• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 방전 플라즈마 유기절연재료 초전도 자성체연구회
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• pp.30-33
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• 2004

A surge counter is installed under surge arrester, which is protecting the power system apparatuses against abnormal voltage and surges originated in power system line. A surge counter is the device of knowing the times of surge flowed in. There are two methods to get the electric power for mechanical movement and detect the surge. One is using ZnO varistor resister and the other is using the current transformer. In this paper, the characteristics of these methods are presented with using the test and evaluation of them. The process of evaluating the characteristics is essential to develop the domestic surge counter.

• 한국안전학회지
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• 제30권4호
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• pp.39-45
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• 2015

This paper deals with development of integrity evaluation instrument for the power line surge protective device. A reliable power supply is an essential element in the developed information and communication society by highly advances in IT technology. However, the lightning incidence also increased with the recent extreme weather events. In Korea, in order to protect the electrical system from lightning surge, SPD(Surge Protective Device) has been used for these past 30 years. However, the method of diagnosing the safety of the SPD in the industry is insufficient. In this paper, SPD integrity evaluation system was composed of a variable DC power source unit, voltage-current sensor and the embedded controller. In order to measure V-I characteristics of MOV, 3 type samples were degraded by impulse current generator. After impulse tests, the varistor voltage of all samples and nonlinearity coefficient were decreased. It confirmed the utility of the developed equipment by this experimental test and the reliability of SPD is expected for surge accident prevention when applied to industrial plant.

• 천문학회보
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• 제37권1호
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• pp.88.1-88.1
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• 2012

We observed a surge associated with an Ellerman bomb using the Fast Imaging Solar Spectrograph(FISS) of the New Solar Telescope at Big Bear Solar Observatory. The surge was seen in absorption and varied rapidly both in H alpha and Ca II 8542 line. It originated from the Ellerman bomb, and was impulsively accelerated to 20km/s of the blueshift(upward) motion. Then the gradual change from blueshift of 20km/s to redshift of 40km/s occurred in 20 minutes. Based on the measured line-of-sight velocities, we estimated the material reached up to about 5,000km height. We inferred physical parameters of the surge by adopting the cloud model, and found that the temperature of the surge material was about 25,000K and the non-thermal velocity was about 10km/s. Our results suggest that the surge might be heated intensely after it was ejected from the Ellerman bomb.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권6호
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• pp.253-259
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• 2002

This paper deals with the effects of grounding conductors for metal oxide surge arresters. When surge arresters are improperly installed, the results can cause costly damage of electrical equipments. In particular, the route of surge arrester connection is very important because bends and links of leads increase the impedances to lightning surges and tend to nullify the effectiveness of a grounding conductor. Therefore, there is a need to know how effective installation of lightning surge arresters is made in order to control voltage and to absorb energy at high lightning currents. The effectiveness of a grounding conductor and 18 [㎸] metal oxide distribution line arresters was experimentally investigated under the lightning and oscillatory impulse voltages. Thus, the results are as follows; (1) The induced voltage of a grounding conductor is drastically not affected by length of a connecting line, but it is very sensitive to types of grounding conductor. (2) The coaxial cable having a low characteristic impedance is suitable as a grounding conductor. (3) It is also clear from these results that bonding the metal raceway enclosing the grounding conductor to the grounding electrode is very effective because of skin effect. (4) The induced voltages of grounding conductors for the oscillatory impulse voltages are approximately twice as large as those for the lightning impulse voltages.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1892-1896
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• 2008

Inverter-fed induction motors (IFM) are prevalent in traction vehicles. However, the winding insulation of IFM is substantially more stressed than of line-powered motors by surge voltages. Consequently, the winding insulation of IFM should be estimated by surge voltages. Also, the weakness of coil insulation can be detected by the surge voltage test. This paper described the insulation evaluation of induction motors by application of surge voltages. A surge voltage generator with the maximum voltage of 5 kV and the selectable rise-time in ranges of $50\;ns\;{\sim}\;500\;ns$ was fabricated. In the experiment, we applied surge voltages into induction motors with the magnitude and the risetime according to IEEE 522. By the analysis of applied surge voltage and current waveforms, we could find difference between normal and defection windings.

• 전기학회논문지
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• 제62권10호
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• pp.1376-1382
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• 2013

This paper analyzes the propagation characteristics of lightning surge according to the type of branch line in distribution system. The types of branch line considered are H-type and PI-type. At each type, the length of main feeder is same, while the number and length of branch line are different. The distribution line is modeled and the various lightning locations are simulated by Electromagnetic Transient Program(EMTP). For each lightning, the various measuring points are selected. Based on the simulation results, the propagation characteristics of lightning surge at each measuring point are analyzed. The analyzed results are verified by travelling wave theory.

• 한국자동차공학회논문집
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• 제6권5호
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• pp.111-118
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• 1998

Surge pressure problem at the oil return line of the hydraulic circuit of an active suspension system for passenger cars was investigated by experiments and numerical analyses. In the numerical analyses, the method of characteristics was used for simulating unsteady flow in the hydraulic system and gas discrete model was adopted for estimating gas volume variation in separated liquid column. In the experiments and analyses, effects of the physical parameters of the accumlator on smoothing surge pressure was elucidated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1698-1699
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• 2007

This paper deals with the surge measurement system for low voltage power line of industrial plants. It consists of a capacitive divider, A/D conversion part, signal processing and control part. A FPGA and a DSP board were designed to fast signal processing and control. Also, in order to measure lightning surge and switching surge for a long time, data backup device was applied by using SD memory. A performance of the measurement system was verified through evaluation test using impulse calibration generator.

• 전기학회논문지
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• 제60권10호
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• pp.1811-1816
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• 2011

This paper describes switching surge analysis for reclosing decision in 345kV combined transmission line with GIL. Reclosing operation should be decided based on the detailed technical analysis in combined transmission line because this line includes power cable section which is week on insulation. Insulation of power cable can be breakdown at the week point in case of reclosing moment. Therefore the detailed analysis has to be carried out by considering several conditions such as charging rate, inserting resistance, arrester, length ratio of power cable section, grounding resistance, etc. Analysis is performed by EMTP/ATP.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.371_372
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• 2009

This paper describes surge characteristics on 345kV combined transmission system mixed overhead line and GIL(Gas Insulated Transmission Line). Then, it is compared with the results of the system mixed overhead line and XLPE power cables. Finally the lightning overvoltages are also discussed according to surge arrester installation in two kinds of combined transmission systems when the lighting strikes on the phase conductor.