Gyeonggi, South Korea
Gyeonggi, South Korea

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Kim Y.-S.,Korea Electrical Safety Corporation | Kim T.-H.,Korea Electrical Safety Corporation | Kim C.-M.,Korea Electrical Safety Corporation | Shong K.-M.,Korea Electrical Safety Corporation
Transactions of the Korean Institute of Electrical Engineers | Year: 2016

This paper presents few case studies of state diagnosis of XLPE cables using very low frequency techniques. The power cables of 22.9kV which have installation fault were assessed using VLF technique in addition to other techniques like insulation resistance and DC voltage withstand test. From the experimental results, The dielectric loss(tanδ) values of degradation of the cable(joint, knife, needle) at U0 were 5.839, 5.526 and 6.251, respectively and all values were "further study advised". VLF PD measurement was also found defective portion. These method was effective in defect to fault in the degradation of the cable. However, the breakdown did not occur in the degradation of the cable because of properties of XLPE insulation. Few case studies of using VLF tanδ diagnosis for fault are measured and analyzed. The tanδ values at U0 were "further study advised" or "action required". © The Korean Institute of Electrical Engineers.

Kim Y.-S.,Korea Electrical Safety Corporation | Kim T.-H.,Korea Electrical Safety Corporation | Kim C.-M.,Korea Electrical Safety Corporation | Shong K.-M.,Korea Electrical Safety Corporation
Transactions of the Korean Institute of Electrical Engineers | Year: 2016

In this paper, we investigated the fusing current of carbon fiber and thermal properties of carbon fiber and metal shielded cable due to over-current. The fusing current value for the metal-coated carbon fiber was 5.3A in 3K, 7.4K and 13.05A in 12K. And if it exceeds 50% of the fusing current was broken with a rapid voltage rise. In the case of carbon fiber shielded cable, the temperature of the PVC sheath increased somewhat in the allowable current range. However, the temperature of PVC sheath rapidly increased to 128.1°C in the 2 time allowable current range. This value is 10°C higher than the temperature of PVC sheath on the metal screen cable, because the resistance of the carbon fiber is high and heat transfer rate is slow. © The Korean Institute of Electrical Engineers.

Kim S.H.,Gyeongsang National University | Choi J.H.,Gyeongsang National University | Kim W.J.,Gyeongsang National University | Kim K.L.,Korea University | And 4 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2012

A high-temperature superconducting (HTS) DC cable system has attracted a great deal of interest from the view point of low loss, dense structure and large capacity compared to HTS AC cable system. It has a HTS cable and a termination. A HTS DC cable system consists of a conductor, cooling system and electrical insulation. To realize the 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. The electrical insulation technology of HTS DC cable and termination must be solved for the long life, reliability and compact of cable.In this paper, we will discuss mainly on the electrical insulation characteristics and the insulation design of 220 kV class HTS DC cable. Voltage-time (V-t) characteristics of laminated polypropylene paper (PPLP) in LN 2 were studied. Furthermore, the surface flashover characteristics of glass fiber reinforced plastic (GFRP) for termination insulators under DC and lightning impulse voltage were studied. © 2011 IEEE.

Jung S.,Korea University | Lee H.,Kyungil University | Song C.S.,Korea University | Han J.-H.,Korea Electrotechnology Research Institute | And 2 more authors.
IEEE Transactions on Power Electronics | Year: 2013

Owing to the consistent increase in energy efficiency issues, studies for improving the charging efficiency and energy density of batteries have been receiving attention in the electric vehicle transportation sector. This paper deals with an online electric vehicle (OLEV) system which utilizes the dc power system for reducing loss as well as reducing the size of the required battery capacity. Intensive research on grid integration with OLEV has not been performed until recently and it is necessary to calculate the power flow analysis considering the unique characteristics of OLEV for the commercialization of this new transport system (for the application of this new system in the transport sector). In this paper, the dc OLEV power system is being investigated for reducing line losses and peak power thereby reducing the electric cost levied on the substation. Verification processes are performed through simulation for various scenarios to examine the effectiveness of the proposed system in terms of power consumption, battery state of charge, peak power, and loss reduction. © 1986-2012 IEEE.

Kil G.-S.,Korea University | Gil H.-J.,Korea Electrical Safety Corporation | Park D.-W.,Korea University
Journal of Electrical Engineering and Technology | Year: 2012

This paper proposes a reduced-scale simulator that can replace numerical analytic methods for the estimation of potential distribution caused by ground faults in various grounding systems. The simulator consists of a hemispherical electrolytic tank, a three-dimensional potential probe, a grounding electrode, and a data acquisition module. The potential distribution is measured using a potentiometer with a position-tracing function when a test current flows to the grounding electrode. Using the simulator, we could clearly analyze the potential distribution for a reduced- scale model by one-eightieth of the buried depth and length of the grounding rod and grounding grid. Once both the shape of the grounding electrode and the fault current are known, the actual potential distribution can be estimated.

Kim Y.,Korea Electrical Safety Corporation | Shong K.,Korea Electrical Safety Corporation
IEEE Transactions on Power Delivery | Year: 2011

Inspections and diagnoses of corona discharges are important in order to prevent electrical faults of external insulation in power systems. This paper studies the measurement of ultraviolet rays (UV) strength of corona discharges on polymer insulators using a UV sensor with an optic lens. The data have been compared with the images of a UV camera. The UV signal by corona discharge was detected from more than 60 kV, which was equivalent to around 37.5% of the breakdown voltage. The UV strength increased with increasing high voltage and the supplying dc voltage. Also, UV image was observed. However, the longer the distance was, the greater the reduction in UV signals would be. The robust, inexpensive sensor can detect corona discharge activity on polymer insulators when the applied voltage exceeds 37.5% of the breakdown voltage. © 2011 IEEE.

Kim Y.-S.,Korea Electrical Safety Corporation | Shong K.-M.,Korea Electrical Safety Corporation
Proceedings of the 2010 IEEE International Conference on Solid Dielectrics, ICSD 2010 | Year: 2010

This paper studies a measurement of ultra-violet (UV) emission of corona discharges on polymer insulators using an UV rays sensor including an optical lens. In addition, these data have been compared with the images of an UV rays camera. The detection of an UV rays signal begins at 60kV, which is about 37.5% of the breakdown voltage of the polymer insulator and the stronger the high voltage supplied to the polymer insulator was. Also, the corona discharge quantity sharply increased at 60kV when the image of the UV rays was observed. It can be determined that the polymer insulator mounted on a live part must be examined when the discharge risk exceeds approximately 40%. In conclusion, the status of power utilities can be checked using an UV sensor, relevant products to which can be developed at moderate cost. ©2010 IEEE.

Choi S.-H.,Soongsil University | Huh J.-S.,Soongsil University | Han W.-K.,Korea Electrical Safety Corporation | Kim J.-C.,Soongsil University
Transactions of the Korean Institute of Electrical Engineers | Year: 2014

Recently, various measures have been discussed for overcoming depletion of fossil fuels and environmental pollution. One of the measures is electric vehicles. But electric vehicles has some limitations from high cost of battery and low efficiency, so operation distance of electric cars is limited. Also there are difficulties that charging lines should be connected by an electric car whenever it charges. Thus, many studies have been conducted to overcome the limitation using conventional batteries of electric vehicles. As a result, the OLEV(On-Line Electric Vehicle) was developed. But the OLEV system is some limitations. The OLEV system causes power quality problems when it charges. Power quality problem cannot be ignored because OLEV systems are closely connected by distribution grids. In this paper, the OLEV system is designed by using PSCAD/EMTDC, and the power quality is measured and evaluated. Power quality is divided by two cases; harmonics and high-frequency. Harmonics were evaluated according to IEEE Std. 519-1992. But the evaluation of High-frequency could not take it because there was no standard. For this reason, the data measured by OLEV system was compared with the EN50065 regulation.

Shin H.-K.,Inha University | Kim D.-S.,Korea Electrical Safety Corporation | Chung Y.-K.,Omni LPS Co. | Lee B.-H.,Inha University
2014 International Conference on Lightning Protection, ICLP 2014 | Year: 2014

Surge protective devices (SPDs) play an important role to protect the valuable electrical and electronic equipment against transients originating from lightning. Class I tested SPDs are needed to divert surge currents due to direct lightning flashes. In order to achieve the effective protection of sensitive electrical and electronic systems, coordinated SPD systems should be designed and installed. This paper presents the experimental results obtained from the actual installation conditions of SPDs with the aims to understand the energy sharing of the cascaded Class I and II SPDs and to propose the effective selection and installation methods of SPDs. The residual voltage of each SPD and energy coordination between the upstream Class I tested SPD and the downstream Class tested II SPD were measured using a 10/350 μs current wave. © 2014 IEEE.

The present disclosure relates to a method and apparatus for measuring corona discharge of power facilities by a UV sensor with an optical lens. The apparatus includes a UV sensor array receiving UV rays from an analyzing target of a power facility at a location separated a predetermined distance from the target, an optical lens unit focusing the UV rays to the UV sensor array, a signal detector detecting the UV rays in the form of a pulse voltage waveform signal, a UV image processor processing the detected pulse voltage waveform signal into a UV image, a real image measurement unit photographing a real image of the analyzing target, a real image processor displaying a photographed real image; a matching unit combining the photographed real image with the UV image, and an image/data output unit detecting a location of corona discharge based on the combined UV image and real image.

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