Jin-Wook Choi

The Insulation Design of 154 kV HTS Transformer and on Load Tap Changers

The HTS transformer is one of the promising HTS power applications that are expected to be commercialized in the near future. Among the auxiliary functions of a transformer, the voltage regulation function is known to be the most important one. For the voltage regulation of HTS transformers, they are normally equipped with the on-load tap changers (OLTC). It is also required that, in order to develop a HTS transformer as a complete system, not only the basic technologies for all the components including OLTC and bushing, but also the technologies for the insulation of these components at a cryogenic temperature should be well established as applicable. Taking such facts into account, the breakdown characteristics of the insulation components have been evaluated for such application areas as turn-to-turn insulation, layer-to-layer insulation, c, drive shaft-to-drive shaft insulation, tap connecting terminal insulation and others. In overall, this paper discusses the electric insulation design and experimental results with regard to HTS transformer, OLTC and bushing.

Manufacture and Insulating Test of a Mini-Model for 154 kV-Class HTS Cables

High-temperature superconductor (HTS) power cables enable larger transmission of electrical power than that of the conventional counterparts. As electrical power consumption is increased, HTS power cables are expected to play an important role in a next generation electrical power transmission grid because of their smaller transmission loss and, in consequence, better efficiency of operational cost. Currently, a world-wide research has been undertaken, particularly focused on the development and practical applications of HTS cables. With the importance of an insulation design of a 154 kV-class HTS power cable taken into consideration, this paper presents research on AC breakdown characteristics of various thickness insulators. Based on the present research results, the layer thickness of an insulator that will be used for a 154 kV-class HTS cable was optimized. Also, an effect of bending in an HTS cable on the ac breakdown characteristics was also investigated with various testing conditions, such as different radii of bending curvature.

Influence of Defects on Electrical Characteristics of Distributing Cable Termination

This paper introduces experimental investigates of an electrical accident of the distributing cable termination with simulated a shoddy construction. We prepared two termination kites, one is built-in type, the other is heat contraction type. Also, we manufactured cable termination that have simulated defect by badness construction and investigated their insulation characteristics such as ac (35[kV], 1[min]) and impulse (95[kV], ) withstand test. The influence of defects such as thickness decrease, the gap between stress-con of housing and semiconductor and heating time on insulating properties of the termination have been studied. The thickness decrease of an insulator decreases ac breakdown strength suddenly and the breakdown traces of the insulator that is damaged by knife displayed elliptic shape. The gap of between stress-con and semiconductor deteriorates dielectric strength of insulator seriously. In heat contraction type, the ac breakdown voltage became low when the heating time is short.

A Study on Electrical Accident of Distributing Cable Termination Considering PL Law Environment

This paper introduces experimental investigates of an accident pattern for the distributing cross linking-polyethylene(XLPE) cable terminations considering product liability(PL) law environment. The influence of defects such as thickness and length decrease of XLPE, an impurity on XLPE and the gap between stress-con of housing and semi-conductor on insulating properties of the termination have been studied. The thickness and length decrease of XLPE decrease ac breakdown strengths. Breakdown traces of XLPE that is damaged by knife displayed ellipse shape. The gap of between stress-con and semiconductor deteriorates dielectric strength of XLPE seriously.

A Study on the Electrical and Mechanical Properties of a Epoxy Powder for Compact Bus Duct

Insulated methods of compact bus duct has been applied a way of coating Epoxy powder. The problem which is caused by degradation during operation is very important in severe environment. Therefore, this study compared and verified many kind of properties ; electrical breakdown by thermal and water aging, v-t characteristic, arc discharge, mechanical properties, bending test and cross cut. Sample D was stable before the to be about decrease in the breakdown test according to temperature change. In case of V-t and arc discharge, it had been kept up suitable characteristic. Also, in case of electrical and mechanical characteristic, both sample D and A have excellent capacity.

Basic Insulation Characteristics of 2.5 MJ Class HTS SMES

The basic electrical insulation design of 2.5 MJ conduction cooling high temperature superconducting magnetic energy storage (HTS SMES) have been studied in this paper. The high voltage is generated both ends of magnet of HTS SMES by quench or energy discharge. Therefore, the insulation design of the high voltage needs for commercialization, stability, reliability and so on. In this study, we analyzed the insulation composition of a HTS SMES, and investigated about the insulation characteristics of the materials such as Polyimide, Al2O3 , GFRP and vacuum at cryogenic temperature. Base on these results, the basic insulation design for 2.5 MJ conduction cooling HTS SMES was performed.

Electrical Degradation Pattern Analysis according to XLPE Cable

XLPE cable is using insulator for Cross Linked Polyethylene(XLPE), because insulation Performance is superior and easy comparatively. Need systematization of accident transaction for electrical equipment accident, It is no disposal standard for defect of manufacture and second to accidents. in this paper deals with the change of XLPE cable insulation. To understand the electrical properties of XLPE insulation. Made of XLPE block sample, Penetration fracture Sample and flashover sample. Ogura needles having tip radius of were inserted into each sample. AC voltage of 1[kV/sec] increased at 60[Hz] were apple to breakdown sample and flashover sample. AC voltages of 12[kV], 17[kV] at 60[Hz] were a lied to XLPE block sample. The electrical properties of specimens were measured were measured from initiation of tree and breakdown to their characteristics were analyzed.

Design of Insulation and Bending Test for a 154 kV Class HTS Cable

It is important that study on cryogenic electrical insulation design to develop the cold dielectric(CD) type HTS cable because the cable is operated under the high voltage environment in cryogenic temperature. This paper proposes two types of insulation design to carry out the maximum insulation design for 154 kV-class HT cable. The proposed insulation design method takes into consideration AC and lightning impulse withstand voltage so as to prevent AC breakdown for power frequency operating voltage during operating the cable and breakdown for lightning impulse voltage. The final insulation thickness is determined by selecting high value out of two insulation thickness calculated through the two insulation design methods. And we researched electrical insulation characteristics of HTS cable according to bending ratio and the number of bending.