• 한국전기전자재료학회논문지
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• 제20권10호
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• pp.907-911
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• 2007

This paper dealt with the frequency spectrum analysis of acoustic signal produced by partial discharge (PD) in insulation oil and the positioning of PD occurrence to apply in diagnosis of oil insulated transformers. Three types of electrode system ; the needle-plane, the plane-plane, and the wire-wire structure were assembled to simulate partial discharges in oil insulated transformers. A low-noise amplifier and a decoupling circuit were designed to detect acoustic signal with high sensitivity The frequency spectrum of the acoustic signal were 50 kHz ${\sim}$ 260 kHz in the needle-plane, 50 kHz ${\sim}$ 250 kHz in the plane-plane, and 45 kHz${\sim}$195 kHz in the wire-wire electrode system. Their peak frequencies were 145 kHz, 130 kHz and 114 kHz, respectively The position of PD occurrence was calculated by the time difference of arrival (TOA) using three acoustic emission (AE) sensors, and we could find the position within the error of 1 % in the experimental apparatus.

• 한국전기전자재료학회논문지
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• 제25권9호
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• pp.727-731
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• 2012

This paper dealt with the measurement and analysis of electromagnetic waves radiated from a partial discharge (PD) source in insulation oil to apply condition monitoring of oil-immersed transformers. Two types of narrow-band monopole antennas with the resonant frequency of a 500 MHz and a 1 GHz were designed and fabricated. Also, a needle-plane electrode system was manufactured to simulate PDs and the curvature radius of the needle is 10 ${\mu}m$ and the diameter of the plane is 60 mm. Electromagnetic wave was measured by the PD measurement system with the monopole antennas. Detection sensitivity of the fabricated antenna was compared for the same PD magnitude; 620 $mV_{peak}$ for the 500 MHz antenna and 960 $mV_{peak}$ for the 1 GHz antenna to the PD magnitude of 74 pC. Consequently, the 1 GHz monopole antenna is more effective to detect PDs in oil-immersed transformers.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권4호
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• pp.247-252
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• 1999

In this paper, in order to investigate availability of the OW-PD measurement method which has been proposed as an alternative of AC-PD measurement method to an after laying test and/or diagnosis for the power cable system, partial discharges owing to the needle-type defect integrated into the cable have been measured using AC and OW(Oscillating Wave) voltages. In the AC-PD measurement, the magnitude, phase and pulse number of partial discharges have been changed with the duration of voltage application, which can be analyzed through the relation with the process of the electrical tree initiation and propagation. In addition, the characteristics of partial discharges using OW voltage are appeared to be similar to those in case of AC-PD measurement and to be different with the shapes of electrical tree. From these results, it is concluded that the OW-PD measurement method is available to the tests for the cable system.

• 한국조명전기설비학회지:조명전기설비
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• 제8권3호
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• pp.54-63
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• 1994

본 연구에서는 판상스페이서 위에 침전극을 고정하고 gap간격 40[mm]에 평판전극을 설치한 gap 간에 10[mm]간격으로 나누어 각 구간내에 스페이서와 같은 재질의 Barrier를 설치하고 파티클을 두었을 때 AC 및 정극성 DC 전압에서의 방전로와 FOV에 대해 연구한 결과 다음과 같은 결론을 얻엇다. 1) Barrier가 고전위측에 위치한 경우와 파티클이 Barrier뒤에 은폐된 경우가 FOV가 높다. 2) 침전극 선단에 파티클 위치할 때 심한 FOV의 감소가 있다. 3) 파티클이 전극간에 게재되면 방전로는 파티클을 경유하므로 FOV는 감소한다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권10호
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• pp.492-499
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• 2002

This paper presents the method for an estimation of discharge current waveform in short gap discharge by radiated electromagnetic fields. The method of current waveform estimation is to use the one antenna method (single field method) with a measured electric or magnetic field at given field point by a time domain antenna. In order to verify the availability of the estimation theory, the discharge current waveform estimation was performed by one antenna methods using the measured electric fields of Wilson & Ma and compared with experiments. In addition diagnosis technique for power equipments is able to prevent from large accidents by finding signs of tile accidents before they happen. From the results of the estimation of discharge current, we have a possibility for the application of insulation diagnosis technique for power equipments using S$F_6$ gas. From this point of view, this paper simulated discharge progress and partial discharge by using needle-plan electrodes system in S$F_6$, studied the distribution of frequency spectrum of the radiated electromagnetic waves using a biconical antenna and a spectrum analyzer. From the experimental results of this study, according to the consideration of the mutual relation between frequency spectrum of the radiated electromagnetic waves and discharge progress, it was confirmed that detecting Partial discharge and estimating discharge progress in S$F_6$ could be Possible.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.296-299
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• 1991

This paper reports the characteristics of sparkover discharge in flowing gas ranging from 0[m/s] to 30[m/s] under the needle-rod gap. The important results obtained from this paper are as followers. 1. The maximum sparkover voltage of flowing gas are about 3.1[kv](d=1[cm], 5.4[kv](d=2[cm]), 8.1[kv](d=3[cm]) higher than those of static gas 2. The empirical equation obtained from this experiment is [%]$\frac{Vs}{Re}=A\;log_{10}\;Re+B$ where A=$-7.79{\times}10$ B=$5.60{\times}10^2$ 3. The duration time of sparkover decreases with increasing the Reynolds number. 4. The discharge pattern can be controlled by adjustment of the Reynolds number

• 전기학회논문지
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• 제56권5호
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• pp.933-937
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• 2007

A point plate type nonthermal plasma reactor, with a grounded cylindrical third electrode which closely- encompasses the needle point, have been investigated with an emphasis on the role of the third electrode. It was found that the point plate airgap, with the grounded third electrode, had a switching characteristic on its I V characteristics for negative and positive discharges, which is very different from that of a conventional point plate airgap without a third electrode. The corona discharge and ozone generation characteristics of the plasma reactor with the grounded cylindrical third electrode, such as the corona onset voltage. the breakdown voltage. the corona current. and the amount of output ozone, were influenced significantly by the height of the third electrode. and these characteristics can be controlled by adjusting the height of the third electrode.

• 한국대기환경학회지
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• 제15권1호
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• pp.33-39
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• 1999

This study has been performed to develop an efficient electrocharged scrubber. To improve collection efficiency of the scrubber, electric-charger was installed at the forefront of the packed crossflow scrubbers, and an experiment of changing discharge electrode shape and fluctuating electric field strength was undertaken. After using a light-oil boiler for generation of particles in the about 80% weight of submicron size particles was exhausted. Collection characteristics of the electrocharged scrubber were similar to those of two-stage electrostatic precipitator. In this study the collection efficiency of submicron size particles has been much improved, compared with the previous ones. In an experiment of changing discharge electrode and electric field strength, a needle-spike shape wire electrode showed a higher collection efficiency than round shape wire. The collection efficiency becomes increased with an increase of electric field strength.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.534-536
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• 2000

This paper describes measurement and diagnosis methods for enclosed switchboards using antenna. In the laboratory partial discharges are generated on a needle-plate electrode configuration, the detected electromagnetic wave is analyzed by FFT. The detected electromagnetic wave in real enclosed switchboards is also analyzed by FFT, which is compared with frequency spectra of the laboratory to detect the partial discharge. The relationship between the partial discharge characteristics and the electromagnetic wave has been discussed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.560-562
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• 2002

This paper describes measurement and diagnosis methods for electromagnetic wave using a VHF(Very High Frequency) antenna. In the laboratory partial discharges are generated on a needle-plate and a plate-plate configuration. The detected electromagnetic wave is analyzed by FFT(Fast Fourier Transform). We propose a methode to classify creeping partial discharge and corona partial discharge that are detected in three frequency bands.