15-Auxiliary-fan-failure-Vale.pdf

High Speed Auxiliary Fan High Speed Auxiliary Fan Failure and Subsequent Fan Failure and Subsequent Fan

and Electric Motor and Electric Motor ModificationsModifications

HistoryHistory

Auxiliary ventilation has been used in underground coal Auxiliary ventilation has been used in underground coal mining for many yearsmining for many years

In the seventies 9mIn the seventies 9m33 fans were the norm, in the fans were the norm, in the eighties 13meighties 13m3, i3, in the nineties 18m3 and today 22.5mn the nineties 18m3 and today 22.5m33

and larger fans are requiredand larger fans are required

With the increase in fan capacity comes the need for With the increase in fan capacity comes the need for more Kilowatts, more impeller mass and greater more Kilowatts, more impeller mass and greater system inertia.system inertia.

HistoryHistory

9 cubic metre per second

13 cubic metre per second

HistoryHistory

18 cubic metre per second

22.5 cubic metre per second

HistoryHistoryIn 1991 MDG3 was initially published to provide In 1991 MDG3 was initially published to provide manufactures of auxiliary fans with the construction and manufactures of auxiliary fans with the construction and safety features for fans required to be approved under the safety features for fans required to be approved under the Coal Mines Regulation Act of 1982Coal Mines Regulation Act of 1982

Industry expectations and the publishing of this document Industry expectations and the publishing of this document resulted in the upgrading of fans from having a very basic resulted in the upgrading of fans from having a very basic onboard explosion protected enclosure housing a basic onboard explosion protected enclosure housing a basic isolator, contactor, overload and receptacle configuration to isolator, contactor, overload and receptacle configuration to a more sophisticated control system as we see todaya more sophisticated control system as we see today

Occurrence Occurrence of Fan of Fan

FailuresFailures1994 Tower Fan Failure1994 Tower Fan Failure

2006 Austar, Mandalong, 2006 Austar, Mandalong, Wambo, Ashton Coal and Wambo, Ashton Coal and Newpac Newpac

The failures were similar in all The failures were similar in all fans:fans:

Contact between rotor shaft Contact between rotor shaft and the flame path and the flame path ““bushingbushing””generated heat due to frictiongenerated heat due to friction

Flame path Flame path ““bushingbushing”” and shaft and shaft ““friction weldedfriction welded””

HistoryHistory

As you can see in the significant incident report, in April As you can see in the significant incident report, in April 1994 an auxiliary ventilation fan failure occurred in the 1994 an auxiliary ventilation fan failure occurred in the Southern Coal Fields of NSW resulting in an under ground Southern Coal Fields of NSW resulting in an under ground fire on the fan. This failure was almost identical to the fire on the fan. This failure was almost identical to the catastrophic failure which occurred at Newpac Mine which is catastrophic failure which occurred at Newpac Mine which is the subject of todaythe subject of today’’s presentations presentation

There have also been many fan failures which have There have also been many fan failures which have occurred in the past 20 years and these fans have been occurred in the past 20 years and these fans have been simply repaired, rebuilt and returned to service. It should simply repaired, rebuilt and returned to service. It should be noted that all fan failures recorded occurred on fans be noted that all fan failures recorded occurred on fans having two pole motors rotating at 2980 RPMhaving two pole motors rotating at 2980 RPM

A number of these failures have been very close to A number of these failures have been very close to resulting in catastrophic fan failures as a number of you resulting in catastrophic fan failures as a number of you here today would have witnessedhere today would have witnessed

HistoryHistoryThe Department, with assistance from key industry The Department, with assistance from key industry representatives, published an updated Mines Department representatives, published an updated Mines Department Guideline MDG 3 in 1996, in an attempt to set minimum Guideline MDG 3 in 1996, in an attempt to set minimum design standards for Australian Ventilation Fans and to design standards for Australian Ventilation Fans and to reflect current safety expectations. This guideline was reflect current safety expectations. This guideline was quickly adopted by the industry as the standard for the quickly adopted by the industry as the standard for the rebuild and overhaul of fans. The key engineering safety rebuild and overhaul of fans. The key engineering safety controls which were reinforced in this MDG3 document controls which were reinforced in this MDG3 document were:were:

•• Vibration monitoring of the Drive TrainsVibration monitoring of the Drive Trains•• Temperature monitoring of BearingsTemperature monitoring of Bearings•• Anti Wind Milling ProtectionAnti Wind Milling Protection•• Noise level controlsNoise level controlsTo mention just a few of the key design criteria .To mention just a few of the key design criteria .

In 2006 a number of fan failures occurred which were as a In 2006 a number of fan failures occurred which were as a direct result of the onboard electric motor failure. The fan direct result of the onboard electric motor failure. The fan configurations included the impeller directly mounted to the configurations included the impeller directly mounted to the motor shaft, no carrier shaft was incorporated into the fan motor shaft, no carrier shaft was incorporated into the fan designsdesigns

Ashton CoalAshton CoalAshton Coal fan taken out of service due to repeated trips Ashton Coal fan taken out of service due to repeated trips caused by vibration caused by vibration

Impeller balance checked on site and found to be Impeller balance checked on site and found to be ““okayokay””

Motor bearings appeared to be source of vibrationMotor bearings appeared to be source of vibration

Motor stripped and inspected at G & D DonnellyMotor stripped and inspected at G & D Donnelly

Flame path exhibited signs of high temperature Flame path exhibited signs of high temperature (discolouration)(discolouration)

Flame path housing scored by contact with shaftFlame path housing scored by contact with shaft

Drive End Flame Path Bushing

Ashton Coal FanAshton Coal Fan

Flame Path on Rotor Shaft at Drive End

•• Flame path surface on shaft damaged by friction Flame path surface on shaft damaged by friction welding and scoring by contact with housingwelding and scoring by contact with housing

Ashton CoalAshton Coal

Bearing mounting bore in DE end shield worn by rolling Bearing mounting bore in DE end shield worn by rolling outer raceouter race

Damage to bearing outer race

Bearing Mounting Bore in DE End Shield

DE Bearing Outer Race

NewpacNewpac

On 14 August 2006 a catastrophic failure occurred to On 14 August 2006 a catastrophic failure occurred to a 22.5 cube high speed fan operating underground in a 22.5 cube high speed fan operating underground in the hazardous area at Newpac Coal Mine in the Hunter the hazardous area at Newpac Coal Mine in the Hunter Valley. The impellor was direct mounted to the motor Valley. The impellor was direct mounted to the motor shaft.shaft.It is this failure and the findings that this session will It is this failure and the findings that this session will cover in detail todaycover in detail today

Initial InvestigationInitial Investigation

On the morning of 14 August we received a phone call On the morning of 14 August we received a phone call from the acting Engineering Manager at Newpac Mine, from the acting Engineering Manager at Newpac Mine, advising that a Hire Fan, Plant Number AF20214, had advising that a Hire Fan, Plant Number AF20214, had catastrophically failed while operating underground in catastrophically failed while operating underground in the hazardous zonethe hazardous zone

The Department of Primary Industry had been notified The Department of Primary Industry had been notified and an underground inspection was pendingand an underground inspection was pending

After the underground inspection was completed by After the underground inspection was completed by the Department of Primary Industry inspectors, we as the Department of Primary Industry inspectors, we as equipment OEM, were advised that the fan was being equipment OEM, were advised that the fan was being transported to the surface where the fan was transported to the surface where the fan was quarantined, until further investigation into the failure quarantined, until further investigation into the failure could be undertakencould be undertaken

Initial InvestigationInitial Investigation

As the OEM Fan Manufacturer, we were summoned to As the OEM Fan Manufacturer, we were summoned to a site meeting with colliery representatives, mine site a site meeting with colliery representatives, mine site officials, and DPI investigators. The site meeting officials, and DPI investigators. The site meeting involved interviews with relevant mine staff including involved interviews with relevant mine staff including the underground manager, maintenance personnel the underground manager, maintenance personnel and statutory officials, plus OEM representativesand statutory officials, plus OEM representatives

During the meeting every attempt was made to track During the meeting every attempt was made to track and document the operation and maintenance issues and document the operation and maintenance issues of the fan, in particular the shifts leading up to failureof the fan, in particular the shifts leading up to failure

The maintenance and service documentation/manuals The maintenance and service documentation/manuals provided by the OEM were tabled along with Colliery provided by the OEM were tabled along with Colliery Maintenance recordsMaintenance records

Result of Fan failureResult of Fan failureLoss of explosion protection methods Exd due to the motor Loss of explosion protection methods Exd due to the motor junction box breaking away from the motorjunction box breaking away from the motor

Motor hold-down bolts

Result of Fan failureResult of Fan failure

Impeller detached from motor shaft and laying in fan casing

Damaged inlet eye

Result of Fan failureResult of Fan failure

Bent motor shaft –flame path subjected to temperatures above 8500C

Result of Fan failureResult of Fan failure

Structural and mechanical damage

Fan ConfigurationFan Configuration22 m22 m33 high speed (2850 RPM) centrifugal auxiliary high speed (2850 RPM) centrifugal auxiliary ventilation fanventilation fan

Impeller direct mounted to motor shaftImpeller direct mounted to motor shaft

150 kW, 2 pole, 1000 volt Exd motor with side mounted 150 kW, 2 pole, 1000 volt Exd motor with side mounted terminal boxterminal box

Protection System FittedProtection System Fitted

The fan was manufactured in August 2005 and fully The fan was manufactured in August 2005 and fully complied with MDG3.complied with MDG3.

Fan protection included:Fan protection included:•• Vibration monitoring including an (External Accelerator)Vibration monitoring including an (External Accelerator)•• Bearing temperature monitoring on both the D.E. and Bearing temperature monitoring on both the D.E. and

N.D.E BearingN.D.E Bearing•• Relay logic control Relay logic control

•• Anti WindAnti Wind Milling ProtectionMilling Protection

Block DiagramBlock Diagram

Electrical Electrical SystemSystem

Control System AuditControl System AuditOn 25 August the fan electrical system was examined jointly On 25 August the fan electrical system was examined jointly by Vale and DPI personnel with the following issues reported;by Vale and DPI personnel with the following issues reported;

•• Motor overload screwed up above normal trip settingsMotor overload screwed up above normal trip settings

•• Vibration system failed to trip (accelerometer on motor foot Vibration system failed to trip (accelerometer on motor foot inactive)inactive)

•• Accelerometer mounted with its axis incorrectly orientedAccelerometer mounted with its axis incorrectly oriented

•• Bearing temperature monitoring on double ended housing active Bearing temperature monitoring on double ended housing active but didnbut didn’’t register on over temperature statust register on over temperature status

Examination at OEM FactoryExamination at OEM Factory

On 28 August the fan was systematically disassembled in On 28 August the fan was systematically disassembled in the presence of representatives of the DPI, CCI Pope on the presence of representatives of the DPI, CCI Pope on behalf of Newpac Mine, WEG, G&D Donnelley, Airgasco behalf of Newpac Mine, WEG, G&D Donnelley, Airgasco (Vale fan consultant) and Vale Engineering personnel(Vale fan consultant) and Vale Engineering personnel

Key motor components were sent to CCI Pope for detailed Key motor components were sent to CCI Pope for detailed metallurgical analysismetallurgical analysis

Airgasco were to compile a detailed report in the form of a Airgasco were to compile a detailed report in the form of a Failure Mode Effect AnalysisFailure Mode Effect Analysis

Finding by all parties were reported to subsequent meetings Finding by all parties were reported to subsequent meetings at the DPI offices in Maitlandat the DPI offices in Maitland

Safety alerts were issued to mines using this type of fanSafety alerts were issued to mines using this type of fan

Most Likely Failure SequenceMost Likely Failure SequenceImpact damage or uneven build up of particulate on the Impact damage or uneven build up of particulate on the impeller caused above normal fan running vibration impeller caused above normal fan running vibration (3mm/sec)(3mm/sec)

Vibration not detected by faulty accelerometer Vibration not detected by faulty accelerometer –– fails to fails to shut down fan (6mm/sec)shut down fan (6mm/sec)

Vibration not detected by mine personnel Vibration not detected by mine personnel –– attending attending toolbox talk in crib roomtoolbox talk in crib room

Combination of shock loading from vibration and the Combination of shock loading from vibration and the bearing outer race sliding fit causes damage and wear to bearing outer race sliding fit causes damage and wear to bore in DE end shield as the bearing outer race rolls in the bore in DE end shield as the bearing outer race rolls in the borebore

Wear in DE end shield decreases radial clearance in flame Wear in DE end shield decreases radial clearance in flame pathpath

The bearing retainer/flame path The bearing retainer/flame path ““bushingbushing”” comes in comes in contacts with the rotor shaftcontacts with the rotor shaft

Most Likely Failure Sequence Most Likely Failure Sequence (cont(cont’’d)d)

Friction heat is generated between the Friction heat is generated between the ““bushingbushing”” and and the rotor shaftthe rotor shaft

Rapid heat build up destroys the bearing grease Rapid heat build up destroys the bearing grease causing the bearing to fail catastrophicallycausing the bearing to fail catastrophically

Shaft temperature at the flame path exceeds 850Shaft temperature at the flame path exceeds 850ooC C reducing rotor shaft material propertiesreducing rotor shaft material properties

Shaft reaches critical condition and yields, causing Shaft reaches critical condition and yields, causing massive bending and centrifugal forcesmassive bending and centrifugal forces

Large centrifugal forces cause an unstoppable chain of Large centrifugal forces cause an unstoppable chain of events leading to the damage observed in the fanevents leading to the damage observed in the fan

Damage included detachment of motor terminal box Damage included detachment of motor terminal box from motor frame parting stater pig tails which defrom motor frame parting stater pig tails which de--energised the motor stopping the fanenergised the motor stopping the fan

Root CauseRoot CauseRoot cause of drive end bearing failure is a combination of Root cause of drive end bearing failure is a combination of vibration and bearing outer race fit in the end shield.vibration and bearing outer race fit in the end shield.As the severity of vibration caused by imbalance increases As the severity of vibration caused by imbalance increases the impeller develops an the impeller develops an ““orbital motionorbital motion””..Since the bearing outer race fit is a slide fit the outer race Since the bearing outer race fit is a slide fit the outer race begins to begins to ““rollroll”” in the end shield bore due to the in the end shield bore due to the circumferential difference between the outer race and the circumferential difference between the outer race and the end shield bore, the bore being greaterend shield bore, the bore being greaterMetal removed from the bearing and the end shield by this Metal removed from the bearing and the end shield by this process further exacerbates the wear accelerating process further exacerbates the wear accelerating deterioration of the bearing and its mountingdeterioration of the bearing and its mountingEventually the flame path bushing comes in contact with Eventually the flame path bushing comes in contact with the rotor shaftthe rotor shaftThe heat generated by this contact results in failure of the The heat generated by this contact results in failure of the bearing and destruction of the shaft in a catastrophic modebearing and destruction of the shaft in a catastrophic mode

IssuesIssuesLarge inlet screen size (50 x 50) allows objects Large inlet screen size (50 x 50) allows objects capable of causing damage to enter impellercapable of causing damage to enter impeller

Less than ideal vibration transducer location may Less than ideal vibration transducer location may not trip fan when large vibrations occurnot trip fan when large vibrations occur

Failure in single transducer disables vibration Failure in single transducer disables vibration monitoring systemmonitoring system

Close clearance between bearing retainer/flame path Close clearance between bearing retainer/flame path housing and shaft makes contact inevitable if wear housing and shaft makes contact inevitable if wear occurs between DE bearing outer race and mating occurs between DE bearing outer race and mating bore in end shield or, if the bearing failsbore in end shield or, if the bearing fails

IssuesIssues (cont(cont’’d)d)

Flame path housing material is not conducive to Flame path housing material is not conducive to acting as a bearing so when it comes in contact with acting as a bearing so when it comes in contact with the rotor shaft at the high relative surface speeds the rotor shaft at the high relative surface speeds rapid friction heating occursrapid friction heating occurs

Bearing fit used by WEG does not follow SKF Bearing fit used by WEG does not follow SKF recommendationsrecommendations

Possibility that fixed (DE) bearing outer race is not Possibility that fixed (DE) bearing outer race is not positively clamped on the outer race shoulders by positively clamped on the outer race shoulders by bearing retainers increasing likelihood that it can bearing retainers increasing likelihood that it can rotate in end shield borerotate in end shield bore

ConsiderationsConsiderationsWEG motor bearing LWEG motor bearing L1010 life under normal loads is life under normal loads is more than adequate but bearings can fail more than adequate but bearings can fail prematurely for a variety of reasons prematurely for a variety of reasons –– usually usually lubrication or vibration related lubrication or vibration related

Premature bearing failure will normally result in Premature bearing failure will normally result in detectable vibration before axis constraint (bearing detectable vibration before axis constraint (bearing condition) is seriously compromised condition) is seriously compromised

A small but significant increase in bearing clearance A small but significant increase in bearing clearance will result in shaft contact with the inboard bearing will result in shaft contact with the inboard bearing retainer/flame path bushingretainer/flame path bushing

WEG rotor shaft stiffness is adequate WEG rotor shaft stiffness is adequate -- ratio of ratio of critical speed to actual speed approx 1.4critical speed to actual speed approx 1.4

These are high speed machines with limited These are high speed machines with limited tolerance of large out of balance or foreign body tolerance of large out of balance or foreign body impactimpact

Considerations Considerations (cont(cont’’d)d)

Out of balance can occur over time due to uneven Out of balance can occur over time due to uneven buildbuild--up of particulate on the impellerup of particulate on the impeller

Jack shafts are not free of problems in service eitherJack shafts are not free of problems in service either

•• Alignment between motor and jack shaft to be Alignment between motor and jack shaft to be maintained throughout life of fanmaintained throughout life of fan

•• Coupling between motor and jack shaft must Coupling between motor and jack shaft must accommodate angular and radial missaccommodate angular and radial miss--alignmentalignment

•• Longer drive train must withstand mounting base Longer drive train must withstand mounting base deflectiondeflection

•• Two additional bearing assemblies to maintainTwo additional bearing assemblies to maintain

•• Skating bearing outer races have also been observed in Skating bearing outer races have also been observed in jack shaft bearingsjack shaft bearings

•• No flame path in jack shaft housingNo flame path in jack shaft housing

Possible Remedies Possible Remedies –– Hard BarriersHard Barriers

Locate vibration transducers to measure horizontal Locate vibration transducers to measure horizontal vibration at the motor DE on the vibration at the motor DE on the ‘‘xx’’ axis normal to the axis normal to the ((‘‘zz’’ ) shaft axis. This should detect vibrations ) shaft axis. This should detect vibrations sufficiently early to prevent major damagesufficiently early to prevent major damage

Fit second vibration transducer Fit second vibration transducer –– if possible directly to if possible directly to DE bearing outer raceDE bearing outer race

Revise DE bearing outer race fit to comply with SKF Revise DE bearing outer race fit to comply with SKF recommendationrecommendation

Rework existing motors to install steel sleeve in DE Rework existing motors to install steel sleeve in DE end shield (Donnelly modification) to accomplish SKF end shield (Donnelly modification) to accomplish SKF fit and provide harder material in which outer race is fit and provide harder material in which outer race is mountedmounted

Possible Remedies Possible Remedies –– Hard Barriers (contHard Barriers (cont’’d)d)

Ensure bearing retainers apply a positive clamping Ensure bearing retainers apply a positive clamping force to DE bearing outer raceforce to DE bearing outer race

Fit longer bolts for motor terminal box attachment Fit longer bolts for motor terminal box attachment ––to more closely match strength of motor frame to more closely match strength of motor frame materialmaterial

On new fans, use alternative motor with better history On new fans, use alternative motor with better history of reliabilityof reliability

Fit a smaller mesh screen to prevent large objects Fit a smaller mesh screen to prevent large objects impacting the impellerimpacting the impeller

Possible Remedies Possible Remedies –– Soft BarriersSoft Barriers

Introduce vibration transducer inspection and change Introduce vibration transducer inspection and change out program out program –– similar to used with radio remote similar to used with radio remote transmitterstransmitters

Regularly inspect and clean the impeller and remove Regularly inspect and clean the impeller and remove debris from the stone drop out box debris from the stone drop out box

Adopt predictive maintenance techniques that can Adopt predictive maintenance techniques that can detect bearing deterioration preceding failure allowing detect bearing deterioration preceding failure allowing preventive action to be taken preventive action to be taken –– regular vibration regular vibration surveysurvey

Update preUpdate pre--despatch check list to ensure all key despatch check list to ensure all key features are installed and functioningfeatures are installed and functioning

WEG Motor Bearing MountingWEG Motor Bearing Mounting

G & D Donnelly have been recovering motor end G & D Donnelly have been recovering motor end shields by installing a press fit steel sleeve bored to a shields by installing a press fit steel sleeve bored to a closer (but not tighter) machining tolerancecloser (but not tighter) machining tolerance

Motors fitted with steel sleeve have subsequently not Motors fitted with steel sleeve have subsequently not been returned as the result of the same failurebeen returned as the result of the same failure

Motor on Kestrel fan modified in Dec 2003 Motor on Kestrel fan modified in Dec 2003 –– sleeve sleeve machined to WEG tolerances (+0.018 / machined to WEG tolerances (+0.018 / --0.000)0.000)

Returned in May 2004 with suspected bent shaftReturned in May 2004 with suspected bent shaft

Shaft found to be not bent, sleeve bore still goodShaft found to be not bent, sleeve bore still good

Returned in Dec 2005 sleeve bore oversize 0.060Returned in Dec 2005 sleeve bore oversize 0.060

SKF Recommended Fit

Housing – fixed bearingFit class - K7150.000+0.012 / -0.028

150.012149.972

Outer RaceFit Class - h5150.000+0.000 / -0.018

150.000149.982

Theoretical fit: 0.028 interference0.030 clearance

Probable fit: 0.021 interference0.023 clearance

Median fit: 0.001 clearance

Bearing FitBearing FitActual Fit Used in Motor

Housing – fixed bearingFit class – H5150.000+0.018 / -0.000

150.018150.000

Outer RaceFit Class - h5150.000+0.000 / -0.018

150.000149.982

Theoretical fit: 0.000 interference0.036 clearance

Probable fit: 0.005 clearance0.031 clearance

Median fit: 0.018 clearance

SKFSKF MOTORMOTOR

Alternative Motor ManufacturerAlternative Motor ManufacturerBearing Size: 6316 C4Bearing Size: 6316 C4

Housing Housing –– DE fixed bearingDE fixed bearingFit class Fit class –– M6M6170.000 170.000 --0.008 / 0.008 / --0.0330.033169.992169.992169.967169.967Outer RaceOuter RaceFit Class Fit Class –– h6h6170.000+0.000 / 170.000+0.000 / --0.0250.025170.000170.000169.975169.975Theoretical fit:Theoretical fit: 0.033 interference0.033 interference

0.017 clearance0.017 clearanceProbable fit:Probable fit: 0.026 interference0.026 interference

0.010 clearance0.010 clearanceMedian fit:Median fit: 0.008 interference0.008 interference

Bearing Size: 6316 C4Bearing Size: 6316 C4

Housing Housing –– NDE floating bearingNDE floating bearingFit class Fit class –– closest to G7closest to G7170.000+0.030 / +0.055170.000+0.030 / +0.055170.055170.055170.030170.030Outer RaceOuter RaceFit Class Fit Class –– h6h6170.000+0.000 / 170.000+0.000 / --0.0250.025170.000170.000169.975169.975Theoretical fit: 0.030 clearanceTheoretical fit: 0.030 clearance

0.080 clearance0.080 clearance

Comparison Alternate Motor Versus Motor FittedComparison Alternate Motor Versus Motor Fitted

Alternative Motor

Bearing Size: Bearing Size: 6316 C46316 C4Housing Housing –– DE fixed bearingDE fixed bearingFit class Fit class –– M6M6

170.000 170.000 --0.008 / 0.008 / --0.0330.033169.992169.992169.967169.967

Outer RaceOuter RaceFit Class Fit Class –– h6h6170.000+0.000 / 170.000+0.000 / --0.0250.025

170.000170.000169.975169.975

Theoretical fit:Theoretical fit: 0.033 interference0.033 interference0.017 clearance0.017 clearance

Probable fit:Probable fit: 0.026 interference0.026 interference0.010 clearance0.010 clearance

Median fit:Median fit: 0.008 interference0.008 interference

Weg Motor Fitted to Fan

Bearing Size: 6314 C3Housing – fixed bearingFit class – H5150.000+0.018 / -0.000150.018150.000Outer RaceFit Class - h5150.000+0.000 / -0.018150.000149.982Theoretical fit: 0.000 interference

0.036 clearanceProbable fit: 0.005 clearance

0.031 clearanceMedian fit: 0.018 clearance

WEG Investigation WEG Investigation -- Fan TestsFan Tests

Flakt WoodsFlakt Woods

•• Limited clean air tests were conducted on a fan at Limited clean air tests were conducted on a fan at Melbourne factoryMelbourne factory

•• Run time was short motor not reaching normal operating Run time was short motor not reaching normal operating temperaturetemperature

•• Air flow vanes adjusted to different settings Air flow vanes adjusted to different settings demonstrating no measurable affect of different flow demonstrating no measurable affect of different flow volumes on vibration levelsvolumes on vibration levels

•• Test results demonstrated the base line operation of new Test results demonstrated the base line operation of new product prior to shipment on a solid concrete floor baseproduct prior to shipment on a solid concrete floor base

WEG Investigation WEG Investigation -- Fan Tests (contFan Tests (cont’’d)d)

Vale SMSVale SMS•• Test setup outside factory with approx 50m of duct Test setup outside factory with approx 50m of duct

attached to fan intakeattached to fan intake•• The operational results showed acceptable vibration The operational results showed acceptable vibration

levels and no indication of bearing defectslevels and no indication of bearing defects•• After tests similar to those at Flakt Woods were After tests similar to those at Flakt Woods were

complete solids were introduced into the air stream at complete solids were introduced into the air stream at the duct intakethe duct intake

•• Sand, coal and small stones were thrown into the intake Sand, coal and small stones were thrown into the intake duct passing through the fan exiting as dustduct passing through the fan exiting as dust

•• Larger rocks were introduced but these did not get past Larger rocks were introduced but these did not get past the screen and were found in the stone drop out box in the screen and were found in the stone drop out box in front of the inlet vanesfront of the inlet vanes

•• Other debris such as a hard hat, rain coat, rubber hose Other debris such as a hard hat, rain coat, rubber hose and paper were thrown inand paper were thrown in

•• Air flow control vanes were also adjusted to various flow Air flow control vanes were also adjusted to various flow rates but no noticeable changes in vibration levels were rates but no noticeable changes in vibration levels were detecteddetected

WEG Investigation WEG Investigation -- Fan Tests (contFan Tests (cont’’d)d)Mine TestsMine Tests•• Tests were conducted at three minesTests were conducted at three mines

Wambo Coal, Newpac Mine and Ashton CoalWambo Coal, Newpac Mine and Ashton Coal

•• A total of five fans tested under normal underground A total of five fans tested under normal underground operating conditionsoperating conditions

•• All fans were operating at acceptable vibration levelsAll fans were operating at acceptable vibration levels•• These fans had been in service for between 5 days and These fans had been in service for between 5 days and

10 months since their last OEM service/overhaul10 months since their last OEM service/overhaul•• Four motors showed lubrication deficienciesFour motors showed lubrication deficiencies•• In some sites vibration analysis had only been In some sites vibration analysis had only been

introduced recentlyintroduced recently•• Vibration levels as high as 16mm/sec had been reportedVibration levels as high as 16mm/sec had been reported•• Vibration sensors were mounted in various locations Vibration sensors were mounted in various locations

from motor feet to control enclosuresfrom motor feet to control enclosures•• Vibration levels indicated by portable equipment differed Vibration levels indicated by portable equipment differed

from the levels indicated by on board systemsfrom the levels indicated by on board systems

WEG Motor ModificationWEG Motor ModificationUpUp--grade instructions for all existing 150kW 2 pole Exd grade instructions for all existing 150kW 2 pole Exd motors in direct mounted 22mmotors in direct mounted 22m33/sec auxiliary fans/sec auxiliary fans

•• Initial inspection Upon removal of motor from fan, Initial inspection Upon removal of motor from fan, disassemble motor and record:disassemble motor and record:

DE and NDE bearing housing diameter DE and NDE bearing housing diameter DE and NDE Bearing OD DE and NDE Bearing OD Record quantity and condition of grease in motor bearing Record quantity and condition of grease in motor bearing and capsand capsMotor serial numberMotor serial numberFan serial numberFan serial number

•• Flame path inspectionFlame path inspectionA full inspection of motor flame paths, as per AS/NZS 3800 A full inspection of motor flame paths, as per AS/NZS 3800 is requiredis requiredProceed with necessary repairs, if requiredProceed with necessary repairs, if requiredReport any problems to WEGReport any problems to WEG

WEG Motor Modification WEG Motor Modification –– (cont(cont’’d)d)

UpUp--gradegrade•• New endNew end--shield with M6 shield with M6

bearing housing tolerance to bearing housing tolerance to be fittedbe fitted

•• The DE bearing will change to The DE bearing will change to 6314 C46314 C4

•• The bearing caps must be The bearing caps must be fully packed with Esso Polyrex fully packed with Esso Polyrex

EM greaseEM grease

WEG Motor Modification WEG Motor Modification –– (cont(cont’’d)d)

Comparison between old and new bearing fitComparison between old and new bearing fit

Existing fit Revised fit

Fan ModificationFan ModificationProgressively modify existing fans to add jack shaftProgressively modify existing fans to add jack shaftSupply jack shafts on all new high speed fansSupply jack shafts on all new high speed fansDesign includes bearing vibration and temperature Design includes bearing vibration and temperature monitoringmonitoringVale offers an alternative motor on new fansVale offers an alternative motor on new fans

Jack shaft Toshiba motor

Fan ModificationFan Modification –– (cont(cont’’d)d)Mount vibration transducers to the impeller end of the jack Mount vibration transducers to the impeller end of the jack shaft housing and the foot on the motor DE to monitor shaft housing and the foot on the motor DE to monitor lateral axis vibrationlateral axis vibration

Motor transducer Jack shaft transducer

Fan ModificationFan Modification –– (cont(cont’’d)d)If not already modified, modify WEG motor when fans are returnedIf not already modified, modify WEG motor when fans are returnedto add jack shaftto add jack shaft

Replace existing 50 x 50 mesh screen in ADV with 25 x 25 mesh toReplace existing 50 x 50 mesh screen in ADV with 25 x 25 mesh tocatch a higher percentage of objects in the air stream capable ocatch a higher percentage of objects in the air stream capable of f causing impact damage to the impellercausing impact damage to the impeller

Strengthen motor jacking bolt blocks to prevent bending as Strengthen motor jacking bolt blocks to prevent bending as occurred on Newpac fanoccurred on Newpac fan

Reinforced motor jacking bolts blocks ADV screen

The Future?The Future?

Are high speed fans with or without jack shafts a Are high speed fans with or without jack shafts a permanent solution to the problem of bearing and permanent solution to the problem of bearing and electric motor reliability?electric motor reliability?

Do we need a new generation of fans?Do we need a new generation of fans?

Smarter maintenance strategies?Smarter maintenance strategies?

Smarter monitoring systems?Smarter monitoring systems?

Are low speed fans a better option?Are low speed fans a better option?