• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.917-918
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• 2007

The former earth leakage breaker is operating by total leakage current which is the vector-sum of resistive leakage current and capacitive leakage current. However, the electric disaster like the electric shock and fire is caused mainly by resistive leakage current. Therefore, the earth leakage breaker is ideal when it is operating by resistive leakage current. In this paper, the theory for finding the component of resistive leakage current from total leakage current is suggested and it is embodied to actual circuit. The resistive leakage current can be found by integrating the total leakage current during half cycle of line voltage. Thus, we can simply find resistive leakage current by using OP-AMP integrators, and we can confirm that the resistive leakage current is computed exactly from total leakage current obtained by resistive leakage current and capacitive leakage current. The results that the earth leakage breaker is operating within regular interrupt time are verified when the former earth leakage breaker's controller circuit is replaced by the proposed controller circuit.

• 전기학회논문지
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• 제56권8호
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• pp.1397-1404
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• 2007

It is important to measure the resistive component separately from the total leakage current at power distribution line. It is because electric disasters such as electric shock and fire are caused mainly by the resistive component of the total leakage current. In this paper, a new theory for measuring the resistive component separately from the total leakage current is suggested, and is embodied to an actual circuit using operational amplifiers, analog switch and R-C low pass filter. Through experiments for various cases containing both the resistive and capacitive leakage currents, the suggested algorithm is confirmed to be able to measure the resistive leakage current within 4.1% of error even when the capacitive leakage current is much bigger than the resistive one. The suggested method is expected to lower the total cost because it can be realized using simple and cheap devices, and implies the measuring time can be possibly reduced because the resistive leakage current is computed exactly from the signals during only a half period of power voltage.

• 전기학회논문지
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• 제57권2호
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• pp.198-207
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• 2008

The conventional Residual Current Protective Devices(RCD, or earth leakage circuit breaker, ELB) operates depending on the total leakage current which is the vector-sum of resistive and capacitive components of a leakage current. However, the electric disaster such as electric shock or fire is mainly caused by the resistive component. Therefore, in this view point, the RCD is more realistic when it operates by the resistive component of the leakage current. In this paper, a new algorithm for measuring the resistive leakage current from the total leakage current is suggested, and is realized to an actual circuit. According to the suggested algorithm, the resistive component of the leakage current can be found by integrating the total leakage current over only a half cycle of the line voltage, and it is realized by using analog switches and resettable integrators. It is confirmed through experiments that the suggested algorithm detects, within maximum average error of 6.74%, the resistive leakage current from the total leakage current, and the RCD employing the suggested algorithm brakes the circuit within the regular interrupt time(30msec).

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권10호
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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.

• 한국전기전자재료학회논문지
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• 제30권12호
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• pp.817-821
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• 2017

As a ZnO varistor is subjected to electrical and environmental stresses, it degrades gradually, which may result in power interruption by short circuit. This study investigates changes in the electrical characteristics of ZnO varistors due to deterioration owing to energy absorption, and determines the optimal parameters for on-line diagnosis of the varistor. Two types of varistors were used for an accelerated aging experiment involving the application of the $8/20{\mu}s$ standard lightning impulse current. The electrical characteristics in terms of the reference voltage, total leakage current, resistive leakage current, and third-harmonic component of the total leakage current were measured, and their change rates were analyzed. The results revealed that the total leakage current increased slightly with an increase in the varistor absorbed energy, while the resistive leakage current and the third-harmonic component increased apparently. Therefore, the third-harmonic component of the total leakage current was proposed as the optimal parameter for on-line monitoring of ZnO varistor conditions.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 춘계학술대회 논문집
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• pp.360-363
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• 2009

변압기 누설전류 통합 감시 장치는 변압기 중성선에 흐르는 누설전류를 검출하여 실시간으로 모니터링이 가능한 장치로, 지정 값 이상의 누설전류가 검출되면 관리자에게 경보함으로써 전기적인 사고를 사전에 예방할 수 있다. 본 논문에서는 변압기 누설전류 통합 감시장치에 대해 설명하고, 국내 현재 설비상황 및 실제 사고 사례를 통해 변압기 누설전류 통합 강시장치의 필요성에 대해 설명하였다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 추계학술대회 논문집
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• pp.51-54
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• 2009

변압기 누설전류 통합 감시 장치는 변압기 중성점 접지선에 흐르는 누설전류를 검출하여 실시간으로 모니터링이 가능한 장치로, 지정 값 이상의 누설전류가 검출되면 관리자에게 경보함으로써 전기적인 사고를 사전에 예방할 수 있다. 본 논문에서는 변압기 누설전류 통합 감시장치에 대해 설명하고 실제 변압기 누설전류 통합 감시장치가 설치된 수용가의 누설전류량 측정을 통해 안전성 여부를 판단하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.1082-1084
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• 1998

In this paper, we developed a diagnosis device for ZnO arrester to detect on-line leakage current and acquire data from the power distribution system. The arrester is important power equipment used in power transmission and distribution systems to protect the generator and the main transformer from surge and overvoltage. First of all we developed a diagnosis device for ZnO arrester leakage current. And then we detect the total leakage current by the developed device without disconnecting the arrester ground wire and analysis the 3rd order harmonic by Fast Fourier Transform(FFT) to diagnose the ZnO arrester deterioration. With measuring the total current and the resistive current of power distribution system in operation, we analysis the trend of resistive current component in the total leakage current. We expect the result will be promote the method to protect electrical utility and customer from accident.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.132-134
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• 2007

The conventional method used low pass filter for computing resistive leakage current from total leakage current. Therefore, it takes long time for computation. In this paper, a new algorithm is proposed to reduce the computation time. In the theory, the resistive leakage current is computed exactly from the signals during only a half period of power voltage. The suggested method uses integrator and sample-hold circuit and it is confirmed to be able to measure the resistive leakage current from total leakage current by simulation.