Publisher : The Korean Institute of Electrical Engineers
DOI : 10.5370/JEET.2014.9.1.280
Title & Authors
Characteristics of Insulation Diagnosis and Failure in Gas Turbine Generator Stator Windings Kim, Hee-Dong;
In order to evaluate the insulation deterioration in the stator windings of five gas turbine generators(137 MVA, 13.8 kV) which has been operated for more than 13 years, diagnostic test and AC dielectric breakdown test were performed at phases A, B and C. These tests included measurements of AC current, dissipation factor, partial discharge (PD) magnitude and capacitance. and in all three phases (A, B and C) of No. 1 generator stator windings showed that they were in good condition but PD magnitude indicated marginally serviceable and bad level to the insulation condition. Overall analysis of the results suggested that the generator stator windings were indicated serious insulation deterioration and patterns of the PD in all three phases were analyzed to be internal, slot and spark discharges. After the diagnostic test, an AC overvoltage test was performed by gradually increasing the voltage applied to the generator stator windings until electrical insulation failure occurred, in order to determine the breakdown voltage. The breakdown voltage at phases A, B and C of No. 1 generator stator windings failed at 28.0 kV, 17.9 kV, and 21.3 kV, respectively. The breakdown voltage was lower than that expected for good-quality windings (28.6 kV) in a 13.8kV class generator. In the AC dielectric breakdown and diagnostic tests, there was a strong correlation between the breakdown voltage and the voltage at which charging current increases abruptly (, ).
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Hee-Dong Kim, "Analysis of Insulation Aging Mechanism in Generator Stator Windings", Journal of the KIEEME, Vol. 15, No. 2, pp. 119 -126, 2002.
Hee-Dong Kim, "Assessment of Insulation Condition in Operating Large Turbine Generator", Trans. KIEE, Vol. 53C, No. 6, pp. 324-329, 2004.
Hee-Dong Kim, Tae-Sik Kong, Young-Ho Ju and Byong-Han Kim, "Analysis of Insulation Quality in Large Generator Stator Windings", Journal of Electrical Engineering & Technology, Vol. 6, No. 2, pp. 384-390, 2011.
Y. Ikeda and H. Fukagawa, "A Method for Diagnosing the Insulation Deterioration in Mica-Resin Insulated Stator Windings of Generator", Yokosuka Research Laboratory Rep. No. W88046, 1988.
B.K. Gupta and I.M. Culbert, "Assessment of Insulation Condition in Rotating Machine Stators", IEEE Trans. on Energy Conversion, Vol. 7, No.3, pp. 500-508, 1992.
G.C. Stone, "Recent Important Changes in IEEE Motor and Generator Winding Insulation Diagnostic Testing Standards", IEEE Trans. on Industry Applications, Vol. 41, No. 1, pp. 91-100, 2005.
H. Yoshida and U. Umemoto, "Insulation Diagnosis for Rotating Machine Insulation", IEEE Trans. on Electrical Insulation, Vol. EI-21, No. 6, pp. 1021-1025, 1986.
C. Hudon and M. Belec, "Partial Discharge Signal Interpretation for Generator Diagnostics", IEEE Trans. on Dielectrics and Electrical Insulation, Vol. 12, No. 2, pp. 297-319, 2005.
H.G. Sedding, R. Schwabe, D. Levin, J. Stein and B.K. Gupta, "The Role of AC & DC Hipot Testing in Stator Winding Aging", IEEE EIC/EMCW Conference, pp. 455-457, 2003.
J.E. Timperley, and J.R. Michalec, "Estimating the Remaining Service Life of Asphalt-Mica Stator Insulation", IEEE Trans. on Electrical Conversion, Vol. 9, No. 4, pp. 686-694, 1994.
J.H. Dymond, N. Stranges, K. Younsi and J. E. Hayward, "Stator Winding Failures: Contamination, Surface Discharge, Tracking", IEEE Trans. on Industry Applications, Vol. 38, No. 2, pp. 577-583, 2002.
R. Morin and R. Bartnikas, "A Three-Phase Multi-Stress Accelerated Electrical Aging Test Facility for Stator Bars", IEEE Trans. on Energy Conversion, Vol. 15, No.2, pp. 149-156, 2000.