http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Properties of ZnO varistor blocks under multiple lightning impulse voltages
이복희,Sung-Man Kang 한국물리학회 2006 Current Applied Physics Vol.6 No.5
Thispaperpresentstheeectofmultipleimpulsevoltagesontheelectricalandphysicalpropertiesofazincoxide(ZnO)varistor.Toinvestigate the dynamic characteristics of a ZnO varistor subjected to multiple impulse voltages, we designed and fabricated the multi-plecombinationwavegenerator.Themultiplecombinationwavegeneratorcanproducequintuple1.2/50l simpulsevoltagesof100 kVandquintuple8/20l simpulsecurrentsof12 kA.Applyingthesevoltagesandcurrents,theelectricalandphysicalpropertiesoftheZnOvaristor were evaluated. The multiple impulse failures of a ZnO varistor are mainly caused by the surface ashover. When multipleimpulse voltages are injected, the charge enhancement near the joined edges of a ZnO varistor and metal electrodes plays a decisiverole on the surface ashover or breakdown initiation and developments. Also, after the injection of the quintuple 8/20l s impulse cur-rents of 10 kA, the residual voltage and quiescent current of the ZnO varistor were changed markedly.
이복희,Young-Hwan Baek,Hwee-Sung Choi,Sung-Kyun Oh 한국물리학회 2007 Current Applied Physics Vol.7 No.3
shaped protrusion in SF6 gas. The breakdown voltagetime (Vt) characteristics and the breakdown voltagegas pressure (Vp) char-acteristics of a highly non-uniform SF6 gas gap under positive and negative lightning impulse voltages are investigated in the pressurerange between 0.1 and 0.5 MPa. The pre-breakdown developments are examined by the corona current and light emission measurementswith high time resolution. As a result, the dielectric strengths versus time-to-breakdown of SF6 gas gap under positive lightning impulsevoltages were nearly independent of the gas pressure. The rst streamer corona was initiated at the tip of the needle electrode, and thestreamer corona pulses developed with a stepwise propagation. The discharge paths were zigzag, and the branches of the discharge chan-nel for positive polarity were created. On the other hand, the leader channel in the negative polarity was thicker and brighter than that inthe positive polarity.
준평등전계에서 임펄스전압에 대한 N<sub>2</sub>가스의 절연파괴특성
이복희,김동규,이봉,Lee, Bok-Hee,Kim, Dong-Kyu,Li, Feng 한국조명전기설비학회 2010 조명·전기설비학회논문지 Vol.24 No.8
This paper presents dielectric characteristics of $N_2$ gas under impulse voltages in a quasi-uniform electric field gap. The experiments were carried out at the test gap applied by the 1.2/50[${\mu}s$] lightning impulse voltage, 180/2500[${\mu}s$] switching impulse voltage, 500[ns]/1[MHz] very fast transient overvoltage(VFTO). The gap separation of sphere-to-plane electrodes was 14[mm] and the electric field utilization factor was about 71.2[%]. The gas pressure ranges from 0.2 to 0.6[MPa]. As a result, the electrical breakdowns are occurred by streamer discharge. Breakdown voltages are linearly increased with the gas pressure and the highest breakdown voltage is appeared under the VFTOs having fast rising time. Breakdown voltages under the positive impulse voltages were higher than those under the negative ones, and also the time to breakdown in the positive polarity is longer than that in the negative polarity. 본 논문은 준평등전계중에서 임펄스전압에 대한 $N_2$가스의 절연파괴특성에 관한 것으로 실험은 1.2/50[${\mu}s$] 표준뇌임펄스전압, 180/2500[${\mu}s$] 개폐임펄스전압과 500[ns]/1[MHz] 급준성 과도과전압이 인가된 전극계에서 이루어졌다. 구-평판 전극의 간격은 14[mm]이고, 전계이용률은 71.2[%]이었으며 가스압력은 0.2~0.6[MPa]범위로 하였다. 그 결과 절연파괴는 스트리머방전에 의하여 일어났으며, 절연파괴전압은 상승시간이 빠른 급준성 과도과전압에서 가장 높게 나타났다. 정극성 절연파괴전압이 부극성보다 높았으며, 정극성의 경우 절연파괴까지의 시간도 더 긴 것으로 나타났다.