• Progress in Superconductivity and Cryogenics
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• v.11 no.2
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• pp.25-28
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• 2009

A 154kV class high-temperature superconducting (HTS) power cable system is developing in Korea. For insulation design of this cable, it is important that study on cryogenic electrical insulation design to develop the cold dielectric type 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 cold dielectric type HTS cable adopting the partial discharge-free design under ac stress, based on the experimental results such a ac breakdown strength, partial discharge inception stress, $V_{ac}$-t characteristics, $V_{imp}$-n characteristics, and impulse breakdown strength of liquid nitrogen/laminated polypropylene paper (LPP) composite insulation system in which the mini-model cable is immersed into pressurized liquid nitrogen.

• Progress in Superconductivity and Cryogenics
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• v.5 no.3
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• pp.43-47
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• 2003

For an electrical insulation design of HTS cable, it is important to understand the dielectric characteristics of insulation materials in $LN_2$ and the insulation type. Generally, the electrical insulation of HTS Cable is classified into two types of the composite insulation and solid insulation type. In this research, we selected the insulation paper/$LN_2$ composite insulation type for the electric insulation of a HTS cable, and studied electric insulation characteristics of synthetic Laminated Polypropylene Paper (LPP) in liquid nitrogen ($LN_2$) for the application to high temperature superconducting (HTS) cable. Furthermore, we compared the breakdown characteristics of the butt gap and bended mini-model cable. It is necessary to understand the winding parameter of insulation paper/$LN_2$ composite insulation.

• Progress in Superconductivity and Cryogenics
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• v.9 no.1
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• pp.61-66
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• 2007

A transmission class high-temperature superconducting(HTS) power cable system is being developed in Korea. For insulation design of this cable the grading method of insulating paper is proposed. Two kinds of laminated polypropylene paper that has different thickness has been used as the electrical insulation material. The use of graded insulation gives improved mechanical bending properties of the cable. In a HTS cable technology the terminations are important components. A HTS cable termination is energized with the line-to-ground voltage between the coaxial center and outer surrounding conductors. in the axial direction. There is also a temperature difference from ambient to about 77 K. For insulation design of this termination, glass fiber reinforced plastic(GFRP) was used as the insulation material of the termination body, and the capacitance-graded method is proposed. This paper will report on the experimental investigations on impulse breakdown and surface flashover characteristics of the insulation materials for insulation design of a transmission class HTS power cable and termination. Based on these experimental data, the electrical insulation design of a transmission class HTS power cable and termination was carried out.

• Progress in Superconductivity and Cryogenics
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• v.8 no.1
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• pp.29-33
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• 2006

A 154 kV class high temperature superconducting (HTS) power cable system is developing in Korea. For insulation design or this cable, the grading method of insulating paper is proposed. The use of graded insulation gives improved bending properties of the cable. Therefore, we discussed the electrical stress distribution and calculation for grading insulation design of a HTS cable. Also. the basic insulation design of 154 kV class HTS power cable was done.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.213-217
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• 2003

In this paper, we studied electric Insulation characteristics of synthetic Laminated Polypropylene Paper (LPP) in liquid nitrogen (L$N_2$) for the application to high temperature super-conducting (HTS) cable. And, we selected the insulation paper/L$N_2$composite insulation type for the electric insulation design of a HTS cable. Furthermore, we compared the breakdown characteristics of the butt gap and bended 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/L$N_2$composite insulation.

• Progress in Superconductivity and Cryogenics
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• v.5 no.3
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• pp.52-56
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• 2003

This paper describes the results of a basic study (on a model samples) for the development of 22.9 kV high temperature superconducting (HTS) cable. The authors have established that the factors that decide the performance of HTS cables are butt gaps in tape insulation and carbon particles from semiconductive layer. The insulation performance of HTS cables is determined by size and quality of these elements. In the model tests of HTS cables, the minimum PD inception stress of the tape insulation impregnated with liquid nitrogen was found and insulation thickness was calculated from this result.

• Progress in Superconductivity and Cryogenics
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• v.9 no.3
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• pp.52-56
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• 2007

A high temperature superconducting (HTS) DC cable is ideal for transmitting large blocks of electrical power over a long distance. However, it must be designed to operate reliably within the constraints of the electrical systems. Therefore, a study of the electrical insulation is important to develop a HTS DC cable because it is operated in a cryogenic high voltage environment. This paper discusses the dielectric constructions of the cable and summarizes the experimental results on the DC and impulse dielectric characteristics of the insulation material. in sheet form and mini-model cable configuration. This shows how to design such insulation to be operated reliably. These studies are essential for the insulation design of a HTS DC cable operated in cryogenic environment.

• Progress in Superconductivity and Cryogenics
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• v.11 no.1
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• pp.35-38
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• 2009

The high temperature superconducting(HTS) power cable, as a key component of the next generation power transmission system, operates cost-effectively because of much less transmission loss. Currently, a world-wide research has been undertaken actively. In this research, we designed insulation thickness and investigated thickness effect of laminated polypropylene paper(LPP) which is insulation material of HTS cable in case of AC and impulse breakdown.

• Progress in Superconductivity and Cryogenics
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• v.5 no.2
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• pp.58-65
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• 2003

The high temperature superconductivity(HTS) cable must be cooled below the nitrogen liquefaction temperature to applicate the cable in power generation and transmi-ssion system under the superconducting state. To obtain superconducting state. a reliable cryocooler system is required. Structural and thermal design have been performed to design cryocooler system operated with reverse Brayton cycle using gas neon as refrigerant. This cryocooler system consists of compressor. recuperator. coldbox. control valves and has 1 kW cooling capacity. Heat loss calculation was conducted for the given cryocooler system by considering the conduction and radiation through the multi-layer insulation(MLI) and high vacuum. The results can be summarized as: conduction heat loss is 7 W in valves and access port and radiation heat loss is 18 W through the surface of cryocooler. The full design specifications were discussed and the results were applied to construct in house HTS cable cooling system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.7
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• pp.545-549
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• 2013

To realize the high-Tc superconducting (HTS) DC cable system, it is important to study not only high current capacity and low loss of conductor but also optimum electrical insulation at cryogenic temperature. A model HTS DC cable system consists of a HTS conductor, semi-conductor, cooling system and insulating materials. Polypropylene laminated paper (PPLP) has been widely adopted as insulating material for HTS machines. However, the fundamental insulation characteristics of PPLP for the development of HTS DC cable have not been revealed satisfactorily until now. In this paper, we will discuss mainly on the breakdown characteristics of 3 sheets PPLP in liquid nitrogen ($LN_2$). The characteristics of the diameter, location of butt-gap, distance between butt-gap length, pressure effect, polarity effect under DC and impulse voltage were studied. Also, the DC polarity reversal breakdown voltage of mini-model cable was measured in $LN_2$ under 0.4 MPa.