• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.560-561
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• 2005

For the insulation design of a HTS cable, the withstand voltage of three kinds were proposed. One of them is the AC design withstand voltage, another is the impulse design withstand voltage, and the other is the partial discharge inception stress. However, the multi-layered effect was not considered on insulation design of a HTS cable at existent design process. Therefore in this paper, the electrical breakdown characteristics by multi-layered effect of LPP insulation paper were investigated. Based on these results, the insulation thickness of 22.9 kV class HTS cable was designed, and compared with existent design process.

• 조명전기설비학회논문지
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• 제16권1호
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• pp.27-34
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• 2002

본 연구에서는 불평등 전계인 침대침 갭을 수평배치하였을 때, 고전압 전극 부근에 설치한 화염에 의한 교류 및 직류 섬락전압 특성을 조사하였다. 화염에 의해 섬락이 발생할 때, 코로나 개시전압과 섬락극성을 조사하기 위해 전압 및 전류파형을 측정하였으며, 인가전압의 상승에 따른 코로나풍과 쿨롱력에 의한 화염의 형상이 왜곡되고 요동되는 현상을 관찰하였다. 실험 결과, 화염이 전극의 중간위치에 있을 때 화염에 의한 교류 섬락전압은 화염이 없는 경우에 비해 평균 62.7[%] 저하된 것으로 나타났으며, 화염의 높이에 따른 섬락전압의 특성에서 화염의 높이 h=5, h=7 및 h=9[cm]인 경우 교류 섬락전압의 평균값은 화염이 없을 때에 비해 각각 34.2[%], 27.3[%] 및 21.4[%] 저하된 것으로 나타났다.

• Transactions on Electrical and Electronic Materials
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• 제16권6호
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• pp.323-327
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• 2015

In this paper, parameters related with partial discharge (PD) were analyzed in SF₆ gas under AC and DC voltages. Three electrode systems (protrusion on conductor, protrusion on enclosure, and free particle) were fabricated to simulate PD defects in a gas-insulated switchgear (GIS). All electrode systems were filled with SF₆ gas at 0.5 MPa. PD pulses were detected using an oscilloscope and a data acquisition (DAQ) based on IEC 60270. To analyze the PD characteristics under AC and DC voltages, parameters such as discharge inception voltage (DIV), discharge extinction voltage (DEV), pulse magnitude, repetition rate, and T-F map were compared. From the experimental results, PD was revealed to have different characteristics under AC and DC, and these results may be useful for diagnosis of power facilities operated under HVDC.

• 한국초전도ㆍ저온공학회논문지
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• 제5권3호
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• pp.48-51
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• 2003

HTS power transmission cable is expected to transport large electric power with a compact size. We are developing a 3-core, 22.9 kV, 50 MVA class HTS power cable, and each core consists of a conductor and shield wound with Bi-2223 tapes, electrical insulation with laminated polypropylene paper (LPP) impregnated with liquid nitrogen. This paper describes the design and experimental results of the model cable for the 22.9 kV, 50 MVA class HTS power transmission cable. The model cable was used the SUS tapes instead of HTS tapes because of testing the electrical characteristics only. The model cable was 1.3 m long and electrical insulation thickness was 4.5 mm. The model cable was evaluated the partial discharge (PD), AC and Impulse withstand voltage in liquid nitrogen. The AC and Impulse withstands voltage and PD inception stress was satisfied with the standard of Korea Electric Power Corporation (KEPCO) in the test results. The 3-core 22.9 kV, 50 MVA class HTS power cable has been designed and manufactured based on these experimental results.

• Journal of Electrical Engineering and Technology
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• 제10권5호
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• pp.2089-2098
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• 2015

With the continuous development in insulation of electrical equipment design, the reliability of the system has been enhanced. However, in the manufacturing process and during operation under continues stresses introduce local defects, such as voids between interfaces that can responsible to occurrence of partial discharge (PD), electric field distortion and accumulation of charges. These defects may lead to localize corrosion and material degradation of insulation system, and a serious threat to the equipment. A model of three layers of PI film with air gap is presented to understand the influence of interface and voids on exploitation conditions such as strong electrical field, PD activity and charge movement. The analytical analysis, and experimental results are good agreement and show that the lose contact between interfaces accumulate more residual charges and in consequences increase the electric field intensity and accelerates internal discharges. These residual charges are trapped charges, injected by the electrodes has often same polarity, so the electric field in cavities increases significantly and thus partial discharge inception voltage (PDIV) decreases. Contrary, number of PD discharge quantity increases due to interface. Interfacial polarization effect has opposite impact on electric field and PDIV as compare to void.

• 한국안전학회지
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• 제21권1호
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• pp.53-58
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• 2006

This paper has been addressed on the discharge characteristics of the ignition coil by Weibull function. It analyzed discharge number and amount of discharge using Weibull distribution to know the inter-relationship between partial discharge and mileage. We detected the discharge which happens for 10 seconds. The applied voltage increased by 0.5[kV] at discharge inception voltage. We diagnosed failure rate using the shape parameters. As a result, we confirmed that the failure rate was increased, because the shape parameter showed the value of 5 according to increasing mileage degradation. Also, it is considered to increase the degradation of inner insulator of ignition coil. Because failure rate of virgin was increased from 0[%] to 25[%] after degradation, stability analysis of the ignition coil using Weibull analysis is possible.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.519-520
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• 2006

Research was performed to increase the efficiency of a plasma reactor for $H_2$ yield. In the preceding studies $H_2$ was increased by adding Ni as a transitional metal catalyst and $TiO_2$ as a photocatalyst. In these experiments, it was found that distilled water, discharge frequency, and electrode configuration had a significant impact on $H_2$ generation. A substantial amount of hydrogen yield was observed at 2 kHz of discharge frequency and 12 kV of applied voltage. Within this favorable discharge conditions, the weight rate of $TiO_2$ and Ni powders was investigated. Plasma phenomenon was measured by electrical, optical and acoustical devices. It was found that emitted light, electric current and acoustical signals acquired from the discharge demonstrated systematical correlation. Changing the electrode's configuration allowed discharge distribution along the perimeter of the electrode's tip, which increased the density of streamers and plasma energy loadings, as the value of inception voltage for the discharge propagation decreased.

• 한국전기전자재료학회논문지
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• 제29권7호
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• pp.429-434
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• 2016

This paper deals with the characteristics of partial discharge (PD) for the purpose of a condition based maintenance (CBM) of gas insulated switchgears (GIS) in power equipment. Four types of electrode systems such as a protrusion on enclosure (POE), a particle on spacer (POS), a free particle (FP) and a Floating were designed and fabricated. PD pulses were measured using UHF sensor with a frequency range of 300 MHz~1.4 GHz and a DAQ with a sampling rate of 250 MS/s. Discharge inception voltage (DIV), discharge extinction voltage (DEV), and phase resolved partial discharge (PRPD) were analyzed depending on electrode systems. The average DIV in the POS was 28.8 kV. It was about 1.7 times higher than that in the FP, which was the lowest value of 17.2 kV. The FP shuffled and jumped at the applied voltage of 23.5 kV. Over 95% of PD pulses in the POE were generated in the negative polarity ($181^{\circ}{\sim}360^{\circ}$) of applied voltage. The results showed the phase (${\Phi}$)-magnitude (dBm) of PD pulses by UHF sensor, a cluster was formed separately depending on electrode systems.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 방전 플라즈마 유기절연재료 초전도 자성체연구회
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• pp.25-29
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• 2004

Corona on polymer materials causes deterioration by the combined action of the discharge striking the surface and the action of certain chemical compounds that are formed by the discharges. In the design and manufacture of polymer insulators must be sufficiently large to avoid corona discharges, otherwise a shielding or corona ring (grading ring) needs to be installed on the insulator. To conduct this purpose, many researchers have investigated end-fitting of polymer insulator by voltage distribution simulation and electrical test. Grading rings are used to improve the performance of the insulator in multiple ways. They can reduce corona and associated audible noise and radio influence and television interference. The factors determining the uses of a grading ring are line voltage, geometry and dimensions of end fittings, geometry and dimensions of line hardware, and environmental conditions. In this paper, electrical property of polymer insulator with end-fitting design have been investigated by electrical field analysis, various end-fitting design, tracking wheel test, corona inception voltage and extinction voltage. Electrical field analysis is conducted by FEM program and various end-fitting is designed through this result. Designed end-fittings are manufactured and their performance is conducted by electrical performance test.

• Transactions on Electrical and Electronic Materials
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• 제11권1호
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• pp.42-47
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• 2010

Polymer insulating materials such as cross linked polyethylene (XLPE) are employed in electric cables used for extra high voltage. These materials can degrade due to chemical, mechanical and electric stress, possibly caused by voids, the presence of extrinsic materials and protrusions. Therefore, this study measured discharge patterns, discharge phase angle, quantity and occurrence frequency as well as changes in XLPE under different temperatures and applied voltages. To quantitatively analyze the irregular partial discharge patterns measured, the discharge patterns were examined using a statistical program. A three layer sample was fabricated, wherein the upper and lower layers were composed of non-void XLPE, while the middle layer was composed of an air void and copper particles. After heating to room temperature and $50^{\circ}C$ and $80^{\circ}C$ in silicone oil, partial discharge characteristics were studied by increasing the voltage from the inception voltage to the breakdown voltage. Partial discharge statistical analysis showed that when the K-means clustering was carried out at 9 kV to determine the void discharge characteristics, the amount discharged at low temperatures was small but when the temperature was increased to $80^{\circ}C$, the discharge amount increased to be 5.7 times more than that at room temperature because electric charge injection became easier. An analysis of the kurtosis and the skewness confirmed that positive and negative polarity had counterclockwise and clockwise clustering distribution, respectively. When 5 kV was applied to copper particles, the K-means was conducted as the temperature changed from $50^{\circ}C$ to $80^{\circ}C$. The amount of charge at a positive polarity increased 20.3% and the amount of charge at a negative polarity increased 54.9%. The clustering distribution of a positive polarity and negative polarity showed a straight line in the kurtosis and skewness analyses.