[1] This work is carried out before and after major repairs, 1 year or during minor repairs [2] Remove the connection between the generator outgoing line and the enclosed busbar

[3] Use the KST-402B generator insulation resistance tester dedicated to the generator to measure the insulation resistance of the three-phase stator winding to ground and between phases. During the measurement, it is required to fully pre discharge the stator winding between phases and between phases to ground, and short circuit the three-phase winding at both ends to avoid the influence of capacitance distribution between the winding turns. The measurement results require that under similar test conditions, the insulation resistance value should not decrease to less than 1/3 of the normal value over the years, and the difference in insulation resistance values of each phase should not exceed 100% of the minimum value. The absorption ratio shall not be less than 1.3; The polarization index shall not be less than 1.5

[4] After each phase is tested and fully discharged, disassembly and wiring can only be carried out

[1] This work is carried out during major repairs and after a short circuit at the generator outlet [2] Remove the connection between the generator outgoing line and the enclosed busbar When using the KST-205A DC resistance tester to measure the DC resistance of the motor, the generator should be in a cold state, that is, the difference between the surface temperature of the winding and the surrounding air temperature should not exceed ± 3 ℃. Generally, six or more calibrated thermometers are placed on slot wedges, ventilation holes, winding ends, and other places near the winding, and the average of these temperatures is taken as the temperature of the winding. Infrared thermometer can also be used as a reference for measurement

[4] The measurement results require that the DC resistance values of each phase should not differ by more than 1.5% of the minimum value after correcting for errors caused by different lead lengths and comparing them with the initial (factory or handover) measurement values. When the difference is greater than 1%, attention should be paid

[1] This project is conducted before and after major repairs, 1 year or minor repairs, and after winding replacement. The pre overhaul test should be conducted in the hot state before cleaning up the dirt after shutdown Before the test, the cooling water quality should be checked to ensure that it is transparent, pure, and free of mechanical impurities. The conductivity requirement is 1.5 when the water temperature is 20 ℃ × 102 µ S/m

[3] During minor repairs and after major repairs, the test voltage shall be 2.0Un, i.e. 54kV; After partial replacement and repair of the stator winding, the test voltage is 2.5Un, i.e. 67.5kV; After replacing all stator windings and repairing them, the test voltage is set at 3.0Un, which is 81kV Before the test, the insulation resistance should be checked and qualified before starting the test. The test voltage is increased in stages of 0.5Un per stage, and the leakage current value is read after staying for 1 minute in each stage Under the specified test voltage, the difference in leakage current of each phase should not exceed 100% of the minimum value; When the maximum leakage current is below 20 µ A, there should be no significant change in the phase difference compared to previous test results The leakage current does not increase with time When the leakage current significantly increases disproportionately with voltage, attention should be paid to analysis

[1] This project is conducted before major repairs and after winding replacement Before the test, all thermocouples used to detect the temperature of the stator winding, generator core, and other temperature components of the generator body should be grounded. Use copper wires with a cross-sectional area of no less than 2.5mm2 as protective grounding and working grounding for the test equipment

[3] Use the KST-430A insulation resistance tester to measure the insulation resistance. After water supply, the insulation resistance is greater than 3.9M ω Afterwards, a series resonant voltage withstand device can be used for AC voltage withstand test, and its schematic wiring diagram is shown in Figure 1-1

[4] Connect the test wiring and the three-phase AC power supply leads, and pay attention to the correct phase sequence