• Journal of Welding and Joining
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• v.15 no.2
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• pp.72-80
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• 1997

The spatter generation rate of GMA welding with $CO_2$ gas shielding was measured with the change of welding conditions such as wire feeding rate and welding voltage and then the results were analized with the accompanying changes in metal transfer mode and in bead geometry. The spatter generation rate (SGR) was relatively low not only wit the short circuit transfer but with the truely globular transfer mode. However, the SGR resulted with the mixed mode were consistantly high. The resultant wave pattern of mixed mode was due to the coexistance of short-circuit and globular transfer and characterized by the frequent appearance of instantaneous short circuit. Considering the result of SGR and that of bead geometry, it could be concluded that when the wire feeding rate (or welding current) was either low or high, the optimum bead shape could be obtained along with the low spatter generation. However, in the middle range of wire feeding rate, the optimum bead shape was only obtained in the mixed mode condition resulting in the high spatter generation.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.35 no.2
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• pp.67-76
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• 1986

It is observed that an appreciable short-circuit current (Is) flows by the time variation of temperature without applying external field in M1(metal)-P(polymer)-M2(metal)system. In M1-P-M2(A1) system, Is flows in the direction from the electrode(A1) having a lower workfunction to the counter electrode(M1) during heating and its magnitude increases as the thickness of polymer is decreased and as the heating rate is raised. The sign of Is is reversed in lower temperature region (under glass transition temperature) when the direction of temerature variation is changed during heating and cooling. From these experimental results, we can sugest that Is flows in the external short-circuit during the space charge distribution formed around both interfacial surfaces (M1-P and P-M2) is continuously maintained in the non-equilibrium state but not in equilibrium state.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.1
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• pp.27-32
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• 2005

This study presents an analysis technique that can consider all variables which are needed in the design of short circuit current capability of electrical contacts. Required variables in the design are material of contact, contacting area, applied force, asperity of surface, current and so on. Short circuit current capability test was carried out for the interrelation of design variables and the verification of analysis technique. Temperature rise equation of the contacts was obtained from the test results, and also, a standard that is criterion of the occurrence availability of melting or spot of contact surface from test results was established.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.11
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• pp.572-576
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• 2006

As the increasing of capacity and technology of power facilities, rotating machines such as turbine generators and water turbines are getting higher at capacity but smaller in size. Thus the monitoring and diagnosis of generators for fault detection and protection has attracted intensive interest. Most of electrical faults of rotating machines appear in their windings. In case of an after-fault in high capacity rotating machines, the recovering cost is usually very expensive and additional time is necessary for returning in a normal situation. In this paper, the magnetic flux patterns in air-gap of a generator under various fault states as well as a normal state are simulated by a conventional FEM tool. These results are successfully applied to detection and diagnosis of the short-circuit condition in rotor windings of a high capacity generator.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.1
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• pp.23-30
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• 2013

This paper proposes a parametric model for inter-turn fault detection in a fault-tolerant permanent-magnet (FTPM) machine, which can predict the effect of the short-circuit fault to various physical quantity of the machine. For different faulty operations, a new effective stator inter-turn fault detection method is proposed. Finally, simulations of vector-controlled FTPM machine drives are given to verify the feasibility of the proposed method, showing that even single-coil short-circuit fault could be exactly detected.

• Journal of Magnetics
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• v.20 no.4
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• pp.400-404
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• 2015

Various kinds of winding arrangements can be used to enable fault current limiters (FCL) to tolerate higher forces without resulting in a substantial increase in construction and fabrication costs. In this paper, a distributed winding arrangement is investigated in terms of its effects on the short-circuit forces in a three-phase FCL. The force magnitudes of the AC supplied windings are calculated by employing a finite element-based model in the time stepping procedure. The leakage flux and radial and axial force magnitudes obtained from the simulation are compared to those obtained from a conventional winding arrangement. The comparison shows that the distributed winding arrangement significantly reduces the radial and, especially, the axial force magnitudes.

• Journal of Welding and Joining
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• v.12 no.4
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• pp.76-84
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• 1994

Droplet transfer modes due to welding conditions and the effect of Ca in welding wire on droplet transfer were investigated. Droplet transfer mode in CO$_{2}$ welding was classified into 2 modes, that is, short circuit and globular transfer, with increasing welding current and voltage. With increasing Ca content in wire, repulsive pressure due to vaporization of Ca was considerably increased. In short circuit transfer region, arcing time was increased and droplet transfer cycle was decreased, with increasing Ca content. In globular transfer region, welding condition for globular transfer was lower current region, with increasing Ca content.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.166-170
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• 1998

The metal transfer of CO2 arc welding machine can be devided into short-circuit(low current) metal transfer. Especially in large crrent region, the main problem of CO2 arc welding machine is much spatter generation which is caused by mainly instant short-circuit matal transfer. So in this paper descrives new current control method in large current region, which can improve welding performance and lessen spatter generation. And as a result of experiment, the effect of proposed control method is demonstrated.

• Transactions on Electrical and Electronic Materials
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• v.10 no.1
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• pp.9-15
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• 2009

There is a growing demand for a high voltage silicone rubber composite with high mechanical property and high electrical property. The effect of modified cross-linking agent on the mechanical, electrical properties, and short-circuit test performance of silicone rubber insulators have been investigated. To use base polymer, the various silicone polymers were prepared by the equilibrium polymerization. Aluminum trihydrate surface was treated by vinyl silane. Liquid silicone rubber nanocomposite was prepared from the compounding of VPMPS, HPDMS, catalyst, and alumina trihydrate modified with 1,3,5-trivinyl-l,3,5-trimethylcyclotrisiloxane. The mechanical property and electrical property for insulation materials were measured, indicating the high tensile strength and the good short-circuit property.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.7
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• pp.358-363
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• 2004

A new 600 V dual gate transistor employing thyristor action, which incorporates floating PN junction and trench gate IGBT, is proposed to improve the forward current-voltage characteristics and the short circuit ruggedness. Our two-dimensional numerical simulation shows that the proposed device exhibits low forward voltage drop and eliminates the snapback phenomena compared with conventional trench gate IGBT and EST The proposed device achieves high current saturation characteristics by separating floating N+ emitter and cathode. The proposed device achieves low saturation current value compared with conventional devices, and the short-circuit ruggedness is improved. The proposed device may be suitable for the use of high voltage switching applications.