In order to optimize the insulation design of a cold dielectric high temperature superconducting (HTS) cable, the composite insulation system has been investigated according to the arrangement of ...laminated polypropylene paper (LPP) and kraft paper in liquid nitrogen. LPP is a prominent insulating material with a high dielectric strength and low dielectric loss, which has been used previously as a HTS cable insulating materials. In addition kraft paper has been used for oil-field (OF) cable as insulating materials for a long time. In this paper, the dielectric properties on composite insulation system according to the arrangement of LPP and kraft paper was compared. The economic and dielectric performances of two insulating materials were considered and applied toward a HTS cable. Furthermore, from an economic satisfaction point the most suitable arrangement, and compared the dielectric properties of the mini-model cables were examined.
The 16 toroidal field (TF) coils of the Korea Superconducting Tokamak Advanced Research (KSTAR) device are connected in series through inter-coil buses. The 15 inter-coil buses connecting nearby TF ...coils used the superconducting cable-in-conduit conductor (CICC) that is identical to the conductor of the main TF bus-lines. In addition, two half-turn buses are connected to the remaining two TF coil terminals, and finally routed to the vicinity of the inter-coil buses to minimize the cross-sectional area of the closed loop between inter-coil buses and half-turn buses. Strand-to-strand (STS) joints are utilized to join the TF coil terminals to the end parts of inter-coil buses. The TF current feeder system (CFS) has two pairs of superconducting (SC) bus-lines and current leads. This arrangement has an advantage in the reliable current discharging of SC bus-lines because one half of the current (17.5
kA) flows through each bus-line. In this paper, general design features, manufacturing and operational results of the superconducting TF bus-line are reported in detail, including analysis results for the quench-safety of the half-turn bus.
A 22.9 kV/50 MVA class high-temperature superconducting (HTS) power cable system was developed in Korea. For the optimization of electrical insulation design for HTS cable, it is necessary to ...investigate the ac and impulse breakdown and partial discharge inception stress of the liquid nitrogen (LN 2 )/ laminated polypropylene paper (LPP) composite insulation system. These results were used to insulation design of the model cable for a 22.9 kV class HTS power cable and the model cable was manufactured. The insulation test of the manufactured model cable was evaluated in various conditions and was satisfied standard technical specification in Korea. Based on these experimental data, the single-phase and three-phase HTS cable of a prototype were manufactured and verified.
It is important that study on cryogenic electrical insulation design to develop the cold dielectric (CD) type high temperature superconducting (HTS) cable because the cable is operated under the ...high-voltage environment in cryogenic temperature. Therefore, this paper describes a design method for the electrical insulation layer of the CD type HTS cable adopting the partial discharge (PD)-free design under ac stress, based on the experimental results such a partial discharge inception stress (PDIE) and
V–
t characteristics, and an impulse breakdown strength of liquid nitrogen (LN
2)/laminated polypropylene paper (LPP) composite insulation system in which the mini-model cable is immersed into pressurized LN
2.
The KSTAR superconducting magnetic coils, which are made of cable in-conduit conductor (CICC), maintain a superconducting state with forced-flow supercritical helium (4.5 K, 5.5 bar). During current ...changing of the superconducting magnetic coils, AC losses are generated in the CICC due to dl/dt, and the heat generated from the loss is removed by high heat capacity supercritical helium. At the same time, reversed flow of the helium occurs due to a rapid increase of the helium temperature and momentary changing of the pressure inside the CICC. This phenomenon has been detected in all of the poloidal field (PF) coils, especially in the upper (U) and lower (L) PF1~PF4 coils. The maximum change of the magnetic field in the PF1UL~PF4UL coils is located near the inlet and outlet of the helium cooling channels, and that of the PF5UL~7UL coils is located at the center of the cooling channel. The temperature variation at the helium inlet was always measured to have a time delay after each shot. In the PF1 coil tests, it was measured to have a delay of 26 sec. During the first plasma campaign, this phenomenon was more severe in the case of all PF coils operating together than for a single PF operation. In this paper, we investigated the thermal-hydraulics of this phenomenon.
The conduction cooled high-temperature superconductor (HTS) SMES (superconducting magnetic energy storage) was operated in cryogenic temperature and high vacuum conditions. Thus, the insulation ...design at the conditions is an important element that should be established to accomplish compact design is a big advantage of HTS SMES. However, the behaviors of insulators for the conditions are virtually unknown. Therefore, we need to researches and development of insulation concerning application of the conduction cooled HTS SMES. In this study, we experimented on insulation characteristics of SMES system. Also, we investigated about insulation characteristics of suitable materials to insulator for conduction cooled HTS SMES. As these results, we had basic data for insulation materials selection and insulation design of cryocooler-to-magnet coil for the development of 600 kJ class conduction cooled HTS SMES.
In this paper, we studied electric insulation characteristics of synthetic Laminated Polypropylene Paper (LPP) in liquid nitrogen (LN/sub 2/) for the application to high temperature superconducting ...(HTS) cable. And, we selected the insulation paper/LN/sub 2/ composite insulation type for the electric insulation design of a HTS cable. Furthermore, we compared the breakdown characteristics of the butt gap and bent mini-model cable that comes into being in this kind of cryogenic insulation type. It is necessary to understand the winding parameter of insulation paper/LN/sub 2/ composite insulation.
A conduction cooled high temperature superconducting (HTS) magnetic energy storage (SMES) is operated at a cryogenic temperature and high vacuum condition. Thus, insulation design at this condition ...is a key and an important element that should be established to accomplish miniaturization that is a big advantage of HTS SMES. However, the properties of insulators for cryogenic conditions in vacuum are virtually unknown. Therefore, we need active research and development of insulation concerning application of the conduction cooled HTS SMES. In this study, we investigated the basic insulation characteristics of some materials such as Kapton films, aluminium nitride (AlN) plates, vacuum and so on. As this result, we possessed basis data for insulation material selection and insulation design for the development of a 600kJ class conduction cooled HTS SMES. Also, the insulating test of the mini-model was performed by the above insulation design.
The KSTAR current lead system (CLS) was commissioned during the first campaign of the plasma experiments. The current lead system is divided into a toroidal field (TF) system and a poloidal field ...(PF) system. Two pairs of current leads for the TF system and 7 pairs for the PF system were installed. Instead of the copper leads, vapor-cooled type brass current leads (CLs) were mounted in order to minimize the cryogenic load. The CLs were installed after the verification of the components through helium leak tests, low current charging tests at room temperature, and high voltage tests. The stability of the CLS was inspected through LN 2 cool down tests, helium leak tests, flow control tests, and temperature control tests using a ceramic heater after the installation all of their components. During the first campaign, it was cool down until liquid helium temperature after vacuum pumping and the helium flow rates of the CLs were controlled successfully at the optimum values. In case of the TF CLs were 0.20 g/s and 0.26 g/s at zero current and 15 kA respectively. On the other hands the PF CLs kept 0.2 g/s during PF coil operation at 4 kA and zero current. And a ceramic heater was reliably operated to prevent water condensation at the warm terminal of the CL.
Background: Diabetics and experimental animal models exhibit high oxidative stress due to persistent and chronic hyperglycemia, thereby deplete the activity of the antioxidative defense system and ...thereby promote the generation of free radicals. The current study examined the effects of vitamin E on oxidative stress and membrane fluidity in the brain of diabetes-induced rats.
Methods: Sprague–Dawley male rats were randomly assigned to normal and streptozotocin (STZ)-induced diabetic groups. The diabetic groups were fed a vitamin E-free diet, 40 mg vitamin E/kg diet, or 400 mg vitamin E/kg diet. Diabetes was induced with STZ after 3 weeks of the experimental diet, then the rats were sacrificed 9 days later to determine the oxidative stress and cell membrane fluidity in the brain.
Results: Dietary vitamin E strengthened the antioxidative defense system with an increased activity of the antioxidant enzymes, such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) and increased vitamin E content, in the brain of the diabetes-induced exeperimental rats. Accordingly, vitamin E was found to reduce the accumulation of reactive oxygen species (ROS), such as superoxide radical decrease the generation of oxidative damage substances, such as the carbonyl value, increase the membrane fluidity lowered by oxidative damage, and significantly improve the lipid composition.
Conclusions: Vitamin E was found to be excellent for strengthening the antioxidative defense system, reducing the generation of ROS and damaging oxidative substances, and maintaining membrane fluidity in the brain of diabetes-induced rats.
