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V-t Characteristics of a Mini-Cable Model Wound with PPLP for Superconducting Cables
Shin Woocheol,Jo Uhyeon,Park Jinhyung,Oh Seunghee,Handito Ragil,Jeong Minkyung,Park Seongkeon,Kang Hyoungku 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.1
A distribution-level high-temperature superconducting (HTS) cable connecting the Shingal and Heungdeok substations in South Korea was commercialized in 2019. This project successfully installed a 23 kV HTS cable between the secondary buses of two 154 kV substations. Furthermore, a triaxial HTS cable connecting the Munsan and Seonyu substations is scheduled for commercialization in 2024. An HTS cable wound with polypropylene laminated paper (PPLP) as an insulation medium operates in liquid nitrogen (LN2) because of its superior dielectric characteristics under cryogenic conditions. Generally, an HTS cable is known for its high efficiency and extended lifespan compared with conventional power cables because it experiences no thermal degradation owing to Joule heat generation. However, the dielectric characteristics of HTS cables may deteriorate over time because of their long-term operation in high-voltage environments. We conducted dielectric experiments on two types of PPLP with varying polypropylene (PP) ratios and pressures and examined their V-t characteristics using a mini-cable model.
전극 재질에 따른 고진공 환경에서의 절연내력 특성 분석
신우철(Woocheol Shin),박준영(Junyoung Park),강형구(Hyoungku Kang) 한국조명·전기설비학회 2024 조명·전기설비학회논문지 Vol.38 No.1
This study investigates the insulation breakdown characteristics of superconducting magnets under high vacuum conditions, focusing on the effects of localized vacuum degradation and the material properties of the stabilizer layer used in superconducting wires. To understand the influence of vacuum pressure variations and electrode material on insulation strength, experiments were conducted using spherical electrodes composed of five different materials. These experiments demonstrated how changes in vacuum pressure affect insulation breakdown characteristics, following the pattern of Paschen’s curve. A notable decrease in breakdown voltage was observed in mid-vacuum regions, while an increase was seen in high vacuum conditions, underscoring the significant impact of vacuum pressure on insulation breakdown mechanisms. The results also highlighted the role of electrode material’s work function in high vacuum conditions, where materials with higher work functions exhibited higher breakdown voltages. This was particularly evident in the comparison of alloys like Brass, which, despite having a high work function, showed lower breakdown voltages due to surface impurities promoting discharge. In contrast, high-strength metals like Stainless Steel demonstrated higher breakdown voltages, attributed to their chemical stability and resistance to oxidation and corrosion.