• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2089-2092
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• 1999

Partial discharge(PD) tests were performed both when the pumped storage generator(rated 13.8kV and 220MVA) was on-line and off-line. This generator has been equipped with 12 bus coupler sensors in directional mode. PD tests were conducted using partial discharge analyzer(PDA), partial discharge meter(PDM) and digital partial discharge detector. PDA showed that the patterns of the normalized quantity number(NQN) and the partial discharge magnitude are in accord with on-line and off-line. The insulation condition was estimated by diagnostic tests(off-line) such as PD magnitude and dissipation factor.

• 전기학회논문지P
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• 제58권4호
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• pp.469-475
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• 2009

Accident dangerousness of domestic hydro power generators which are operated in Korea is on the increase because of use at the long term. On this, the Off-line diagnosis techniques developed to the On-line by continued domestic technical development since 2000. Especially, On-line insulation diagnosis of domestic hydro power generator is possible by localization of partial electric discharge sensor and On-line insulation diagnosis system. This paper shows the diagnosis result that is applied localized Ceramic Coupler and PDMS-HG(Partial Discharge Monitoring System for Hydro Generator) at four Chung-ju hydro Generator used for 25 years. Particularly, the confidence of insulation diagnosis is improved by using high frequency filter and sampling the partial discharge signals which occur in site. For reviewing the confidence of On-Line insulation diagnosis system, we measured the outside noises and partial discharge signals during practical operation by using the partial discharge diagnosis system of the Full A/D process. And we reviewed the confidence of the On-Line insulation diagnosis system by comparing and analyzing these data.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1846-1849
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• 2000

Off-line and on-line partial discharges were measured on a 828MVA, 22kV and direct hydrogen-cooled large turbine generator. Partial discharge tests were conducted using digital partial discharge detector(PDD) and turbine generator analyzer(TGA). PDD and TGA showed that off-line partial discharge pattern seems to be very, similar to that found with on-line. Most of the partial discharge is originating with the stator slot in the three phases. As the partial discharge activity is very low, the stator insulation condition of this generator is very good.

• 대한전기학회논문지
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• 제45권2호
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• pp.294-300
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• 1996

In hydro-generator, a groundwall insulation of stator windings gradually deteriorates due to mechanical, thermal, electrical and environmental stresses. These stresses combine to result in loose windings, delamination of the stator insulation and/or electrical tracking of the endwinding, all of which can lead to stator insulation failures. Conventionally, off-line tests such as partial discharge measurement, DC/AC current and .DELTA.tan.delta. tests has been used for estimation of winding condition. However, off-line test requires large power supply and generator outage. In addition, major cause of insulation problems such as loose wedges and slot dischages may not be found with off-line diagnoses. This paper introduces the on-line partial discharge measurement techniques using frequency spectrum analyzer(FSA) for the generator stator windings. The experimental results from the UIAM #1 hydro-generator confirms a optimistic application of on-line generator diagnosis method as a reliable tool for evaluation of winding condition.

• 한국전자통신학회논문지
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• 제19권2호
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• pp.355-360
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• 2024

본 논문에서는 4-코일 방식의 자기공진 무선전력전송 시스템을 구현하는 데 있어서, 송전 공진코일의 끝단에서 발생하는 선간 방전현상을 연구하였다. 자기공진 무선전력전송은 급전코일, 송전 공진코일, 수전 공진코일, 부하코일로 구성되어 있다. 여기서 송전 공진코일은 급전코일에서 발생한 자기장을 증폭하여 전방의 수전 공진코일로 전달하는 역할을 한다. 큰 전력을 전송하기 위하여 급전코일에 높은 전류를 흘려주면 송전 공진코일 끝단에 높은 전압이 유기되어 선간 방전현상이 일어나게 된다. 선간 방전현상은 송전기 케이스를 손상시키게 되고, 송전기를 사용할 수 없는 상태로 만든다. 따라서 이러한 선간 방전현상을 제거하기 위하여, 선간 방전을 일으키는 송전 공진코일에 유기되는 전압을 분석하고, 해결 방안을 제시하였다.

• 한국전기전자재료학회논문지
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• 제28권1호
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• pp.34-39
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• 2015

In this study, the characteristics of partial discharge was measured for the four core silicone cable (0.6/1.0 kV, $1.0SQ{\times}4C$) with insulated part of 15 cm and conductor of 1cm. The following results have been confirmed as a result of this study. When the first line of cable is connected to the positive electrode and the second, third line of cable is connected to the negative electrode, it found that the inception voltage and extinction voltage decreased with increasing the line of negative electrode, and the partial discharge charge quantity(Q) increases, while the number of discharge occurrence has decreased. The inception voltage and extinction voltage of partial discharge has decreased with increasing the degradation rate in the 33%, 67%, 100%. Also, it confirmed that the partial discharge charge quantity(Q) and the number of discharge occurrence has decreased.

• 한국정보통신학회논문지
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• 제8권2호
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• pp.413-419
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• 2004

본 논문은 전기설비로부터 방전신호 검출을 통한 전기화재 예측 기법에 관하여 기술하였다. 방전현상으로부터 전기화재 예측에 필요한 전기적 정보를 얻기 위하여 절연지를 통한 연면 방전, 선간 단락 등 다양한 방전현상을 실험적으로 모의하였다. 실험결과로부터 전기화재 발생시 전원주파수와는 다른 특징적인 주파수 신호가 대부분 차지하는 것을 알 수 있었다. 최종적으로 실험결과에 근거한 방전신호 검출장치를 설계ㆍ제작하였으며, 전원선에서 방전신호를 모니터링하는 것으로 전기화재의 예측이 가능함을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.1015-1018
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• 1999

Partial discharge patterns were analyzed in the pumped storage generator stator winding. These were measured using partial discharge analyzer(PDA) and digital partial discharge detector(PDD). Slot discharge was discovered in phase A. Discharges at conductor surface were occurred in phase B and in Phase C. Partial discharge patterns from on-line PDA system were compared with those off-line PDD system. The results of two systems are very same in phase A, B and C.

• KIEE International Transactions on Electrophysics and Applications
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• 제2C권6호
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• pp.297-303
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• 2002

We have developed an on-line ultrasonic detector to monitor partial discharge in an operating transformer. The ultrasonic sensor has 150[KHz] resonance frequency and contains a pre-amplifier with 60[㏈] gain. The on-line ultrasonic detector has 50~300[KHz] frequency band-pass filter to remove electrical and mechanical noises from the transformer. This detector has an ultrasonic signal discrimination algorithm which discriminates ultrasonic signals due to partial discharge in a transformer. A moving average method of ultrasonic signal number was employed to effectively monitor the increasing trend of the partial discharge. This paper describes an experience of partial discharge detection in a 154[㎸] operating transformer using an ultrasonic detector. With regards to gas analysis in oil, C2H2 gas was produced with a warning level in this transformer We detected ultrasonic signals on the transformer steel wall, and estimated the position of partial discharge. With further inspection, we found carbonized marks due to partial discharge on the supporting bolt which fastens the windings.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권4호
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• pp.189-198
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• 2006

In order to improve the reliability of stator windings for hydro generators, it is necessary to detect the defective point and life assessment of the high voltage windings. Especially the on-line partial discharge (PD) test provides the ability to monitor effects, such as slot discharge, internal discharge, and end-winding discharge without interrupting generators, this method has been proven the major testing technology in high voltage rotating machines nowadays. The purpose of this paper is to describe the method of the on-line PD measurement on stator windings for hydro-generator with 13 [kV] class ceramic coupler (CC), on-line PD measuring system, terminal box, and index parameters. Also, the developed PD measuring system and 13 [kV] class CC were installed Daechung-dam generator #2. It was found that this installed sensor and system had good electrical characteristics to detect PD activity during the operating condition with its detection frequency band is between several and several tens MHz.