Quality Evaluation of Stator Coils and Bars under Thermal Cycling Stress

Zhu, Lu; Morton, C.P.; Cherukupalli, S.

doi:10.1109/elinsl.2006.1665338

Cited by 12 publications

(7 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, after stator bar #1 deteriorated significantly as a result of accelerated aging, its capacitance showed a large change compared to that of stator bar #2. This result is consistent with the conclusion of other study [7]. Therefore, the change in capacitance increases with accelerated aging and the value of the capacitance usually increases at a lower voltage.…”

Section: Capacitance Analysissupporting

confidence: 82%

“…Considerable increase in the dissipation factor and decrease in the capacitance indicated a significant increase in the amount of voids within the groundwall insulation. The increase in average effective airgap due to the voids should decrease the capacitance between the copper strands and the groundwall insulation [7]. Before the two stator bars were placed under the accelerated aging procedure, the capacitance measurements of stator bars #1 and #2 were 8.73 and 8.12 nF, respectively.…”

Section: Capacitance Analysismentioning

confidence: 99%

“…Therefore, as mentioned in the accelerated aging test results on the generator stator bars, the P i1 of AC current, the point at which the dissipation factor increases, and the DIV tend to be high when the insulation condition is fair. However, these voltages decrease with an increase in accelerated aging time in generator stator bars [7]- [9]. …”

Section: Analysis Of Pd Magnitudementioning

confidence: 99%

See 2 more Smart Citations

Analysis of Insulation Quality in Large Generator Stator Windings

Kim¹,

Kong²,

Ju³

et al. 2011

Journal of Electrical Engineering and Technology

View full text Add to dashboard Cite

-To evaluate the condition of stator winding insulation in generators that have been operated for a long period of time, diagnostic tests were performed on the stator bars of a 500 MW, 22 kV generator under accelerated thermal and electrical aging procedures. The tests included measurements of AC current (∆I), dissipation factor (tanδ), partial discharge (PD) magnitude, and capacitance (C). In addition, the AC current test was performed on the stator winding of a 350 MW, 24 kV generator under operation to confirm insulation deterioration. The values of ∆I, ∆tanδ, and PD magnitude in one stator bar indicated serious insulation deterioration. In another stator bar, the ∆I measurements showed that the insulation was in good condition, whereas the values of ∆tanδ and PD magnitude indicated an incipient stage of insulation deterioration. Measurements of ∆I and PD magnitude in all three phases (A, B, C) of the remaining generator stator windings showed that they were in good condition, although the ∆tanδ measurements suggested that the condition of the insulation should be monitored carefully. Overall analysis of the results suggested that the generator stator windings were in good condition. The patterns of PD magnitude in all three phases (A, B, C) were attributed to internal discharge.

show abstract

Section: Capacitance Analysissupporting

confidence: 82%

Section: Capacitance Analysismentioning

confidence: 99%

Section: Analysis Of Pd Magnitudementioning

confidence: 99%

See 1 more Smart Citation

Analysis of Insulation Quality in Large Generator Stator Windings

Kim¹,

Kong²,

Ju³

et al. 2011

Journal of Electrical Engineering and Technology

View full text Add to dashboard Cite

show abstract

“…Many specialists make researches about generator insulation failure mechanism, discharging and fault monitoring after insulation aging [1][2][3][4][5][6][7][8][9][10]. Dr. H. Zhu and C. Morton made a detailed research on the diagnosis about thermal aging of stator windings [11,12]. It can be defined that main insulation occurs delamination and shelling by evaluating the insulation conditions after thermal cycling test.…”

Section: Introductionmentioning

confidence: 99%

Research on Stator Main Insulation Temperature Field of Air-Cooled Turbo-Generator after Main Insulation Shelling

et al. 2018

Energies

View full text Add to dashboard Cite

The stator main insulation is the key component of turbo-generator, which is related to the thermal aging of turbo-generator. It is vital to accurately judge the generator aging by calculating the temperature distribution under main insulation normal operation and fault operation. In this paper, taking a 150 MW air-cooled turbo-generator as an example, the temperature field of the main insulation was studied after the stator main insulation shelling. Based on the finite element method, the stator temperature field after the main insulation shelling was calculated. The main insulation position of maximum temperature drop and the temperature distribution of the stator main insulation along the circumference and the axial direction were analyzed. At the same time, with the shelling gap of main insulation increases, the temperature distribution between shelling gap δ = 0.5 mm and δ = 1.0 mm was compared. The results can provide a theory for fault monitoring and diagnostics of the large-scale turbine generator.

show abstract

“…Defects in the insulation system of generator stator windings can be produced during manufacturing or due to thermal, mechanical, electrical, or chemical deterioration when the generator is operated for a long time. With insulation degradation due to a combination of such operating stresses, voids can be formed inside the insulation material, and dielectric breakdown may eventually result from partial discharge activity [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Partial Discharge Patterns for Generator Stator Windings

Kong¹

2015

EPES

View full text Add to dashboard Cite

Forced outage of generators due to stator winding insulation failure can result in significant financial loss because of the high cost repair and loss of production. In recent years, the demand for insulation diagnosis is increasing to prevent unexpected failures, as the capacity of generators has increased. Insulation diagnosis is composed of the insulation resistance measurement, polarization index measurement, dissipation factor (DF) tip-up test, AC current increasing ratio measurement, and the partial discharge (PD) measurement. In this paper, the results of the PD measurement and PD pulse pattern analysis performed on a healthy generator and two generators that experienced dielectric breakdown failure during operation is presented.

show abstract

Quality Evaluation of Stator Coils and Bars under Thermal Cycling Stress

Cited by 12 publications

References 3 publications

Analysis of Insulation Quality in Large Generator Stator Windings

Analysis of Insulation Quality in Large Generator Stator Windings

Research on Stator Main Insulation Temperature Field of Air-Cooled Turbo-Generator after Main Insulation Shelling

Analysis of Partial Discharge Patterns for Generator Stator Windings

Contact Info

Product

Resources

About