7/28/2019 Bearing 1 high shaft vibration , Ramagundam , 500 MW, 00-01.pdf

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FEED BACK NO. 11

PROTECT

UNIT NO.

SUBJECTRAMAGUNDAM 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. Sub-

harmonic 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, Yokekey clearances found more thandesign values. Bearing No.1 babbit

found loose in Ultrasonic test.

Bearing No.1 was replaced with newone. All bearing side packer, Yokeclearances were maintained as per

design values.

Swing check value at journal No.1was found 0.37 mm.

Swing check value brought down to0.12 mm by resorting to correction ofHP-IP coupling face run outs.

HP-IP roll check values, centeringreadings found disturbed.

HP, IP Roll check values andcentering readings were adjusted asper design values.

Catenery of total shaft system wasnot in order.

Catenary of the shaft system broughtto design limits by resorting toalignment adjustment of all therotors.

LP-GEN misalignment noticed. LP-GEN, alignment was readjusted.

7/28/2019 Bearing 1 high shaft vibration , Ramagundam , 500 MW, 00-01.pdf

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During 1998 and 1999 vibrationrectification attempts 1.50 mmto 1.80 mm shims were addedunderneath the pedestal no.lafter coupling all rotors asrecommended by KWU GermanExpert.

These shims were removedeventhe German KWU Expert opinedto keep the shims again, ifrequired.

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 andsub harmonic vibration is also absent. Allthe

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 BHEL-

SAS/Secunderabad for resolving the vibration problem.

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7/28/2019 Bearing 1 high shaft vibration , Ramagundam , 500 MW, 00-01.pdf

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FEED BACK NO. 11

PROTECT

UNIT NO.

SUBJECTRAMAGUNDAM 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. Sub-

harmonic 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, Yokekey clearances found more thandesign values. Bearing No.1 babbit

found loose in Ultrasonic test.

Bearing No.1 was replaced with newone. All bearing side packer, Yokeclearances were maintained as per

design values.

Swing check value at journal No.1was found 0.37 mm.

Swing check value brought down to0.12 mm by resorting to correction ofHP-IP coupling face run outs.

HP-IP roll check values, centeringreadings found disturbed.

HP, IP Roll check values andcentering readings were adjusted asper design values.

Catenery of total shaft system wasnot in order.

Catenary of the shaft system broughtto design limits by resorting toalignment adjustment of all therotors.

LP-GEN misalignment noticed. LP-GEN, alignment was readjusted.

7/28/2019 Bearing 1 high shaft vibration , Ramagundam , 500 MW, 00-01.pdf

4/5

During 1998 and 1999 vibrationrectification attempts 1.50 mmto 1.80 mm shims were addedunderneath the pedestal no.lafter coupling all rotors asrecommended by KWU GermanExpert.

These shims were removedeventhe German KWU Expert opinedto keep the shims again, ifrequired.

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 andsub harmonic vibration is also absent. Allthe

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 BHEL-

SAS/Secunderabad for resolving the vibration problem.

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