• 조명전기설비학회논문지
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• 제15권6호
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• pp.58-64
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• 2001

본 논문은 LVI시험기 및 모델 변압기의 설계와 제작에 관하여 기술하였다. 이들을 이용하여 LVI 시험 분석기 술을 개발하였다. LVI시험기는 본테, 터미널 박스 및 케이블로 구성하였고, ANSI규격에서 요구하는 출력특성을 갖는 것으로 평가되었다. 모델변압기는 탭들을 만들어 변압기의 권선변형 모델을 만들 수 있도록 하였고, LVI시험기로써 실험을 실시하여 LVI시험분석 기술에 관하여 논하였다.

• 조명전기설비학회논문지
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• 제16권5호
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• pp.97-103
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• 2002

본 논문은 LVI 시험기를 개발하여 모델 변압기 및 유입식 변압기에 적용해 LVI 시험 분석기술을 개발하였다. LVI시험기는 본체, 터미널 박스 및 케이블로 구성하였고, ANSI규격에서 요구하는 출력특성을 갖도록 설계 제작하였다. 모델 변압기는 탭들을 만들어 변압기의 권선변형 모델을 만들 수 있도록 하였고, 유입식 변압기는 실제 현장에서 사용되는 3상 변압기이다. LVI 시험기는 펄스폭이 1000 ㎱ 이하의 파두 시간과 펄스 최대 전압 500 V로 제작되었다. LVI 시험기로써 실험을 실시하여 성능을 평가한 결과 측정된 파형 분석으로 권선의 축방향과 반경방향으로의 움직임을 구별할 수 있어 변압기 예방 진단에도 효과가 기대된다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2000년도 학술대회논문집
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• pp.251-256
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• 2000

The assessment of the condition of a transformer winding which is suspected of having suffered short circuit damage can be difficult. Conventional test such as winding resistance, magnetisation current or insulation resistance will only detect damage if a permanent electrical fault exists. Visual inspection of windings necessitates the removal of oil and in many cases only a very small proportion of the winding can be seen. We describe the characteristics. As the front rise time of recurrent-surge generator pulse less than 1000ns and the peak value of pulse is about 500V, we have the good results of detecting winding deformation in the LVI test of transformers.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1737-1739
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• 1997

We describe the characteristic of LVI test system and methods to detect the deformation of windings in the power transformers. As the front rise time of recurrent-surge generator pulse less than 1000ns and the peak value of pulse is about 500V, we have the good results of detecting winding deformation in the LVI test of transformer. And we discuss the application of LVI test method and the condition of RSG pulse through results of in one and three pole transformers under Lab. tests.

• Steel and Composite Structures
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• 제48권3호
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• pp.305-320
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• 2023

The mechanical properties of polymeric composites are degraded under elevated temperatures due to the effect of temperature on the mechanical behavior of the resin and resin fiber interfaces. In this study, the effect of temperature on the impact response of the carbon fiber reinforced plastics (CFRP) was investigated at low-velocity impact (LVI) using a drop-weight impact tester machine. All the composite plates were fabricated using a vacuum infusion process with a stacking sequence of [45/0_2/-45/90_2]s, and a thickness of 2.9 mm. A group of the specimens was exposed to an environment with a temperature cycling at the range of -30 ℃ to 65 ℃. In addition, three other groups of the specimens were aged at ambient (28 ℃), -30 ℃, and 65 ℃ for ten days. Then all the conditioned specimens were subjected to LVI at three energy levels of 10, 15, and 20 J. To assess the behavior of the damaged composite plates, the force-time, force-displacement, and energy-time diagrams were analyzed at all temperatures. Finally, radiography, optical microscopy, and scanning electron microscopy (SEM) were used to evaluate the effect of the temperature and damages at various impact levels. Based on the results, different energy levels have a similar effect on the LVI behavior of the samples at various temperatures. Delamination, matrix cracking, and fiber failure were the main damage modes. Compared to the samples tested at room temperature, the reduction of temperature to -30 ℃ enhanced the maximum impact force and flexural stiffness while decreasing the absorbed energy and the failure surface area. The temperature increasing to 65 ℃ increased the maximum impact force and flexural stiffness while decreasing the absorbed energy and the failure surface area. Applying 200 thermal cycles at the range of -30 ℃ to 65 ℃ led to the formation of fine cracks in the matrix while decreasing the absorbed energy. The maximum contact force is recorded under cyclic temperature as 5.95, 6.51 and 7.14 kN, under impact energy of 10, 15 and 20 J, respectively. As well as, the minimum contact force belongs to the room temperature condition and is reported as 3.93, 4.94 and 5.71 kN, under impact energy of 10, 15 and 20 J, respectively.