Major Overhaul Procedure for Synchronous Generators
1. Generator Disconnection
Before disconnecting the generator, test the insulation resistance of the generator excitation circuit and the insulation resistance of the power motor that should be started during shutdown.
2. Gradually Reduce Generator Speed
During the process of reducing generator speed, measure the AC impedance of the generator at different speeds.Vacuum Degree Tester is a product improved by our company based on feedback from field users, building upon the previous generation. This vacuum degree tester features higher testing accuracy, better stability, and a higher degree of intelligence.
3. Operation to Switch Generator to Maintenance
Before the operation to switch the generator to maintenance, a work permit must be received and reviewed, and the duty operator must measure the generator insulation resistance.
4. Commencement of Generator Maintenance Work
Before starting maintenance work, power outage for auxiliary power must be completed, then auxiliary motors should be overhauled. Before and after auxiliary motor maintenance, calibration of auxiliary power relay protection and instruments is required; also, calibration of generator relay protection and all indicating measuring instruments must be performed. For hydrogen-cooled synchronous generators, hydrogen replacement must be done before maintenance work begins.
5. Major Overhaul of Generator Body
Before formally disassembling for body overhaul, tests before rotor extraction must be conducted; to synchronize sectional maintenance of auxiliary power, corresponding power outage for auxiliary power should also be arranged.
6. Generator Assembly
After the body overhaul, the generator should be assembled. Before assembly, pre-assembly tests and tests of the generator cooler must be conducted. After assembly, for hydrogen-cooled generators, a tightness test is required; for water-cooled generators, a hydraulic test is required. As maintenance and testing work concludes, auxiliary power should be restored, then adjust and test the generator relay protection devices and calibrate all testing instruments; subsequently, conduct the complete generator unit test.
7. Completion of Generator Overhaul
After the entire overhaul cycle is completed, the generator overhaul is finished. Auxiliary power is restored.
8. Generator Restoration to Standby
After the generator is restored to standby, the duty operator (electrical test team personnel) measures generator insulation and performs interlock tests. For hydrogen-cooled generators, hydrogen replacement is required.
9. Generator Start-up. After starting, complete the generator no-load and short-circuit tests; phase alignment and false synchronization tests;
10. Generator Grid Connection. Thus entering formal operation after the major overhaul.
