• Journal of Electrical Engineering and Technology
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• v.6 no.2
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• pp.167-173
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• 2011

This paper presents a method for the development of the impedance locus to test the dynamic characteristics of protective relays. Specifically, using the proposed method, the impedance locus can comprise three impedance points, and the speed of impedance trajectory can be adjusted by frequency deviation. This paper is divided into two main sections. The first section deals with the configuration of impedance locus with voltage magnitude, total impedance magnitude, and impedance angle. The second section discusses the control of the locus speed with the means of the deviation between two frequencies. The proposed method is applied to two machine equivalent systems with offline simulation (i.e., PSCAD) and real-time simulation (i.e., real-time simulation environment) to demonstrate its effectiveness.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1407-1412
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• 2004

Impedance calculations of electric railway traction systems is essential to define characteristics and to design it. The self impedance is defined voltage drop rate per unit length, the mutual impedance is represented as a voltage induced to transmission line from transmission line. The self and the mutual impedance are influenced by ground return currents. The earth is considered as a semi-infinitely extended non-ideal conductor. The current of transmission line produces earth current induced magnetically and it flow through a path having minimum impedance. Carson proposed the impedance calculation formula using wave equations and magnetic field equations. Though the formula have an improper equation, that is still used as a standard impedance calculation method. This paper introduced an impedance calculation method that the complex depth of earth return method assumes that the current in conductor returns through an imagined earth depth path located directly under original conductor at a depth of. In this paper, we showed that this proposed method has a closed form and is easier than Carson's.

• Journal of Power Electronics
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• v.12 no.1
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• pp.10-18
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• 2012

This paper proposes a finite element method (FEM)-based model of an interior permanent magnet (IPM)-type BLDC motor having stator inter-turn faults. We also propose impedance modeling of the magnetic characteristics. By integrating the developed model with a current-controlled voltage source inverter (CCVSI) model, the distributed characteristics of an inter-turn fault operated by a six-switch inverter are investigated considering speed control. Moreover, this paper presents the flux density distribution and torque characteristics for analyzing the inter-turn fault of an IPM-type BLDC motor. Additionally, fault impedance is required to calculate the circulating current that causes magnetic distortion. Thus, this paper proposes a method for estimating the circulating current taking into account the voltage at the shorted turn and the rotating speed. The analysis data were verified experimentally.

• Journal of KSNVE
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• v.7 no.6
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• pp.937-943
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• 1997

Viscoelastic materials have the characteristics of elasticity and viscosity. Unlike the metals which show negligible damping characteristics, the damping characteristic of viscoelastic materials like rubber mounts is very important in the analysis of the dynamic system. So there has been a great interest in measuring the damping characteristics of the material can be measured. One is the resonant method which loss factor can be measured only in the resonant frequency. The other is the nonresonant method. In this paper, the test procedure and the physical meaning of the impedance method are introduced. The impedance test results, the loss factor by the impedance method, are compared to the results of the resonant method including some recommendations in the experimental setup.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.311-314
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• 2009

This paper presents the characteristics of grounding impedance of counterpoises buried at various soil structures. Grounding impedance measurements were made by the Fall-of-Potential method. The experiments were carried out in 50 m counterpoise of 25 $mm^2$ buried at a depth of 0.5 m. The test current was injected by the impulse generator having the front time of $1{\sim}60{\mu}s$. As a result, the soil structures greatly influences on the grounding impedance characteristics of counterpoise. The transient grounding impedances strongly depend on the injection mint and the front time of impulse current.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.4
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• pp.158-163
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• 2002

The pulsed Power system has been widely used to many applications, such as E/P(Electrostatic Precipitator), DeNOx/DeSOx power system, often generator, etc. In this paper, we study EMTP analysis and characteristics of critical voltage and load in impedance on various electrode length of pulse corona. To obtain a stable pulse voltage, we designed a compact pulse generator switched MOSFET and tested their characteristics by adjusting electrode length and pulse repetition. As a re sult, critical voltage of pulse corona and load impedance on increasing electrode length were decreased. These results indicate we can control critical voltage of pulse corona and suppress arc discharging between two electrodes.

• Journal of the Korean Institute of Telematics and Electronics
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• v.3 no.3
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• pp.2-13
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• 1966

The impedance characteristics of vertical antennas over a finite image plane were analyzed and measured. Two kinds of image plane, one rectangular and the other circular, were used for the mesurements. And the length of antennas was varied at fixed frequency. All kinds of terminal zone effects which possible raise questions because of antenna mounting system were discussed. It is observed from the results that the measured impedance of antennas over a comparativley large rectangular plane is approximatly identical with the theoretical value, and also the impedance of antennas over a comparatively small circular plane had similar characteristics to a comparatively thick antennas over an inifinite image plane.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.9
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• pp.744-749
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• 2011

Recently, annual usage of energy is dramatically increasing because industrialization is going faster and more electricity is needed due to various electronic devices. This study focused on the performance characteristics of solar cell using the impedance technique. The experiment measured an impedance according to frequency's from 2 mHz until 1 MHz. It could know that the impedance was decreased according to the frequency increases in solar cell. The imaginary part was changed from capacitance component to inductance component.

• Journal of the Korean Society of Safety
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• v.27 no.4
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• pp.33-37
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• 2012

This paper describes the characteristics for ground impedance of counterpoise according to position of auxiliary probe and frequency using the fall-of-potential method and the testing techniques to minimize the measuring errors are proposed. The fall-of-potential method is theoretically based on the potential and current measuring principle and the measuring error is primarily caused by the position of auxiliary probes. In order to analyze the effects of ground impedance due to the distance of the current probe and frequency, ground impedances were measured in case that the distance of current probe was located from 10[m] to 100[m] and the measuring frequency was ranged in 55 [Hz], 128[Hz], 342[Hz], and 513[Hz]. The results could be help to determine the position of auxiliary probe when the ground impedance was measured at grounding system.

• Journal of Biomedical Engineering Research
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• v.13 no.1
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• pp.47-54
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• 1992

We studied the characteristics of the compound electrode and found that the compound electrode provides the four-electrode method in a compact form. We developed a new method of measuring the skin impedance using simple electrodes at low frequencies. At high frequencies where the effect of internal tissue impedance is not negligible, we used the compensation method using compound electrodes since they measure the voltage right under the skin. At 50 kHz, we measured the real part of the skin impedance of less than $80{\Omega}$ on the thorax. We propose a simple instrument which can measure accurate skin impedance at various frequencies.