Actual Over Speed of Main turbine
- Bypass the Electrical Over Speed trip set at 109% ( 3270 RPM) of rated speed .
- Select the machine on Hydraulic Governor as per the standard procedure
- Isolate the EHC oil line from the Gov rack .
- Slowly increase the speed from the SD & SG ( Both should be 100 % ) The max speed attained is 3210 RPM ( 107%)
- Further speed raising will be done through the acceleration lever provided on the casing of the Hyd Governor . ( Lever to be pressed towards the generator end)
- Observe the tripping of the Machine , Note down & record the actual speed (110%) of tripping & the primary oil pressure at that point.
- If the Machine does not trip at desired speed (110 %) then hand trip the Machine at 112 % speed ( 3360 RPM) .
- Check Both O/S trip devices are operated through the alarm as well as physical verification . If any discrepancy observed then inform C&I
- Check the other parameters such as Max Bearing Vibrations /Max Shaft Vibr etc .
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