condition based monitoring training

CONDITION MONITORING

James Anantharaj.TOperational Energy Group of India (P) Ltd

CONDITIONMONITORING Condition monitoring is defined as the

continuous or periodic measurement &interpretation of data to indicate the condition of an equipment to determine the need for maintenance .

MAINTENANCE TYPESBREAKDOWN MAINTENANCE

REGULAR PREVENTIVE MAINTENANCE

CONDITION BASED MAINTENANCE

WHY CONDITION MONITORING ?

Determination of the condition of a machine or device and its change with time in order to determine its condition at any given time.

PHYSICAL PARAMETERS OF MEASUREMENTvibrationNoiseTemperatureOil Contaminationwear debris etc

CONDITION MONITORING THROUGH VIBRATION ANALYSISWhat is Vibration?

It is the response of a system

to an internal or external force which causes the system to oscillate.

AMPLITUDE MEASUREMENT1. Displacement :

Total distance traveled by the mass.

Unit : Microns

2. Velocity :

Rate of change of displacement. It is the

measure of the speed at which the mass is

vibrating during its oscillation.

Unit : MM/Sec, Inch/sec

3. Acceleration :

It is the rate of change of velocity. The

greater the rate of change of velocity the

greater the forces (P=mf) on the machines.

Unit : MM/Sec2, Inch/sec2

VIBRATION SENSITIVITY DISPLACEMENT

VELOCITY

ACCELERATION

FREQUENCYCPM

60 600 6000 60000 600 000

10

1

.1

.01

.001

When To Use Disp., Vel. & Acc.?

WHAT IS THE ADVANTAGE OF USING VELOCITY?

Flat frequency range compared to displacement & acceleration.

Almost all machines generate fault frequency between 600CPM to 60KCPM

Velocity indicates fatigue. Velocity is the best indicator of vibration severity.

MEASUREMENT DIRECTION - HORI, VERT, AXIAL

CAUSES OF VIBRATION (CONT.,)1. Unbalance (Static, Couple, Quasi-Static),

2. Misalignment (Angular, Parallel, Combination)

3. Eccentric Rotor, Bent Shaft

4. Mechanical Looseness, Structural Weakness,

Soft Foot

5. Resonance, Beat Vibration

6. Mechanical Rubbing

7. Problems Of Belt Driven Machines

CAUSES OF VIBRATION 8. Journal Bearing Defects

9. Antifriction Bearing Defects

(Inner race, Outer race, Cage, Rolling Elements)

10. Hydrodynamic & Aerodynamic Forces

(Blade Or Vane, Flow turbulence, Cavitation)

11. Gear Problems (Tooth wear, Tooth load, Gear eccentricity,

Backlash, Gear misalignment, Cracked Or Broken Tooth)

12. Electrical Problems of AC & DC Motor ( Variable Air Gap,

Rotor Bar Defect, Problems of SCRs)

CAUSES OF UNBALANCE Uneven distribution of mass of rotor.

Dirt accumulation on fan rotors.

Rotor eccentricity

Roller deflection, especially in paper machines

Machining errors

Uneven erosion and corrosion of pump impellers

Missing balance weights

TYPES OF UNBALANCE Static Unbalance

Couple Unbalance

Overhang Rotor Unbalance

Case Study 1:

ID FAN:Technical Data:Motor Make: Nayayang, ChinaMotor Power: 650 KW, 658.8 A, 690 VMotor Speed: 994 rpmFan Make: FLAKT WOODSFan Design Capacity: 46.57 Nm3/sFan Normal Capacity: 40.50 Nm3/sStatic Inlet Design Pressure: 636 mm WCNormal Inlet Pressure: 530 mm WCType of Coupling: Resilient coupling Type of foundation: Common metal frame

Measurement Location

Vibration velocity in mm/sec RMS

Horizontal

Vertical Axial

Motor Non Drive End 4.1 3.5 3.2Motor Drive End 6.9 5.6 3.3Fan Drive End 5.0 4.9 6.5

Fan Non Drive End 3.5 1.4 3.5

At 977 rpm

At 914rpm

Measurement Location

Vibration velocity in mm/sec RMS

Horizontal

Vertical Axial

Motor Non Drive End 5.4 1.7 2.1Motor Drive End 5.9 4.3 2.5Fan Drive End 4.3 4.7 8.6Fan Non Drive End 2.4 0.8 2.6

Remarks: 1. Maximum vibration value of 8.6 mm/sec was observed at Fan Drive End (914 rpm). 2. Observed that overall vibration is less (7.0 mm/sec) in 933 rpm. So 933 to 951 rpm are recommended for operating speed instead of 914 rpm.3. During dynamic balancing they have added 3.4 kg in impeller .This weight (3.4 kg) was not exactly placed in the required area. Hence the dynamic balancing (weight & phase angle) to be rechecked. 4. Lubricate Fan Non Drive End bearing.

CAUSES OF MISALIGNMENT Thermal expansion - Most machines align cold.

Machine vibrations.

Forces transmitted to the machine by pipe or

support structure.

Soft foot.

Direct coupled machined are not properly aligned.

Poor workmanship.

TYPES OF MISALIGNMENT

Angular

Centre lines of two shafts meet at an angle

Offset

The shaft centre lines are parallel, but

displaced from one another.

A combination of angular and offset misalignment

Case Study 2:

MCWP:Technical Data:Pump Make KIRLOSKAR Pump Capacity 1400 m3/hHead 27 mPump speed 1480 rpmType of Coupling Pin-bush couplingType of foundation Common metal frame for motor & pump

Measurement Location

Vibration velocity in mm/sec RMS

Horizontal

Vertical Axial

Motor Non Drive End 3.9 1.3 6.2

Motor Drive End 4.6 2.5 6.9

Pump Drive End 1.5 2.5 5.7

Pump Non Drive End 3.3 4.1 6.6Remarks: •Maximum vibration value of 6.9 mm/sec was observed at Motor Drive End.•Check for coupling misalignment between motor and pump.•High temperature (up to 98 deg C) measured in motor drive side hence guard cover at motor cooling fan side to be modified.

Spectrum:

MECHANICAL LOOSENESS: It alone can not create vibration but in the

influence of Unbalance, Misalignment, Bearing problems it amplify the amplitude.

It should be corrected first.

Types:1.Structural frame/base looseness (1X)2. Cracked structure/bearing pedestal (2X)

3. Rotating looseness - Loose bearing/improper

fit between component parts. (Multiple)

Case Study 3:

ACWP:Technical Data:Motor Make: CROMPTON GREAVESMotor Power: 75 KW, 415 V, 119 ASpeed: 1415-rpmPump Make: KIRLOSKARHead: 45 mCapacity: 4.5 kg/cm2

Type of foundation: Common metal frame for motor & pumpHandling media: Cooling water

Measurement Location

Vibration velocity in mm/sec RMS

Horizontal Vertical Axial

Motor Non Drive End 1.1 2.1 4.3Motor Drive End 1.5 3.0 4.3Pump Drive End 8.1 5.7 4.3Pump Non Drive End 4.3 4.8 3.9Remarks:

•Maximum vibration value of 8.1 mm/sec was observed at Pump Drive End.•Found that looseness between common base frame to foundation in Motor Drive End. Hence the grouting to be checked.•Check the impeller for defects or proper sitting/Flow problem.

Spectrum:

OIL WHIRL

Cause: Excessive clearance and light radial loading. This results in the oil film building up and forcing the journal to migrate around in the bearing at less than one-half RPM.

It can create metal to metal contact.

WHY DOES BEARING FAIL?1. Improper lubrication

2. Contaminated lubrication

3. Heavier loading from unbalance,Misalignment,

bent shaft etc.

4. Improper handling or installation.

5. Old age (Surface fatigue) .

Adaptor Sleeve Looseness

Type of BearingDefects Amplitude Frequency

High in AxialUsually 2X RPM

Along with 6 to 10X RPM

Axial Play High in Axial Usually 2X RPMAlong with 12 to 15X RPM

Axial Thrust High in Axial Usually 1X RPM, 2X RPMAlong with 15 to 18X RPM

Increased ClearanceHigh in Vertical & AxialUsually 2X RPM Along with 15 to 18X RPM

Cage Inaccuracies High in Radial DirectionVery High Frequencies(some times Noise also)

Improper Fit with Housing

High in Radial

High Frequencies with Increased Temperature; Phase analysis indicates slow movement of

reference mark depending on the severity of improper fit.

Improper Fit with ShaftHigh Radial & Axial with Erratic Readings

Very High Frequency Sometimes with Knocking Noise.

Characteristics

Case Study 4:PA FAN:Motor Make: NANYANG EXPLOSION PROTECTION GROUPMotor Power: 830 KW, 6600 V, 88 ASpeed: 1490-rpmType of coupling: Voith couplingFan Flow (Design): 32.8 m³/sFan Flow (Opts): 21.1 m³/sInlet static pressure: 30 mmwc (-ve)Type of lubrication in Fan: Oil (Servo system 68)Handling media: Atmospheric air

Measurement Location

Vibration velocity in mm/sec RMS

Horizontal

Vertical

Axial

Motor Non Drive End

0.4 0.2 0.1

Motor Drive End 0.6 0.3 0.1

Voith Drive End 1.0 0.9 1.8Voith Non Drive End

1.1 0.8 2.0

Fan Drive End 1.0 0.4 1.3Fan Non Drive End

0.6 0.4 0.5

Remarks: •Maximum vibration value of 2.0 mm/sec was observed at Voith Non Drive End. •Minor bearing defects are started in VDE and FNDE. Hence monitor the bearing condition.

Spectrum:

GEAR BOX

RPM1

RPM2

Z1

Z2

GMF (Gear Mesh Frequency)Z1 .RPM1 = Z2 .RPM2

where Z = no. of teeth and RPM shaft speed

GEAR BOX DEFECTSTooth wearGear eccentricity & backlashGear misalignmentCracked or broken toothHunting tooth

Case Study 5:

ACC FANTechnical Data:Motor Make: ABBMotor Power: 90KW, 415 V, FLC 153.3 ASpeed: 1475 rpm Type of coupling: Pin bush couplingHandling media: Atmospheric air

Measurement Location

Vibration velocity in mm/sec RMS

Horizont

al

Vertical

Axial

Motor Non Drive End 4.69 2.58 2.72

Motor Drive End 2.60 3.02 1.63

Gearbox Output Non Drive End

4.04 2.72 8.59

Remarks: 1. Maximum vibration value of 8.59 mm/sec was observed at GB OP Non Drive End.2. Check the gearbox for gear mesh frequency and check gearbox output bearings.

Spectrum:

HYDRAULIC & AERODYNAMIC FORCESFLOW TURBULENCE

• Flow turbulence often occurs in blowers due to variations in pressure or velocity of air in ducts

• Random low frequency vibration will be generated, possibly in the 50 - 2000 CPM range

Case Study 6:MOTOR

PUMP

MNDEPNDEMDE PDE

CEPTechnical Data:Motor Make: SIEMENSMotor Power: 200 KW, FLC 323 ASpeed: 2985-rpmType of lubrication : Lithium complex greasePump make: SULZERType of lubrication : Turbine oil servo -46Type of foundation: Rigid Handling media: Condensate water

Measurement Location

Vibration velocity in mm/sec RMS

Horizontal

Vertical

Axial

Motor Non Drive End 1.2 0.5 0.8Motor Drive End 1.4 0.4 0.5Pump Drive End 7.4 7.1 3.1Pump Non Drive End 4.0 4.3 3.7

Remarks: 1. Maximum vibration value of 7.4 mm/sec was observed at Pump Drive End.2. Check the Pump Drive End bearing for clearance on opportunity.•Check the Pump impeller for flow/defect problem.

Spectrum:

FANS

Mainly radial vibrations

FBPF with 1X RPM sidebands.

Unbalanced horizontal or axial vibrations.

Inadequate blade clearance (at FBPF or RPM harmonics)

Uneven velocity distribution across fan inlet gives FBPF vibrations

Fan Blade Pass Frequency = RPM x no. of fan blades(FBPF)

PUMPSVibration signature depends upon operating condition.

pressure, temperature, speed, cavitation….

Centrifugal pumps at Vane Pass Frequency = RPM . no. of impeller vanes and harmonics.

Gear pumps at Gear Mesh Frequency and 1X sidebands

Screw pumps at thread rate = RPM . number of threads and its harmonics.

ELECTRICAL PROBLEM Unequal magnetic forces due to rotor not round

Eccentric armature journals

Rotor and stator misalignment

Elliptical stator bore

Broker bar

Open and shorted windings

VIBRATION TRANSDUCER Piezoelectric transducer

(Accelerometer) Induction transducer

(velocity probe) Proximity probe

(Displacement probe)

THERMOGRAPHYObjectives of Test

To detect hot or cold area’sTo determine absolute temperatureTo view Thermal profilesTo detect temperature loss

HEAT TRANSFER MODESConductionConvectionRadiation

Radiation

Conduction

Convection

THERMOGRAPHYInfra Red is part of the Electromagnetic Spectrum

It travels in straight lines at the speed of lightThe useful part is divided between Short and

Long wavelengthsUse of the correct wavelength is essential

WHY THERMOGRAPHY?Non ContactRapid ScanningData can be recorded in differing formats Images produced are comprehensive & reliable Is there a viable alternative?

Eg:These two glasses visually appear the

same.

Thermal Imaging with an infrared camera.

“ Paints a different picture.”

ELECTRICALSwitch GearFuse boxesCable runsElectrical connectors InsulationTransformers

REFRACTORY LININGSTorpedo ladlesBoilersFurnacesExhaustsDucting Kilns

ELECTRIC MOTOR BEARING

PUMP BEARING

BELT DRIVE

Loose or tight belt heats up abnormally

PIPE SEDIMENT

QUERIES?

THANK YOU!!!