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Diagnosis of Medium Voltage Cables for Nuclear Power Plant
Che-Wung Ha,Do Hwan Lee 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.4
Most accidents of medium-voltage cables installed in nuclear power plants result from the initial defect of internal insulators or the initial failure due to poor construction. However, as the service years of plants increase, the possibility of cable accidents is also rapidly increases. This is primarily caused by electric, mechanical, thermal, and radiation stresses. Recently, much attention is paid to the study of cable diagnoses. To date, partial discharge and Tanδ measurements are known as reliable methods to diagnose the aging of medium-voltage cables. High frequency partial discharge measurement techniques have been widely used to diagnose cables in transmission and distribution systems. However, the on-line high frequency partial discharge technique has not been used in the nuclear power plants because of the plant shutdown risk, degraded measurement sensitivity, and application problems. In this paper, the partial discharge measurement with a portable device was tried to evaluate the integrity of the 4.16kV and 13.8kV cable lines. The test results show that the high detection sensitivity can be achieved by the high frequency partial discharge technique. The present technique is highly attractive to diagnose medium voltage cables in nuclear power plants.
Diagnosis of MV Power Cables for Nuclear Power Plants
Ha, Che-Wung,Jang, Kyung-Nam,Jeong, Sun-Chul 대한전기학회 2012 The Journal of International Council on Electrical Vol.2 No.3
The diagnosis of MV (Medium Voltage) cable used in NPPs (Nuclear Power Plants) has become one of the most urgent issues. In accordance with PSR (Periodic Safety Review) results, continuous condition monitoring of cables is also continuously required. In this paper, HFPD (High Frequency Partial Discharge) measurement and an infrared imaging thermography test were performed to check the status of 13.8 and 4.16 kV MV cables installed in the domestic power plant. The diagnosis was found to be good for the target cable. The on-line diagnostic technology to assess the condition of MV cables during the operation of a power plant will contribute to enhance the safety of NPPs. In the future, these latest technologies will be applied to perform condition monitoring of HV (High Voltage) cables in NPPs.
Diagnosis of Medium Voltage Cables for Nuclear Power Plant
Ha, Che-Wung,Lee, Do Hwan The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.4
Most accidents of medium-voltage cables installed in nuclear power plants result from the initial defect of internal insulators or the initial failure due to poor construction. However, as the service years of plants increase, the possibility of cable accidents is also rapidly increases. This is primarily caused by electric, mechanical, thermal, and radiation stresses. Recently, much attention is paid to the study of cable diagnoses. To date, partial discharge and Tan${\delta}$ measurements are known as reliable methods to diagnose the aging of medium-voltage cables. High frequency partial discharge measurement techniques have been widely used to diagnose cables in transmission and distribution systems. However, the on-line high frequency partial discharge technique has not been used in the nuclear power plants because of the plant shutdown risk, degraded measurement sensitivity, and application problems. In this paper, the partial discharge measurement with a portable device was tried to evaluate the integrity of the 4.16kV and 13.8kV cable lines. The test results show that the high detection sensitivity can be achieved by the high frequency partial discharge technique. The present technique is highly attractive to diagnose medium voltage cables in nuclear power plants.
하체웅(Che-Wung Ha),주광호(Kwang-Ho Ju),임우상(Woo-Sang Lim) 대한전기학회 2011 전기학회논문지 Vol.60 No.8
Electric cables are one of the most important components in a nuclear power plant since they provide the power needed to operate electrical equipment. Despite their importance, cables typically receive little attention since they are considered passive, long-lived components that have been very reliable over the years when subjected to the environmental conditions for which they were designed. The operating experience reveals that a defect of the insulator or poor construction causes the initial failure of cable. However, the number of cable failures increase with plant aging, and these cable failures are occurring within the plants’ 40-year licensed period. These cable failures have resulted in plant transients, shutdown, loss of safety functions or redundancy, entries into limiting conditions for operation, and challenges for plant operators. Therefore, diagnosis of MV cable installed in NPPs has become one of the most urgent issues in recent years. In accordance with PSR, condition maintenance for cables is also continuously required. Recently, HFPD tests have been widely performed to diagnose cable in the transmission and distribution cable system. However, on-line HFPD wasn’t used in the NPPs because of the danger of plant shutdown, measurement sensitivity and application problems, etc. In this paper, HFPD measurement with portable device was performed to evaluate the integrity of the 4.16㎸ & 13.8㎸ cable lines. The test results show that HFPD is highly attractive to the diagnosis of MV cables in NPP by high detection sensitivity on-site.
하체웅(Che-wung Ha),주광호(Kwang-ho Joo),한성흠(Sung-heum Han) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.7
국내 원자력발전소에 설치되어 있는 고압케이블은 장기운전에 따라 열화진단 및 유지보수의 필요성이 증대되고 있다. 주기적 안전성 평가(Periodic Safety Review) 및 계속운전과 관련하여서도 고압케이블의 관리방안이 지속적으로 요구되고 있다. 본 논문에서는 원자력발전소에 설치되어 있는 13.8㎸ 및 4.16㎸급 고압케이블의 건전성을 확인하기 위하여 국내 최초 원자력발전소 운전 중 부분방전 진단을 수행하였고 추가로 열화상 측정을 통한 케이블 열화진단을 수행 하였다. 원자력발전소를 정지하지 않고 진단하는 운전 중 경년열화 진단 기술은 발전소 내 고압케이블 뿐만 아니라 향후 초고압케이블의 진단에도 적용하여 케이블 경년열화 진단을 주기적으로 수행할 경우 원자력발전소의 안정적 운영에 기여할 것으로 사료된다.
하체웅(Che-Wung Ha),이도환(Do-Hwan Lee) 대한전기학회 2015 전기학회논문지 Vol.64 No.2
On January 30, 2012 an auxiliary component of Byron Unit 2 was tripped on bus under voltage. The cause of the event was the failure of the C-phase insulator track for the Unit 2 station auxiliary transformer(SAT) revenue metering transformer. In addition to this event, other events have occurred at other plants resulting in an open-phase condition.[1] Therefore, Nuclear Regulatory Commission(NRC) has requested that not only nuclear power plant(NPP) operating company but also its Design Certification(DC) applicant have to prepare open-phase detecting system in their operating plants and design document. In this paper, various open-phase conditions are simulated in NPP using Electromagnetic Transient Program(EMTP) and Atpdraw, and open-phase condition detecting system is proposed for Main Transformer(MT), Unit Auxiliary Transformer(UAT) and SAT connected power line in NPP.