VibrationVibrationVibrationSystem

VibrationSystemSystemSystem

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ContentsContents

Standard1

Sensors2

Application3

The Rathbone Chart,The Rathbone Chart,

Introduced by a UL agent named T. C. Rathbone in 1939(measured in Inch Per Second-IPS))

ISO 2372:ISO 2372:Released in 1974

Withdrawn in 1995, being replaced by ISO 10816, g p y

ISO 10816ISO 10816

Released in August 2000, establishes the general conditions and procedures for theestablishes the general conditions and procedures for the measurement and evaluation of vibrations using measurements made on the non-rotating parts of machines

Zone A Green: Vibration values from machines just put into operation.

Zone B Yellow: Continuous operation without any restrictions

Z C O C diti i t bl l f li it d i d f tiZone C Orange: Condition is acceptable only for a limited period of time.

Zone D Red: Dangerous vibration values – damage could occur at any time.

ISO 10816ISO 10816

API 670 (American Petroleum Institute) API 670 (American Petroleum Institute)

The standard details the following measuring techniques

Casing VibrationRadial Shaft VibrationRadial Shaft VibrationShaft Axial PositionSh f R i l S dShaft Rotational SpeedPhase ReferenceOverspeedCritical Machinery TemperaturesCritical Machinery Temperatures

Two out of three majority voting for turbine overspeed protectionTwo out of three majority voting for turbine overspeed protection

SensorsSensors

SensorsSensorsSensorsSensors

ProximityProximity VelocityVelocity AccelerometerAccelerometerProximityProximity yy

Eddy CuttentEddy Cuttent

Eddy current probes are non-contact sensors primarily used to y p p ymeasure shaft vibration , shaft rotor position and clearance .

VelocityVelocity

An iron core moving within a coil in a limited magnetic field .

Piezoelectric AccelerometersPiezoelectric Accelerometers

A crystal generates a low voltage or charge when stressed as for example during compression.

The Relationship The Relationship

The relationship of acceleration and displacement and velocity

Keyphaser Probe for Speed & Phase MeasurementKeyphaser Probe for Speed & Phase Measurement

Mounted on the shaft of the driver machine. The target notch t i h ld b it bl t t th t i lor protrusion should be suitable to generate the correct signal

at all machine states

0°

-VONE

REVOLUTION

0°

-V

ONEREVOLUTION

Overspeed ProtectionOverspeed Protection

API 670, 4th edition, calls for a segregated electronic 6 0, ed t o , ca s o a seg egated e ect o coverspeed detection system with three independent sensors, monitors and relays, with a 40-millisecond

Probe A Probe A

response time.

Probe BProbe B obeProbe B

Probe C Probe C

Trust TransducersTrust Transducers

Two non-contact proximity displacement transducers in a dual voting configuration to be installed in accordancedual-voting configuration to be installed in accordance with API 670 4th edition

For SIL 3 applications, three probes shall be installed, connected to triple modular redundant monitors.

Thrust Collar 12” Max12 Max

12” Max12 Max

Radial VibrationRadial Vibration

Two orthogonally mounted shaft-relative non-contact proximity transducers (XY) shall be installed at each radial bearing, using a mounting position directly

f d t th b ireferenced to the bearing.

R t

“X” ProximityProbe

“Y” ProximityProbe

Rotor

Bearing

Casing VibrationCasing Vibration

In some fluid film bearing machines, the casing can exhibit a high degree of compliance. In this case seismic vibration g g ptransducers should be installed. Two orthogonal casing mounted piezo-velocity transducers shall be installed at each Turbine bearing housing. Where possible, the tansducersTurbine bearing housing. Where possible, the tansducers should be aligned with the internally mounted proximity probes in conjunction with non-contacting proximity probes, to monitor machine integrity

machine integrity.

BearingHousingRotor Housing

Journal Bearingg

Shaft Differential ExpansionShaft Differential Expansion

Differential expansion is the measurement of the axial position of the rotor with respect to the machine casing at some distance from the thrust bearing.

Shaft Differential ExpansionShaft Differential Expansion

There are two types of Shaft Differential Expansion , Ramp shaft Direction and Normal shaft Diff ExpensionRamp shaft Direction and Normal shaft Diff.Expension

EccentricityEccentricity

Eccentricity is the measurement of shaft bow at slow-rollEccentricity is the measurement of shaft bow at slow-roll speed.

Gas TurbineGas Turbine

Shaft Position/ Speed/

Gas Turbine Gearbox Centrifugal Compressor

S d/Casing

Vibration PhaseReference

Speed/Load

Vibration

Thrust Position

Keyphaser AxialPosition

Thrust PositionExcentricity

Steam TurbineSteam Turbine

Dual Thrust

X/Y Displacement sensors

Dual ThrustPosition

Speed/PhasePhaseReference

EccentricityDifferentialExpansiony

SensorExpansionSensorCase

ExpansionSensorSensor

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