• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1939-1941
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• 2000

Nondestructive and destructuve insulation tests were performed the high voltage rotating machine in the local thermal power plants. Nondestructive tests include measurements of insulation resistance. polarization index, AC current. tan$\delta$, partial discharge. Destructive tests include measurements of AC hipot and DC hipot. This paper propose to establish the insulation diagnosis cycle for high voltage rotating machine.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.12a
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• pp.158-161
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• 2002

Many methods were proposed for insulation degradation diagnosis to High voltage and capacity Transformer in live. IDD is difficult by those methods because insulation degradation circumstances and characteristics of electrical plant are different with other Therefore, it is necessary to design diagnosis algorithms fitting for each. In this paper, We develop IIDS that used diagnosis algorithm with fuzzy model and hardware with MCU.

• Proceedings of the KIEE Conference
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• 2006.05a
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• pp.71-73
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• 2006

Our company(KOWACO) has periodically performed off-line diagnostic test for 14 hydro generators (rated 11 kV over) for 15 years. In this paper, we summarized results of dissipation factor tip-up test and partial discharge test about these generators. Among these, we chose two generators and performed insulation reinforcement (cleaning and varnish Painting). We compared change of insulation condition for the stator winding based upon off-line diagnostic test result before and after repair. Test result shows that insulation condition was improved after insulation reinforcement. This insulation reinforcement has a function to reduce cause of deterioration, so we can know that it extends lifetime of generator and it is a very important factor for stable operation of facilities.

• Proceedings of the KIEE Conference
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• 2006.07e
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• pp.51-52
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• 2006

Our company(KOWACO) has periodically performed off-line diagnostic test for 14 hydro generators (rated 11 kV over) for 15 years. In this paper, we summarized results of dissipation factor tip-up test and partial discharge test about these generators. Among these, we chose two generators and performed insulation reinforcement (cleaning and varnish painting). We compared change of insulation condition for the stator winding based upon off-line diagnostic test result before and after repair. Test result shows that insulation condition was improved after insulation reinforcement. This insulation reinforcement has a function to reduce cause of deterioration, so we can know that it extends lifetime of generator and it is a very important factor for stable operation of facilities.

• Progress in Superconductivity and Cryogenics
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• v.8 no.1
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• pp.29-33
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• 2006

A 154 kV class high temperature superconducting (HTS) power cable system is developing in Korea. For insulation design or this cable, the grading method of insulating paper is proposed. The use of graded insulation gives improved bending properties of the cable. Therefore, we discussed the electrical stress distribution and calculation for grading insulation design of a HTS cable. Also. the basic insulation design of 154 kV class HTS power cable was done.

• Progress in Superconductivity and Cryogenics
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• v.3 no.1
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• pp.29-34
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• 2001

A Bi-2223 tape has been developed for low-field Power applications such as Power cables or transformers working at liquid nitrogen temperature For such applications it is required to understand fault current characteristics of the Bi-2223 tape. In this paper we report fault current characteristics using two types of samples, straight sample and pancake coil sample. It was found that the fault current characteristics of the Bi-2223 tape are independent of external fields and frequencies . However they depend on electrical insulations and fault durations strong1y Also it was shown that the fault current characteristics in the insulated straight sample are similar to those in the pancake sample with a conductor insulation. Finally. it was shown that the Pancake sample with a layer insulation has better characteristics than that with a conductor insulation fur fault currents.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.2
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• pp.20-25
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• 2016

This paper describes the effectiveness of continuous water removal in oil immersed transformers. Insulation oil in which insulation papers were immersed were prepared for tests and water concentrations in oil with heating time were measured at five oil temperatures. Also, the tests that water dissolved in $100^{\circ}C$ oil was removed at once and continuously at $50^{\circ}C$ and $100^{\circ}C$ were performed for consideration of effective method for water removal. Test results indicated that the oils for water measurement have to be extracted at similar temperatures and water in oil has to be continuously removed at higher temperatures for more effective water management of transformers.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.11
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• pp.2011-2014
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• 2008

We measured the permittivity and electromagnetic wave propagation velocity of used insulation oil with wide frequency range including ultra-high frequency by time domain reflectometry. The permittivity or propagation velocity is essential for locating discharge faults of oil filled power transformer. We derived 2.21 as a permittivity and $2.03{\times}10^8 m/s$ as a velocity from the measurement of pulse travelling time along a coaxial line filled with used insulation oil or air. The permittivity measurement system we designed shows high measurement accuracy and the convenience for field use.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2002.11a
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• pp.335-338
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• 2002

In this paper the experiments of insulation characteristics by temperature change of SF6 gas and insulation characteristics about liquid SF6 in GIS(Gas Insulated Switchgear) were described. From this result, at low temperature, the breakdown voltage was increased with a drop of temperature and an increase of the inner pressure in GIS. The ability of insulation in liquid SF6 was higher than that of the highly pressurized SF6 gas.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.976-979
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• 1992

There are lots of problem which are delaminations and partial discharge of insulation materials in high-voltage rotating machines caused by mechanical, electrical and thermal aging. Several experiments have been aiming at finding the useful diagnostic parameters from the partial discharge characteristics by applying a new measurement techniques. This paper deals with the partial discharge characteristics (pulse height, pulse angle, pulse frequency spectrum and time interval), which may be a useful diagnostic concept in predicting insulation condition of mica/epoxy composite insulation materials, by using several measurement equipments (frequency spectrum analyzer. multichannel analyzer and time interval analyzer).