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Study on Reliability of Water Absorption Diagnosis through Precise Water Absorption Test
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 Title & Authors
Study on Reliability of Water Absorption Diagnosis through Precise Water Absorption Test
Kim, Hee-Soo; Bae, Yong-Chae; Kim, Hee-Dong;
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 Abstract
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.
 Keywords
Generator;Stator windings;Insulation breakdown;Precise water absorption test;
 Language
English
 Cited by
 References
1.
Technical Information Letter-1098, GE Power Generation, 1993.

2.
Kim, H. D., Lee, Y. J. and Ju, Y. H., "Characteristics of Insulation Aging in Large Generator Stator Windings", Trans. KIEE, Vol. 58, No. 7, pp. 1375-1379, 2009.

3.
Worden, A. Joseph, Mundulas, M. Jorge, "Understanding, Diagnosing, and Repairing Leaks in Water-Cooled Generator Stator Windings", GE Power Systems GER-3751A, 2001.

4.
H. S. Kim, Y. C. Bae, W. R. Lee, D. Y. Lee and H. D. Kim, "Analysis of Leak and Water Absorption Test Results for Water - Cooled Generator stator Windings", J. of Electrical Engineering & Technology, Vol. 7, No. 2, pp. 230-235, 2012. crossref(new window)

5.
Kim, H. S., Bae, Y. C. and Kee, C. D., "Wet Bar Detection by Using Water Absorption Detector", J. of Mechanical Science and Technology, Vol.22, pp. 1163-1173, 2008. crossref(new window)

6.
Kim, H. S., Bae, Y. C. and Kee, C. D., "A Study on the Water Absorption Diagnosis Method through Capacitance Measurement for Generator Stator Windings", J. of KSPE, Vol. 23, No. 11, pp. 50-57, 2006.

7.
Kim, H. S., Bae, Y. C., Lee, W. R., and Lee, D. Y., "A Study on the Capacitance Change Analysis by Using Water Absorption Detector(II)", Proceedings of the KSPE 2009 Autumn Annual Meeting, pp. 479-480, 2009.