• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.3
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• pp.97-106
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• 2000

This paper proposes on-line based a deterioration diagnosis device for diagnosis pole transformers using tan$\delta$ and FFT(fast Fourier transform). We measured tan$\delta$ and temperature to diagnose pole transformer insulating oil, diagnostic results are processed by FFT. For measuring convenience, we use R/F(radio frequency) wireless data communication module operating by secondary voltage of pole transformer. We have voltage variation test and oil temperature variation test to prove usability of proposed diagnosis device. The result of this paper shows that the proposed device can be used as deterioration diagnosis device of pole transformers.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.1
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• pp.37-44
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• 2003

This paper proposes on-line based a deterioration diagnosis pole transformers using various sensors such as thermistor, current transformer and potential transformer. We measured load current and temperature to diagnose pole transformer using R/F( radio frequency ) wireless data communication module. We represent the graphs of their feature. The result of this paper shows that the proposed device car be used as deterioration diagnosis device of pole transformers.

• 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.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.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.3
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• pp.131-137
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• 2005

This paper describes a new approach to the algorithm and fundamental characteristics of the device for monitoring the leakage currents flowing through zinc oxide (ZnO) surge arresters. In order to obtain a technique for a new on-line monitoring device that can be used in the deterioration diagnosis of ZnO surge arresters, the new algorithm and on-line leakage current detection device for extracting the resistive and capacitive currents using the phase shift addition method were proposed. The computer-based on-line monitoring device can sense accurately the power frequency leakage currents flowing through ZnO surge arresters. The on-line leakage current monitoring device of ZnO surge arresters proposed in this work has the high sensitivity compared to the third harmonic leakage current detection devices. As a consequence, it was found that the proposed leakage current monitoring device would be useful for forecasting the defects and degradation of ZnO surge arresters.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1079-1081
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• 1998

This paper describes the dissipation factor measuring device for insulating oil in operating pole transformer by DSP(digital signal processor). After applying voltage to the sensor which is installed in a transformer, acquire source voltage and current of sensor using FFT techniques, then we could evaluate the dissipation factor of insulating oil. To improve measuring accuracy and processing speed, we use TMS320C31 DSP, FFT and data analysis techniques. Also we suggest deterioration criterion of insulating oil and compared the developed diagnosis device with schering bridge on deteriorated insulating oil. The result of this paper show that the developed measuring device can be used as diagnosis device for the pole transformers.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1668-1670
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• 2003

This paper deals with a development of the high precise measuring device of resistive leakage current for the deterioration and diagnosis of ZnO arresters. The resistive leakage current increasing with time leads to a thermally unstable state that may even experience a disaster. So, the resistive leakage current can be used as an indicator to discriminate whether the ZnO arrester blocks is in good state or in bad. The resistive leakage current measuring system with an analysis program operated with micro-processor using the time delay addition method was designed and fabricated. The proposed measuring systems for the resistive leakage current can effectively be used to develop the techniques of forecasting the deterioration of ZnO arresters in electric power systems.⨀ᔌ?؀㔳㤮㈻Ԁ䭃䑎䷗ᜒं6〰Ԁ䭃䑎䴀

• 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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.1
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• pp.203-210
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• 2017

In this paper, we propose a electrical/mechanical method to effectively diagnose the local deterioration of a 10m long power shielded twist pair cable defined by the American Wire Gauge (AWG) 14 specification using electrical/mechanical methods. The rapid deterioration of the cable proceeded by using the heating furnace, which is based on the Arrhenius equations proceeds from 0 to 35 years with the deteriorated equivalent model. In this paper, we introduce a method to diagnose the characteristics of locally deteriorated cable by using $S_{21}$ phase and frequency change rate measured by vector network analyzer which is the electrical diagnostic method. The measured $S_{21}$ phase and rate of change of frequency show a constant correlation with the number of years of locally deteriorated cable, thus it can be useful for diagnosing deteriorated cables. The change of modulus due to deterioration was measured by a modulus measuring device, which is defined by the ratio of deformation from the force externally applied to the cable, and the rate of modulus change also shows a constant correlation with the number of years of locally deteriorated cable. Finally, By combining the advantages of electrical/mechanical diagnostic methods, we can efficiently diagnose the local deterioration in the power shielded cable.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.9
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• pp.596-601
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• 2017

The advancement and diversification of urban functions has caused an increasing need to improve the reliability of power supplies. The diversification of urban areas causes social disruptions by paralyzing urban functions during power outages. A large power outage occurs in the event of an accident, owing to the subduction of distribution lines. Therefore, in recent years, for the sake of the environment and safety, the safety diagnosis of electric power facilities has become an important issue. In this system, because thermal information changes rapidly during unattended monitoring owing to heat concentration phenomenon due to abnormal load or deterioration, studies have been conducted on the development of a device that can notify the manager at all times.