• Title, Summary, Keyword: short-circuit current

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Analysis of Welding Phenomena and Effect of Short Circuit Current Rise Slope in the High Speed $CO_2$ Welding of Steel Sheets ($CO_2$박판 고속용접에서 용접현상 분석과 전류상승기울기의 영향)

  • Kim, Young-Sam;Ryoo, Hoi-Soo;Kim, Hee-Jin
    • Journal of Welding and Joining
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    • v.23 no.5
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    • pp.14-19
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    • 2005
  • In high speed $CO_2$ welding, it has been blown to produce no sound bead with undercut or humping bead. In this study welding phenomena through synchronized high speed camera and output welding voltage and current waveform has been analyzed. For the purpose to improve a welding bead, effect of short circuit current rise slope has been examined. With commercial power source it was produced no sound bead by instantaneous short circuit, long arc period and stubbing at welding speed 2.5mm/min Humping bead or undercut were showed by instantaneous short circuit and long arc period. Also, the weld bead was not formed during the long short circuit period after stubbing start and long arc extinguishment period after wire sticking by failure of arc regeneration, because the droplet was not transferred to weld pool. With increasing short circuit current rise slope the frequency of stubbing was decreased and the normal short circuit rate was increased. A control of short circuit current rise slope was effective factor in high speed welding.

Three-phase Fault Calculation by IEC 60909 (IEC 60909에 의한 삼상 고장계산)

  • Son, Seok-Geum
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.63 no.1
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    • pp.12-18
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    • 2014
  • This paper analyzes how to calculate the three phase short circuit current calculation procedures used in the IEC 60909 short circuit. It presented the new procedure of the fault current for the interrupting capacity of the circuit breaker. This procedure is applied to the future power system and calculates the fault current. Power demands are increased because of the growth of the economy for this reason, the fault current of the power system is largely increased and the fault current procedure for the proper interrupting capacity calculation of the existing or the new circuit breaker is essential. How to calculate the three phase short circuit current for ac electrical system and select the high voltage and low voltage circuit breaker based on IEC 60909 standards.

Short-circuit Protection for the Series-Connected Switches in High Voltage Applications

  • Tu Vo, Nguyen Qui;Choi, Hyun-Chul;Lee, Chang-Hee
    • Journal of Power Electronics
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    • v.16 no.4
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    • pp.1298-1305
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    • 2016
  • This paper presents the development of a short-circuit protection mechanism on a high voltage switch (HVS) board which is built by a series connection of semiconductor switches. The HVS board is able to quickly detect and limit the peak fault current before the signal board triggers off a gate signal. Voltage clamping techniques are used to safely turn off the short-circuit current and to prevent overvoltage of the series-connected switches. The selection method of the main devices and the development of the HVS board are described in detail. Experimental results have demonstrated that the HVS board is capable of withstanding a short-circuit current at a rated voltage of 10kV without a di/dt slowing down inductor. The corresponding short-circuit current is restricted to 125 A within 100 ns and can safely turn off within 120 ns.

Analysis on the Short Circuit Current of a Low Voltage Direct Current(DC) Distribution System using PSCAD/EMTDC (PSCAD/EMTDC를 이용한 저전압 직류 배전 시스템의 단락 고장 전류 분석)

  • Ahn, Jae-Min;Jeon, Jeong-Chay;Lim, Young-Bae;Bae, Seok-Myeong;Byeon, Gil-Sung;Lee, Kyoung-Ho
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.59 no.4
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    • pp.473-476
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    • 2010
  • In this paper, we analyzed the short circuit current of a low voltage direct current distribution system. For the analysis, we performed the modeling of the low voltage direct current distribution system with a 6-pulse three-phase thyristor rectifier using the PSCAD/EMTDC, surveyed impedance of sources, transformers and distribution lines to run a simulation. A result of the simulation is that short circuit currents of the direct current distribution system with the rectifier decreased due to a thyristor-ON-resistance(Ron). But in case of the low thyristor-ON resistance, output fault current of the rectifier increased over three-phase short circuit current of an AC power system without a rectifier by regular ratio of the rectifier. Because the output fault current of the rectifier can increase over interrupting the capacity of circuit breakers, studying short circuit currents of a low voltage direct current distribution system with a rectifier is necessary for introducing the direct current distribution systems.

A Technique for a Short-Circuit Current Calculation to The Single-Phase Transformer in the Three-Phase Systems (3상계통에서 단상변압기에 대한 단락전류계산 기법)

  • Park, Jae-Hwae;Jin, Tae-Seok
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.57 no.2
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    • pp.170-175
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    • 2008
  • This paper describes the exact short-circuit current calculation technique for the single-phase transformer which is installed in the three-phase systems and shorted in the secondary side. Not only the results for a short-circuit current calculation in the existing literatures are wrong, but also little literature deals with the short-circuit current for a single-phase transformer. So, this paper presents a theoretical study and calculation method for a single-phase short current. The validity of the presented method is investigated through Simulation using "Power Tools" and "PSim" program.

LOW DIRECT-PATH SHORT CIRCUIT CURRENT OF THE CMOS DIGITAL DRIVER CIRCUIT

  • Parnklang, Jirawath;Manasaprom, Ampaul;Laowanichpong, Nut
    • 제어로봇시스템학회:학술대회논문집
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    • pp.970-973
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    • 2003
  • Abstract An idea to redce the direct-path short circuit current of the CMOS digital integrated circuit is present. The sample circuit model of the CMOS digital circuit is the CMOS current-control digital output driver circuit, which are also suitable for the low voltage supply integrated circuits as the simple digital inverter, are present in this title. The circuit consists of active MOS load as the current control source, which construct from the saturated n-channel and p-channel MOSFET and the general CMOS inverter circuits. The saturated MOSFET bias can control the output current and the frequency response of the circuit. The experimental results show that lower short circuit current control can make the lower frequency response of the circuit.

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The construction of 3-phase 90 MVA short-time withstand current testing facilities (3상 90 MVA 단시간전류시험 설비 구축)

  • Suh, Yoon-Taek;Kim, Yong-Sik;Yun, Hak-Dong;Kim, Maeng-Hyun
    • Proceedings of the KIEE Conference
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    • pp.700-702
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    • 2005
  • The most electrical apparatus should be able to withstand short-time current and peak current during a specified short time until circuit breakers have interrupted fault current. It defines the short-time withstand ability of electric a apparatus to be remain for a time interval under high fault current conditions. It is specified by both dynamic ability and thermal capability. KERI(Korea Electrotechlology Research Institute) recently constructed the new short-time current and low voltage short circuit testing facilities. This paper shows short- circuit calculation of transformer and describes high current measuring system, and evaluate the result of short-time withstand test used in $3{\phi}$ 90MVA short-time current testing facilities.

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Study on Application of Superconducting Fault Current Limiter Considering Risk of Circuit Breaker Short-Circuit Capacity in a Loop Network System

  • Kim, Jin-Seok;Lim, Sung-Hun;Kim, Jae-Chul
    • Journal of Electrical Engineering and Technology
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    • v.9 no.6
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    • pp.1789-1794
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    • 2014
  • This paper suggests an application method for a superconducting fault current limiter (SFCL) using an evaluation index to estimate the risk regarding the short-circuit capacity of the circuit breaker (CB). Recently, power distribution systems have become more complex to ensure that supply continuously keeps pace with the growth of demand. However, the mesh or loop network power systems suffer from a problem in which the fault current exceeds the short-circuit capacity of the CBs when a fault occurs. Most case studies on the application of the SFCL have focused on its development and performance in limiting fault current. In this study, an analysis of the application method of an SFCL considering the risk of the CB's short-circuit capacitor was carried out in situations when a fault occurs in a loop network power system, where each line connected with the fault point carries a different current that is above or below the short-circuit capacitor of the CB. A loop network power system using PSCAD/EMTDC was modeled to investigate the risk ratio of the CB and the effect of the SFCL on the reduction of fault current through various case studies. Through the risk evaluations of the simulation results, the estimation of the risk ratio is adequate to apply the SFCL and demonstrate the fault current limiting effect.

Effect of Short Circuit Time Ratio and Current Control Pattern on Spatter Generation in $CO_2$ Welding ($CO_2$용접의 스패터 발생에 미치는 단락시간비 및 단락전류 파형제어의 영향)

  • 조상명
    • Journal of Welding and Joining
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    • v.21 no.1
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    • pp.48-53
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    • 2003
  • The object of this study is to examine the effect of short circuit time ratio (SCTR) and current rise delay time (Td) on the spatter generation at low and medium current range in $CO_2$ welding. The spatter was evaluated by the weight generated in the welding of bead-on-plate for 30 seconds (3 times). Td was varied by order of 0, 0.4, 0.8 and 1.2 msec. At each Td, the short circuit time ratio was varied by the output voltage of the welding power source. In the low current range, it was found that the optimum SCTR was 20~25%, and the minimum spatter generation weight was obtained in the case of Td=0.4msec and SCTR=22% even though the remarkable difference was not showed by the application of Td. In the medium current range, it was confirmed that the arc was stable though the SCTR was increased from 20% to 40% by the control of current wave. Spatter generation weight depended on the variation of Td, and the lowest value of spatter generation weight occurred at Td=0.8~1.2msec.

Short Circuit Waveform Control Type SMAW Welding Power Source Development and Characteristic Evaluation (단락파형제어형 SMAW용 용접전원 개발 및 특성평가)

  • Yang, Hyun-Min;Ryoo, Hoi-Soo;Hyun, Soong-Keun
    • Journal of Welding and Joining
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    • v.34 no.3
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    • pp.40-46
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    • 2016
  • The digital controlled SMA welding power source having the hot start current and short circuit waveform control was developed. The inverter power controller was used an analog circuit and the short circuit waveform controller was developed using a 8-bit MCU. For the evaluation of the developed SMA welding power source it were compared with a domestic welding power sources. Using the high titanium oxide type and low hydrogen type electrodes, the characteristics of hot start and short circuit was evaluated. Developed SMA welding power source shows good start performance. Also, arc stability and low current weldability were improved by the short circuit waveform control.