• Proceedings of the KSR Conference
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• 2005.05a
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• pp.819-824
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• 2005

This paper describes the measurement result of leakage current flowing arresters connected in feeder lines to propose an optimal management method. Twenty seven arresters set in seven areas were analyzed on a regular basis for 4 months. The results showed that the RMS and the peak value of the total leakage currents for soundness arresters were a range of $200uA{\sim}00uA$. respectively. During the period of measurement, the magnitude of the leakage current didn't show conspicious changes and there were impossible places to analyze arrester's status due to including high THD rate in a feeder line, From the study, leakage current measurement has to be performed at a condition without running an electric train in the line, and the allowable RMS value of soundness arrester is bellow 600uA.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.367-368
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• 2006

This paper presents an analytic derivation of phase measurement error. The analysis derives the measurement error caused by the finite-bit quantization of both input signals and twiddle factors used in the recursive implementation of the phasor measurement algorithm. The derivation is based on the statistical exploration of the error dynamic equations. The effect of frequency deviation and the number of DFT points are also included in the study. The analysis results are verified with the data obtained from the computer simulation by widely varying the values of error causing factors.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.4
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• pp.573-576
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• 2013

In this paper, analysis method for current collection performance based on real-time current of catenary system is proposed. An innovative method based on track-side of railway system is used for measurement of currents for overhead contact line during the collection with pantograph. The evaluation of a qualitative ratio for current collection performance were conducted using proposed algorithm under various conditions such as laboratory and track-side. To check the validity of our approach, we compared between calculation results from current of contact wire and measurement results from arcing of pantograph using simulator in laboratory conditions. The results show that the behavior of current collection performance were analysis from currents of overhead contact line in AC electric railway system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.10
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• pp.635-640
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• 2016

This paper dealt with the deterioration characteristics and an on-line diagnosis equipment for SPDs (surge protective devices). An accelerated aging test was carried out using a $8/20{\mu}s$ standard lightning impulse current to analyze the changes of electrical characteristics and to propose the diagnostic parameters and the criterion for deterioration of ZnO varistor which is the core component of SPDs. Based on the experimental results, an on-line diagnosis equipment for SPD was fabricated, which can measure the total leakage current, reference and clamping voltage. The leakage current measurement circuit was designed using a low-noise amplifier and a clamp type ZCT. A linear controller, the leakage current measurement part and a HVDC were used in the measurement of reference voltage. The measurement circuit of clamping voltage consisted of a surge generator and a coupling circuit. In a calibration process, measurement error of the prototype equipment was less than 3%.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.5
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• pp.204-212
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• 2002

In order to improve the reliability of high voltage rotating machines, it is necessary to understand the breakdown mechanism of stator windings. Especially partial discharge(PD) inception and growth are important in stator winding insulation. Recently, many research on the diagnosis of stator winding insulation for large rotating machines have been developed since the 1970s. Capacitive couplers have been the most widely used sensor for on-line partial discharge detection in rotating machines. This paper deals with the electrical on-line monitor characteristics of ceramic coupler(CC) which has been developed to continuously measure the PD activity in operating high voltage motor stator windings on site. We investigated the electrical characteristics(PD quantity, breakdown voltage and frequency response) to develop CC. This paper presents frequency characteristics and laboratory test result to compare conventional 80([F] epoxy-mica coupler(EMC) and 105[pF] CC for PD measurement with 6.6㎸ model stator windings.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2005.11a
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• pp.356-358
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• 2005

• Proceedings of the Optical Society of Korea Conference
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• 2007.02a
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• pp.317-318
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• 2007

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.4
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• pp.29-36
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• 2002

In this paper, a new edge detection method for area images is presented based on the scan-line image segmentation technology. The existing algorithms are lack of precision in its detections due to the noise factors such as depth perception and illumination problems when processing the 3D image into a 2D image. The general process of applying the scan-line method is to extract straight line components to determine the shape of the objects. However, we implement this method to an arc curve for precise detections. the paper proved precise detections that from off line to on line.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1347-1350
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• 2005

Recently, as the road capacity reaches a limit and environmental problems become serious, there exists a gradual increasing need for railway vehicles that are environment-friendly, punctual, reliable and safe. Accordingly, in addition to conventional railroad vehicles, lots of vehicles are being newly developed. Using the developed installed measurement system, the performance characteristics of railway vehicle could be monitored precisely. After recording the input real time data of each signal from railway vehicle to the network line, we could acquire the needed information through post processing program. We could verify the running performances of railway vehicle using this system. As a result, many latent defects have been found and corrected in the prototype train. The measurement systems have contributed to dramatic reduction of the developing period.

• Journal of Electrical Engineering and Technology
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• v.7 no.1
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• pp.103-108
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• 2012

The present study describes the considerations on the long-term reliability of the on-line partial discharge (PD) ceramic sensor for thermal power generators. Voltage acceleration aging tests were carried out under continuous and impulsive thermal aging at more than $100^{\circ}C$, considering the practical service environment. Experimental results show that the sensors have a life that could last for more than 100 years, excellent dielectric characteristics, and insulation strength. In addition, the ceramic on-line PD sensors were installed in a thermal power generator in Korea for demonstration. The results of the PD calibration and test voltage application prove that the on-line ceramic sensors have satisfactory performances for on-line PD measurement.