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On-Line Condition Monitoring of Electrical Equipment Using Temperature Sensor
崔龍成(Yong-Sung Choi),金宣在(Sun-Jae Kim),金榮敏(Yeong-Min Kim),宋煥基(Hwan-Kee Song),李炅燮(Kyung-Sup Lee) 대한전기학회 2008 전기학회논문지 P Vol.57 No.2
Condition monitoring technologies allow achieving this goal by minimizing downtime through the integrated planning and scheduling of repairs indicated by condition monitoring techniques. Thermal runaways induced by conduction problems deteriorate insulating material and cause disruptive dielectric discharges resulting in arcing faults. Therefore, having the ability to directly measure the temperature of the contacts while in service will provide more information to determine the true condition of the equipment. It allows corrective measures to be taken to prevent upcoming failure. Continuous temperature monitoring and event recording provides information on the energized equipment's response to normal and emergency conditions. On-line temperature monitoring helps to coordinate equipment specifications and ratings, determine the real limits of the monitored equipment and optimize facility operations. Using wireless technique eliminates any need for special cables and wires with lower installation costs if compared to other types of online condition monitoring equipment. In addition, wireless temperature monitoring works well under difficult conditions in strategically important locations. Wireless technology for on-line condition monitoring of energized equipment is applicable both as stand alone system and with an interface for power quality monitoring system. The paper presents the results of wireless temperature monitoring of electrical equipment at a power plant.
吳鏞(Yong Oh),崔龍成(Yong-Sung Choi),黃宗善(Jong-Sun Hwang),李炅燮(Kyung-Sup Lee) 대한전기학회 2008 전기학회논문지 P Vol.57 No.2
A field-oriented UHF system for on-line PD monitoring of transformers is designed, which has been installed inside the oil tank of transformer in a substation by two ways: on-line installing mode through the oil-valve and pre-installing mode through the man hole/hand hole cover. This system has successfully captured long intermittent discharge signals that hadn't been detected through conventional techniques, and solved the problem successfully. The results demonstrate that UHF technique has great advantages for on-line PD monitoring of transformers. By adopting the peak detection technique, it becomes easy and effective for the transplantation of the phase-resolved pattern recognition technique from conventional method to UHF method, and then to realize continuous on-line monitoring, source characterization and trending analysis.
Amplification of Current Harmonics Due to Self-Excitation Capacitors for Wind Induction Generators
吳鏞(Yong Oh),崔龍成(Yong-Sung Choi),黃宗善(Jong-Sun Hwang),李炅燮(Kyung-Sup Lee) 대한전기학회 2008 전기학회논문지 P Vol.57 No.2
The value of this paper is to use reduced size apparatuses to perform field measurement in order to identify and validate that the harmonic-current effects are due to the presence of self-excitation capacitance connected at stator's terminals of the studied SEIG. This paper has presented the measured electrical quantities of a three-phase Δ-connected wind induction generator (WIG) under sudden connection and disconnection of resistive loads. An intelligent power-system recorder/monitor has been employed to measure three-phase voltages and currents of the studied system at the terminals of the studied WIG and the load. The measured electrical quantities have been analyzed. Total harmonic distortion (THD) of current using cumulative probability density function has been employed to determine the penetration of harmonic distortion at load side. The results show that the harmonic currents generated by the studied WIG can be severely amplified by the connected self-excited capacitance at the stator's terminals.
XLPE 전력케이블의 부분방전 검출을 위한 HPF 적용 시험
李龍成(Yong-Sung Lee),金正允(Jung-Yoon Kim),梁種璟(Jong-Kyung Yang),朴魯埈(Noh-Joon Park),崔龍成(Yong-Sung Choi),朴大熙(Dae-Hee Park) 대한전기학회 2006 전기학회논문지C Vol.55 No.4
In this paper, we developed HPF(high pass filter) consists of lumped LC components to decrease the noises that are detected in PD (partial discharge) measuring test, and adapted it to field test. We tested it under laboratory circumstances like the fields, and measured the phase change properties of detected signal in UHF sensor with Lemke Probe and oscilloscope (TDS-3054, Tektronix). As a result, we obtained available data showing the decrease of noises in the experiments with the developed HPF from the joint box of 22.9㎸ distribution line. The result can be adapted to prevent the degeneration of the XLPE power cable, and to observe and diagnosis the underground power transmission cable at the ultra-high voltage.
宋鎭沅(Jin-Won Song),崔龍成(Yong-Sung Choi),李炅燮(Kyung-Sup Lee) 대한전기학회 2007 전기학회논문지 Vol.56 No.1
LB method is one of the most interesting technique to arrange certain molecular groups at precise position relative to others. Also, the LB deposition technique can fabricate extremely thin organic films with a high degree of control over their thickness and molecular architecture. In this way, new thin film materials can be built up at the molecular level, and the relationship between these artificial structures and the properties of materials can be explored. In this paper, evaluation of physical properties was made for dielectric relaxation phenomena by the detection of the surface pressures and displacements current on the monolayer films of phospolipid monomolecular DLPC. Lipid thin films were manufacture by detecting deposition for the accumulation and the current was measured after the electric bias was applied across the manufactured MIM device. It is found that the phospolipid monolayer of dielectric relaxation takes a little time and depend on the molecular area. When electric bias is applied across the manufactured MIM device by the deposition condition of phospolipid mono-layer, it wasn't breakdown when the higher electric field to impress by increase of deposition layers.