• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.8
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• pp.82-87
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• 2011

Induction motor is most widely used as the driving power in the industrial site. Induction motor current is composed of two parts, magnetizing current and load current. Load current uses energy what is doing the work. Load current varies with load variance but magnetizing current is constant, regardless of load variation. Magnetizing current needs for establishing the rotating magnetic field of induction motor and lags behind the voltage. Generally capacitor is used for power-factor compensation of inductive load. Self-excitation occurs when the capacitive reactive current from the capacitor is greater than the magnetizing current of the induction motor. When this occurs, excessive voltages can result on the terminals of the motor. This excessive voltage can cause insulation degradation and ultimately result in motor insulation failure. In this paper, we analyzed that how the magnetizing current and condenser current is operating at the allowable limit by the load variation. Condenser current is below allowable limit of magnetizing current but magnetizing current is above allowable limit at the lower load operation condition.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.3
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• pp.134-139
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• 2012

The power characteristics of the Mg-Air fuel cell were investigated with regard to variation of load conditions. The types of load current using for the Mg-Air fuel cell with 10% NaCl electrolyte were step type, ramp type and pulse type. It was found that transient phenomena occurred in the step current load, which is due to activate of the oxidation-reduction reaction process. And the transient time increase with the load current increase. In the load current of ramp type, the slop of voltage drop increased with current load slop ${\alpha}$ increase. The load voltage and power decreased according to the pulse period of load current decrease were attributed to the metal sludges.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.2
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• pp.259-267
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• 1994

This paper describes a current control of a single-phase PWM inverter. The proposed PWM inverter utilizes the instantaneous control method which is based on the real-time digital feedback control and the microprocessor-based deadbeat control. The deadbeat current controller is proposed to control the output current regardless of load component variations by the same method as voltage control. That is, in current control, with a very short sampling time and the successive feedback of the output current, the load current is mainly effected by the magnitude of load impedance rather than load component, the load current is mainly effected by the magnitude of load impedance rather than load component. Therefore, by treating the load as an impedance, the system's order is reduced and the instantaneous current control using the proposed deadeat controller is simplified.

• Journal of IKEEE
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• v.25 no.3
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• pp.506-510
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• 2021

In this paper, we propose an LDO that improves the load regulation change due to the current detection structure. The proposed LDO regulator adds the proposed current detection circuit to the output stage. Thereby to improve the load regulation of the delta value coming in on the output has a voltage value of an improved load Regulation characteristics than conventional LDO regulator. Using the proposed current detection structure, it was possible to improve the output change according to the change of the load current by about 60%. The proposed circuit has been simulated and verified characteristics by using a Spectre, Virtuoso simulation of Cadence.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.91-94
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• 2003

A DC railway system has low feeder voltage, The fault current can be smaller than the current of load starting. So it is important to discriminate between the small fault current and the load starting current. The load starting current increases step by step but the fault current increases all at once. So the type of ${\Delta}I$ relay(50F) was developed using the different characteristics between the load starting current and the fault current. As for the load starting current, the time constant of load current at each step is much smaller than that of the fault current. First, to detect faults in DC railway systems, an algorithm using the time constant calculated by the method of least squares is presented in this paper. Secondly, to compose a protection scheme for DC railway systems is presented in this paper.

• Journal of Electrical Engineering and Technology
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• v.5 no.2
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• pp.307-318
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• 2010

In this work, an accurate analysis of low frequency current ripple in residential fuel cell power generation systems is performed based on the proposed residential load model and its unique operation algorithm. Rather than using a constant dc voltage source, a proton exchange membrane fuel cell (PEMFC) model is implemented in this research so that a system-level analysis considering the fuel cell stack, power conditioning system (PCS), and the actual load is possible. Using the attained results, a comparative study regarding the discrepancies of low frequency current ripple between a simple resistor load and a realistic residential load is performed. The data indicate that the low frequency current ripple of the proposed residential load model is increased by more than a factor of two when compared to the low frequency current ripple of a simple resistor load under identical conditions. Theoretical analysis, simulation data, and experimental results are provided, along with a model of the load usage pattern of low frequency current ripples.

• Progress in Superconductivity and Cryogenics
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• v.11 no.1
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• pp.30-34
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• 2009

This paper deals with charging and persistent-current mode operating characteristics of BSCCO magnet load using high-temperature superconducting (HTS) power supply. The HTS power supply consists of two heater-triggered switches, an iron-core transformer with the primary copper winding and the secondary BSCCO solenoid, and a BSCCO magnet load. The magnet load was fabricated by double pancake winding and its inductance is about 21 mH. A hall sensor was installed at the middle of the magnet load to measure the current in the load. In order to investigate the efficient pumping characteristics, operating tests of heater-triggered switch with respect to dc heater current were carried out, and the electromagnet current was determined by considering saturation characteristics of its iron core. The saturation characteristics of charged current in the magnet load were observed with respect to various pumping periods: 12 s, 14 s, 24 s and 32 s. After charging the magnet load, the persistent current was measured. The operating characteristics of the persistent current mode were mainly determined by joint resistance and magnet load.

• Journal of IKEEE
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• v.23 no.2
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• pp.364-369
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• 2019

The ratios of compliant branch circuit of leakage current and insulation resistance were 68.4% and 90.8%, respectively at the lamp load, 64.6% and 96.5% at the heat load, 86.7% and 88.9% at the power load. Limit of residual current of the zero phase secondary current value at the zero phase primary current was 100 A when rated primary current 400 A more than. The reason why the ratio of branch circuit of the leakage current was less than the ratio of compliant branch circuit of the insulation resistance might be that the leakage current includes the capacitive leakage current and the zero phase current.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.609-612
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• 2007

This paper describes a new method to predict the load current of a dc-dc converter. The load current is calculated using the video information of the PDP. The output capacitance of the dc-dc converter can be reduced by utilizing the predicted load current, which results in a cost reduction of the power system in the PDP.

• 전기의세계
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• v.16 no.1
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• pp.7-13
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• 1967

There are many kinds of motors operating by rated voltage which is constant. In this paper, the characteristics of separately excited direct current motor is analyzed when its terminal voltage is varied as its load current. As for this source, direct current generator of a series field is used, and it is driven at constant speed by a primemover. The induced voltage of the generator is propotional to its load current but it saturates as its load current is large. The charateristics of motor is studied by analog computer because of the nonlinearity of generator. The results are as follows: (1) The load current and the rotor speed of motor increase as the load of motor increases. But the speed of rotor decreases for the influence of the saturation of the iron of generator field when its load current is large. (2) Decreasing the inertia of motor and increasing the inductance of the armature circuit improve the stability of motor and the region of stable state. (3) By changing the field current of the motor, the speed and the direction of rotor can be controlled in wide range.