• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.406-410
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• 1995

A superconducting cable is one of the promising methods of undground transmission of high electric power in the future. It is very important that composite insulation system of $LN_2$ and polymer films takes into consideration for application high $T_c$ superconductor. This study is about both the partial discharge and properties V-t in $LN_2$. As result, applied voltage doesn't depend on the radius of non-eroded area but eroded area. And eroded area is observed the formation such as the ring of a tree.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.2
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• pp.252-255
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• 2008

A study for discharge pattern analysis partial and fault location by use of UHF sensors in GIS. However, in the latter case, the results considered the velocity of EM waves modified by the waveguide characteristics of GIS bus bar were not reported yet. In this paper, UHF wide band sensor to detect partial discharge signals have been designed and manufactured to get the widest band characteristic by an application of Fat-Dipole UHF antenna and the result that the transmission velocity of EM waves is 2/3 of the light have been got through the consideration of waveguide characteristics. Also, to verify applicability on site of the developed method, self-designed external type UHF sensor have been installed on operating GIS in Korea Midland Power co. and detected location of the fault. Through the fault have been found at the location, the reliability of the developed method have been proved.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1999.11a
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• pp.285-289
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• 1999

Insulation diagnosis techniques of power equipments for the stable power supply and prevention from accidents are of high importance. Diagnosis techniques is able to prevent from large accidents before they happen by finding signs of the accidents. From this point of view, this paper simulated discharge progress and partial discharge using needle-plan electrode system in air, studied the distribution of frequency spectrum of the radiated electromagnetic waves using biconical antenna and spectrum analyzer. From results of this study, the new method was introduced for measurement and analyzation of the radiated electromagnetic waves in accordance with discharge progress in air, Besides, according to the consideration of the mutual relation between frequency spectrum of the radiated electromagnetic waves and discharge progress, it was confirmed that detecting partial discharge and estimating discharge progress were possible.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.601-604
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• 2001

The insulation materials of cables used for underground power transmission requires a higher insulating capability. and the most popular method to examine the cable is partial discharge test due to applying variation voltage. In the thesis. air void. silicone oil. of which may possibly exist real cables. are simulated by Electra 2D program. Also the relations between calculated field strength and the void defect type in the cable joint materails. In the modeling. electic field inner to the cable joint material composed by XLPE and EPDM is modeling simulated. We obtained the electric field distribution in void due to two conditions.

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

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2305-2307
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• 1999

Partial discharge measurement using a ultrasonic technique allows us to detect degradation of the electrical insulation in a power transformer. However, The ultrasonic measurement studies don't offer a good solution in operating conditions. In this paper, we investigated characteristics of ultrasonic noise caused by a 345kV power transformer under operating conditions. The ultrasonic noises generated by corona in air, vibration of core, pump and fan, etc. An ultrasonic frequency caused by corona in air was appeared 9 and 18[MHz] at the outside wall of the transformer. And a spectra of core vibration was detected below 2.5[kHz]. These spectrum were compared with 20 $\sim$ 200[kHz] of the internal partial discharge in the model transformer.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2335-2337
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• 1999

In this paper, using AE (Acoustic Emission) sensor the electrical and emitted-sound signals are measured by treeing breakdown in the epoxy resin, and the corresponding frequency spectrum of the AE signals are analyzed. We also examined the relationship between partial discharge magnitude and pulse number of AE signals to diagnose the deterioration of the electrical insulation due to treeing breakdown. From these results, a frequency band of AE signals through treeing breakdown was set to about 230 [kHz], and it appeared that pulse number of AE signal was proportional to partial discharge magnitude.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.5 no.4
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• pp.347-352
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• 2005

PD(Partial discharges) are small electrical sparks that occur within the electric insulation of cables, transformers and windings on motors. PD analysis is a proactive diagnostic approach that uses PD measurements to evaluate the integrity of this equipment. Recently, several diagnostic algorithms for classifying the type of PD and locating the defect position have been developed. In this work, a new PD recognition system is proposed, which utilizes approximate coefficients of wavelet transform as a feature vector, furthermore, introduces bank of Elman networks to recognize the various PD phenomena. In order to verify the performance of the proposed scheme, it is applied to the simulated PD data.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.712-717
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• 2005

In this thesis, it is investigated that the effect of the cross linked polyethylene(XLPE) insulator do to breakdown phenomenon by the insertion of the needle and bar electrode into XLPE which is used of electric power cable for the ultra-high voltage. The result of the partial discharge properties in the specimen showed that in case of the insertion of needle or bar electrode into XLPE, the effect of the inner discharge become large when the air void is bigger then the clearance of the electrode of the specimen. The closer the distance between the insulator and needle electrode, it takes less time to the insulation breakdown.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.1995-1999
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• 2009

A partial discharge(PD) measurement is a very effective method to assess the insulation condition of high-voltage machines. It is necessary that the life time of the on-line PD measurement sensor is assessed. Therefore, the electrical life time assessment method of ceramic element was reviewed in order to estimate the life time of the on-line PD measurement sensor. The samples were prepared according to the reviewed method and were tested at 8kV, 9kV and 10kV. Based on the obtained results, the life time constant is shown above 59. Also, it is assumed that the estimated life time constant can be used to anticipate the life time and to assess the conformity of the on-line PD measurement sensor.