• Title, Summary, Keyword: On-line ceramic sensor

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Considerations on the Long-term Reliability of On-line Partial Discharge Ceramic Sensor for Thermal Power Generators and its Demonstration in the Field

  • Sun, Jong-Ho;Youn, Young-Woo;Hwang, Don-Ha;Kang, Dong-Sik
    • Journal of Electrical Engineering and Technology
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    • v.7 no.1
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    • pp.103-108
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    • 2012
  • The present study describes the considerations on the long-term reliability of the on-line partial discharge (PD) ceramic sensor for thermal power generators. Voltage acceleration aging tests were carried out under continuous and impulsive thermal aging at more than $100^{\circ}C$, considering the practical service environment. Experimental results show that the sensors have a life that could last for more than 100 years, excellent dielectric characteristics, and insulation strength. In addition, the ceramic on-line PD sensors were installed in a thermal power generator in Korea for demonstration. The results of the PD calibration and test voltage application prove that the on-line ceramic sensors have satisfactory performances for on-line PD measurement.

Electrical Life Time Constant Estimation of Ceramic Element for Sensor (센서용 세라믹 소체의 전기적 수명지수 산출)

  • Jeong, Joo-Young;Kang, Dong-Sik;Sun, Jong-Ho;Heo, Jong-Cheol;Choo, Young-Bae;Park, Chung-Hoo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.10
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    • pp.1995-1999
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    • 2009
  • A partial discharge(PD) measurement is a very effective method to assess the insulation condition of high-voltage machines. It is necessary that the life time of the on-line PD measurement sensor is assessed. Therefore, the electrical life time assessment method of ceramic element was reviewed in order to estimate the life time of the on-line PD measurement sensor. The samples were prepared according to the reviewed method and were tested at 8kV, 9kV and 10kV. Based on the obtained results, the life time constant is shown above 59. Also, it is assumed that the estimated life time constant can be used to anticipate the life time and to assess the conformity of the on-line PD measurement sensor.

Evaluation of Reliability on the 6.6kV Class Ceramic Coupler for On-line Partial Discharge Measurement in Winding Machines (권선형기기 On-line 부분방전 측정용 6-6kV급 Ceramic Coupler의 신뢰성 평가)

  • Kang Dong-Sik;Kim Yong-Joo;Yun Youn-Ho
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.54 no.2
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    • pp.69-75
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    • 2005
  • In order to improve the reliability of high voltage rotating machines and mold transformers, it is necessary to understand the breakdown mechanism and life assessment of the high voltage winding parts. Especially the on-line PD test provides the ability to monitor effects, such as slot discharge, internal discharge, and end-winding discharge without interrupting the electrical machines, this method has been proven the major testing technology. Capacitive couplers have been the most widely used sensors for the on-line partial discharge detection in rotating machines nowadays. This paper deals with the electrical characteristics and long-term reliability of a ceramic coupler(CC), which can be easily mounted into high voltage input terminal part, has been developed and tested to continuously measure PD activity during operating condition. This paper presents electrical characteristics (dielectric loss angle, capacitance, PD inception level, breakdown voltage, and frequency response bandwidth) and long-term life test result of the developed 6.6 kV class on-line ceramic coupling sensor. It was found that this sensor had good electrical characteristics to detect PD activity during the operating condition with its detection frequency band is between several and several tens MHz. Also, the voltage life of the 6.6kV class ceramic coupler was calculated over 60 years.

Analysis and lest of On-line and off-line PD Testing for High Voltage Rotating Machines Stator Windings using Ceramic Coupler (세라믹 커플러를 이용한 고전압회전기 고정자권선의 On-line 및 off-line 부분방전 특성 시험 및 분석)

  • Oh, Bong-Keun;Kim, Hyun-Il;Kang, Seong-Hwa;Lim, Kee-Joe
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.20 no.10
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    • pp.895-900
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    • 2007
  • Partial discharge(PD) test can be performed either when the rotating machine is not operating(off-line) or during normal machine operation(on-line). This paper presents an on-line and off-line PD test on a large hydro-generator and induction motor using the same PD acquisition system(PDAS) and ceramic coupler(CC) sensor. PD signal characteristics of CC sensor proved similar with that of epoxy mica coupler(EMC) sensor as a results of PD test for simulated defect winding and frequency response test. A comparison of on-line and off-line PD test for PD characteristic parameters-phase resolved PD(PRPD), maximum PD value(Qmax) and PD occurrence energy(POE)-indicated that on-line PD test could reliably and effectively diagnose insulation conditions which were verified by off-line PD test.

Development of the On-line Partial Discharge Measuring Sensor and System on Stator Windings for Hydro Generator (수력발전기 고정자권선용 운전중 부분방전 측정 센서 및 시스템 개발)

  • Kang, D.S.;Sun, J.H;Hwang, D.H.;Yun, Y.H.;Seo, I.S.;Shin, B.C.;Klm, H.I.;Lee, K.H.
    • Proceedings of the KIEE Conference
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    • pp.103-106
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    • 2005
  • A lot of R&D on the diagnosis of stator winding insolation for large rotating machines has been carried out since the 1970s. The on-line partial discharge measurement has proved to be an effective technique in the evaluation of the state of stator insulation in high voltage rotating machines. The purpose of this paper is to describe the method of the on-line partial discharge measurement on stator windings for hydro- generator with ceramic sensor and measuring system. We developed ceramic coupling sensor, partial discharge measuring system, terminal box and index parameters.

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Analysis of Off-Line and On-Line Partial Discharge in High Voltage Motor Stator Windings

  • Kim, Hee-Dong;Kong, Tae-Sik;Lee, Sang-Kil;Kim, Beom-Soo;Kim, Doo-Young
    • Journal of Electrical Engineering and Technology
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    • v.10 no.3
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    • pp.1086-1092
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    • 2015
  • The off-line and on-line partial discharge (PD) in the stator winding of three high-voltage (HV) motors (1,400 HP, 6.6 kV) is measured and analyzed in this paper. The off-line PD is measured at high values between 24,300 ~ 36,100 pC after 18 years of motor operation. Spare replacement motors were not available for testing the degree of deterioration of the stator windings in standstill status. Therefore, on-line periodic analysis was conducted to monitor the trend of PD after installing a ceramic sensor (110 pF, 6.6 kV) in the terminal box for each phase of each motor. In the stator winding of the No.1 and No.2 HV motors, which showed high magnitudes of off-line PD and low magnitudes of on-line PD, defects are expected to appear in the neutral end of the winding. On the contrary, in the stator windings of the No.3 HV motor, which exhibits high off-line and on-line PD magnitude, defects are expected to appear in the terminal end of the winding where a voltage close to the phase voltage is applied.

Development of Ceramic Humidity Sensor for the Korean Next Generation Reactor

  • Lee, Na-Young;Hwang, Il-Soon;Song, Chang-Rock;Yoo, Han-Ill;Park, Sang-Duk;Yang, Jun-Seong
    • Nuclear Engineering and Technology
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    • v.30 no.5
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    • pp.435-443
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    • 1998
  • Leak-before-break(LBB) approach has been shown to be both cost effective and risk reductive when applied to high energy Piping in nuclear Power Plants. For the Korean Next Generation Reactor (KNGR) development, LBB application is considered for the Main Steam Line(MSL) piping inside containment. Unlike the primary system leakages, the MSL leak detection systems must be based on principles other than radioactivity measurements. Among humidity, heat and acoustic noise currently being considered as indicators of leakage, we explored humidity as an effective one and developed ceramic-based humidity sensor which can be qualified for LBB applications. The ceramic material, sintered and annealed MgCr$_2$O$_4$-TiO$_2$, is shown to increase its electrical conductivity drastically upon water vapor adsorption over the entire temperature range of interest. With this ceramic sensor specimen, we suggested installation-inside-the-piping method by which we can detect leakage more rapidly and sensitively. In this paper, we describe the progress in the development and characterization of ceramic humidity sensor for the LBB application to the MSL of KNGR.

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Reliability Evaluation of the Partial Discharge Measuring Sensor for Hydro Generator (대용량 수차발전기 부분방전 검출용 센서의 신뢰성 평가)

  • Byun, Doo-Gyoon;Hong, Jin-Woong
    • Journal of the Korean Society of Safety
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    • v.21 no.5
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    • pp.40-45
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    • 2006
  • In the operation of large capacity hydro generators, it's a very important thing that to minimize several kind of electrical trouble and accident. In order to overcome these problems, the on-line and off-line partial discharge (PD) measuring method has become an important one. Nowadays, epoxy mica coupler(EMC) has been the most widely used sensors for on-line PD detection in rotating machines. This time, we have made a ceramic coupling sensor using $SrTiO_{3}$, because at present, most of sensors has high cost and difficult procedure to making. This paper deals with the electrical characteristics of a ceramic coupling sensor, which has been made to continuously measure PD activity during the operation condition for 13kV class hydro generator. And we have performed the evaluation of sensor life and reliability based on the characteristic testing. The experimental results confirm that the sensor has satisfied at electrical required performance and output characteristic for simulated input signal.

Development of an On-Line Insulation Diagnosis System when operating a High-Voltage Motor Using a Ceramic Coupler (세라믹 커플러를 이용한 고압 전동기 운전 중 절연 진단 시스템 개발)

  • Se, Il-Soo;Shin, Byoung-Chol;Lee, Sang-Min;Oh, Bong-Keun;Kim, Hyeon-Il
    • Proceedings of the KIEE Conference
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    • pp.1440-1442
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    • 2007
  • A high-voltage motor has had many problems due to its frequent startup, standstills and occasions of long period operation. As for a solution to the problem, many advanced countries have developed an on-line insulation diagnosis sensor and a same type of system and put them in use. Recently, even in the domestic market, a ceramic coupler has been developed and attempted to be applied in the field. This paper proposes an on-line insulation diagnosis system when operating a high-voltage motor along with the use of a domestic ceramic coupler. The proposed system is composed with a ceramic sensor, a PDMS-HM, and a Remote Monitoring System. As the result of comparing this system with a PDAS, which is an expensive full A/D method, the reliability of the system has been verified, and furthermore, it is in the process of being commercialized.

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A Study on the characteristics of degradation sensor for insulation oil (절연유(絶緣油) 열화(劣化)센서 특성(特性) 연구(硏究))

  • Chon, Y.K.;Sun, J.H.;Kang, D.S.;Joo, B.S.;Yoon, J.Y.;Chung, S.J.
    • Proceedings of the KIEE Conference
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    • pp.1371-1374
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    • 1995
  • It is well known that the degradation of transformer oil conseqently lead to the failure of transformer. This paper discussed the characteristics of the degradation sensor checking transformer oil condition in live line. The degadation sensor is composed of base ring, electrodes and porous ceramic, passed through the transformer oil and checks the transformer oil condition through sensor's leakage current. So it is important to minimize the leakage current of base ring and connection parts. To investigate the leakage current of base ring and connection parts the characteristics of V-T-I and DC 2 KV and other examinations were performed. It is verified that ionized transformer oil caused by the expansion of temperature increases in the leakage current of porous ceramic sensor. It is certification that the leakage current of other parts of porous ceramic is very small(about 2%) compared with the porous ceramic body and it is confirmed that the leakage current in porous ceramic is changed sensitively according to the new oil(NO) and and the degradation oil(DO).

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