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기계적 분석을 통한 송전용 자기 애자의 열화 판단 및 파손 부위에 대한 연구
손주암,최인혁,구자빈,김태용,전성호,이윤정,이준신 한국전기전자재료학회 2020 전기전자재료학회논문지 Vol.33 No.1
Porcelain insulators have been used for a long time in 154 kV power transmission lines. They are likely to be exposed to sudden failure because of product deterioration. This study was conducted to evaluate the quality of porcelain insulators. After stresses were applied, the damaged regions of aged insulators were investigated in terms of chemical composition, material structure, and other properties. For porcelain insulators that were in service for a long time, the mechanical failure load was 126 kN, whereas the average mechanical failure load was 167.3 kN for new products. It was also determined that corrosion occurred at the metal pin part due to the penetration of moisture into the gap between the pin and the ceramic. Statistical analyses of failure were performed to identify the portion of theinsulators that were broken. Cristobalite porcelain insulators fabricated without alumina additives had a high failure rate of 54% for the porcelain component. In the case of the addition of Alumina (Al2O3) to the porcelain insulators to improve the strength of the ceramic component, a more frequent damage rate of the cap and pin of 73.3% and 27%, respectively, was observed. This study reports on the material component of SiO2 and the percentage of alumina added, with respect to the mechanical properties of porcelain insulators. 154kV 송전선로에 설치되어 있는 자기 애자는 장기간 사용으로 인한 성능 저하로 인해 고장 위험에 노출되어 있다. 본 논문은 자기 애자의 건전성 판단을 위해 수행되었다. 스트레스 누적으로 인해 열화가 진행된 자기 애자는 성분, 재료 구조 및 기타 특성 측면으로 분석되었다. 신품 시료의 기계적 하중 파손값은 167.3 kN 로 나타난 반면 장기간 사용된 자기애자의 기계적 하중 파손 값은 126 kN으로 나타났다. 또한, 열화가 진행된 자기 애자는 장기간 사용으로 인해 핀과 시멘트 사이 틈으로 수분이 침투되어 애자가 부식되는 것을 알 수 있었다. 해당시험을 통해 파손 된 자기 애자의 파손부위에 대한 분석을 실시한 결과, Alumina 성분의 자기 애자는 Cap부위의 파손이 73.3%로 나타났으며, Pin부위의 파손은 27%로 나타났다. 반대로, Alumina(A2l O3 ) 성분이 소량 첨가되어 제작된 Cristobalite 성분의 자기애자는 자기부 파손이 54%로 측정되었고, SiO2 성분 및 Alumina 첨가 비율이 자기 애자의 기계적 특성 결정에 큰 비중을 차지하는 것을 확인할 수 있었다.
송전용 자기 애자의 절연 내력 및 시멘트 열화에 대한 연구
손주암(Ju-Am Son),최인혁(In-Hyuk Choi),구자빈(Ja-Bin Koo),김태용(Taeyong Kim),이준신(Junsin Yi) 대한전기학회 2020 전기학회논문지 Vol.69 No.2
Porcelain insulators for transmission play an important role in isolating and supporting power lines and transmission towers. There is a lack of research on porcelain insulators for transmission compared to other power installations. Therefore, in this paper, the measurement and analysis of insulation strength and cement corrosion of porcelain insulators for power transmission were carried out. Domestic pollution level calculation is determined by the equivalent salt deposit density (ESDD). In this paper, insulation strength measurement and cement corrosion analysis were performed by extracting 36,000lbs porcelain insulators from 427.3m, 469.9m and 571m away from the coast. As a result, the average insulation strength of porcelain insulators, 427.3m away from the coast, was measured as 29,400MΩ. The insulation strength of porcelain insulators 571m away from the coast was measured at 2,500MΩ. The measurement results show a 11.8-fold decrease in the insulation strength in porcelain insulators that are relatively far from the coast and closer to the mountainous region than the insulation strength of porcelain insulators near the coast. As a result of cement corrosion measurement of the sample, hydrogen ion concentration(pH) was measured to estimate degradation. Cement corrosion of porcelain insulators that are extracted from the research was measured at pH 13 of porcelain insulators, 427.3m from the coast. The pH of porcelain insulators at 469.9m away was measured at 11, and the pH of porcelain insulators 571m away from the coast and close to the mountainous area was measured at 7. Stress accumulation of cement with humidity is considered to be more important factors for reducing the insulation strength of porcelain insulators to determine cement corrosion than salt in coastal areas.
최인혁,손주암,오태근,윤영근 한국전기전자재료학회 2019 전기전자재료학회논문지 Vol.32 No.2
Porcelain insulators have been used mainly for power line fixing and electrical insulation in transmissiontowers. Porcelain insulators have generally a 30 years desired life, but over 50% exceed their life expectancy. Since thedamage to porcelain insulators is usually accompanied by enormous loss of human resource material, their efficientmaintenance has emerged as an important issue. In this regard, this study applied a frequency response function (FRF)for integrity assessment of the insulator. The characteristics of the FRF according to damage types were identified andanalyzed by the change in natural frequencies, curve shape, attenuation, and Nyquist diagram stability. The resultsshowed significant differences in the FRF according to damage types, which can be used as basic data for the effectiveintegrity assessment of porcelain insulators. 자기애자는 송전탑의 전력선 고정 및 전기적 절연을 위해 사용된다. 자기애자는 사용수명이 30년으로 제작되었지만, 현재 제작수명을 넘어선 애자는 전체의 50%를 상회한다. 자기애자의 손상으로 발생되는 손실은 막대한 인적, 물적 피해를 동반하기 때문에 자기애자의 건전성을 평가하는 방법이 중요한 쟁점으로 떠오르고 있다. 이에 따라 비파괴 검사기법 중 FRF를 활용하여 자기애자의 건전성을 평가하기 위한 방법으로 적용하였다. 본 연구에서는 자기애자의 고유모드 주파수, 곡선 형상, 감쇠 및 나이퀴스트 선도 안정성 분석을 통해 손상유형에 따른 특성을 분석하였다. 본 연구결과를 통해 자기애자의 건전성 평가를 위한 기초자료로 쓰일 수 있기를 기대한다.
자기애자 캡의 금구-시멘트 계면 건전성 평가를 위한초음파법 활용에 대한 연구
윤영근,최인혁,손주암,오태근 한국안전학회 2018 한국안전학회지 Vol.33 No.6
The life span of the porcelain insulator was made to be 30 years, but currently many of the 154kV NGK porcelain insulators using in Korea are found to have passed the production life. Accidents caused by aged mechanical breakdown can lead to disruption of power supply in some areas, large economic losses, and casualties. Therefore, ultrasonic method, which is one of the non - destructive test methods, is applied as a method for evaluating the integrity of porcelain insulators. In this study, the experiment on the interface of cap was conducted and the difference between the energy difference and the attenuation coefficient of the reflected wave was derived according to the interface state of the steel – cement. The results of this study are expected to be used as the basic data of the ultrasonic testing to evaluate the interface condition of the porcelain insulator cap.
자기애자의 유지 관리를 위한 CNN 기법을 이용한 이미지 분석
최인혁,신구용,구자빈,손주암,임대연,오태근,윤영근,Choi, In-Hyuk,Shin, Koo-Yong,Koo, Ja-Bin,Son, Ju-Am,Lim, Dae-Yeon,Oh, Tae-Keun,Yoon, Young-Geun 한국전기전자재료학회 2020 전기전자재료학회논문지 Vol.33 No.3
This study examines the feasibility of the image deep learning method using convolution neural networks (CNNs) to maintain a porcelain insulator. Data augmentation is performed to prevent over-fitting, and the classification performance is evaluated by training the age, material, region, and pollution level of the insulator using image data in which the background and labelling are removed. Based on the results, it was difficult to predict the age, but it was possible to classify 76% of the materials, 60% of the pollution level, and more than 90% of the regions. From the results of this study, we identified the potential and limitations of the CNN classification for the four groups currently classified. However, it was possible to detect discoloration of the porcelain insulator resulting from physical, chemical, and climatic factors. Based on this, it will be possible to estimate the corrosion of the cap and discoloration of the porcelain caused by environmental deterioration, abnormal voltage, and lightning.