vibration analysis level-I syllabus by skf conduct exams.Full description
Vibration analysis and breakdown preventionFull description
MW
shaft designDescripción completa
FEED BACK NO. 11
PROTECT UNIT NO. SUBJECT
RAMAGUNDAM RAMAGUNDAM STPP - 500 MW 4 HIGH SHAFT VTBRATIQN IN BEARING NO.l
PROBLEM REPORTED:
Shaft vibration of bearing No.l was in the range of 100 to 200 microns with sub-harmonic vibration ranging from 25 to 60 microns. To limit the shaft vibration, control valve no.4 was fully closed. Subharmonic vibration at bearing No.l was around 22 microns with control valve No.4 fully closed condition. Unit-4 was stopped on 20.03.2000 for major overhaul of HP, IP, IP, Generator and Turbine Stop / Control Valves.
DEVIATIONS NOTICED AND RECTIFICATIONS CARRIED OUT:
DEVIATIONS
RECTIFICATIONS
Bearing No.1 side packers, Yoke key clearances found more than design values. Bearing No.1 babbit found loose in Ultrasonic test.
Bearing No.1 was replaced with new one. All bearing side packer, Yoke clearances were maintained as per design values.
Swing check value at journal No.1 was found 0.37 mm.
Swing check value brought down to 0.12 mm by resorting to correction of HP-IP coupling face run outs.
HP-IP roll check values, centering readings found disturbed.
HP, IP Roll check values and centering readings were adjusted as per design values.
Catenery of total shaft system was not in order.
Catenary of the shaft system brought to design limits by resorting to alignment adjustment of all the rotors.
LP-GEN misalignment noticed.
LP-GEN, alignment was readjusted.
During 1998 and 1999 vibration rectification attempts 1.50 mm to 1.80 mm shims were added underneath the pedestal no.l after coupling all rotors as recommended by KWU German Expert.
These shims were removed even the German KWU Expert opined to keep the shims again, if required.
The unit was attended for bearing no.1 shaft vibration problem earlier on two occasions (Overhaul) and HP cylinder checked for horn drop test also.
RESULT:
After completion of above rectification works. Unit was synchronized and fully loaded on 17.05.2000. Shaft vibration at bearing No.1 has come down to 40 to 50 microns and sub harmonic vibration is also absent. All the control valves are in open condition and there was no need felt to dose control valve No.4. NTPC-RSTPP has appreciated the efforts of BHELSAS/Secunderabad for resolving the vibration problem.
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FEED BACK NO. 11
PROTECT UNIT NO. SUBJECT
RAMAGUNDAM STPP - 500 MW 4 HIGH SHAFT VTBRATIQN IN BEARING NO.l
PROBLEM REPORTED:
Shaft vibration of bearing No.l was in the range of 100 to 200 microns with sub-harmonic vibration ranging from 25 to 60 microns. To limit the shaft vibration, control valve no.4 was fully closed. Subharmonic vibration at bearing No.l was around 22 microns with control valve No.4 fully closed condition. Unit-4 was stopped on 20.03.2000 for major overhaul of HP, IP, IP, Generator and Turbine Stop / Control Valves.
DEVIATIONS NOTICED AND RECTIFICATIONS CARRIED OUT:
DEVIATIONS
RECTIFICATIONS
Bearing No.1 side packers, Yoke key clearances found more than design values. Bearing No.1 babbit found loose in Ultrasonic test.
Bearing No.1 was replaced with new one. All bearing side packer, Yoke clearances were maintained as per design values.
Swing check value at journal No.1 was found 0.37 mm.
Swing check value brought down to 0.12 mm by resorting to correction of HP-IP coupling face run outs.
HP-IP roll check values, centering readings found disturbed.
HP, IP Roll check values and centering readings were adjusted as per design values.
Catenery of total shaft system was not in order.
Catenary of the shaft system brought to design limits by resorting to alignment adjustment of all the rotors.
LP-GEN misalignment noticed.
LP-GEN, alignment was readjusted.
During 1998 and 1999 vibration rectification attempts 1.50 mm to 1.80 mm shims were added underneath the pedestal no.l after coupling all rotors as recommended by KWU German Expert.
These shims were removed even the German KWU Expert opined to keep the shims again, if required.
The unit was attended for bearing no.1 shaft vibration problem earlier on two occasions (Overhaul) and HP cylinder checked for horn drop test also.
RESULT:
After completion of above rectification works. Unit was synchronized and fully loaded on 17.05.2000. Shaft vibration at bearing No.1 has come down to 40 to 50 microns and sub harmonic vibration is also absent. All the control valves are in open condition and there was no need felt to dose control valve No.4. NTPC-RSTPP has appreciated the efforts of BHELSAS/Secunderabad for resolving the vibration problem.
