Generator Assessment Process - An Overview
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The GAP* process is a generator assessment process that provides a solution for evaluating the health and reliability of large generators over their lifetime. It involves four stages of inspection and testing called GAP1, GAP2, GAP3 and GAP4 that are conducted at regular intervals. These assessments monitor deterioration factors and provide residual life analysis and recommendations to maximize availability and prevent failures. The multiple stages also increase confidence in the generator's condition over time.
Generator Assessment Process - An Overview
- 1. GAP * generator assessment process a solution to life assessment of large generators anilscoob@gmail.com omsaiempl@gmail.com
- 2. First Turbo Generator (1884) anilscoob@gmail.com
- 3. The deterioration of large generators or for that matter any electrical equipment is normal, and this process begins as soon as generator is installed. If deterioration is not checked, it can cause electrical failures and malfunctions. anilscoob@gmail.com
- 4. In addition a TEAM of stresses - Thermal - Electrical - Ambient - Mechanical further contributes to the deterioration process. anilscoob@gmail.com
- 5. Thermal Electrical Stress Mechanical Ambient anilscoob@gmail.com
- 6. The purpose of a good maintenance program shall be • to discover the potential reasons of deterioration • take remedial measures for correction to avoid catastrophic failures. failures. The other important purpose of maintenance program is to maximize reliability and availability, improve operational efficiency and productivity. productivity. anilscoob@gmail.com
- 7. GAP* is the answer anilscoob@gmail.com
- 8. GAP* is a proactive action and the solution to ensure availability and reliability of generators as well as improve operational efficiency and productivity to ensure smooth and trouble free running of the plant. GAP* is an inspection and maintenance process during the lifetime of a generator and is planned for during either operation or outage. GAP* can be linked to the generator planned outage time thereby ensuring minimum downtime of the plant and at the same time assessing the healthiness of the generator. anilscoob@gmail.com
- 10. 1 GAP 2 GAP GAP* GAP 4 GAP 3 anilscoob@gmail.com
- 11. • During operation of the generator • Data collection and on- line measurement when the generator is in GAP 1 operation • Recommended after 8,000 hours of operation • Usually takes 1 day anilscoob@gmail.com
- 12. GAP 1 deliverables Thermal Life Assessment by Arrhenius Equation Thermal Life Assessment by N-Y method Schedule for GAP2, GAP3 and GAP4 anilscoob@gmail.com
- 13. • During outage with power cables removed from the generator • Data collection and off- line electrical GAP 2 measurements • Recommended after 16,000 hours of operation • Usually takes 2 days anilscoob@gmail.com
- 14. GAP 2 deliverables Condition Assessment based on Diagnostic Tests Residual Life Assessment by D-map Method May include GAP1 deliverables Schedule for GAP3, GAP4 and GAP1 anilscoob@gmail.com
- 15. • During outage on partially disassembled generator (end-covers and inspection windows removed) GAP 3 • Inspection and tests to the extent possible • Recommended after 32,000 hours of operation • Usually takes 3-5 days anilscoob@gmail.com
- 16. GAP 3 deliverables Visual Examination and inspection Residual Life based on Stress Analysis May include GAP1 & GAP2 deliverables Schedule for GAP4, GAP1 and GAP2 anilscoob@gmail.com
- 17. • During outage on fully disassembled generator with rotor threaded-out • Inspection and appropriate testing GAP 4 • Recommended after 64,000 hours of operation • Usually takes 10-12 days anilscoob@gmail.com
- 18. GAP 4 deliverables Residual Life based on Stress Analysis Condition Assessment and Index Risk Assessment and Index may include GAP1, GAP2 & GAP3 deliverables Schedule for GAP1, GAP2 and GAP3 anilscoob@gmail.com
- 19. GAP Concept Life Cycle Concept anilscoob@gmail.com
- 20. Life Cycle Concept Value to Customer through Maintenance Optimized Maintenance Line } Continuous Upgrading/ Replacement Maintenance Overhaul Aging Repair Upgrade and Time Warranty Period Modernization Period Replacement & Recycle Period Maintenance Period Customer Project Lifecycle anilscoob@gmail.com
- 21. GAP Concept Confidence Level anilscoob@gmail.com
- 22. Strength Stress Calculated calculated from GAP1 from GAP1 Strength Calculated Stress from GAP2 calculated from GAP2 Strength Calculated from GAP3 Stress calculated from GAP3 Strength Stress Calculated calculated from GAP4 from GAP4 anilscoob@gmail.com
- 23. uncertainty Strength Strength/stress Stress Time anilscoob@gmail.com
- 24. GAP Concept Stator Winding Failures anilscoob@gmail.com
- 25. Failure statistics Detection during Normal Operation 11% 5% Bearing 3% 37% Winding 6% Rotor Shaft/coupling Brushes/slipring 5% External devices Not specified 33% anilscoob@gmail.com
- 26. Failure statistics Detection during maintenance or test 10% 4% Bearing 7% Winding Rotor Shaft/coupling 8% Brushes/slipring 2% External devices 8% Not specified 61% anilscoob@gmail.com
- 27. Failure Statistics Conclusion • Bearings fail frequently • Windings also share a significant failure rate • Very few winding failures are detected in maintenance (8.3%) as against the total failure of 33% in normal operation • This indicates poor insulation problems detection technique anilscoob@gmail.com
- 30. THANK YOU ध यवाद ا ﮨﮯ ﯾہ ادا ந றி ಧನ ಾದಗಳ