TURBOVISORY INSTRUMENTS

What is T.S.I. The T.S.I. perform function of monitoring turbine health by measuring certain parameters of turbine continuously.

T.S.I parameters I. Speed II. Shaft Vibration III. Axial shift IV. Rotor expansionV. Differential expansion VI. Casing overall expansion

*PMI Revision 00 *

*PMI Revision 00 *ABS EXPANSIONDIFF. EXPANSIONREL SHAFT VIBRATIONABS BRG VIBRATIONABS EXPANSIONAXIAL SHAFT POSITIONREL SHAFT VIBRATIONABS BRG VIBRATIONREL SHAFT VIBRATIONABS BRG VIBRATIONDIFF. EXPANSION

DIFF. EXPANSIONRELATIVE SHAFT VIBRATIONABSOLUTE BRG VIBRATIONABSOLUTE BRG VIBRATIONREL SHAFT VIBRATION

ABSOLUTE BRG VIBRATION

*6543271HALL PROBES1OVERALL EXPANSION22DIFFERENTIAL EXPANSIONAXIAL SHIFT4RELATIVE SHAFT VIBRATIONABSOLUTE BRNG. VIBRATION56TURNING GEAR765333656NUMBER OF THERMOCOUPLE48225662LOCATION OF DETECTORS2NUMBER OF RTD

SPEED MEASUREMENT

*HALL PROBE

*BASIC ARRANGEMENT OF HALL PROBES AT BEARING 1SENSORWIREBRACKETPERMANENT MAGNETSN-POLES-POLEDISK

*HALL PROBE (USED FOR SPEED MEASUREMENT)PRINCIPLE :IxIxFy EyAB(+)(-)ExF = q (E + V*B)In Y direction the force is= q( Ey Vx Bz )Bz Ey = Vx Bz Ey = Hall EffectVAB = (Rh. B. I )/ WHALL VOLTAGEMagnetic Field Applied Perpendicular To The Direction Of Driftw

*HALL PROBE IN BEARING NO. 1 PEDESTAL

*PMI Revision 00 *OVERSPEED TRIP BOLTS IN TURBINE ROTOR

OVERSPEED TRIP BOLTS IN BEARING NO. 1 PEDESTAL

VIBRATION MEASUREMENT

*VIBRATION MONITORING

WHAT IS VIBRATION ?

WHAT CAUSES VIBRATION ?

HOW DO WE MEASURE VIBRATION ?

HOW DO WE ANALYSE VIBRATION ?

*Basic Theory Of VibrationSimple Spring Mass SystemUpper LimitNeutral PositionLower PositionDisplacementMax Acceleration, Min VelocityMax Acceleration, Min VelocityMax Velocity, Min AccelerationIT FOLLOWS SINE CURVE

*What Is Vibration?It is the response of a system to an internal or external force which causes the system to oscillate.

*2. Measurement direction - Horizontal, Vertical, Axial.

*

*VIBRATION MONITORINGModes of Amplitudes

DISPLACEMENT

VELOCITY

ACCELERATION

SPIKE ENERGY

*Physical Significance Of Vibration Amplitude Displacement : Strain Indicator

Velocity : Fatigue Indicator

Acceleration : Force Indicator

*VIBRATION SENSITIVITYDISPLACEMENTVELOCITYACCELERATIONFREQUENCYCPM60600600060000600 00010

1

.1

.01

.001WHEN TO USE DISPLACEMENT, VELOCITY & ACCELERATION

*The significance Displacement gives the strain energyVelocity gives the kinetic energyAcceleration gives the forceSpike energy/HFD/gE are special ways to measure acceleration only.

*VIBRATION MONITORINGUNITS OF MEASUREMENT

DISPLACEMENT -MICRONS

VELOCITY -MM / SEC.

ACCELERATION -MM / SEC2 , G

*Vibration SensorsAcceleration Sensor - Accelerometer Velocity sensor Velocity sensor or seismic sensorDisplacement sensor - Non Contact pickup

*PMI Revision 00 *AccelerometerPiezoelectricityEmf proportional to forceEmf proportional to acceleration (Mass constant) Hence called accelerometer

Accelerometer

*Accelerometer

*Accelerometer cont..Uses piezoelectric crystal Normally uses internal amplifier for boosting signal It will have low temp application up to 150 degree CFor high temperature application amplifier is not given insideThis causes low signal strength and we use gold plated contacts and small cable lengths (output rated in pc per g). The amplification is done outsideNormal accelerometer (amplifier inside) will have strong signal output and can sustain cable lengths of 300 meterCan measure Acceleration, velocity and displacementAvailable in several design, can go from DC to 10k Hz freq (600,000 CPM)It is advised to involve suppliers or persons knowledgeable in this area to choose accelerometers for on line monitoring applications

*Velocity sensorCoilOutput=B*l*VB & l are constantOutput is proportional to velocity, hence the name Velocity sensorMagnetMagnetAluminum caseDamperSpringTerminals

*Velocity sensor cont.This is self generating (764 mv per mm/sec)Can sustain cable length of 1000 feet easilyFor longer length intermediate amplification is neededThe temperature rating is higher up to 250 degree C (no electronics inside)Sensitive to 60,000 CPMCan check velocity and displacement only

*Non contact type

*Non contact sensor Installation in a Turbine

*VIBRATION MEASURING INSTRUMENTATIONSHAFT VIBRATION PROXIMITY PROBE

BEARING VIBRATION- VELOCITY PICK UP

*ABSOLUTE BEARING VIBRATIONVELOCITY TRANSDUCERSEISMIC MASS TYPE Works on PLUNGER COIL PRINCIPLE.Two permanent magnets rigidly fixed to the casing with coils arranged as seismic mass.The Relative motion between the coil and magnet generates voltage proportional to vibration velocity.

123456Exciter of vibrationPermanent MagnetPlunger CoilMagnetic Return PathSpringSensor CaseSIESMIC MASS : Plunger Coil principleNatural frequency of spring mass system = 2f = c/mm = mass of plunger coil with springC = spring constantAbove ,coil stands still due to its mass inertia When coupling the siesmic sensor to vibrating structure,a relative movement isgenerated between permanent magnet & plunger coil.a voltage is induced in the coilWhich is proportional to the vibration velocity :

e = B . l . Vl= Length of conductorsB= magnetic inductionv =speed of vib.

ABSOLUTE SHAFT VIBRATIONRELATIVE SHAFT VIBRATION IS BASED ON EDDY CURRENT PRINCIPLE.PROXIMOTY PROBE SENSES THE DISTANCE BETWEEN THE PROBE TIP AND THE OBSERVED SURFACE.PROXIMETER GENERATES A RADIO FREQUENCY SIGNAL, WHICH IS RADIATED THROUGH THE PROBE TIP INTO THE OBSERVED SURFACE. EDDY CURRENTS ARE GENERATED IN THE SURFACE AND LOSS OF STRENGTH IN THE RETURN SIGNAL IS DETECTED BY THE PROXIMETER.

*PROXIMITY TRANSDUCERSENSES THE DISTANCE BETWEEN THE PROBE TIP AND OBSRVED SURFACEPROXIMETER GENERATES RF SIGNAL, RADIATED THROUGH PROBE TIP INTO OBSERVED SURFACE.EDDY CURRENTS ARE GENERATED IN THE SURFACE AND THE LOSS OF STRENGTH IN THE RETURN SIGNAL IS DETECTED.LOSS OF POWER PROPORTIONAL TO GAP BETWEEN PROXIMETER & CONDUCTIVE BODY.

*PROXIMITY SENSOR :

*CONDUCTIVEMATERIALPROXIMITOREddy CurrentRadio FrequencySignalThe oscillator in the matching unit supplies(RF signal) the coil in the sensor with a load Independent,high frequency alternating current.if the sensor isbrought near to a metal object,the eddy currents are induced in surface of the object and the power is absorbed thus alternating the voltage across the coil.The alternating voltage is proportional to the distance between the measured Object and the sensor.the output amplifier forms a load independent D.C. Voltage signal.

THE PROXIMITY PRINCIPLE:

**SHAFT & BEARING VIBRATION PICK UP

BEARING / SHAFT VIBRATION PICK UP MOUNTED ON BEARING NO. 4 PEDESTAL

*PROXIMITY PROBE

RELATIVE AND ABSOLUTE EXPANSION

*EXPANSION MEASURING INSTRUMENTSOVERALL EXPANSION POSITION TRANSMITTER

DIFFERENTIAL EXPANSION MEASUREMENT PROXIMITY PROBE

AXIAL SHIFT MEASUREMENT PROXIMITY PROBE

*OVERALL EXPANSION PICK UP

*OVERALL EXPANSION MOUNTED ON BEARING NO. 1 PEDESTAL

PMI Revision 00 *DIFFERENTIAL EXPANSION (FOR SMALL EXPANSION) & AXIAL SHIFT PICK UP

*I-L1 L2 Sensor Coils d1 d2 Air gapl1l2d1d2Turbine ShaftMeasuring AttachmentTurbine CasingPower Supply UnitSmall relative Expansion,Shaft with CollarIf a relative movement is occur between turbine shaft and casing ,the air gap changes and, as a result the inductance of sensor coils changes inverselyRELATIVE EXPANSION

IP DIFFERENTIAL EXPANSION PICK UP MOUNTED ON BEARING NO. 3 PEDESTAL

*DIFFERENTIAL EXPANSION (FOR LARGE EXPANSION) PICK UP

*AXIAL SHIFT MEASUREMENT AT IP COLLAR

I-MeasuringAttachmentPower Supply UnitLarge Relative Expansion, Shaft with double coneL1 L2 Sensor Coils d1 d2 Air gapRELATIVE EXPANSION :

*DIFFERENTIAL EXPANSION (FOR LARGE EXPANSION) PICK UP

LP DIFFERENTIAL EXPANSION PICK UP MOUNTED ON BEARING NO. 4 PEDESTAL

RANGE OF MEASUREMENTAXIAL SHIFT BEFORE : -0.5mm TO +0.5mmAXIAL SHIFT AFTER RECOMMENDATION OF TRIP COMMITTEE : -1mm TO +1mmDIFF. EXPANSION BRNG 1 : -5 TO +16 mmDIFF. EXPANSION BRNG 3 : -5 TO +16 mmDIFF. EXPANSION BRNG 4 : -10 TO +38mm

THANK YOU

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