• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.1
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• pp.47-53
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• 2005

Most of the loads in industrial power distribution systems are balanced and connected to three power systems. However, in the user power distribution systems, most of the loads are single & three phase and unbalanced, generating voltage unbalance. Voltage unbalance factor is mainly affected by load system rather than stable power system. Unbalanced voltage will draw a highly unbalanced current. As a result, the three-phase currents may differ considerably, thus resulting in an increased temperature rise in the machine. This paper presents a scheme on the characteristics of voltage and current unbalance factor under the load variation at the three phase 4-wire system. Load unbalance factor is measured by the power quality measurement apparatus and compared by the current unbalance factor. Two methods are indicated similar results. The voltage unbalance factor of the three-phase 4-wire system is approved by the field measurement. Each phase has an impedance each other by the unbalanced operation pattern and give rise to voltage unbalance.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.55 no.2
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• pp.67-72
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• 2006

Most of the load distributions in low voltage power feeder distribution systems are designed with approximately balanced and connected at the three phase four wire systems. However, in the user power distribution systems, most of the loads are single & three phase and unbalanced, generating load unbalance. Load unbalance factor is mainly affected by the impedance of load system. Unbalanced current will draw a highly unbalanced voltage. This paper presents a new calculation method for unbalance factor under the load variation at the three phase four wire system. Load unbalance factor is measured by the power quality measurement apparatus and compared with the current unbalance factor. Two methods are indicated similar results.

• Journal of the Korean Institute of Rural Architecture
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• v.18 no.3
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• pp.35-42
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• 2016

For the reason of economy, farmers and structural engineers prefer the vinyl house frame members that have the lightest cross sections. Therefore, in order to reach this aim, rod bracing system is the best method for multiple vinyl house frames. In this study, wire rods (tension members) are used to be bracing members in multiple vinyl house frames. The effects of additional wire rods in the frames are investigated by the variations of the bending moments, axial forces, displacements and combined stresses in the main frames that are reinforced by different shapes of rod bracing system. Vinyl house frames are usually made by steel pipe members and collapsed by the excessive wind and snow loads. Two kinds of bracing models are used for wind and snow loads separately in this study. The effective bracing models for each load are finally figured out.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.8
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• pp.1291-1296
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• 2017

Single-phase and three-phase load can be used together in 3-phase 4-wire system. Single-phase and three-phase loads can be classified as linear loads without harmonics and nonlinear with harmonics. Single-phase linear loads are linear loads such as lamps and heat, and single-phase nonlinear loads are power converters such as rectifiers. It is recommended that the distribution of loads in the 3-phase, 4-wire distribution lines be evenly distributed within a certain range. However, harmonic currents generated in a nonlinear load flow on the neutral line and affect the phase current magnitude. The difference in the magnitude of the individual phase current due to the influence of the harmonic current present in the neutral line can produce a difference in current and load unbalance. In this study, current unbalance ratio and load unbalance ratio which can occur when a combination of linear and nonlinear loads are applied to 3-phase 4-wire distribution line are calculated.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.2
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• pp.88-93
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• 2005

Most of the LV customer have been applied the distribution system of 3-phase four wire system because of its advantage of supplying both of 1-phase & 3-phase loads simultaneously. Due to its structural simplicity, it is more convenient for use rather than the conventional separated scheme. But uneven load distribution or unclean voltage quality has occurred various problems such as de-rating, losses increase and vibration, etc. In this paper, voltage, current and power waveform in the actual fields have measured and analyzed in relation with internationally allowable voltage unbalance limits and compared the current unbalance factor with the load unbalance factor.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.6
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• pp.948-954
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• 2008

Now, but task for stringing trolley wire is worked manually by a measurement of dip, we need to development the automatic control system for a safety and effective tasks. In this paper, in works of stringing trolley wire by a mobile of robot, a method is proposed tension control for the stringing trolley wire. On the basics of a wire model with hard nonlinear, ac servo motor model for torque generating and stringing wire tension, the tension control scheme is design and implemented with a detected wire tension by a load cell. We experimentally show that the performance of the tension response are satisfactory to regulator tension. The proposed system is simulated and experimented, results is verified the utilities.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.15-17
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• 2004

Most of LV customer has been composed the 3-phase four wire system distribution system which is supplying simultaneously at the 1-phase & 3-phase load. In this system, the composition of the power apparatus system is simple rather than conventional separation mode of the 1-phase & 3-phase, But due to uneven load unbalance or unclean power quality, various kinds such as derating or power losses become an issue. In this paper, we measured and analyzed voltage and current waveform in the field, compared with internationally allowable voltage unbalance limits.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.3
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• pp.78-83
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• 2006

In this study, we analyzed the influence or electrical pole by FEM(Finite Element Method) and developed protective system by designing and interpreting protective system for electrical pole when abnormal strength worked on messenger wire. Protective system did not shed messenger wire under wind pressure and discontent load but did assign a part to preventing rupture of electrical pole through automatically shed messenger wire over fred strength. Structure of protective system analysis by FEM and prove property by measuring tensile strength for practical product.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.3
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• pp.99-104
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• 2017

The three-phase four-wire power distribution system can be used to supply power to single-phase and three-phase loads at the same time. There are linear loads and nonlinear loads as single-phase loads connected to each phase. The nonlinear load generates a harmonic current during the power energy conversion process. In particular, the single-phase nonlinear load has a higher proportion of generation of the third harmonic current than the harmonics of the other orders. In a three-phase four-wire system, the third harmonic current flows through the neutral wire to the power supply side, affecting the power supply side and the line. Furthermore, the magnitude of the current flowing in the neutral line can be higher than the current flowing in the individual phase. If the neutral current is higher than the phase current, the breaker may be blocked. Therefore, it is necessary to reduce the amount of current flowing in the neutral line by harmonics. There is a method of zigzag connecting a single phase transformer by a method of reducing 3 harmonic current. In this study, the method of reducing the magnitude of the three harmonic currents flowing through the zigzag wire by comparing the polarity and the negative polarity characteristics of the single phase transformer was compared through measurement and simulation.

• Journal of Power Electronics
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• v.9 no.6
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• pp.874-883
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• 2009

This paper deals with an integrated voltage and frequency (VF) controller for isolated asynchronous generators (IAG) driven by a constant power pico-hydro uncontrolled turbine feeding three-phase four-wire loads. The proposed VF controller is used to control the frequency and voltage of an IAG with load leveling. Such a VF controller is also known as an integrated electronic load controller (IELC) which is realized using an isolated star/polygon transformer with a voltage source converter (VSC) and a battery at its DC bus. The proposed generating system with a VFC is modeled and simulated in MATLAB along with Simulink and Simpower system (SPS) toolboxes. The simulated results are presented to demonstrate the performance of an isolated asynchronous generator feeding three-phase four-wire loads with neutral current compensation.