Download - Vibration Problem
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VIBRATION wK ?GKwUwwZvcK KwVb c`v_ wKsev
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mvwiZ nq , ZvKIVIBRATION wnmeAvLvwqZ Kiv hvq|
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vibration Gi gyLvgywL nB|
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wPwKrmv vibration eenvi Kiv nq|
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VIBRATION cavbZt `yB cKvi t
Free (gy) vibrationhLb Kvb eK GKwU cv_wgKfve ej cqvM KwiqvZvnvK
gyfve Qvwoqv `Iqv nq , ZLb h wKQyb Kgvb _vwKqv
Avcbv Avcwb wwZevq PwjqvAvm|
hgb t vjbv |
Forced (ejcqvMKZ ) vibrationhLb GKwU cwieZbkxb ej ev MwZ GKwU eZcqvM Kiv
nq , ZLb Dnvi Kbi wdKvqx cqvMKZ ej wKsev
MwZi wdKvqxi mgvb nq|
hgb ; evmUvK Bwb nBZmvibration , fwgK m
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Vibrations are generally caused by:
1. UNBALANCE.
2. MISALINGMENT
3. MECHANICAL LOOSENESS
4. DEFECTIVE SLEEVE BEARINGS
5. ECCENTRICITY6. GEAR PROBLEMS
7. ELECTRICAL PROBLEMS
8. RESONANCE
9. AERODYNAMIC AND HYDRAULIC FORCES
10. RUBBING
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UNBALANCE:
AbZg vibration DeKvix| Nbbgvb eifii Amgvb fiieUbiKvibDe nq|
weqvwis- radial direction -G AwZwi Pvc c`vb Ki hvnvidj weqvwis-G fvBekb Gi De nq |
vibration-Gi djh fvimvgnxbZvi mwnq Zvnvstatic
or dynamic nZcvi |
Static
Unbalance
Dynamic Unbalance
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MISALIGNMENT
Angular : the center line of the two shafts meet at an angle.
Offset : the shaft center lines are parallel but detached from
one another
A combination of angular and offset misalignment.
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Effect :
Misalignment conditions result
in
destructive vibration
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MECHANICAL LOOSENESS
The causes of mechanical looseness could
be loose mounting bolts, excessive bearing
clearance or a crack in' the structure of
bearing housing .
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ECCENTRICITY
Eccentricity means that the shaft
(rotating) centerline is not the same asthe rotor (geometric) center line.
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High levels of vibration or noise in sleeve bearings generally
result from Excessive bearing clearance caused by wiping
lubrication problems.
DEFECTIVE SLEEVE BEARINGS
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GEAR PROBLEMSCommon problems, which cause vibration in gear,
Cause :
excessive gear wear,
gear tooth inaccuracies,
faulty lubrication and dirt or foreign
material trapped in the gear teeth.
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ELECTRICAL PROBLEMS
Electrical problems normally consist of
unequal magnetic forces acting on the rotor or
stator. These unequal magnetic forces
may be due to :
Rotor not round
Rotor and stator misaligned (rotor not centered in
the stator)
Elliptical stator bore
Broken bar
Open or shorted windings
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RESONANCE
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AERODYNAMIC AND HYDRAULIC FORCES
Machine which handle fluids will
have vibration and noise due tothe reaction of the vanes or
blades on the impeller strikingthe fluid.
This type of vibration is common
on pumps, fans and blowers.
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RUBBING
Rubbing between the stationary and rotating
parts of a machine may cause theVibration
If the rubbing is continuous, no particularvibration characteristics are likely.
However, a very high frequency of vibration
and noise may be present due to friction
exciting natural frequencies of the system.
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VIBRATION MEASUREMENT
The three essential functional elements
are
1. Transducer element
2.Signal conditioning element
3.Display or recording element.
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mvavibZt `yB cKviVIBRATIONGi GKKKcKvk Kiv nq ;
1)ACCELARATION mm/sec
2)Displacement micro-meter.
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MARK V DISPLAY ON VIBRATION MONITORING SYSTEM
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Vibration Protection
If All Gas Turbine Sensors
are Disabled or Faulty
If All Generator Sensors areare Disabled or Faulty
If 3 or more GT Sensors
are Disabled or Faulty
If 2 or more Generator
sensors Disabled or faulty
OR
OR
T
T
GROUPDISABLED
ALARM &
TRIP
START
INHIBIT
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L39VGTT --Vibration Trip Gas TurbineL39VGT --Vibration trip Generator
L39VT --Vibration trip
Here ,
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Vibration Trip
OPTVTD
Any Trip and if any Adj.
Pair Disabled or Alarmed
Any Trip and any Alarmfrom other Sensor
Any Trip and if 2 or more
Sensors are Disabled
Any Trip and Any Alarm
from another Sensor
Any Trip if 2 Sensor
Inputs or Disabled
Adjacent Sensor
OR
OR
RESET
T
T
SET
ANDLATCH
RESET
SET
AND
LATCH
RESET
L39VGTT
Gas Turbine
Trip
L39VGT
Generator
Trip
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Vibration Trip Contd..
L39VGTT
L39VGT
OR
L39VT
HIGH
VIBRATION
TRIP
BB 1
BB 2
A
A > B
B ORT
LK39DIFF
OTHER SIMILAR
GROUPS
Vibration
DifferentialAlarm
+_
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