• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.3
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• pp.184-189
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• 1999

In this paper, we develope a diagnosis device for ZnO arrester by detecting the leakage current in service. To diagnose the deterioration of ZnO arrester, the device detects the total leakage current which flows between an arrester and ground, and analyzes the resistive current(third harmonic current) which is an indicator of deterioration of ZnO arrester. We use the optical cable which can transfer a detected data without a noise, also use a microprocessor for a data storage, processing, and trend analysis. Experiment are executed to verify its performance in laboratory and the results show that the diagnosis device exactly detects the total leakage current and the resistive current, so it can diagnose the deterioration of ZnO arrester. Also the leakage current of ZnO arrester is detected using the developed diagnostic device in field, these results are presented.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.1
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• pp.42-46
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• 2003

Arresters are deteriorated by overvoltages or impulse currents, and the resistive leakage current of arresters increases as the deterioration of the arrester progresses, showing an increase in the 3$^{rd}$ harmonic component of the leakage current. In this reason, arrester diagnostic techniques based on the 3$^{rd}$ harmonic leakage current as a reference parameter of deterioration are widely used. The technique, however, includes an error due to the harmonics of power system voltage. Therefore, the influence of the harmonics on arrester diagnostics should be considered. In this paper, we designed a PSpice ZnO arrester model to simulate the influence of the voltage harmonics described above. A pure sinusoidal voltage and its the 3r harmonic voltage were applied to the model, and the leakage current components were analyzed. From the simulation results, it is confirmed that the peak value of resistive leakage current depends not only on the phase of the 3$^{rd}$ harmonic voltage but also on the magnitude of it. Consequently, the errors caused 1)y the harmonic voltage could be minimized by correcting the magnitude of leakage current upon analyzing the harmonics.cs.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.4
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• pp.152-157
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• 2002

This paper describes an effect of a single- and a quadruple-lightning impulse currents on electrical characteristics of ZnO blocks, and an expert system to diagnose arrestor deterioration. To deduce the parameters needed for diagnosing arrester deterioration, an accelerate deterioration teat is carried out. In the experiment, leakage current components are measured. Also, wave height distribution of the leakage current according to the progress of arrester deterioration is analyzed. From the experimental results, the wave height distribution of the leakage current showed conspicuous difference even in an immaterial leakage current increase. Therefore, the use of wave height distribution of the leakage current in deterioration diagnostic technique makes more accurate diagnosis than the conventional method by using only a leakage currant value. Finally, the expert system based on the experimental results is developed and the system can diagnose arrestor deterioration by measuring the leakage current and its wade height distribution.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.142-145
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• 2002

This paper describes an influence of system voltage harmonics on arrester deterioration diagnostic techniques based on leakage current measurement because the resistive current is composed of two components caused by nonlinear characteristics of arrester and by system voltage harmonics. Resistive leakage currents of arresters, which can be evaluated by the third harmonic component of total leakage currents, increase with its deterioration progress. In this paper, we developed a PSpice model for ZnO arrester to simulate the harmonics' effect described above. In simulation, pure sinusoidal voltage and the $3^{rd}$ harmonic voltage are applied to the model, and the leakage current changes are compared. The simulation results showed that the magnitudes of resistive leakage current depend not only on the phase of system voltage harmonics but also on the magnitude of it.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.10
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• pp.469-475
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• 2003

Resistive leakage current flowing ZnO blocks increases with its ages, which is an important indicator of arrester deterioration. However, a complicated circuitry is essential to measure the resistive leakage current included in the total leakage current, and the difficult handling of the measurement makes few applications to the fields. In this paper, we propose a resistive leakage current measurement device which is composed of a current detection circuit and an analysis program operated on a microprocessor. The device samples the input leakage current waveform digitally, and discriminate the zero-cross and the peak point of the waveform to analyze the current amplitude vs. phase. The capacitive leakage current is then eliminated from the total leakage current by using an algorithm to extract the resistive leakage current only. Also, the device can be operated automatically and manually to analyze the resistive leakage current even when the leakage current waveform is distorted due to various types of arrester deterioration. To estimate the performance of the device, we carried out a test on ZnO blocks and lightning arresters. From the results, it is confirmed that the device could analyze most parameters needed for the arrester diagnostics such as total leakage current. resistive leakage current, and the $3^rd$ harmonic leakage current.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.319-320
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• 2005

This paper describes the principles and structures of an expert system for arrester diagnosis. The expert system analyzes and decides the arrester condition by total leakage current, its harmonic component, and temperature because the deterioration of arresters appeared in an increase of leakage current and surface temperature of it. Additionally, influence of system voltage harmonics and ambient temperatures on leakage current changes were considered in the design. The expert system is consisted of a data acquisition module and a computer for monitoring. The acquired analog data are digitalized and transmitted to the computer by an optical link which is free from interference.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.74-76
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• 1995

In this paper, the results of development of arrester leakage current detector using micro computer are described. This detector is based on harmonic analysis of the leakage current by FFT. The change of leakage current is the recognized measure of deterioration. For low sensitivity to disturbance, this device used optical fiber. This will be a great benefit of detecting deterioration ZnO arrester.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.1422-1424
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• 2004

Various deterioration diagnostic techniques and devices are suggested, and most of which measure leakage current components as an indicator of arrester ageing. However, the techniques based on the magnitude of leakage current measure simply RMS or peak value of leakage current components and do not provide detailed information needed in the diagnosis. In this study, we found that the phase vs. wave height of total leakage current is changed or a new wave height is produced with arrester ageing. To complete the new technique, we designed an arrester diagnostic device which is composed of a current detection circuit, an optical transmission circuit, and an analysis program. After measurement of the total leakage current, magnitudes, phase vs. wave height, and harmonics of the leakage current components are analyzed by the microprocessor based device. From the experimental results, we confirmed that the device can measure most parameters needed for the arrester diagnostics and analyze an initial deterioration state.

• Journal of the Korean Society for Railway
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• v.7 no.4
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• pp.307-311
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• 2004

Arresters are the best protective device on electrical power systems against transient overvoltages generated by lightning and/or switching operation. Nonetheless, arresters are deteriorated by absorption of moisture in the environments of its use, repetition in the protective operation to overvoltages, and some defects at manufacturing. It is therefore important to estimate the electrical characteristic changes of ZnO blocks. In this paper, an accelerated ageing test by a standard lightning impulse current was carried out to extract parameters needed for arrester diagnosis, and leakage current components were measured. Total energy applied to the ZnO blocks at each time is about 1,050[J] in 8/20[${\mu}\textrm{s}$] impulse current. From the experimental results, we proposed electrical parameters and leakage current level to diagnose arrester soundness.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.12
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• pp.685-690
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• 2000

Multiple-lightning impulse currents are a general feature of the lightning ground f=flash. It is therefore necessary for lightning arresters used in power systems to be estimated by applying not only a single-lightning impulse current but also a multiple-lightning impulse currents. This paper presents the effects of multiple-lightning impulse currents on deterioration of ZnO arrester blocks. The multiple-lightning impulse generator which can produce quadruple 8/20$[\mus]$ 5[kA] with separation time of 30~120[ms] is designed and fabricated. The total energy applied to the arrester block at each impulse is about 1,200[J]. In experiment, various parameters such as leakage current component, reference voltage, and temperature are measured with the number of applied impulse current. Also, micro-structure changes of the ZnO blocks after applying the single and the multiple-lightning impulse currents of 200 times are compared. The experimental results indicate that the types of arrester blocks are more vulnerable to deterioration or damage by multiple-lightning impulse currents.