse current of a unipolar or oscillatory waveform, and the standard current waveform actually used is a current waveform in which the standard front duration / standard tail duration is 8 / 20 μs in a clamping voltage test and 4 / 10 μs in a discharge withstand test. It is preferable that the DC voltage value when this lightning impulse current is applied and a DC current of 1 mA is applied is equal to or less than a predetermined value. Specifically, the value is preferably, for example, 5 kV or less. By using a zinc oxide element that has a voltage value of 5 kV when a DC current of 1 mA is applied as the deteriorated zinc oxide element 21, it is possible to more closely resemble deterioration caused by lightning.

[0033] In addition, the reference current value determination process includes a first step of replacing one of the zinc oxide elements 11 with a degraded zinc oxide element 21 and applying a DC voltage, and a second step of replacing two or more of the zinc oxide elements 11 with degraded zinc oxide elements 21 and applying a DC voltage, so that the reference current value can be determined based on the degraded state of one zinc oxide element 11.

[0034] (Connection process) Next, the person who implements the method for evaluating deterioration of a lightning arrester according to the present embodiment performs a connection step of connecting the lightning arrester 10 to be evaluated to a device capable of passing a direct current. This device is not particularly limited as long as it passes a direct current. For example, this device is preferably a diode ladder circuit capable of boosting a direct current.

[0035] (Measurement process) Next, the practitioner of the lightning arrester deterioration evaluation method according to this embodiment performs a measurement step in which a direct current is applied to the lightning arrester 10 connected to the device at a reference current value, and the voltage at that time is measured. Here, the reference current value is the value determined in the reference current value determination step. For example, when the results shown in Fig. 3 are obtained, it is preferable to set the reference current value to 1 mA. A reference current value of 1 mA makes it easier to determine the degree of deterioration.

[0036] (others) In this embodiment, the reference current value determining step, the connecting step, and the measuring step are performed in this order. However, after the reference current value is determined by the reference current value determining step, only the connecting step and the measuring step may be performed. Even in this case, if the reference current value determining step has been performed once, the performing of the connecting step and the measuring step corresponds to the implementation of the present invention. [Explanation of symbols]

[0037] 10 Lightning arrester 11 Zinc oxide element 12 Insulating outer casing 20 Normal zinc oxide element 21 Degraded zinc oxide element

Claims

1. A method for evaluating deterioration of a lightning arrester including a stack of a plurality of zinc oxide elements, comprising: a reference current value determining step of determining a reference current value; A connecting step of connecting the lightning arrester to a device capable of passing a direct current; a measuring step of applying a direct current at the reference current value and measuring a voltage at that time; Includes: A method for evaluating deterioration of a lightning arrester.

2. In the reference current value determining step, a DC voltage is applied to a test arrester in which some of the zinc oxide elements have been replaced with deteriorated zinc oxide elements, so as to obtain a predetermined current, and a reference current value is determined by comparing the result with a case in which all of the zinc oxide elements are normal zinc oxide elements; The method for evaluating deterioration of a lightning arrester according to claim 1 .

3. In the reference current value determining step, The DC voltage is imposed by a lightning impulse generator.

3. The method for evaluating deterioration of a lightning arrester according to claim 2.

4. The deteriorated zinc oxide element is The voltage value when 1 mA of DC current is applied is equal to or less than a predetermined value.

3. The method for evaluating deterioration of a lightning arrester according to claim 2.

5. In the reference current value determining step, a first step of replacing one of the zinc oxide elements with a deteriorated zinc oxide element and applying a direct current voltage; a second step of replacing two or more of the zinc oxide elements with deteriorated zinc oxide elements and applying a direct current voltage; Including, The method for evaluating deterioration of a lightning arrester according to claim 1,

6. The reference current value is 1 mA. The method for evaluating deterioration of a lightning arrester according to claim 1 .

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