KR100593710B1 - Deterioration Diagnosis Apparatus and Method of Zinc Oxide Gapless Lightning Arrester Using Nonlinear Operation Characteristics - Google Patents

Abstract

The present invention relates to an arrester, and more particularly, to a device for diagnosing deterioration of a zinc oxide element gapless arrester using a nonlinear operating characteristic of determining a deterioration determination by connecting a current transformer to an arrester and measuring leakage current flowing from the current transformer. It is about.

According to the present invention, a current transformer mounted at a lower part of the lightning arrester for current flow of the lightning arrester leakage current flowing through the arrester, a current measuring circuit for acquiring the lightning arrestor leakage current from the current transformer, and processing the current into the current information, the current information provided from the current measuring circuit And a deterioration diagnosis system of the zinc oxide gapless arrester using nonlinear operating characteristics, including a deterioration determination system for processing and determining the deterioration determination.

Through the present invention, it is possible to determine the exact degree of arrester deterioration by implementing the algorithm proved through several arrester destruction tests and field demonstrations, and to determine the leakage current of the arrester based on accurate frequency information without judging only the effective value of the fundamental wave. This provides the effect of accurately determining the deterioration state of the arrester.

Lightning arrester, leakage current, current transformer, current measurement circuit, deterioration determination system

Description

Diagnostic Apparatus and Method for Gapless Type Lightning Arrester Using the Nonlinear Impedance Characteristics of Zinc Oxide Gapless Lightning Arrester Using Nonlinear Operation Characteristics

1 is a conceptual diagram for explaining the function of the zinc oxide gapless lightning arrester of the prior art,

2 is a view showing an electrical equivalent circuit of a zinc oxide gapless arrester of the prior art;

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3 is a diagram showing an equivalent circuit for explaining the deterioration of a zinc oxide gapless lightning arrester of the prior art;

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4 is a diagram showing a voltage vs. current characteristic curve of a zinc oxide gapless arrester of the prior art;

5 is a fatigue arrester diagnosis system coupled to an arrester counter according to an embodiment of the prior art,
6 is a lightning arrester diagnostic system using a resistance current measurement according to another embodiment of the prior art,
7 is a diagram illustrating a arrester degradation diagnostic system and a detection waveform using the arrester leakage current according to an embodiment of the present invention;
8 is a view showing the flow of the arrester leakage current,
9 is a view showing the arrester limiter characteristics,
10 is a view showing the arrester dead band characteristics,
11 is a view showing a relationship between resistance current and three harmonics of a general arrester;

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12 is a block diagram of an arrester diagnostic system according to an embodiment of the present invention,

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13 is a configuration diagram of the current measurement circuit of FIG.

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14 is a configuration diagram of the deterioration determination system of FIG. 12.

<Explanation of symbols on the main parts of the drawing>

1. Transmission Line 2. Processing Line

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3. phase conductor 4. circuit breaker

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5. Transformer winding 6. Ground

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7. Arrester 8. Substation

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9. Lightning arrester leakage current 21. Series resistance

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22. Parallel Resistor 23. Capacitor

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24. Lightning arrester equivalent circuit 41. Lightning arrester phase 1 area

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42. Lightning arrester phase 2 area 43. Lightning arrester action phase 3 area

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44. Protective Level

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45. Maximum Continuous Operating Voltage (MCOV)

51. Main bus 52. Arrester upper terminal

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53. Arrester lower terminal 54. Down-conductor wire

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55. Lightning arrester counter 56. Counter

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57. Ammeters 61, 71 Current transformers (CT)

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62. Capacitor Coupled Transformer (PT) 63 Conventional Lightning Arrestor Diagnosis

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64.PT voltage terminal 65.Arrester diagnostic through-current (i ₁ )

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66. Voltage at PT voltage terminal (V) 67. Phase difference (θ)

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70 Lightning arrestor diagnostics 72. Lightning arrester diagnostic current (i ₂ )

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73. Voltage waveform input to the arrester 74. Voltage vs. current characteristic curve of the arrester

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75. Harmonic waveform that occurs after the voltage waveform input to the arrester crosses the voltage-to-current characteristic curve of a typical arrester.

81. Device through-current ( I _A ) 82. Internal leakage current ( I _B )

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83. External leakage current (I _C) 84. arrester element

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121. Current measurement circuit 122. Deterioration determination system
123. Display 131. Impedance matching circuit
132.HPF Circuits133.LPF Circuits
134. A / D converter
142. Frequency Analyzer 143. Current Information by Frequency
144. Degradation Algorithm

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The present invention relates to an arrester, and more particularly, to a device for diagnosing deterioration of a zinc oxide element gapless arrester using a nonlinear operating characteristic of determining a deterioration determination by connecting a current transformer to an arrester and measuring leakage current flowing from the current transformer. It is about.
In the power system, the transmission line 1 mainly passes through a terrain such as a mountain and is exposed to lightning. When a large lightning strike is applied to the overhead line 2 of the power transmission line, the potential rises to the overhead line and the steel tower, and this potential passes through the air and flashes to the conductor 3. This is called reverse flashover, and when reverse flashover occurs, the lightning current passes through the breaker 4 to the substation 8 through the superconductor 3 and reaches the transformer winding 5 again, which burns the transformer winding or leads to dielectric breakdown. And weakens the dielectric strength.
1 is a conceptual diagram for explaining the function of a zinc oxide gapless lightning arrester.
For this reason, the surge arrester 7 is mounted on the front end of the transformer winding 5 to discharge only the surge voltage and the overvoltage which become a certain voltage (operation start voltage) to the ground through the ground 6. As a result, the lightning arrester works well to protect the insulation of power equipment such as the transformer winding 5 and the circuit breaker 4.
FIG. 2 is a diagram illustrating an electrical equivalent circuit of the zinc oxide gapless arrester according to FIG. 1. In the electrical equivalent circuit of the general lightning arrester 7, the parallel resistor 22 and the condenser 23 are connected in a parallel circuit. The series resistor 21 is connected in series with this parallel circuit.
This is the equivalent circuit of a universal lightning arrester already used internationally.
The arrester cell constituting the arrester 7 is configured in a cylindrical shape of a zinc oxide element.
Such arrester elements are locally burned or broken.
That is, as shown in Figure 3, the arrester cell acts as if a plurality of arrester equivalent circuits 24 are arranged in parallel, and each equivalent circuit is partially damaged to exhibit deterioration characteristics.
3 is a diagram showing an equivalent circuit for explaining deterioration of a zinc oxide gapless lightning arrester.
Deterioration of the arrester occurs locally as in the model of FIG. 3, in which each arrester model 24 individually has the voltage-current characteristics of the typical arrester of FIG. 4.
In FIG. 3, when any one of tens or hundreds of deterioration models is deteriorated, the voltage-current characteristic of the deteriorated model is lowered. Therefore, the operation of the arrester is made very finely at the voltage applied to the arrester.

When the arrester 7 is deteriorated, it has the following deterioration characteristics.
First, when the arrester element 84 is normal, the arrester leakage current 9 is changed into a phase current which is faster than the phase of the bus voltage, or is in phase current when the arrester 7 is deteriorated.
That is, as the arrester 7 deteriorates, the resistance current of the arrester leakage current 9 increases.

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Second, when the arrester element 84 is normal, the arrester leakage current 9 is close to a sine wave that contains little harmonic, but becomes a distortion wave current including harmonic components as the arrester deteriorates.
This is caused by the nonlinear characteristics of the arrester element due to the breakage of some of the arrester elements. In particular, an increase in the three harmonic components that occur proportionally as the arrester 7 deteriorates tends to coincide with an increase in the resistance current.
4 is a diagram showing a voltage versus current characteristic curve of a conventional zinc oxide gapless lightning arrester. Referring to the drawings, the voltage versus current characteristic of the arrester 7 may be divided into three steps.
In stages 1 and 41, a current of several mA flows through the arrester in the state of the arrester 7 normally. At this time, the flowing current becomes a fast current in which the phase of the current precedes the phase of the voltage. At this time, the voltage applied to the arrester 7 is less than or equal to the maximum continuous operating voltage (MCOV, 45) that is the operating voltage of the system.
Stages 2 and 42 are operating characteristics when a voltage greater than the protective level 44 of the arrester 7 characteristics is applied to the arrester 7, and the arrester voltage is constant as the actuation start voltage. While retained, the current increases to tens of kA. This characteristic is the normal operation characteristic of the arrester. Even in this normal operation, the arrester 7 has a characteristic that spasms deteriorate little by little.
Stages 3 and 43 are areas in which the arrester 7 is not capable of performing the arrester's original performance, that is, voltage and current increase together. Therefore, it does not function to suppress overvoltage. If this situation is repeated, the arrester 7 quickly deteriorates and is destroyed.
That is, when the arrester operates, the arrester acts as a nonlinear impedance. In stage 2 and 42 of FIG. 4, the arrester shows a limiter characteristic (FIG. 9) among the nonlinear characteristics. The current contains fundamental and various harmonics,
In addition, the third stage (stage 3, 43) of FIG. 4 shows a dead band characteristic (FIG. 10) among the nonlinear characteristics. The current passing through the deadband also causes harmonics.

On the other hand, there are currently two kinds of conventional arrester diagnostic methods.

The first method is a method of diagnosing the arrester by combining the arrester counter as shown in FIG.
This method of measuring the current leakage current (Figs. 5 and 9) by attaching an ammeter to the lower conductor wire 54 of the arrester, because of the use of an analog ammeter, the accuracy is lowered, and the large current when the arrester 7 operates Often burned out.
The lightning arrester leakage current 9 is composed of a current 81, an internal leakage current 82, and an external leakage current 83 passing through the element as shown in FIG. 8, and the lightning arrester 7 is deteriorated. The current component causing the change in magnitude and phase is the current 81 through the device.
Therefore, the method of attaching an ammeter to the arrester down-conducting wire 54 has a fear of misunderstanding that the arrester has a problem when the external leakage current 83 increases regardless of the failure of the arrester 7 and the deterioration of the arrester 7. .
After all, this method of measuring the total leakage current is the simplest, but the problem is that it is unreliable and misunderstood as deteriorated even though the arrester has not deteriorated.

The second method is as described in FIG. 6, and measures the voltage of the bus line 51 applied to the arrester 7 through the transformer 62, and measures the arrester leakage currents (FIGS. 6 and 9) in the current transformer 61. It is a method of determining the deterioration of the arrester by measuring the phase difference between the voltage and the current using the voltage 66 through the transformer and the current 65 through the current transformer.
More specifically, the resistance current measurement method measures the leakage current of the arrester leakage current 9 through the current transformer 61, measures the voltage of the corresponding bus 51 as the voltage of the transformer 62, and measures the current. 65 and using a voltage 66 analog, by using a digital circuit or processor voltage v (66) and if after obtaining the phase difference θ (67) of the current i ₁ (65) calculates a i ₁ cosθ resistance minutes Only current can be obtained.
However, in this case, there is a problem and inconvenience caused by having to measure the bus bar 51. When considering only one arrester, it may not be difficult to supply a voltage corresponding to each arrester 7, but in the case of a large-scale power installation, dozens or hundreds of arresters 7 are installed in one region. In this case, incidental costs such as cable costs and construction costs will increase. It is also impossible to use this method in the case of an arrester 7 which cannot easily supply voltage, such as a distribution line.
After all, the above method is a method for measuring the deterioration of the arrester, but there is a problem that it is accompanied by an additional construction, material costs increase, and is almost impossible to apply in the case of a distribution arrester.

Accordingly, the present invention was devised to solve the above problems, and deterioration of the zinc oxide gapless arrester using nonlinear operating characteristics of measuring the arrester deterioration degree by measuring only the arrester leakage current and then performing harmonic analysis. The object of the present invention is to provide a diagnostic method and an apparatus thereof.
Other objects and advantages of the invention will be described below and will be appreciated by the embodiments of the invention. In addition, the objects and advantages of the present invention can be realized by means and combinations indicated in the claims.

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표1은 피뢰기의 열화특성를 나타내는 것으로, 표 1에서의 결과를 이용하여 도 11에서는 저항분 전류와 3고조파의 전류를 비교하여 도시화하였다.
도 11에서 나타난 바와 같이, 피뢰기가 열화되면서 저항분 전류의 증가와 3고조파 전류의 증가는 비례관계가 형성됨을 알 수 있다.
결국 피뢰기의 열화를 측정하는 요소로서 저항분 전류와 3고조파 전류 모두 유효하다는 것을 알 수 있으며, 본 발명에서는 전압의 분석없이 누설전류만으로도 분석과 피뢰기의 열화진단이 가능한 3고조파 전류만으로 피뢰기의 열화를 진단하는 방법이 적용된 것이다.
따라서, 피뢰기의 누설전류만으로 피뢰기의 열화정도를 측정함으로써 저렴한 측정기의 개발이 가능하고 설치가 용이하고 피뢰기에 인가된 전압요소가 필요 없이 측정이 가능하므로 운전 중인 피뢰기의 열화판정이 간편하다.The present invention for achieving the above object is a current transformer circuit for arranging the arrester leakage current flows through the arrester mounted on the lower end of the arrester, current measuring circuit for acquiring the arrester leakage current from the current transformer to process the current information, the current Deterioration diagnosis apparatus of a zinc oxide gapless arrester using nonlinear operating characteristics, including a deterioration determination system for processing and determining deterioration determination by obtaining current information provided from a measurement circuit, and a display device for informing a user of the deterioration state of the arrester. It includes.
In another aspect, the present invention comprises the steps of acquiring the arrester leakage current through the current transformer, processing the leakage current of the arrester from the current transformer as current information in the current measurement circuit, receiving current information from the current measurement circuit in the deterioration determination system Performing deterioration determination and controlling the system.
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.
Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.
7 or 12 is a view showing the arrester degradation diagnostic system and the detection waveform according to an embodiment of the present invention.
13 and 14 show the configuration of the current measurement circuit and degradation determination system of FIG. 12, respectively.
Referring to the drawings, the arrester degradation diagnosis system includes a current transformer 71, a current measurement circuit 121, a degradation determination system 122 and a display device 123.
The current transformer 71 is configured to flow the lightning arrestor leakage current 9 which is mounted at the bottom of the arrester and flows through the arrester.
The current measuring circuit 121 is configured to acquire the leakage current of the arrester from the current transformer 71 and process it into current information which becomes a determination condition of deterioration determination.
The current measurement circuit 121 discretizes the impedance matching circuit 131 for minimizing the burden on the current transformer, the HPF circuit 132 / LPF circuit 133 and the current information for filtering the noise component of 10 kHz or more and the magnetic field in the atmosphere. And an A / D converter 134 for converting into a signal.
The degradation determination system 122 is configured to obtain information from the current measuring circuit 121 to process and determine the degradation determination.
The deterioration determination system 122 converts the current information converted from the current measurement circuit 121 into the discretized signal into frequency-specific information by applying a pre-converter method and the frequency-by-frequency converted by the frequency analyzer 142. The deterioration determination algorithm 144 for determining the deterioration state of the arrester by the current information is included.
The display device 123 is configured to inform the user of the state of the arrester 7 based on the result of the deterioration determination system 122.
Operation description according to the configuration of the degradation diagnostic apparatus of FIG. 7 or FIG. 12 is as follows.
First, the step of acquiring the arrester leakage current through the current transformer 71 will be described.
FIG. 8 is a diagram showing the flow of the arrester leakage current, and there are three kinds of the arrester leakage current 9.
First, the element passing current 81, I _A passing through the arrester element 84 is the current most closely related to the deterioration of the arrester 9, which is initially in phase with the arrester deteriorating at the fastening current. Proceed to
Second, the arrester element 84 is mounted in a sealed space made of a material of the insulator 85. However, if moisture or the like penetrates due to any cause, current leaks to the inner surface. The current at this time is an internal leakage current 82, I _B which is an in phase component.
Third, external leakage current (83, I _C ), which is an in-phase component generated when water is present together with salt or the like attached to the outer surface of the arrester.
That is, in the above three kinds of leakage currents 9, the leakage current 9 applied in the present invention is the device through current I _{A which has} passed through the device.
Next, the step of processing the leakage current input from the current transformer 71 into current information in the current measurement circuit 121 will be described.
In order to accurately process the device passing current I _A coming from the clamp-type current transformer 71, the impedance matching circuit 131 is first passed.
In the impedance matching circuit 131, a portion capable of minimizing the burden of the current transformer 71 and a current measured in the actual field include many noise components due to the influence of the magnetic field in the air and the electric field.
This noise component is mainly removed through a filter for removing a signal of 10 kHz or more, and also a DC component included in the current information obtained from the current transformer 71 is also removed.
The current information from which the noise component and the DC component are removed passes only the frequency band (50 Hz to 600 Hz) necessary for determining the degradation of the arrester while passing through the HPF 132 and the LPF 133 constituted by the operational amplifier.
The current information passing through the HPF 132 and the LPF 133 is converted into a discrete signal through the A / D conversion 134 and transferred to the deterioration determination system 122 which is digital processing hardware.
Third, the deterioration determination system 122 performs the deterioration determination on the current information output from the current measurement circuit 121 and controls the system.
The current information output from the current measuring circuit 121 becomes a discretization signal to reach the deterioration determination system.
The current information converted into the discretized signal is passed through the frequency analyzer 142 using the free frequency conversion method, which is a frequency analysis method, and is converted into information for each frequency.
The frequency-specific current information 143 converted as described above is in a state capable of determining the deterioration state of the arrester by the arrester deterioration determination algorithm 144.
In the embodiment of the present invention, the deterioration determination algorithm determines that deterioration proceeds when the three harmonic currents are changed by 5% or more in consideration of deterioration characteristics of the arrester.
And when more than 50% of the fundamental wave to notify the user through the display device 123 to stop the arrester.
On the other hand, the deterioration determination algorithm is based on the experimental data of Table 1, and the reference of the experimental data of Table 1 applies an impulse generator with a current waveform of 8 × 20 μs to the arrester cell, where the magnitude of the impulse current is maintained between 65 kA and 90 kA. After 20 seconds of application of the impulse current, a commercial frequency voltage is applied and the voltage and current are measured and analyzed until the arrester cell is destroyed.
When looking at Table 1, there exists only 70 times of data because the arrester cell was destroyed after applying 71 times of current.

Table 1 shows the deterioration characteristics of the arrester. In FIG. 11, the resistance current and the three harmonic currents are compared using the results of Table 1. FIG.
As shown in FIG. 11, it can be seen that as the arrester deteriorates, a proportional relationship is formed between an increase in the resistance current and an increase in the third harmonic current.
As a result, it can be seen that both the resistance current and the 3 harmonic currents are effective as a factor for measuring the deterioration of the arrester.In the present invention, the deterioration of the arrester using only 3 harmonic currents capable of analyzing and deteriorating diagnosis of the arrester without analyzing the voltage is possible. The method of diagnosis has been applied.
Therefore, it is possible to develop an inexpensive measuring device by measuring the degree of deterioration of the arrester using only the leakage current of the arrester, and it is easy to install, and it is possible to measure without the voltage element applied to the arrester, so it is easy to determine the deterioration of the arrester in operation.

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The method and apparatus for diagnosing deterioration of a zinc oxide gapless lightning arrester using the nonlinear operating characteristics of the present invention perform frequency analysis of the pre-serial water supply line to determine the deterioration of the arrester with three harmonics, and the third harmonic increases even if the external leakage current in phase increases. By not doing so, there is an effect that determination of the arrester deterioration without an erroneous judgment is possible.

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In addition, by implementing a proven algorithm through several arrester destruction tests and field demonstrations, it is possible to determine the exact degree of arrester deterioration, and by determining the leakage current of the arrester based on accurate frequency-specific information instead of judging only the effective value of the fundamental wave. It is effective to accurately determine the deterioration state of.
As mentioned above, although this invention was demonstrated by the limited embodiment and drawing, this invention is not limited by this, The person of ordinary skill in the art to which this invention belongs, Of course, various modifications and variations are possible within the scope of equivalent claims.

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Claims (6)

A current transformer mounted on a lower part of the arrester and configured to flow a lightning arrestor leakage current flowing through the arrester; A current measurement circuit which obtains the arrester leakage current from the current transformer and processes the leakage current into current information; A degradation determination system for processing and determining a degradation determination by obtaining current information provided from the current measurement circuit; And Deterioration diagnosis apparatus for a zinc oxide gapless lightning arrester using a non-linear operating characteristics comprising a display device for informing the user of the deterioration state of the arrester. According to claim 1, wherein the current measuring circuit, An impedance matching circuit for accurately processing current information output from a current transformer, HPF / LPF comprising an operational amplifier for passing only the required frequency band of 50Hz to 600Hz to determine the degradation of the arrester, and An apparatus for diagnosing deterioration of a zinc oxide gapless lightning arrester using a nonlinear operation characteristic, further comprising an A / D conversion circuit for converting current information passing through the HPF / LPF into a discrete signal. The deterioration determination system according to claim 1, A frequency analyzer for converting current information into frequency-specific information using a frequency converter method, which is a frequency analyzer method that generally uses, and Considering the deterioration characteristics of the arrester, it is judged that degradation occurs when the 3rd harmonic current fluctuates more than 5%, and the arrester deterioration determination algorithm is transmitted to the manager through the display to stop the arrester when the harmonic current exceeds 50%. An apparatus for diagnosing deterioration of a zinc oxide gapless arrester using a nonlinear operating characteristic further comprising. As a method of measuring the arrester leakage current flowing into the arrester connected to the bottom of the arrester, Acquiring the arrester leakage current through a current transformer; Processing the leakage current of the arrester from the current transformer as current information in a current measurement circuit; And A method for diagnosing degradation of a zinc oxide gapless arrester using nonlinear operating characteristics, comprising: receiving current information from the current measuring circuit and performing deterioration determination in a deterioration determination system and controlling the system. The method of claim 4, wherein the processing of the current information in the current measuring circuit comprises: Correctly processing current information coming from the clamp-type current transformer by the impedance matching circuit 131, Passing the operational amplifier to pass only the required frequency band of 50Hz to 600Hz to determine the degradation of the arrester by the HPF and LPF, and Converting the current information passed through the operational amplifier into a discrete signal using an A / D conversion circuit, and then transferring the current information to a deterioration determination system of the zinc oxide gapless lightning arrester using nonlinear operating characteristics. Deterioration diagnostic method. The method of claim 4, wherein performing the deterioration determination and controlling the system in the deterioration determination system comprises: Converting the frequency information into frequency-specific information by using a frequency converter, using a pre-transformer method, which is a frequency analysis method generally used; and Considering the deterioration characteristics of the arrester due to the arrester deterioration determination algorithm, it is judged that degradation occurs when the 3rd harmonic current is changed by more than 5%, and the user is informed to stop the arrester by 50% of the fundamental wave. A method for diagnosing deterioration of a zinc oxide gapless arrester using nonlinear operating characteristics further comprising the step of: a.

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