• Proceedings of the KIEE Conference
• /
• 2006.10a
• /
• pp.178-179
• /
• 2006

In this paper the experiments of breakdown characteristics SF6 liquid ($LSF_6$) in model GIS(Gas Insulated Switchgear) were described. From the experiments results, The ability of $LSF_6$ insulation is higher than high-pressurized SF6 gas. The breakdown characteristics of $LSF_6$ were produced by bubble formed evaporation of $LSF_6$ and bubble caused by high electric emission. It is considered in this paper that the results are fundamental data for electric insulation design of superconductor and cryogenic equipments machinery which will be studied and developed in the future.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 2003.10a
• /
• pp.218-221
• /
• 2003

In the response to increasing the demands for electrical energy, much effort aimed to develop and commercialize HTS power equipments have been made around the world. Among them HTS transformer is one of very Promising one. For the development, the cryogenic insulation technology should be established. In this paper V-t characteristics of turn insulator, Kpaton, among insulation components of HTS transformer was discussed with Weibull distribution and n-value. V-t tests of Kapton were conducted using Cu tape electrodes shaped HTS tape depending on wrapping number. The n-values of 2 and 3 times wrapped tape are 27.54 and 30.58. Although breakdown strength of the 3 times one is higher than the 2 times the 3 times one have more weak points with overlapping so it have higher probability of incidental accidents.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2005.11a
• /
• pp.297-299
• /
• 2005

In this paper the experiments of insulation characteristics by temperature change of $SF_6$ gas in model GIS(Gas Insulated Switchgear) were described. From this results, the breakdown voltage was increased with a drop of temperature and an increase of the inner pressure in model GIS. It is considered that these result are fundamental data for electric insulation design of superconductor and cryogenic application machinery which will be studied and developed in the future.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.252-253
• /
• 2007

In this paper the experiments of breakdown characteristics $SF_6$ liquid ($LSF_6$) in model GIS(Gas Insulated Switchgear) were described. From the experiments results, The ability of $LSF_6$ insulation is higher than high-pressurized $SF_6$ gas. The breakdown characteristics of $LSF_6$ were produced by bubble formed evaporation of $LSF_6$ and bubble caused by high electric emission. It is considered in this paper that the results are fundamental data for electric insulation design of superconductor and cryogenic equipments machinery which will be studied and developed in the future.

• Journal of Ocean Engineering and Technology
• /
• v.30 no.5
• /
• pp.349-355
• /
• 2016

Divinycell, which functions as both insulation and a supporting structure, is generally applied in the NO96-type liquefied natural gas (LNG) insulation system. Polymer-material-based Divinycell, which has a high strength and low weight, has been widely used in the offshore, transportation, wind power generation, and civil engineering fields. In particular, this type of material receives attention as an insulation material because its thermal conductivity can be lowered depending on the ambient temperature. However, it is difficult to obtain research results for Divinycell, even though the component materials of the NO96-type LNG cargo containment system, such as 36% nickel steel (invar steel), plywood, perlite, and glass wool, have been extensively studied and reported. In the present study, temperature and strain-rate dependent compressive tests on Divinycell were performed. Both the quantitative experimental data and elastic recovery are discussed. Finally, the mechanical characteristics of Divinycell were compared to the results of polyurethane foam insulation material.

• Journal of Advanced Marine Engineering and Technology
• /
• v.35 no.2
• /
• pp.232-237
• /
• 2011

Recently, continuous research on cryogenic valves is being carried out with the rapid development of the cryogenic valve-related industry, and especially, high performance of cryogenic valves is being promoted due to the breakthrough development and demand of users, etc., of the mechanical, shipbuilding, semiconductor and display industry and the aerospace industry field, but it is the reality that technical development and research on cryogenic application equipment on vacuum insulation are insufficient. The present research focused on interception of heat exchange with the outside by keeping low pressure after installing a jacket pipe outside a stem and also considered heat transfer properties on changes in pressure of a vacuum part and radius of a jacket which can reduce heat exchange for effective heat transmission control by studying it in a three-dimensional numerical analysis method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.05e
• /
• pp.65-68
• /
• 2003

In this paper, we researched breakdown characteristics of paper/liquid nitrogen composite insulation system for application of a high temperature superconducting cable. And, we have studied the AC breakdown performance of paper/ice composite insulating system immersed in liquid nitrogen. The electric strength in this paper/ice composite system is higher than that of paper/liquid nitrogen system. Furthermore this system shows a self-healing type breakdown behavior. Among the many kinds of liquid to be immersed and frozen to the ice, deionized water gives the highest electric breakdown strength. The paper/ice composite insulation system is thought to be one of good candidate for the electrical insulating system at cryogenic temperature.

• Progress in Superconductivity and Cryogenics
• /
• v.5 no.2
• /
• pp.46-50
• /
• 2003

In the dielectric insulation design of any high temperature superconducting (HTS) apparatus as well as HTS fault current limiter in the electrical power systems, the breakdown characteristics of cryogenic coolants such as liquid nitrogen ($LN_2$) are an important factor of the insulating engineering. Previous reports concerned with the breakdown characteristics of liquid nitrogen have pointed out that bubbles and gaseous nitrogen have a treat influence on their breakdown phenomena, However, useful data for practical insulation design of HTS fault CUITent limiter operating at subcooled L$N_2$ have not been obtained enough. Therefore, this paper presents an experimental investigate of breakdown phenomena in liquid nitrogen under AC voltage, And, we observed the breakdown voltage (BDV) of liquid nitrogen with lowering temperature. The Weibull plots of the breakdown voltage of subcooled $LN_2$ for the needle-plane electrode with d= 10 mm are studied, The dependence of breakdown voltage for needle-plane and pancake coil-pancake coil electrode on temperature is illustrated, The relationship between the AC breakdown characteristics and the temperature were clarified.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.54 no.8
• /
• pp.355-360
• /
• 2005

In this paper the experiments of breakdown characteristics by temperature change of $SF_6$ gas, $SF_6$ liquid ($LSF_6$) and $N_2$ liquid ($LN_2$) in model GIS(Gas Insulated Switchgear) were described. From the experiments results, the breakdown voltage of $SF_6$ increases with the drop of temperature and the increase of the inner pressure in model GIS. The ability of $LSF_6$ insulation is higher than high-pressurized $SF_6$ gas and $LN_2$. The breakdown characteristics of $LSF_6$ were produced by bubble formed evaporation of $LSF_6$ and bubble caused by high electric emission. It is considered in this paper that the results are fundamental data for electric insulation design of superconductor and cryogenic equipments machine교 which will be studied and developed in the future.

• Proceedings of the KIEE Conference
• /
• 2005.07c
• /
• pp.2085-2087
• /
• 2005

In this paper the experiments of insulation characteristics by temperature change of $SF_6$ gas and liquid $SF_6$ in model GIS(Gas Insulated Switchgear) were described. From this results, the breakdown voltage was increased with a drop of temperature and an increase of the inner pressure in model GIS. The ability of insulation in liquid $SF_6$ was higher than that of the highly pressurized $SF_6$ gas. A liquid $SF_6$ discharge characteristics was caused by bubble formed evaporation of liquid $SF_6$ and bubble caused by high electric emission. It is considered that these result are fundamental data for electric insulation design of superconductor and cryogenic application machinery which will be studied and developed in the future.