• 조명전기설비학회논문지
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• 제24권10호
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• pp.136-142
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• 2010

In this paper, we changed $SF_6$ insulation gases used already in the GIB(Gas Insulated Bus, gas insulated busbar) of switching appliances of power grid 170[kV] GIS(Gas Insulated Switchgear, Gas Insulated Switchgear) with green insulation dry air gases and studied dielectric breakdown voltage characteristics by the AC voltage withstand test. Withstand test AC voltage applied to the standard KEPCO's 170[kV] GIB with dry air insulation and and the equivalent of dry air and $SF_6$ gas were examined. Breakdown voltage of dry air, using an expression of the experiments were calculated and AC Withstand criterion of dry air insulation for the AC voltage test was derived. Using the criterion, dry air gases can be used instead of the $SF_6$ gas was confirmed in the factory acceptance test at 170[kV] GIB.

• 조명전기설비학회논문지
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• 제24권8호
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• pp.142-149
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• 2010

본 논문은 준평등전계에서 뇌임펄스전압에 대한 $SF_6$와 dry-air의 절연파괴 특성에 대하여 기술하였다. 준평등전계로 사용된 구-평판전극계의 전계이용률은 71[%]이다. $SF_6$는 0.1~0.2[MPa] 범위에서, dry-air는 0.2~0.6[MPa]에서 $SF_6$와 dry-air의 절연파괴전압을 임펄스전압의 극성과 가스압력에 따라 측정 분석하였다. 그 결과 뇌임펄스전압에 대한 두 가스의 절연파괴전압은 정극성이 부극성보다 높았으며, $SF_6$의 절연파괴전압이 dry-air의 절연파괴전압보다 약 2.67배정도 높았다. 본 연구결과는 뇌서지에 대하여 우수한 성능을 가지는 배전기기에서 $SF_6$의 대체가스 성능 평가에 유용한 정보가 될 것이다.

• 전기학회논문지
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• 제57권10호
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• pp.1731-1737
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• 2008

This paper present the fundamental insulation characteristics of Dry Air gas and insulation coating in high voltage power apparatus. It is known that the dielectric strength. of Dry Air is approximately one-third that of SF6 gas. we attempt that the insulation coating and dry air gas have replaced the SF6 gas as insulation of the switchgear. We proposed the dry air insulated switchgear(DAIS) for High Voltage apparatus. To acquire technology of insulation characteristic improvement made standards for complex insulation structure and conducted simulations and experiments

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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• pp.238-240
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• 2008

This paper gives a basic data of the breakdown characteristics of Dry-Air and air based on their dew point and humidity variations in experimental GIS model by applying AC voltage. The breakdown voltage of Dry-Air was increased as gap length had been increased. The characteristics of Dry-air which had low dew point were higher. In the case of air, the breakdown voltage curves were like Dry-Air' s. But the curves were slightly folded up and down because of impurities.

• 한국물환경학회지
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• 제23권3호
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• pp.391-396
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• 2007

공기와 모래를 이용한 건식 식기세척기를 주방에 설치하여 운전하였다. 실험을 위하여 30여종의 양념(Dirt 마커) 과 14종의 접시를 사용하였으며 세척효율은 COD-MN에 의해 평가하였다. 건식 공기세척은 일부 양념에는 효과적이었으나 일부 양념에는 전혀 효과가 없는 것으로 분석되었다. 또한 건식공기세척을 통해서 양념의 완벽한 제거는 불가능하였다. 접시의 형태에 따라 세척효율에 큰 차이를 보였다. 모래와 공기에 의한 세척은 COD-MN 제거에 탁월한 성능을 보였다. 본 연구를 통하여 물을 사용하지 않고 모래와 공기에 의한 건식세척 방법이 가능함이 입증되었다.

• 한국전기전자재료학회논문지
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• 제23권10호
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• pp.804-808
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• 2010

In this paper, we studied the dielectric breakdown voltage characteristics by the AC withstand voltage test on using green insulation dry air instead of $SF_6$ insulation gas used in the GIB (gas insulated bus) of 362 kV GIS (gas insulated switchgear). The AC withstand voltage test applied to the standard KEPCO's 362 kV GIB with dry air insulation, and the equivalence of dielectric breakdown voltage for dry air and $SF_6$ gas were examined, and the empirical formulas of dielectric breakdown voltage for dry air were calculated, and the criterion of AC withstand voltage test for dry air insulation was derived. Using the criterion, dry air can be used instead of $SF_6$ gas for 362 kV GIB in the factory acceptance test was confirmed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1502-1504
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• 2006

본 연구는 $SF_6$와 Dry-air(건조공기)가 혼합된 절연매체의 절연 특성과 부분방전 특성 연구를 위하여 기초실험용 쳄버와 70kV급 GIS mock up 을 이용하여 교류전압을 인가하여 실험이 수행되었다. 전자의 경우, Sphere gap 및 Needle/Plate 전극시스템을 이용하여 순수 $SF_6$가스와 Dry-air의 절연내력을 비교하고, 챔버의 압력을 5기압으로 유지한 상태에서 Dry-air와 $SF_6$가스의 혼합비를 변화시키면서 절연내력이 측정되었다. 후자의 경우, 기초실험에서 도출된 $SF_6$가스와 Dry-air의 최적의 혼합비율을 선택한 후, 방전 개시전압과 부분방전 양상을 순수 $SF_6$가스의 결과와 비교 분석하기 위한 실험을 수행하였다. 이를 위하여 GIS 사고의 주요원인이 되는 결함들, 즉 Protrusion, Floating, Free moving particle 들을 인위적으로 모의하여 Mock up 내부에 설치하고 내부 압력을 5기압으로 유지한 상태에서 수행되었다. 전자의 경우, $0.5{\sim}5$ 기압 범위내 에서 Dry-air 압력을 변화시켰을 때 절연내력은 전극시스템에 무관하게 순수 $SF_6$가스의 결과치의 $40{\sim}50%$정도이다. 또한 챔버 압력이 5기압일 경우, Needle/Plate 전극을 이용했을 경우, Dry-air 가 80% 혼합된 절연매체는 순수 $SF_6$가스 절연내력의 80%정도이다. 후자의 경우, 인가전압을 고정 시켰을 때, 부분방전 패턴과 방전크기는, 순수 $SF_6$가스와 Dry-air 가 80% 혼합된 절연매체는 동일한 패턴과 방전크기를 나타내고 있다. 이러한 결과를 근거로, 가스 압력이 5기압에서 운전되는 전력기기의 절연 매체로서 혼합가스를 사용할 경우, $SF_6$가스와 Dry-air의 혼합비는 2:8정도가 적절한 것으로 제안한다.

• 설비공학논문집
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• 제15권12호
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• pp.1018-1027
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• 2003

This study treats the analysis of the performance and the design of plume abatement wet/dry cooling tower with dry type heat exchanger using a numerical method. A two-dimensional analysis is performed using the finite volume method for mechanical draft counterflow and crossflow tower. For a coupling problem between water and air system, a turbulent two phase flow is considered. Effectiveness-NTU method is used for modeling of the dry type heat exchanger. The parameter change simulations of the outer wall shape, the relative flowrate of air, and attachment of an air mixer are performed to examine the effect on plume abatement. It is found that if the relative air flowrate ratio and the adequate air mixer type are chosen well in addition to the ratio of water to air flowrate, the loss of the cooling capacity and the additional cost are reduced and the plume is abated.

• International Journal of Air-Conditioning and Refrigeration
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• 제13권2호
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• pp.61-70
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• 2005

This study treats the numerical analysis of performance and design for plume abatement wet/dry cooling tower with a dry type heat exchanger. A two-dimensional analysis is performed using the finite volume method for mechanical draft counterflow and crossflow tower. For a coupling problem between water and air system, a turbulent two phase flow is considered. The Effectiveness-NTU method is used for modeling of the dry type heat exchanger. The parametric simulations such as the relative flowrate of air and attachment length of an air mixer are performed to examine the effect on plume abatement. It is found that if the relative air flowrate ratio and the adequate air mixer type are chosen well in addition to the ratio of water to air flowrate, the loss of cooling capacity and the additional cost are reduced and the plume is abated.

• 전기학회논문지
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• 제60권8호
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• pp.1560-1565
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• 2011

The environmental pollution caused by green-house gases such as $CO_2$ and $SF_6$ has been becoming the main issue of industrial society. Many developed countries are making efforts to minimize the amount of $CO_2$ emission come from the operation of high voltage electrical apparatuses. As a part of these efforts, 180 countries signed the Kyoto Protocol in 1997 to cut back on their green-house gas emissions. Nowadays, the study on the development of dry air insulated switchgear (DAIS) which is known as an eco-friendly electrical apparatus is in progress. A DAIS is advantageous for minimizing the effect of impurities and enhancing the dielectric characteristics over an air insulated switchgear (AIS) by applying constant pressure to an enclosed cubicle. Therefore, a study on the electrical insulation performance of dry air as a gaseous insulation medium is conducted in this paper to substitute a gas insulated switchgear (GIS) for DAIS. As results, it is verified that the AC dielectric characteristics of dry air are similar to those of air and the lightning impulse dielectric characteristics of dry air are superior to those of air at 1bar pressure condition. However, dry air is of inferior dielectric characteristics to $SF_6$ at 4bar pressure condition. Finally, it is suggested that the internal pressure of DAIS should be over 4bar pressure to develop a high voltage switchgear which has similar electrical performance to a conventional GIS. Also, the empirical formulae on calculating the maximum electric field intensity at sparkover of dry air are deduced by experiments according to pressures. It is expected that these results are helpful to design and develop a high voltage electrical apparatus.