• Title, Summary, Keyword: Water-cooled generator

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Electrical Properties of Wet Bars in Water-cooled Generator Stator Windings (흡습된 수냉각 발전기 고정자 권선의 전기적 특성)

  • Kim, Byeong-Rae;Kim, Hee-Dong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.10
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    • pp.817-823
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    • 2012
  • Insulation breakdown of water-cooled generator stator windings occurs frequently due to leakage of cooling water and absorption into the insulation material. Leakage and absorption problems of water-cooled stator windings are often found during regular preventive maintenance. To evaluate cooling water leakage and absorption, diagnostic tests were performed on two water-cooled turbine generators, which have been in service for 13 and 17 years, respectively. The test results of the measured electrical properties such as dissipation factor($tan{\delta}$), capacitance and AC leakage current for water-cooled generator stator windings with wet bars are reported in this paper.

A Study on the Systematic Mechanical Integrity Evaluation Methods of Water-Cooled Generator Stator Windings (수냉각 발전기 고정자의 기계적 건전성 평가방법)

  • Bae, Yong-Chae;Kim, Hee-Soo;Lee, Wook-Ryun;Lee, Doo-Young;Choi, Hong-Il;Yeon, Se-Heum
    • Proceedings of the KSME Conference
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    • pp.3059-3066
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    • 2008
  • It is reported that the life of generator stator windings is expected about 30 years and a leak and water absorption phenomena can be progressed by fatigue, vibration, and corrosion. The water-cooled generator stator windings which were operated over 15 years are over 20 units and the mechanical problems such as leak and water absorption were found in the generator stator windings. In this paper, the systematic mechanical integrity evaluation methods which are applied to the water-cooled generator stator windings within the country are introduced.

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Investigation on Performance Analysis of Sodium-Water Reaction Pressure Relief System of Prototype Generation-IV Sodium-Cooled Fast Reactor (소듐냉각고속로 원형로 소듐-물 반응 압력완화계통 성능 해석 연구)

  • Park, Sun Hee;Han, Ji-Woong
    • Korean Chemical Engineering Research
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    • v.57 no.1
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    • pp.28-41
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    • 2019
  • We carried out performance analysis of Sodium-Water Reaction Pressure Relief System of Prototype Generation-IV Sodium-Cooled Fast Reactor. We analyzed transient-dynamic behavior of fluids inside the steam generator to vent into a sodium dump tank or a water dump tank when tubes in the steam generator were broken to cause a large-water-leak accident. Accordingly, we preliminarily evaluated design requirements of our system. Our results showed that sodium in the shell side of the steam generator and in Intermediate Heat Transport System was completely vented within 50 s and feed water in the tube side of the steam generator was completely vented within 2.5 s. It was analyzed that pressure of the tube side of the steam generator was higher than pressure of the shell side of the steam generator, which showed that sodium in the shell side did not flow into the tube side. Our results are expected to be used as basis information to performance analysis of Sodium-Water Reaction Pressure Relief System of Prototype Generation-IV Sodium-Cooled Fast Reactor.

An Experimental Study of Water Absorption Characteristics for Generator Stator Winding Insulation (발전기 고정자 권선 절연재 흡습 특성에 관한 실험적 연구)

  • Bae, Y.C.;Lee, D.S.;Kim, H.S.;Kim, Y.H.;Lee, H.
    • Proceedings of the KSME Conference
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    • pp.426-431
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    • 2004
  • Leaking water coolant into stator electrical insulation is a growing concern for the aging water-cooled generator since leaks in the generator water-cooled stator winding can affect machine availability and insulation life. But a domestic techniques of such field are insufficient and depend wholly on GE or TOSHIBA technique. Therefore this paper introduces measuring principle and developed measuring system, which has been used to detecting wet absorption. We accomplished the experiment with a stator promotion of virtue which is used in actual power plant. Also, Experimental method of generator stator winding, which is investigated into wet absorption test.

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Study on Reliability of Water Absorption Diagnosis through Precise Water Absorption Test

  • Kim, Hee-Soo;Bae, Yong-Chae;Kim, Hee-Dong
    • Journal of Electrical Engineering and Technology
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    • v.7 no.5
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    • pp.772-777
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    • 2012
  • Accidents caused by water absorption in water-cooled generator stator windings often occur all over the world. The absorption into the insulator of the coolant, which is used to cool down the heat generated by stator windings during operation, leads to the deterioration of dielectric strength, and insulation breakdown. An insulation breakdown may cause not only an enormous economic loss but also a very serious grid accident that would compromise stable supply of electric power. More than 50 % of domestic generators have been in operation for more than 15 years, and water absorption tests performed on 50 water-cooled generator stator windings during a five-year planned preventive maintenance period beginning in 2006 identified water absorption problems in 10 of them, all of which required repair. Because the existing water absorption test detects this problem by utilizing stochastic methods after measuring the capacitances at the final positions of insulation breakdown, its accuracy is limited. This study demonstrates that water absorption can be more accurately diagnosed by utilizing method along with a more precise one.

Analysis of Leak and Water Absorption Test Results for Water-Cooled Generator Stator Windings

  • Kim, Hee-Soo;Bae, Yong-Chae;Lee, Wook-Ryun;Lee, Doo-Young;Kim, Hee-Dong
    • Journal of Electrical Engineering and Technology
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    • v.7 no.2
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    • pp.230-235
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    • 2012
  • Cases of insulation breakdown damage of water-cooled generator stator windings occur frequently due to coolant leakage and water absorption worldwide. Such serious accidents may cause not only enormous economic loss but also very serious grid accidents in terms of stable supply of electric power. More than 50 % of domestic generators have been operated for more than 15 years, and leak and water absorption problem of windings are often found during the planned preventive maintenance period. Since 2005, leak and water absorption tests have been performed for total watercooled stator windings after fully drying the inside of the windings. The results are then comprehensively analyzed. The result of the test performed by GE, a foreign manufacturer, for 141 generators showed failures in 80 of them (failure rate: 57 %), whereas in the tests carried out in Korean domestic power plants, only 14 out of 50 generators showed failures (failure rate: 28 %).

Investigation on Design Requirements of Vent Lines for Sodium-Water Reaction Pressure Relief System of Prototype Generation-IV Sodium-Cooled Fast Reactor (소듐냉각고속로 원형로 소듐-물 반응 압력완화계통의 배출배관 설계요건 연구)

  • Park, Sun Hee;Han, Ji-Woong
    • Korean Chemical Engineering Research
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    • v.56 no.3
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    • pp.388-403
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    • 2018
  • We investigated design requirements of vent lines for Sodium-Water Reaction Pressure Relief System of Prototype Generation-IV Sodium-Cooled Fast Reactor. We developed design requirements of areas of the rupture disks of the steam generator, a diameter of the gas vent line of the sodium dump tank, a diameter of the gas vent line of the water dump tank, a diameter of the water dump line of the steam generator. With the design requirements, we calculated the time to vent fluid inside the steam generator and analyzed the transient pressure behavior, also evaluated the close pressure value of the isolation valve of the water dump line. Our results are expected to be used as basis information to design Sodium-Water Reaction Pressure Relief System of Prototype Generation IV Sodium-Cooled Fast Reactor.

Signal processing method based on energy ratio for detecting leakage of SG using EVFM

  • Xu, Wei;Xu, Ke-Jun;Yan, Xiao-Xue;Yu, Xin-Long;Wu, Jian-Ping;Xiong, Wei
    • Nuclear Engineering and Technology
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    • v.52 no.8
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    • pp.1677-1688
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    • 2020
  • In the sodium-cooled fast reactor, the steam generator is a heat exchange device between sodium and water, which may cause leakage, resulting in a sodium-water reaction accident, which in turn affects the safe operation of the entire nuclear reactor. To this end, the electromagnetic vortex flowmeter is used to detect leakage of the steam generator and its signal processing method is studied in this paper. The hydraulic experiment was carried out by using water instead of liquid sodium, and the sensor output signal of the electromagnetic vortex flowmeter under different gas injection volumes was collected. The bubble noise signal is reflected by the base line of the sensor output signal. According to the relationship between the proportion of the bubble noise signal in the sensor output signal and the gas injection volume, a signal processing method based on the energy ratio calculation is proposed to detect whether the water contains bubbles. The gas injection experiment of liquid sodium was conducted to verify the effectiveness of the signal processing method in the detection of bubbles in sodium, and the minimum detectable leak rate of water in the steam generator was detected to be 0.2 g/s.

An Experimental Study on Water Absorbtion Characteristics of Generator Stator Bar Insulation by Cooling Water Temperature in 500MW Capacity Power Plant (500MW급 화력 발전기 냉각수 온도에 따른 고정자 권선 절연재의 흡습 특성에 관한 실험적 연구)

  • Bae, Yong-Chae;Kim, Hee-Soo;Lee, Doo-Young;Lee, Wook-Ryun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.8
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    • pp.1392-1397
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    • 2008
  • The mechanical integrity of generator stator windings is one of the critical point because the electric power is generated and conducted to power system through these windings. De-mineralized water is used to cool stator bars during the normal operation of generator in large power plants because the water cooled method has highest cooling efficient. Water absorption of bar insulation is progressed by several causes such as generation of water leak path by corrosion, delamination of insulation by vibration, and inadequate water treatment, etc.. Reliable water absorption diagnostics of generator stator bar is important to ensure the availability of power plant and to reduce maintenance cost by generator accident. It is described that the water absorption characteristics for generator stator bar insulation used in 500MW capacity standard fossil power plant by cooling water temperature. It is verified that the management of stator cooling water temperature is one of the important factors to decrease water absorption rate of generator stator bars.