Generator Assessment Process - Level 1
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The document describes a generator assessment process (GAP) used to evaluate the thermal residual life of large generators. GAP1 uses operational history and accumulated data to estimate consumed life and residual life. Optional diagnostic tests include vibration analysis, current analysis, and infrared imaging. The methodology estimates consumed life from operational history and residual life through calculation of remaining breakdown voltage and future operation. The assessment provides the generator's condition, residual thermal life estimate, preventative maintenance plan, and recommendations.
Generator Assessment Process - Level 1
- 1. GAP 1 generator assessment process a solution to life assessment of large generators anilscoob@gmail.com omsaiempl@gmail.com
- 2. 1 GAP 2 GAP GAP* GAP 4 GAP 3 anilscoob@gmail.com
- 3. GAP1 evaluates the thermal residual life from experience and the accumulated data Optionally diagnosis of faults through on-line testing - vibration signature analysis, current signature analysis and infrared thermal imaging
- 4. Methodology The methodology employed is estimation of consumed life and residual life Consumed life is estimated by operational history Residual life is estimated by consumed life, establishment of calculation method for residual break-down voltage and operation pattern in the future
- 5. Unit Condition The generator is in operation Inspection & tests Performed OEM data and specification Operational history Operational parameters Thermal profile Maintenance history
- 6. Benefits Extent of thermal life degradation Preventive maintenance plan Schedule for GAP2, GAP3 and GAP4 Final Report Standardized format in electronic form Photographs of critical areas Thermal residual life Analysis and recommendation
- 7. Expected Downtime Zero days Option Vibration severity level Vibration signature analysis Electrical Signature analysis Infrared thermal imaging
- 8. Life Assessment Thermal Life Assessment
- 9. Ageing of an Electrical Insulation System
- 10. Assessment of Condition and Residual Life Time
- 11. Inverse Power Law and Arrhenius Law
- 12. Single Stress and Multi Stress Ageing of EIS
- 13. Thermal Life Assessment Arrhenius Equation
- 14. Thermal Electrical Stress Mechanical Ambient anilscoob@gmail.com
- 15. Thermal Ageing Model The thermal ageing in insulating materials is complex and the mechanisms vary in different materials and under different service conditions. To a first approximation, the oxidation process can be expressed by the Arrhenius rate law. It is evident that, the higher the temperature, the shorter is the life expectancy of the insulation. The Arrhenius law is the basis of all accelerated ageing tests which are used to estimate the thermal life of a winding and is also used to define the insulation thermal classes
- 17. Arrhenius Equation Dr. Svante August Arrhenius was a Swedish scientist, professor of physics, and the founder of physical chemistry. In 1903, he received the Nobel Prize for Chemistry for his study of ionic theory
- 18. Lr ∝ f (Y, Yo, N, Tmax, Tavg, Tamb) Lr = Residual thermal life (years) Y = Operating years Yo = Equivalent operating years N = Number of starts/stops Tmax = Maximum allowable temperature (oC) Tavg = Average operating temperature (oC) Tamb = Ambient temperature (oC)
- 19. T HE R MAL L IF E C urves plotted at different winding temperature in o C 100 90 80 70 60 % L ife 50 40 30 100 95 90 85 81 20 10 0 0 5 10 15 20 25 30 35 x 10000 Hours of O peration 81 85 90 95 100 pres ent
- 20. R emaining T hermal L ife vs Winding T emperature 25 x 10000 81 20 R eamaining L ife (No. of hours ) 15 85 10 90 95 5 100 0 80 82 84 86 88 90 92 94 96 98 100 T emperature (deg C )
- 21. Thermal Life Estimation by Arrhenius Equation BHEL 46.25 MVA, 11 KV, 3000 rpm Turbo-generator @ Monnet Ispat, Raipur 100 present life 90 80 70 Residual Thermal Life(%) 60 50 40 30 thermal life 20 10 0 10 15 20 25 30 0 5 Operating Years residual thermal life present life thermal life
- 22. GAP Estimation by Arrhenius Equation BHEL 46.25 MVA, 11 KV, 3000 rpm Turbo-generator @ Monnet Ispat, Raipur 100 90 80 Residual Thermal Life(%) 70 60 50 40 30 20 10 0 0 5 10 15 20 25 30 Operating Years GAP11 GAP21 GAP31 GAP41 GAP12 GAP22 GAP32 GAP42
- 23. Life Index 1 2 3 4 5 6 7 8 9 10
- 24. Thermal Life Assessment N-Y Map Method
- 25. Thermal Electrical Stress Mechanical Ambient anilscoob@gmail.com
- 26. Electrical aging and thermal aging both depend on service operation in year (Y), and aging due to heating and cooling is proportional to the number of starts-stop of a machine (N) From empirical data based on the insulation system study i.e. the electrical, thermal aging characteristics and the heating and cooling cycle characteristics, a NY-map is derived From the equation by experimental data, the residual breakdown strength (%) is as Vr ∝ f (Y, N, No, Tmax, Tavg, Tamb)
- 27. Vr ∝ f (Y, N, No, Tmax, Tavg, Tamb) Vr = Residual breakdown strength (%) Y = Operating years N = Number of starts/stops No = Equivalent number of starts/stops Tmax = Maximum allowable temperature (oC) Tavg = Average operating temperature (oC) Tamb = Ambient temperature (oC)
- 28. Thermal Life Estimation by N-Y Method BHEL 46.25 MVA, 11 KV, 3000 rpm Turbo-generator @ Monnet Ispat, Raipur 90 present life 85 80 Residual Breakdown Strength (%) 75 70 thermal life 65 60 55 50 45 40 0 5 10 15 20 25 30 35 40 Operating Years Residual Breakdown Strength Minimum Breakdown Strength present life thermal life
- 29. Life Index 1 2 3 4 5 6 7 8 9 10
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