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VIBRATION wK ?GKwUwwZvcK KwVb c`v_ wKsev

GKwU Zij c`v_i `vjb eySvq hLb

Zvnvi wwZevK weN NUvbv

nqQ|MwZkxj Aevq GKwU eZh cwZwqv

mvwiZ nq , ZvKIVIBRATION wnmeAvLvwqZ Kiv hvq|

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Avgv`i`bw`bRxeb cvq cwZw`bB

vibration Gi gyLvgywL nB|

GwU cvqkt B evbxq bn |Kb ?

GwU cxov`vqK |

GwU KvVvgvK `ej Kidj|

wKQy wKQyAvevi DcKvix Kb ?

GwU KbxU wgkb nBZ mnvqZvKi|

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

Kb BZvw`|

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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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