• Proceedings of the KWS Conference
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• 2005.06a
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• pp.317-320
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• 2005

In this paper, dynamic behaviour of short circuit occurring in Pulse Gas Metal Arc Welding (GMAW-P) is investigated Welding experiments with different values of pulsing parameters, high speed camera pictures and welding signals such as current and voltage were acquired to identify short circuit conditions in GMAW-P.

• Fire Science and Engineering
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• v.17 no.2
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• pp.1-5
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• 2003

Recently, the occurrences of electrical fire have been suppressed by a residual current protective devices(RCD), a molded case circuit breaker(MCCB) and a fuse in case of an earth leakage, a short circuit and an over current. But it is impossible for the RCD to break the circuit in the case of the conductor fractures, the failure of pressure contacts on connecting points and the momentary short circuit of low voltage wiring. Therefore, it is require to study the constructive problem of the RCD. In this paper, we have tested the operation characteristics of the RCD according to the R load and R-L load in the conductor fractures, the failure of pressure contacts on connecting points and the momentary short circuit of low voltage wiring.

• Journal of Power Electronics
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• v.17 no.1
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• pp.242-252
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• 2017

This paper deals with the blocking of DC-fault current during DC cable short-circuit conditions in HVDC (High-Voltage DC) transmission systems utilizing Modular Multilevel Converters (MMCs), where a new SubModule (SM) topology circuit for the MMC is proposed. In this SM circuit, an additional Insulated-Gate Bipolar Translator (IGBT) is required to be connected at the output terminal of a conventional SM with a half-bridge structure, hereafter referred to as HBSM, where the anti-parallel diodes of additional IGBTs are used to block current from the grid to the DC-link side. Compared with the existing MMCs based on full-bridge (FB) SMs, the hybrid topologies of HBSM and FBSM, and the clamp-double SMs, the proposed topology offers a lower cost and lower power loss while the fault current blocking capability in the DC short-circuit conditions is still provided. The effectiveness of the proposed topology has been validated by simulation results obtained from a 300-kV 300-MW HVDC transmission system and experimental results from a down-scaled HVDC system in the laboratory.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.694-696
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• 2002

Transformers together with all equipment and accessories shall be designed and constructed to withstand the mechanical and thermal stresses produced by external short circuit which include three phase, single line-to-ground, double line-to-ground and line-to-line faults etc. Generally the Short Circuit Test of transformers is tested according to the ANSI/IEEE, IEC/JEC, KS etc, in domestic. In this study, it will be showed and compared the difference of symmetrical current for short circuit test of a Pad -mounted transformer according to with ANSI /IEEE and IEC.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.78-80
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• 2007

The residual flux in transformer's iron cores leads to a distortion of short-circuit current occasionally. And some considerable distortion may have effect on the validation of the test results. To avoid the substantial distortion, a suitable pretest is performed before the actual test. In case of applying this method there must be excessive overvoltage due to switching of an unloaded transformer and chopping of an excitation current. The purpose of this paper is estimate that the effect of the overvoltage results from this phenomenon on insulation performance of short-circuit transformer.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.1958-1968
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• 2015

In this paper, a new definition of short-circuit ratio concept for multi-converter HVDC systems is proposed. Analysis results of voltage interaction between converters show that the reactive power-voltage characteristic of a converter has a dominant effect on voltage interaction level compared with its active power-voltage characteristic. Such a relation between converter reactive power and voltage interaction level supports taking the former into account in the definition of short-circuit ratio concept for multi-converter systems. The proposed definition is verified by the method of maximum power curve for various system configurations. Furthermore, a formula to calculate transient overvoltage for multi-converter systems is derived based on the proposed definition, and the efficiency of the derived formula is verified.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2203-2206
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• 2005

A load flow and short circuit fault simulation of AC electrified railway distribution systems is presented with DIgSILENT PowerFactory software. Load flow of electrified railways distribution system with concerning multi train lines and dynamic characteristics of train load is studied for different time laps. The dynamic characteristics of train load in starting and braking conditions with different starting and stopping times and its moving positions makes the load flow complicated so there is a great need in studying the effects of electrified railways on load flow. Short circuit fault transients is also studied and simulated for both power system or traction distribution system and their effects on the operation of the train sets is investigated.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.9
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• pp.50-55
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• 1997

In order to improve the electrical performance of ITO/InP solar cells, sulfur passivation technique was employed using (N $H_{4}$)$_{2}$ $S_{x}$ solution. Passivation effects were analyzed by measuring the short circuit current density ( $J_{sc}$ ) of solar cells and photoluminescence (PL) of ITO/InP interfaces. This paper firstly reports the sulfur passivation effects by investigating the correlation between the PL intensity and the short circuit current. Generally, PL intensity and the short circuit current of sulfur passivated sampels wer eincreased, and showed the same trend. Especially, samples prepared at 60.deg. C (N $H_{4}$)$_{2}$ $S_{x}$ solution exhibited the highest $J_{sc}$ and PL intensity. These results demonstrated that the short circuit currents was influenced by the ITO/InP interface states.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2342-2348
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• 2009

Even though underground transmission cable is an essential transmission method to supply stable power for downtown and population center, the interaction of electromagnetic force by fault current is very large comparing to overhead transmission line due to restricted installation space such as tunnel, and close consideration is required for it. This paper presents countermeasures to reduce and release the effect of electromagnetic force with rope binding and installation of spacer and describes its efficacy through three phase short-circuit test, which will be utilized as basic materials for improvement and development of cleat, hanger, etc. to reduce and release effect of electromagnetic force in the future.

• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.64-67
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• 2002

To increase the short-circuit testing capacity of distribution transformers, testing facility has been installed for KEPCO in Vi-wang. The power supply of testing facility is directly supplied from the network substation located closely. Testing can be performed up to 300 kVA for single-phase transformers, 500 kVA for three-phase transformers. Operating with this facility, the distribution company is able to maintain the reliable supply of electricity. Also the critical quality of transformers from manufacturers can be verified by short-circuit testing. This paper describes the design concept and specification of newly developed equipment and the procedure of short-circuit test.