• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1694-1696
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• 2001

Partial discharge(PD) tests are used to evaluate the insulation condition of stator windings in six 6.6kV motors. These tests were conducted using a conventional partial discharge detector (PDD), turbine generator analyzer(TGA) and partial discharge analyzer(PDA). Off-line PD measurements were performed on six 6.6kV motors. PD magnitudes ranged from 740 pC to 5,100 pC at the normal line-to-ground voltage. Six 6.6kV motors have been equipped with eighteen 80pF epoxy-mica couplers(one per phase) on the motor terminal boxs. The PD pulse from sensors were measured with the TGA and PDA instruments on a normally operating motors. The PDD, TGA and PDA test results showed that internal discharge was detected in voids of the groundwall insulation.

• 전기학회논문지
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• 제61권2호
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• pp.251-256
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• 2012

This study deals with the location of partial discharges(PDs) for power cables and GIS using 2 PD sensors and long coaxial signal cables. Throughout the experiments by use of simulated PD pulses and corona discharges in the power cable system, it is found out that the impedance matching between the coaxial signal cable and the measuring equipment should be done for good S/N ratio and the on-site measurement using more than 100m-long coaxial signal cable is possible. In addition, new PD location algorithm with the polarities of PD pulses and the arrival time difference between two pulses was proposed and was proved through the partial discharge experiments for the cable joint defect and artificial void defect.

• 한국전기전자재료학회논문지
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• 제11권12호
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• pp.1055-1059
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• 1998

The correlation between the propagation of electrical tree and distributions of partial discharge(PD) pulses accompanying with electrical tree of bush type in low density polyethylene were discussed. We measured the growth of electrical tree by using optical microscope and PD data simultaneously. The PD data detected and analyzed were PD magnitude, repetition rate, average discharge power, average phase angle, and $\psi$-q-n distribution pattern. The average discharge power and repetition rate of PD had good linear relation with area of tree. Repetition rate and peak discharge magnitude and width of discharge phase angle increased with the tree.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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• pp.27-27
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• 2010

The exact partial discharge pulse should be measured in order to estimate the discharge source in the solid insulation and diagnose the degree of deterioration. Partial discharges generated in the insulation occur in the internal voids or at the edge of the insulation, have unique characteristics following the type and location. When external voltage is applied, Partial discharges occurred in the restrictively presented voids increase the quantity of electrical charge at the discharge onset voltage. The discharge characteristics have remained constant as space is filled by the impurity such as a compound of gases accompanied with discharge. In this study, How to design the insulation about the problems of the built-in diagnostics in the transformer is discussed by the interpretation of electric field.

• 한국전기전자재료학회논문지
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• 제21권1호
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• pp.85-89
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• 2008

An objective of this paper is to develop a partial discharge (PD) measurement device for monitoring gas insulated switches installed in power distribution system. A capacitive voltage probe was studied and designed to detect PD pulse without an electrical connection. The PD measurement device consists of the capacitive voltage probe attached outside of a bushing, a coupling network which attenuates AC voltage by 270 dB, and a low noise amplifier with the gain of 40 dB in ranges of 500 kHz${\sim}$20 MHz. The sensitivity of the prototype device calculated by a calibrator was 1.98 m V /pc. An application experiment was carried out in a 25.8 kV gas insulated switch and the peak pulse of 76.7 pC was detected. From the experimental results, it is expected that the PD measurement device can be applied to online monitoring system of gas insulated switches.

• 전기학회논문지
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• 제58권1호
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• pp.126-131
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• 2009

This study was carried out for the reliability of PD(Partial Discharge) pattern recognition. For the pattern recognition, the database for PD was established by use of self-designed insulation defects which occur and were mostly critical in GIS(Gas Insulated Switchgear). The acquired database was analyzed to distinguish patterns by means of PRPD(Phase Resolved Partial Discharge) method and stored to the form with to unite the average amplitude of PD pulse and the number of PD pulse as the input data of neural network. In order to prove the performance of genetic algorithm combined with neural network, the neural networks with trial-and-error method and the neural network with genetic algorithm were trained by same training data and compared to the results of their pattern recognition rate. As a result, the recognition success rate of defects was 93.2% and the neural network train process by use of trial-and-error method was very time consuming. The recognition success rate of defects, on the other hand, was 100% by applying the genetic algorithm at neural network and it took a relatively short time to find the best solution of parameters for optimization. Especially, it could be possible that the scrupulous parameters were obtained by genetic algorithm.

• 한국전기전자재료학회논문지
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• 제25권3호
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• pp.229-235
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• 2012

This paper dealt with the fabrication of a partial discharge (PD) analyzer for insulation diagnosis of power facilities like transformers, cables and gas-insulated switchgears. An analytic algorithm for the phase (${\phi}$), the magnitude (q), and the pulse count (n) of PD pulse was designed and a time-frequency (TF) map algorithm was applied in the system to eliminate noises by analyzing the time and the frequency component of signals. All the algorithms were operated by a LabView graphical program. The detection circuit consists of a coupling capacitor, a detection impedance, and a low noise amplifier. A plane-plane and a point-plane electrode system were fabricated to simulate different types of insulation defects. In the experiment, we could easily understand the characteristics of PD pulses using the prototype PD analyzer.

• Journal of Electrical Engineering and Technology
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• 제8권4호
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• pp.832-839
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• 2013

This paper describes the simulation and experiment for partial discharge (PD) pulse propagation in 22.9kV CNCV power cables. To investigate the propagation characteristics of PD, experiments are carried out by injecting the PD pulse in 100m-long 60 $mm^2$ CNCV cable in the laboratory. The characteristics of PD are also simulated using EMTP to investigate and analyze PD in the same cable. By comparing the simulation and test results, parameter permittivity is recalculated by considering semiconducting screen in the process of simulation and analysis of PD. After it is proved that simulation results and test results are almost similar in the laboratory, extensive simulations are performed to analyse various PD characteristics such as propagation velocity, attenuation, etc. in 60 $mm^2$ and 325 $mm^2$ CNCV cables. Authors are confident that results obtained in this paper will be used as important technical materials to detect and investigate PD generated in transmission and distribution power cables.

• 조명전기설비학회논문지
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• 제13권3호
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• pp.73-81
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• 1999

본 연구는 초음파 측정법을 사용하여 부분방전에 의한 에폭시 몰드형 전력변압기의 열화상태을 진단하기 위해 에폭시수지의 트리진전에 초음파신호를 분석하였으며, 또한 열화시간에 따른 트리길이, 방전전하량 및 초음파 펄스수의 특성을 조사하였다. 실험 결과, 애폭시수지에 발생된 트리는 수지령이면, 인가전압 16[kV]에 대한 트리 길이 및 트리 폭의 평균성 장률은 각각 0.014 및 0.026[mm/min] 이였으며, 20[kV]의 경우 이들 값은 각각 0.032 및 0.063[mm/min]으로 더욱 증가된 것으로 나타났다. 열화중기 이후 트리가 성장함에 따라 초음파 펄스수 및 부분방전 전하량은 급격히 증가된 것으로 나타났다. 그리고 초음파 펄스수는 방전전하량에 비례하여 증가되었다. 또한 몰드형 전력변압기의 초음파 측정시 기본 데이터를 얻기 위해 초음파 발진 및 수신장치를 사용하여 에폭시수지에 대한 초음파신호의 감쇄, 시간지연 및 지향특성도 조사하였다.

• 한국전기전자재료학회논문지
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• 제21권5호
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• pp.481-485
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• 2008

In stator windings of 6.6 kV rotating machine, corona discharge, surface discharge and internal discharge are caused mainly by internal voids and insulation degradation. Also, if partial discharge occurs in inner-part of stator windings, it will be happened electromagnetic pulses at wide frequency range. In case of discharge spark, electromagnetic pulse generated from discharge source, and we can detect it by using various RF resonators as an EM sensor. In order to detect these kind of electromagnetic sources, we have designed and fabricated planar patch sensor using CST MWS simulation, and also PD signals from artificial defected cable were measured by our proposed sensor. Furthermore, HFCT was used as a reference sensor and compared with our proposed new planar patch sensor.