A.K.SINHA, DGM (TURBINE)
WHAT IS PHASE ANGLE
Ø
360 0
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
USES OF PHASE ANGLE MEASUREMENT
1.
BALANCING
2.
STRUCTURE MOTION STUDY
3.
DETECTION OF RESONANCE FREQUENCY

RUN UP & RUN DOWN BEHAVIOUR

BODE PLOT
4.
HEALHINESS OF MATING SURFACES OF TWO VIBRATING MASSESS
5.
UNDERSTANDING THE DEFLECTION MODE OF THE SHAFT
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
STRUCTURE MOTION STUDY
REAR 245
228
0
220 FRONT
1
230
165
FRONT
212
2
170
245 REAR
220
209
127
138
107
101
87
71
3
112
120
96
94
4/5
6
7
LEFT SIDE
53
19
9
63
19
10
24
20
15
11
16
12
`
11
7
21
16
12
-14
17
18
22
17
-23
23
10
15
-9
22
51
56
14
11
21
9
14
33
20
RIGHT SIDE
8
13
13
-25
23
18
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
STRUCTURE MOTION STUDY
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HEALHINESS OF MATING SURFACES OF TWO VIBRATING MASSESS
3
2
1
9
6
8
7
5
4
GENERATOR SIDE
D
LEFT
21 C
20
14
15
13
BASE PLATE
B
A
11 12
RIGHT
10
18
17
19
16
SECONDARY GROUT
TURBINE SIDE
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
UNDERSTANDING THE DEFLECTION MODE OF THE SHAFT
B1
B2
B3
B4
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
Case Studies
on
Vibration Problems in Steam
Turbine Generators
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HIGH VIBRATION IN
500 MW TG SETS
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HIGH VIBRATION IN 500 MW TG SETS
PROBLEM
HIGH HP FRONT SHAFT AND BEARING PEDESTAL VIBRATION
OBSERVATIONS
(A) FREQUENCY ANALYSIS CARRIED OUT WHICH INDICATED
PREDOMINANT 1-X VIBRATION COMPONENTS FOR BOTH SHAFT AND
BEARING PEDESTAL VIBRATION
STEADY PHASE ANGLE
(B) BEARING PEDESTAL VIBRATIONS AND SHAFT VIBRATIONS WERE
HAVING RISING TENDENCY AT RATED SPEED HOWEVER, THEIR RATIO
WAS FOUND TO BE ALMOST CONSTANT
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HIGH VIBRATION IN 500 MW TG SETS
ANALYSIS
PREDOMINANT 1-X VIBRATION WITH SLIGHT CHANGE IN PHASE
ANGLE INDICATED THERE WAS UNBALANCE IN THE ROTOR SYSTEM
LEADING TO INITIATION OF MINOR RUB
MAIN SOURCE OF VIBRATION WAS HIGHER DYNAMIC LOADING FROM
THE SHAFT WHICH WAS GETTING TRANSMITTED TO BEARING
ACTION TAKEN
• TO REDUCE THE HP FRONT SHAFT VIBRATION LEVEL, INSITU
BALANCING WAS CARRIED OUT USING LP ROTOR BALANCING PLANES
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HIGH VIBRATION IN 500 MW TG SETS
RESULT OF INSITU BALANCING
HP SHAFT VIBRATION BROUGHT DOWN TO STEADY VALUE OF 120
MICRONS, 0-PK FROM EARLIER VALUE OF 150 - 200 MICRONS, 0-PK
HP FRONT BEARING VIBRATION CAME DOWN INITIALLY TO 15
MICRONS, 0-PK AT 3000 RPM FROM EARLIER VALUE OF 25 – 40
MICRONS, 0-PK
LATER, WITHIN 2-3 HOURS OF OPERATION, HP FRONT BEARING
VIBRATION INCREASED BEYOND ALARM VALUE (35 MICRONS, 0-PK).
DURING THIS PERIOD, NO INCREASE IN SHAFT VIBRATION WAS
OBSERVED
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HIGH VIBRATION IN 500 MW TG SETS
INTREPRETATION OF RESULTS AFTER INSITU BALANCING
AS HP FRONT BEARING PEDESTAL VIBRATION INCREASED, EVEN
WHEN HP FRONT SHAFT VIBRATION WAS CONSTANT, INDICATED THAT
THE CAUSE OF HIGH BEARING PEDESTAL VIBRATION WAS SOME
FACTORS APART FROM UNBALANCE OF THE SHAFT
ANALYSIS DONE
• BASED UPON THE VIBRATION BEHAVIOUR OF BEARING PEDESTAL AND
SHAFT VIBRATION, IT WAS DECIDED TO SCAN FRONT BEARING
PEDESTAL BY PORTABLE VIBRATION ANALYSER
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HIGH VIBRATION IN 500 MW TG SETS
RESULTS OF SCANNING OF FRONT PEDESTAL
VIBRATION ON LEFT AND RIGHT HAND SIDE OF FRONT BEARING
PEDESTAL (NEAR HP CASING FRONT PALMS) IN THE VERTICAL
DIRECTION WERE HAVING LARGE VARIATION
(LHS VIBRATION IS ABOUT 5 TIMES MORE THAN RHS VIBRATION)
HP CASING PALM VIBRATION AMPLITUDE IN VERTICAL DIRECTION ON
LEFT AND RIGHT PALM WAS FOUND TO BE OF LOWER MAGNITUDE
AND SAME
SCANNING INDICATED THAT THERE WAS NO PROBLEM WITH BASE
PLATE, SECONDARY GROUT & FOUNDATION MATING SURFACES
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HP CASING PAM
(RIGHT HAND
SIDE)
HP FRONT BEARING PEDESTAL
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HIGH VIBRATION IN 500 MW TG SETS
ANALYSIS
SCANNING DATA INDICATED THAT LOAD DISTRIBUTION BETWEEN
PALMS OF HP CASING WAS NOT PROPER
THERE WAS GAP BETWEEN CASING PALM AND PEDESTAL ON LEFT
HAND SIDE
ACTION TAKEN
• 0.15 MM SHIM WAS ADDED BELOW LEFT HAND SIDE PALM WHEREAS
0.1 MM SHIM WAS REMOVED FROM RIGHT HAND SIDE PALM FOR
IMPROVING THE LOADING PATTERN OF HP CASING ON PEDESTAL
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HIGH VIBRATION IN 500 MW TG SETS
RESULT OF CORRECTION IN SHIMS
VIBRATIONS ON BEARING PEDESTAL REDUCED FROM 35 MICRONS, 0PK TO 15 MICRONS, 0-PK AND NO INCREASING TENDENCY WAS
OBSERVED
HP FRONT SHAFT VIBRATION WAS FOUND TO BE REDUCED FROM 120
MICRONS, 0-PK TO 90 MICRONS, 0-PK AND BEARING VIBRATION
SETTLED DOWN TO 10 MICRONS, 0-PK AT FULL LOAD
RATIO OF LEFT AND RIGHT HAND SIDE VIBRATION ON FRONT
PEDESTAL IN VERTICAL DIRECTION CAME DOWN TO 2:1 FROM
EARLIER VALUE OF 5:1
HENCE, UNBALANCE OF ROTOR SYSTEM & UNLOADING OF
LEFT SIDE PALM WAS FOUND TO BE THE ROOT CAUSE OF THE
HIGH HP FRONT SHAFT AND BEARING PEDESTAL VIBRATION
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
CONCLUSION
VIBRATION
IMPORTANT
SCANNING
TOOL
FOR
IS
A
VERY
DIAGNOSTICS
PURPOSES
VIBRATION SCANNING SHOULD BE USED AS
FREQUENTLY AS POSSIBLE
IT HELPS IN RULING OUT OR PIN POINTING
CERTAIN DEFECTS
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HIGH VIBRATION IN
210 MW TG SETS
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HIGH VIBRATION IN 210 MW TG SETS
BACKGROUND
 MACHINE IS OF KWU DESIGN STEAM TURBINE COUPLED WITH LMW
GENERATOR (LP REAR BEARING AND GENERATOR FRONT BEARING IS
LOCATED IN COMMON PEDESTAL)
 VIBRATION BEHAVIOUR WAS FOUND TO BE NORMAL DURING FIRST
COMMISSIONING ON ALL BEARINGS AND LATER ON VIBRATION ON
BEARING NO. 4 / 5 PEDESTAL DETERIORATED GRADUALLY BEYOND
ALARM LEVELS (35 MICRONS, 0-PK)
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HIGH VIBRATION IN 210 MW TG SETS
PROBLEM
 HIGH LP REAR BEARING VIBRATION
 HIGH GENERATOR FRONT BEARING VIBRATION
OBSERVATIONS
FREQUENCY ANALYSIS CARRIED OUT WHICH INDICATED
 PREDOMINANT 1-X VIBRATION COMPONENT FOR BOTH LP REAR AND
GENERATOR FRONT VERTICAL AND AXIAL VIBRATION
 VERTICAL VIBRATION AT LP REAR AND GENERATOR FRONT BEARING
WAS OF THE ORDER OF 100 MICRONS, PK-PK
 AXIAL VIBRATION WAS ABOUT 200 MICRONS, PK-PK FOR BOTH LP
REAR BEARING AND GENERATOR FRONT BEARING
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HIGH VIBRATION IN 210 MW TG SETS
ANALYSIS
BASED ON VIBRATION SYMPTOMS, FOLLOWING CHECKS WERE
SUGGESTED IN PLANNED OVERHAUL
LP / GENERATOR ALIGNMENT
BEARING ASSEMBLY CHECKS
RESULT OF ABOVE WORKS
AFTER
CARRYING
OUT
THE
ABOVE
MENTIONED
CHECKS
&
CORRECTIONS DURING PLANNED OVERHAUL, VIBRATION LEVEL DID
NOT IMPROVE
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HIGH VIBRATION IN 210 MW TG SETS
ACTION TAKEN
FOLLOWING WORKS WERE CARRIED OUT
 VIBRATION ANALYSIS
 SCANNING OF LP REAR BEARING PEDESTAL AND ITS SECONDARY
GROUT AND BASE PLATE AREA
OBSERVATIONS / ANALYSIS
• FREQUENCY BEHAVIOUR OF BEARING VIBRATION FOUND SIMILAR TO
EARLIER OBSERVATION
• WIDE DIFFERENCE IN PHASE ANGLE IN VERTICAL DIRECTION
ACROSS BASE PLATE OF LP REAR PEDESTAL AND SECONDARY
GROUTING WHICH INDICATED THAT VERTICAL LOAD TRANSFER
FROM BEARING TO FOUNDATION IS NOT AS EXPECTED
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
SCANNING OF PEDESTAL
3
2
1
9
6
8
7
5
4
GENERATOR SIDE
D
LEFT
21 C
20
14
15
13
BASE PLATE
B
A
11 12
RIGHT
10
18
17
19
16
SECONDARY GROUT
TURBINE SIDE
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HIGH VIBRATION IN 210 MW TG SETS
ACTION PLAN SUGGESTED
 REGROUTING OF LP REAR PEDESTAL
 REPLACEMENT OF FOUNDATION BOLTS OF LP REAR PEDESTAL AND
PROPER MATCHING OF ANCHOR PLATES
 IN-SITU BALANCING OF GENERATOR ROTOR TO REDUCE EXCITATION
FORCES TO MINIMUM
DUE TO TIME CONSTRAINT AND POWER REQUIREMENT,
FOLLOWING WORKS CARRIED OUT
• EPOXY GROUTING (PRESSURE GROUTING) OF LP REAR PEDESTAL
• RESTRETCHING OF FOUNDATION BOLTS OF LP REAR PEDESTAL
• LP / GENERATOR REALIGNMENT
• BEARING INSPECTION
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HIGH VIBRATION IN 210 MW TG SETS
RESULT OF ABOVE WORKS
AFTER CARRING OUT THE ABOVE MENTIONED CHECKS DURING NEXT
OVERHAUL
VIBRATION LEVEL FOUND REDUCED TO 25 MICRONS, 0-PK ON
BEARING NO. 4 / 5 PEDESTAL
 PHASE DIFFERENCE WAS FOUND TO BE MINIMUM BETWEEN BEARING
PEDESTAL BASE PLATE AND SECONDARY GROUTING
BUT AFTER FEW DAYS OF OPERATION,
• VIBRATION LEVEL STARTED INCREASING GRADUALLY AND TOUCHED
ALARM VALUE OF 35 MICRONS, 0-PK
• PHASE ANGLE DIFFERENCE WAS ALSO FOUND TO BE INCREASING
BETWEEN BASE PLATE AND SECONDARY GROUTING
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HIGH VIBRATION IN 210 MW TG SETS
ANALYSIS
EPOXY GROUTING WAS INSUFFICIENT TO CURE THE VIBRATION
PROBLEM ON PERMANENT BASIS
AT THIS POINT OF TIME, CIVIL EXPERT ALSO CONDUCTED STUDIES ON
FOUNDATION
WHICH
CONFIRMED
THE
BAD
CONDITION
SECONDARY GROUT
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
OF
A.K.SINHA, DGM (TURBINE)
HIGH VIBRATION IN 210 MW TG SETS
ACTION PLAN SUGGESTED:
ONCE AGAIN THE PREVIOUS ACTION PLAN WAS SUGGESTED, THAT IS,
REMOVAL OF LP REAR BEARING PEDESTAL AFTER BREAKING
SECONDARY GROUTING COMPLETELY
REPLACEMENT OF FOUNDATION BOLTS
IN-SITU BALACNING OF GENERATOR ROTOR
DISMANTLING OBSERVATION
• DURING REMOVAL OF LP REAR PEDESTAL, SECONDARY GROUT
MATERIAL WAS FOUND IN PIECES
• OIL SEEPAGE WAS OBSERVED UNDER PEDESTAL
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
HIGH VIBRATION IN 210 MW TG SETS
RESULT OF ABOVE WORKS
 AFTER THE ABOVE MENTIONED WORKS CARRIED OUT (INCLUDING
IN-SITU BALANCING OF GENERATOR ROTOR) IN THE NEXT PLANNED
OVERHAUL, VIBRATION LEVEL OF LP REAR AND GENERATOR FRONT
IMPROVED IN BOTH VERTICAL AND AXIAL DIRECTION
 MACHINE IS RUNNING SATISFACTORILY SINCE THEN
HENCE, LOOSENESS / VOID BETWEEN LP REAR PEDESTAL AND
SECONDARY GROUTING WAS FOUND TO BE THE ROOT CAUSE
OF HIGH LP REAR PEDESTAL AND GENERATOR FRONT
VIBRATION
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
CONCLUSION
HISTORY
OF
THE
PROBLEM
SHOULD
BE
GIVEN
DUE
WEIGHTAGE FOR ANALYSING THE PROBLEM
ATTENTION SHOULD BE PAID TO INTERFACE AREAS BETWEEN
MACHINE
AND
SUPPORTING
SYSTEM
/
STRUCTURE
ADDITION TO MAIN MACHINE
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
IN
A.K.SINHA, DGM (TURBINE)
TIPS FOR BETTER DIAGNOSTICS
HISTORY OF MACHINE WITH RESPECT TO ITS DYNAMIC
BEHAVIOUR SHOULD BE STUDIED
REGULAR VIBRATION READING ON BEARING PEDESTAL AT
PRESCRIBED LOCATIONS SHOULD BE TAKEN FOR ASSESSING
THE TREND OF VIBRATION BEHAVIOUR ACCURATELY
SHAFT
VIBRATION
IN
TWO
ORTHOGONAL
DIRECTIONS
SHOULD BE MEASURED FOR ORBIT ANALYSIS
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
RECOMMENDED LOCATIONS OF VIBRATION MEASUREMENTS ON
BEARINGS AS PER ISO
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
RECOMMENDED LOCATIONS OF SHAFT VIBRATION
MEASUREMENTS AS PER ISO
Measuring
Amplifier
Measuring
Amplifier
45O
L
PROXIMITY
PICK-UP
45O
SHAFT
VERTICAL
R
OR
L
SHAFT
R
HORIZONTAL
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
TIPS FOR BETTER DIAGNOSTICS
EVERY UNIT SHOULD HAVE KEY PHASOR ARRANGEMENT FOR
VIBRATION ANALYSIS.
SCANNING OF VIBRATION PRONE AREAS INCLUDING SYSTEM /
FOUNDATION AROUND THE PROBLEMATIC AREA SHOULD BE
CONDUCTED
DEVIATION
IN
OPERATING
PARAMETERS
SHOULD
BE
RECORDED AND ANALYSED FOR THEIR EFFECT ON VIBRATION
BEHAVIOUR
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
TIPS FOR BETTER DIAGNOSTICS
RUN UP & RUN DOWN VIBRATION BEHAVIOUR SHOULD BE
RECORDED FOR ALL BEARINGS AND SHAFT POSITIONS FOR
REFERENCE WHICH CAN BE USED DURING TROUBLESHOOTING
PRE-OUTAGE SURVEY SHOULD
OVERHAUL
FOR
BETTER
BE CONDUCTED PRIOR TO
PLANNING
OF
ADDITIONAL
ACTIVITIES / SPARES, IF REQUIRED
RECORD OF PREVIOUS BALANCING AT SITE SHOULD BE
MAINTAINED FOR REFERENCE PURPOSES
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
TIPS FOR BETTER DIAGNOSTICS
LAST BUT NOT THE LEAST, DURING TROUBLESHOOTING,
EVERY FEEDBACK / OBSERVATION NEEDS TO BE CONFIRMED.
IF EVERYTHING IS ALRIGHT, VIBRATION PROBLEM WOULD
NOT
HAVE
BEEN
THERE.
SO
VERIFY EACH
&
EVERY
POSSIBILITY AND CONFIRM FROM WRITTEN DOCUMENTS
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA
A.K.SINHA, DGM (TURBINE)
Thank you
BHEL, POWER SECTOR – TECHNICAL SERVICES (HQ), NOIDA