• Title/Summary/Keyword: insulation condition

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Thermal Diffusivity Measurement of Carbon/Epoxy and Porous Thermal Insulation Material under Vacuum Condition Using Cyclic Heating Method (주기가열법을 이용한 탄소/에폭시 및 다공성 단열재의 진공 열확산도 측정)

  • Nam, Gi-Won;Yi, Yeong-Moo;Ohnishi, Akira;Kong, Cheol-Won
    • Composites Research
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    • v.20 no.5
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    • pp.20-25
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    • 2007
  • Cyclic heating method is useful method for measuring the thermal diffusivity of porous materials. The main object of this paper is to develop and verify the thermal diffusivity measuring system of porous materials under vacuum condition. To verify this method, thermal diffusivities of the alumina ($Al_2O_3$) specimen and polystyrene foam were measured. Thermal diffusivities of these specimens were agreed with reference values. Thermal diffusivities of carbon/epoxy and porous insulation material were measured at atmospheric room temperature condition and vacuum condition respectively. Thermal diffusivities of carbon/epoxy and porous insulation material under vacuum are reduced by 66.4% and 64.9% compared to the thermal diffusivities under the atmospheric condition. These differences are considered the effect of the porous insulation material with an air.

Correlation between Insulation Diagnostic Test and AC Breakdown Test for 3.3 kV Class Induction Motor

  • Byun, Doo-Gyoon;Hong, Jin-Woong
    • Transactions on Electrical and Electronic Materials
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    • v.7 no.5
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    • pp.262-266
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    • 2006
  • The insulation diagnostic test and the AC breakdown test were performed under off-line using the 3.3 kV class induction motor which have been served for 10 years. These tests were conducted in means of nondestructive and destructive test. In this paper, we compared the correlation between the nondestructive and destructive test. Furthermore we setup an experimental condition with moisture and compared the insulation characteristics between moist and dry sample. From the results of the nondestructive and destructive test, it was found that the second AC current, which is the previous step of insulation breakdown, suddenly increased at a point of around 8.5 kV. The insulation breakdown of moist sample occurred at 12-14 kV, which is 4-5 kV lower than dry sample.

A Study on the Computation of Hull Temperature Distribution and Boil off Ratio of MRV Type LNG Carrier (MRV형 LNG선의 선체온도분포 및 증발률 산정에 관한 연구)

  • 천병일;김용모;김경근
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.4
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    • pp.986-996
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    • 1994
  • Insulation system of LNG carrier has made important roles such as maintaining a proper Boil off Ratio(BOR) for the cargo and avoiding the excessive low temperature of the adjacent inner hull beyond the permissible limit. At the same time, safety and economy of the LNG transportation by the ship are connected with the performance of the insulation system. Also, thermal insulation system of LNG carrier is one of the most advanced technique with the structure analysis of tank, welding and assembling. In this study a computer program is developed to calculate the hull temperature distribution and BOR, which are important factors in thermal design for the Moss Rosenberg Verft spherical tank type LNG carrier. Detailed results for hhull temperature distribution close to LNG tank, BOR and the thickness effect of insulation material are reported in this paper in the range of standare design sea condition.

AC Breakdown Analysis of Composite-Insulation by the Thickness of epoxy and the Variation of Pressure (복합절연물내 기체의 압력 및 고체의 두께변화가 AC 절연파괴에 미치는 영향 분석)

  • Jung, Hae-Eun;Kim, Byoung-Chul;Yun, Jae-Hun;Kang, Seong-Hwa;Lim, Kee-Joe
    • Proceedings of the KIEE Conference
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    • 2007.11a
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    • pp.194-195
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    • 2007
  • $SF_6$ gas used widely as insulating component in electric power industry has excellent in insulation and arc extinguishing performance in gas-insulated switchgear. However, the concern about eco-friendly alternative gas is currently rising because $SF_6$ gas is one of the main greenhouse gases. In this paper, dry-air and composite-insulation (dry-air+epoxy) as the alternative technology for $SF_6$ gas insulation is studied. Under the gas pressure ranged from 0.1 to 0.6MPa, the breakdown voltage of dry-air were measured in AC electric field. The data of composite-insulation were acquired by changing the thickness of epoxy used in each composite-insulation under the same condition.

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Studies on the Thermal Insulation Effect of Bedding (II) - Thermal Insulation Effect of Quilt - (이부자리의 보온력에 관한 연구(II) -이불의 보온력 -)

  • Lee Song-Ja;Sung Su-Kwang
    • Journal of the Korean Society of Clothing and Textiles
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    • v.16 no.4 s.44
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    • pp.349-355
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    • 1992
  • Comfortable sleeping largely depends on human mental state, physical condition, the temper. ature and humidity in bedrooms, and qualities of quilt and bedcover. Of the qualities of quilt, thermal insulation effect plays the most important role in keeping bedroom in ample temperature and preventing human body from giving off heat. In the present study, which is a sequel study to research on the thermal insulation effect, the real-size quilts with the following items of filling materials in them are designed to research on the variation of each item, and to measure the effect of the weight variation in inner covers on the thermal insulation effect of quilts, the results are as follows: 1. The coefficient between the weight of filling materials and the thermal insulation effect of quilt is shown to be a significant $0.91\~0.97$. 2. The thermal insulation effect of the quilts with in size of $0.5\;Kg/m^{2}$ is surveyed to be high in order down > polyester > cotton > wool. 3. The effect of the texture of inner covers on the thermal insulation effect of quilt is shown to be ignorably low. 4. The weight of filling materials is shown to be in correlation with the thermal insulation effect of quilts, and the estimated regression line has been obtained.

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The sound insulation performance of eco-friendly loess brick wall (친환경 황토벽체의 차음성능 평가에 관한 연구)

  • Lee, Tai-Gang;Kim, Yul;Song, Kook-Gon;Kim, Sun-Woo
    • KIEAE Journal
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    • v.9 no.6
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    • pp.13-18
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    • 2009
  • Korean traditional houses have been developed in harmony with natural environment and comfortable indoor condition by using the natural resources including building layout, space composition and materials. Originally Korea traditional architectures have used wood lintel constructions and loess walls through the many years. Theses loess have many strength such as highly heat capacity, controling of humidity, a deodorant than any other materials. Nowaday it is recommended to use exterior and interior walls in loess wall to meet the eco-friendly materials to improve our residental environmental. Thus this study aims to research the sound insulation performance of traditional loess brick wall varied with thickness, thermal insulation materials and cavity wall. The sound insulation performance of these loess walls are compared with other masonry wall's and sound insulation performance of th walls were tested in anechoic laboratory to measure the sound transmission loss of these walls. The loess brick wall with 75mm thickness of cavity is shown the sound insulation performance with Rw 57 which is nearly same performances of 1B brick wall and cement 8' block wall, The improving effect of insulation materials is shown in the high frequency bandwidth. Especially, there is improving as much as 11 dB using the extruded poly stylene form(75mm) and poly ethylene film(0.7mm).

A Study on the Heat Flux Meter Location for the Performance Test of a Refrigerator Vacuum Insulation Panel (냉장고 진공단열재 성능진단을 위한 열유속계 위치에 관한 연구)

  • Ha, Ji Soo
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.25 no.8
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    • pp.471-476
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    • 2013
  • The present study has been carried out to elucidate the optimal method for the performance test of a refrigerator vacuum insulation panel (VIP), by using numerical heat transfer analysis. Three locations of heat flux meter have been tested, for deriving the best test method to clarify the normal or the abnormal condition of the vacuum insulation panel in a refrigerator. The first location of the heat flux sensor is at the same place as the heater, the second one is at the nearby side location of the heater and the third one is at the opposite side location of heater in the refrigerator. The heat flux and $1/q^{{\prime}{\prime}^2}$ or $q^{{\prime}{\prime}^4}$ were calculated for the cases with the normal VIP, and with the abnormal VIP, and their differences analyzed. From the present study, the first and the second method had a mere difference characteristics of heat flux and $1/q^{{\prime}{\prime}^2}$ or $q^{{\prime}{\prime}^4}$, between the cases with the normal or the abnormal VIP. The magnitude of the heat flux after 300sec had a great difference between the cases with the normal or abnormal VIP for the third method, and it could be considered the most optimal method to test the performance of a refrigerator vacuum insulation panel.

Dielectric Insulation Properties of Double Pancake Coil Type HTS Transformer (Double Pancake Coil형 고온초전도 변압기의 전기적 절연 특성)

  • 백승명;정종만;이현수;한철수;김상현
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.2
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    • pp.151-156
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    • 2003
  • High temperature superconductor can only be applied against an engineering specofication that has to be determined for each particular application form the design requirements for economic viability and for operation margins in service. However, in order to realize the HTS transformer, it is necessary to establish the high voltage insulation technique in cryogenic temperature. Therefore, the composite insulation of double pancake coil type transformer are described and AC breakdown voltage characteristics of liquid nitrogen(LN$_2$) under HTS pancake coil electrode made by Bi-2223/Ag are studied. The Breakdown of LN$_2$ is dominated electrode shape and distance. The influence of pressure on breakdown voltage is discussed with th different electrode. For the electrical insulation design of turn-to-turn insulation for the HTS transformer, we tested breakdown strength of insulation sheet under varying pressure. And we investigated surface flashover properties of LN$_2$ and complex conition of cryogenic gaseous nitrogen(CGN$_2$) obove a LN$_2$ surface. The surface voltage of GFRP was measured as a function of thickness and electrode distance in LN$_2$ and complex condition of CGN$_2$ above a LN$_2$ surface. this research presented information of electrical insulation design for double pancake coil(DPC) type HTS transformer.

Recovery Voltage Measurements of Oil-immersed Transformer

  • Li, Ming-Hua;Dong, Ming;Qu, Yan-Ming;Yan, Zhang
    • Transactions on Electrical and Electronic Materials
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    • v.7 no.5
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    • pp.230-234
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    • 2006
  • One of the methods currently being investigated as a possible non-intrusive diagnostic tool for condition monitoring of power transformer and cable is the recovery voltage measurement, which will be improving the ability to detect the content of water concentration and the ageing process in the insulation system and may thus be an indicator of insulation quality and its ageing status. The polarization phenomenon was studied using RVM with oil-paper samples. In order to interpret its mechanism, the Extended Debye model was introduced. With different circuit parameters, various simulation results were gotten. Furthermore, with the test samples of different ageing condition, measurements are accomplished in the lab. On the basis of this experiment as well as theoretical analysis, correlations between polarizations and ageing were analyzed.

Electrical Insulation Characteristics at Cryogenic Temperature for High Temperature Superconducting Cables

  • Okubo, Hitoshi;Hayakawa, Naoki
    • KIEE International Transactions on Electrophysics and Applications
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    • v.4C no.1
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    • pp.15-20
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    • 2004
  • This paper discusses electrical insulation characteristics at cryogenic temperature, especially focusing on partial discharge (PD) inception characteristics, for high temperature superconducting cables. In liquid nitrogen (L$N_2$) / polypropylene (PP) laminated paper composite insulation system, PD inception strength (PDIE) was evaluated in terms of volume effect and V-t characteristics. Different kinds of butt gap condition were applied in the experiments, using parallel plane and coaxial cylindrical cable samples. Experimental results revealed that the volume effect on PDIE could be evaluated by the statistical stressed liquid volume (SSLV) taking account the discharge probability not only in the butt gap but also in the other thin layers between PP laminated papers. Furthermore, the indices n of V-t characteristics at PD inception were estimated to be 80∼110, irrespective of the butt gap condition.