004 Predictive Maintenance 01 04 07

Predictive Maintenance Planning

PdM*Predictive Maintenance - Dr. Attia Gomaa - 2007

Predictive Maintenance:Condition basedmanagementVisualInspectionVibrationanalysisUltrasonic

Pressureanalysis

TemperatureanalysisOil analysisEfficiency analysisWearanalysis


Atypical machine condition-vibration trend


Predictive Maintenance TechnologiesOil AnalysisVibration AnalysisLaser Alignment & Shaft BalancingThermography (Infrared Camera)Ultrasonic EvaluationElectronic Signature Analysis (Motor Current Analysis)


Oil AnalysisTake periodic samples of oil from equipment and send out for laboratory analysisTests condition and wear of componentsWill warn of impending problems and reduce chance of premature failuresWill possibly point out root causes of failureCosts


Vibration AnalysisVibration is measurement of the periodic motion of equipment (I.e. the shaking). Vibration is measured in units of inches/second (in/sec, IPS).All equipment vibrates, but if this vibration becomes too severe, it indicates problems. Use vibration levels to prioritize repairs.Some Rules of Thumb to judge the condition of your equipment:less than 0.050 IPSExcellent0.050 - 0.100 IPSGood0.100 - 0.200 IPSAcceptable0.200 - 0.400 IPSUnacceptablegreater than 0.400 IPSFailure Likely


Vibration AnalysisThe technician takes a simple hand held instrument out each piece of equipment to be tested.He then attaches a magnetic accelerometer to several specific places and records readings electronically.These readings are then downloaded to a computer and analyzed with a software program purchased with the hand held instrument.


Vibration AnalysisTwo OptionsCosts to set up your own on-site programApproximately $40,000 for software and hardwareOne week training for your technicianYour technician must work on vibration monitoring at least 3 days/month to stay fluent in the technology and analysis

Costs to contract outApproximately $7,000 per year (depends on number of pieces of equipment and accessibility)


Laser AlignmentProvides quicker and more accurate means of shaft alignment than dial gauges.There are many sources of error in dial gauge readings:sagging indicator bracketssticking/jumping dial handslow resolution means rounding lossesplay in mechanical linkagestilted dial indicator leads to offset errorsaxial shaft play leads to gap errorLaser alignment tool costs $13,000 - $15,000.Technician requires one day training about how to use the tool.


Infrared ImagingA handheld camera is used in a way that enables you to see temperature differences. The camera is a lot like a video camera in size and weight.The hotter the temperature, the more yellow the equipmentNot all temperature differences are indicative of problemsYou must be trained to recognize those temperature differences that are significantSome Infrared Imaging Costs: Thermal imaging system ~$30,000Technician training & fluency education


Here is a transformer as seen through a short wave infrared camera.The yellow coloring does not indicate a problem. It is the reflection of sunlight.The maintenance technician must be trained to recognize this. Otherwise he will report false hot spots that will lead to wasted corrective action.Infrared Imaging


Here, the same transformer is seen through a long wave infrared camera.The false hot spots seen through the short wave camera do not show up here but maintenance technician must be trained to recognize significant yellow areas.Maintenance programs that require outdoor surveys are best served by long wave cameras.Infrared Imaging


Ultrasonic EvaluationUltrasonic testing is used to check for: arcing, tracking, corona discharge and vibration.In certain instances it is easier to listen for problems from a distance when it is difficult to get right next to the equipment in question.Ultrasound is an effective, low cost means of evaluating the condition of insulation components on high-voltage transmission and distribution equipment.Initial Equipment Cost: $4300Training Costs:Initial Training = 40 hours offsite, fee= $1,500Recertification = 8 hours, twice per year, offsite


Ultrasonic EvaluationUltrasound should be used in conjunction with Infrared Imaging when Infrared Imaging is not practical.Ultrasound can often detect potential insulation faults that do not show up in an infrared survey.A combination of infrared and ultrasound is often used on high-voltage electrical equipment, particularly enclosed switchgear.Infrared locates resistive faults (e.g. dirty switch contacts or loose joints)Ultrasound locates developing insulation faultsUltrasound instrument can be used on enclosed switchgear that cannot be viewed with an infrared instrument. Removing a few bolts allows ultrasound to penetrate into the inside of the gear.


Ultrasonic EvaluationUltrasound used here to test for vibration problems in hard-to-reach bearing.


Electronic Signature AnalysisElectronic signature analysis (ESA) is a developing predictive maintenance technology that can supplement other technologies.ESA instrument acquires voltage and current supplied to an electric motor. Associated software helps maintenance technician analyze that data and determine the health of the motor, distortion of the incoming power, and vibration characteristics of the driven equipment.Initial & training costs.

Industiral Safety for Maintenance Engineers - Dr. Attia GomaaIndustiral Safety for Maintenance Engineers - Dr. Attia GomaaIndustiral Safety for Maintenance Engineers - Dr. Attia Gomaa

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004 Predictive Maintenance 01 04 07