• Proceedings of the KIEE Conference
• /
• 2005.07e
• /
• pp.103-105
• /
• 2005

The test were performed to analyze the cause of endwinding breakdown of hydro-generator which had been in service after being constructed 1971. we conducted insulation diagnostic tests and checked visual inspection and operating condition of protective relays. On the basis of these test results, this paper tried to present the importance of service environment for the generator stator winding.

• Transactions on Electrical and Electronic Materials
• /
• v.7 no.5
• /
• pp.230-234
• /
• 2006

One of the methods currently being investigated as a possible non-intrusive diagnostic tool for condition monitoring of power transformer and cable is the recovery voltage measurement, which will be improving the ability to detect the content of water concentration and the ageing process in the insulation system and may thus be an indicator of insulation quality and its ageing status. The polarization phenomenon was studied using RVM with oil-paper samples. In order to interpret its mechanism, the Extended Debye model was introduced. With different circuit parameters, various simulation results were gotten. Furthermore, with the test samples of different ageing condition, measurements are accomplished in the lab. On the basis of this experiment as well as theoretical analysis, correlations between polarizations and ageing were analyzed.

• Proceedings of the KIEE Conference
• /
• 2008.05a
• /
• pp.183-184
• /
• 2008

The aim of this study is to find out the effects of thermal aging condition on dielectric strength and degree of crtstallinity of XLPE insulation. Thermal properties of XLPE insulation were investigated by DSC(differential scanning calorimetry) and dielectric strength were analyzed using AC BDV tester. Aging of XLPE samples were conducted through different four conditions. The degree of crtstallinity and AC BDV were changed by thermal history. From these results, it can be suggested that DSC and AC BDV test are suitable for diagnostic method of extra high voltage XLPE cable.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.2008-2009
• /
• 2007

The paper considers the relation between on-line monitoring and diagnostics on the one hand and high-voltage (HV) withstand and partial discharge (PD) on-site testing on the other. HV testing supplies the basic data (fingerprints) for diagnostics. In case of warnings by on-line diagnostic systems, off-line withstand and PD testing delivers the best possible information about defects and enables the classification of the risk. Because alternating voltage (AC) is the most important test voltage, the AC generation on site is considered. Frequency tuned resonant (ACRF) test systems are best adapted to on-site conditions. They can be simply combined with PD measuring equipment. The available ACRF test systems and their application to electric power equipment -from cable systems to power transformers - is introduced.

• Proceedings of the KIEE Conference
• /
• 1998.11c
• /
• pp.941-943
• /
• 1998

Exploitation of equipment with cross linked polyethylene (XLPE) insulation requires its condition monitoring and diagnostic. Traditionally diagnostics of insulation is carried out by means of partial discharge detection. Many researchers have developed a lot of methods to identify the defect by the PD form. However, such identification of a defect, for example, void, inclusion or treeing, does not say about its danger from a point of view of full insulation gap breakdown and insulation construction failure. The information about the form and size of formed upon high voltage treeing is necessary for prediction of the remained resource of XLPE insulation. For this purpose we carry out experimental research for determination of the dependencies between PD characteristics in XLPE upon time and three dimension PD patterns of corresponding treeing. The investigations were carried out by means of electrical measurement of PD current and simultaneous optical recording of treeing image. Test results show that the PD patterns can be applied for detecting tree growth well.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.109-109
• /
• 2010

On-line partial discharge(PD) diagnostic system is the most prominent systems to diagnose insulation condition for the high voltage rotating machines. Partial discharge measuring system(PDMS) series with ceramic coupler(PD detecting sensor) installed hydro generator and high voltage motor have been measured the PD data for many years. The trend of PD magnitude in the on-line PD system increased for some machines. These machines showed a same result in the conventional off-line PD test and PD magnitude decreased after stator winding insulation cleaning. This case study show that PDMS has been proved to be good results by comparing PD magnitude with on-line and off-line PD test and it is important to plan the maintenance project for the hydro generator stator winding because PD value was decreased after insulation cleaning.

• Transactions on Electrical and Electronic Materials
• /
• v.7 no.2
• /
• pp.90-95
• /
• 2006

An on-line diagnostic test has been studied and performed for the pumped storage generator/motor. This study aims at reducing the diagnostic cost, minimizing the technical dependency on third party manufactures. Further design of on-line diagnostic system such as shorted-turn of rotor winding, partial discharge (PD) of stator winding and air-gap between stator and rotor for pumped storage generator/motor has been verified. In addition, it needs to be validated on site performance of the developed continuous on-line monitoring system for corresponding tasks for the improvement of the availability & reliability during operation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.17 no.2
• /
• pp.66-72
• /
• 2003

The global assessment system for medium voltage power cable systems has been developed The minimum purpose of diagnostic activity is the economic discrimination and maintenance of bad cables which is likely to cause cable system failure. I have adapted the Aging Time Constant Method to construct the power cable assessment system for the diagnostic purpose. From the field application test and breakdown test results, it could be concluded that the diagnostic system was successful art convenient for the discrimination and maintenance of the bad cables, which is likely to fail sooner or later, economically.

• Proceedings of the KIEE Conference
• /
• 2008.04b
• /
• pp.214-216
• /
• 2008

회전기 고정자권선 절연물은 전기적, 기계적, 열적, 환경적 열화요인이 단독 또는 복합적으로 작용하여 열화된다. 본 논문에서는 실제 산업현장에서 운영중인 고전압 전동기의 운영환경을 조사하여 건조환경에서 운영중인 전동기와 다습환경에서 운영중인 전동기에 대하여 절연진단시험을 실시하고 각 시험에서 도출된 절연진단인자를 비교하여 환경적 열화요인이 우세한 운영환경에 따른 절연물의 특성변화를 분석하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.28 no.1
• /
• pp.46-50
• /
• 2015

The cable degradation process is largely divided into three steps; Step 1 : Thermal degradation, Step 2 : Weibull degradation, Step 3 : Partial discharge. it is progress in step order. This article aims to explain the process of cable degradation using the method of insulation resistance and accordingly to compose and manufacture a system of measuring the life of electrical cable. Before measuring the insulation resistance, a system of measuring the temperature and current of cables was made, and the established system was installed for test on the site of a power plant to collect the measured data. The current sensor was used TFC30P80A-CL420, and temperature sensor was used the DK-1270 PT100 sensor as RTD sensor. When measured the temperature and the load current at the same position, was confirmed that in case of the load current value was high, also temperature value high. Therefore, the correlation between load currents and temperature was verified, and the analysis of diagnostic data was evaluated, which could be utilized in identifying the fault condition of cable systems.