• Journal of the Korean Society for Railway
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• v.10 no.4
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• pp.388-392
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• 2007

A new dielectric test on main relays of electric traction vehicles, the partial discharge(PD) test, is proposed. The PD test will not affect the insulation performance of specimen during the test and provide much more detailed information on insulation, the types of defects, and so on. Insulation performance of relays is estimated by discharge inception voltage(DIV), discharge extinction voltage (DEV), and apparent charge as a function of test voltage and time. Three main relays of different manufacturing date were estimated by applying AC voltage with three patterns in ranges of $0{\sim}1,200[V]$. From the results, we could estimate insulation state and which types of defects exist in them.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.11
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• pp.62-74
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• 2012

This paper proposes a new secondary battery charger/discharger available for zero voltage discharge which is used for test equipments and formation process. The proposed system is a switching type converter, and thus the system is high efficiency and more compact as compared with linear type charger/discharger. Conventional switching type charger/discharger can not discharge secondary batteries to zero voltage because of voltage drops in the switching elements and long distributing line(typically 10m). However, the proposed system is able to discharge the battery to zero voltage in constant current mode regardless of the voltage drops. In this paper, we analyze the proposed charger/discharger and the validity of the system is verified by simulation and experiment.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.103-104
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• 2000

Voltage transfer curves have been used for analyzing the micro-discharge characteristics of cells in ac-PDP. This paper deals with the effect of working gas species, pressure and frequency of applied voltage on the micro-discharge characteristics. Using the mixture gases of He+Xe or He+Ne+Xe, wall voltage steeply varied compared with only He gas, and also voltage margin increased. Discharge voltage and voltage margin increased with increasing Xe percentage, and also wall voltage more steeply varied. In addition, the variation of effective wall capacitance which is significantly dependent on the discharge strength is discussed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.2 s.245
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• pp.95-100
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• 2006

Electrostatic precipitators(EPs) have low pressure drop and high dust collection efficiency and are widely used for industrial dust collectors. The current-voltage characteristics, which are important to maintain high dust collection efficiency, depend on several factor: discharge electrode shape, gas flow property, dust loading etc. In this study, experiments are performed to investigate the current-voltage characteristics of the corona discharge of various electrode geometries and an empirical model is proposed to predict current-voltage characteristics of the corona discharge. The corona onset voltage correction coefficient$(\alpha)$ and the geometry correction coefficient$(k_g)$ are used to the conventional equation for wire-plate type discharge electrode. The corona onset voltages are -6.3kV and almost constant when the numbers of discharge pins are varied from 3 to 9. The length of discharge pins has very sensitive effects on the corona onset voltage. They are increased from -6.3 to -7.8kV when the discharge pin length are 8.5 and 4.5mm, respectively. The empirical model shows good agreement with experimental results and can predict the effects of discharge pin length and number.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.271-273
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• 2007

This paper presents the experimental results of underwater discharges in 25 mm point-plane gap caused by impulse voltage. Discharge phenomena were observed by digital cameras and recorded by oscilloscope. As a result, discharge patterns in positive and negative polarity have different shapes according to applied voltage amplitudes. The positive discharge is like root but the negative discharge is similar to bush. As the voltage is increased, the discharge routs are thick and have more branches. Also the time to breakdown is inversely proportional to voltage.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1185-1188
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• 2007

The address discharge characteristics by the various scan-low and common-bias voltages are investigated based on measured address discharge time lags and $V_t$ close-curve analysis. The scan-low voltages are changed under the same voltage difference between the X and Y electrodes during an address period. As the voltage difference between the scan and address electrodes is increased during an address period, the address discharge time lag is shortened but the background luminance is increased. It is found that the improved address discharge characteristics is caused by the effect of the higher external applied voltage during an address period than the accumulated wall charges during a reset period and the high background luminance can be prevented by applying an address-bias voltage during a rising-ramp period and low reset voltage.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12
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• pp.1150-1154
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• 2003

The voltage profile during discharge of the zinc air battery has very flat pattern until reach to end of discharge voltage. But, when zinc air battery is discharged by high current, the discharge voltage and energy becomes low. Therefore, we focused on effects of catalyst size to solve this problems by increasing active sites of oxygen reduction reaction. The size of catalyst was reduced from 27 to l${\mu}{\textrm}{m}$ and we examined average discharge voltage, capacity, energy, resistance and characteristics during GSM pulse discharge of zinc air battery with change of current density. And we also measured porosity of the cathode according to the ASTM. So we have got improvement of average discharge voltage and energy when catalyst was minimized and we have got optimum size of catalyst at 5${\mu}{\textrm}{m}$.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.112-116
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• 2004

On-line monitoring of fault discharge is an important approach for indicating the condition of electrical insulation of stator winding in high voltage motor. In this paper, several key aspects of on-line monitoring system are discussed, involving the characteristics of fault discharge of stator winding in high voltage motor, spectrum analysis of four simulation fault signals, feature extraction of internal fault discharge from apply voltage to breakdown. The study of the partial discharge activities allows to highlight the ageing stage in the winding fault under test. During the life of the winding insulation fault, the shape of PD signal change relating to the ageing stage. The ageing of stator winding insulation fault of high voltage motor is investigated based on the characteristics of partial discharge pulse distribution and statistical parameters, such as maximum, skewness and kurtosis using discrete wavelet transform coefficients.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.6
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• pp.65-71
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• 2002

Characteristics of corona discharge of the different types of the plasma reactors which are cone-hole and cone-plate is investigated experimentally. The discharge starts at lower voltage for the cathode corona than the anode corona and spark occurs at higher voltage for the cathode corona. And the cathode corona makes more stable discharge than the anode corona. The effect of the base gas in corona discharge for different O$_2$/N$_2$ concentrations is related with the gas molecular weight. The discharge for the smaller molecular weight gas occurs easier than for the high molecular weight gas. The discharge current decreases with the increase of oxygen concentration and it increases more sharply for anode corona than for cathode corona as discharge voltage increases after corona onset voltage. NO-NO$_2$ conversion increases with the energy density of corona discharge and the addition of O$_2$ in a base N$_2$ gas.

• Nuclear Engineering and Technology
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• v.35 no.3
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• pp.226-233
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• 2003

The discharge characteristics of a prototype ion source was investigated, which was developed and upgraded for the NBI (Neutral Beam Injection) heating system of KSTAR (Korea Superconducting Tokamak Advanced Research). The ion source was designed for the arc discharge of magnetic bucket chamber with multi-pole cusp fields. The ion source was discharged by the emission-limited mode with the control of filament heating voltage. The maximum ion density was 4 times larger than the previous discharge controlled by a space-charge-limited mode with fully heated filament. The plasma (ion) density and arc current were proportional to the filament voltage, but the discharge efficiency was inversely proportional to the operating pressure of hydrogen gas. The maximum ion density and arc current were obtained with constant arc voltage ($80{\sim}100V$), as $8{\times}10^{11}cm^{-3}$ and 1200 A, respectively. The estimated maximum beam current was about 35 A, extracted by the accelerating voltage of 80kV.