• Journal of Electrical Engineering and Technology
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• 제1권1호
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• pp.114-119
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• 2006

This paper reports the investigation results on the leakage currents (LC) on polymeric outdoor insulators. The samples used were EPDM (ethylene prophylene diene monomer) insulators used at 20 kV distribution lines. AC voltage was applied and the LC waveforms were measured under various environmental conditions (humidity and pollution). Digital data of the LC was transferred from a digital storage oscilloscope to a computer for further analysis. The LC waveform parameters such as magnitude and harmonic content (as indicated by the total harmonic distortion (THD)) were analyzed. The experimental results showed that 3rd, 5th and 7th harmonics and higher odd harmonics were observed for symmetrical-distorted LC waveforms while for unsymmetrical-distorted LC waveforms, odd and even harmonics were observed. The LC analysis indicated that there are 5 stages of insulator conditions from normal condition up to flashover correlated with different kind of LC waveforms. The results also showed that in general the magnitude of LC was good enough to show the condition of the insulators. However, under discharge condition (for example as a result of dry band arching) the LC magnitude should be combined by the THD to show a better correlation with the insulator condition. The product between THD and LC magnitude may be used as a diagnostic parameter.

• 조명전기설비학회논문지
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• 제25권3호
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• pp.24-32
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• 2011

[ $SF_6$ ]gas, which has an excellent dielectric strength and interruption performance, is used in various applications such as gas insulated switchgear (GIS) in substations. However, since $SF_6$ has a high global warming potential (GWP), it is necessary to find an eco-friendly alternative insulation gas. In order to examine the possibility of using alternative insulation gases for $SF_6$ in power distribution system equipment, the dielectric strength and physical phenomena of dry air in a quasi-uniform electric field are investigated experimentally in this paper. As a result, the breakdown voltages for positive polarity are higher than those for negative polarity under impulse voltage applications. The negative 50[%] flashover voltage, $V_{50}$ of dry air under conditions above 0.4[MPa] gas pressure, is higher than 150[kV], that is the basic impulse insulation level of distribution equipment. The $V_{50}$ increases linearly with increasing the gas pressure, regardless of the waveform and polarity of the applied impulse voltages. The voltage-time curves are dependent on the rise time of the impulse voltage and gas pressure. Furthermore, streamer discharge was observed through light emission images by an ICCD camera under impulse voltage applications.

• 한국재난정보학회 논문집
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• 제13권4호
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• pp.529-536
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• 2017

본 연구에서는 화재현장에서 소방관들이 느끼는 위험성과 돌발화염에 대한 인식에 관하여 조사하고 연령, 경력 및 계급에 따른 인식의 차이를 통계적으로 비교 분석하였다. 화재현장에서 느끼는 위험성은 계급에 따라 인식의 차이가 있음을 확인하였으며, 화재현장에서의 돌발화염 노출 가능성에 대해서는 70% 이상의 응답자가 노출가능성이 높다고 응답하였으나 연령, 경력, 직급에 따른 인식 차이는 없는 것으로 조사되었다. 그러나 만약 화재현장에서 돌발화염을 겪게 될 경우의 위기대처 능력에 관한 조사에서는 응답자의 연령, 경력, 직급에 따라 인식의 차이가 있는 것으로 나타났다. 이러한 결과를 통해 볼 때 향후 돌발화염의 모의 훈련 등의 강화가 보다 절실히 요구되며, 돌발화염에 따른 표준작전절차의 개선이나 화재진압교육의 보완을 통해 인명사고를 최소화하기 위한 방안들이 강구되어야 할 것으로 판단된다.