Maintenance for Generators and Motors_Training course.pptx

7/23/2019 Maintenance for Generators and Motors_Training course.pptx

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Maintenancefor

Generators and Motors


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Objectives

Identify characteristics of periodicmotor/ Generators maintenance.

Identify the major components of an

AC motor/ Generator. Perform pre maintenance testing.

An eective implementation ofelectrical motor maintenance willtranslate into savings from productionavailability reduced e!uipment repaircosts and improved energy costs.


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Objectives

"o have an appreciation andunderstanding to performoptimal diagnoses and repairs.

#earning the techni!ues andobtain valuable information to

detect motor/ Generatorsproblems prior to failureavoiding costly downtime.


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Introduction

$otating electrical machines can bedivided into%

&otors% which convert electrical

energy into mechanical energy. Generators% which convert mechanical

energy into electrical energy.

'oth types operate through theinteraction between a magnetic (eldand a set of windings.


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Electrical Motors


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Generator


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Electrical Motors

)lectric motors convert electricalenergy into useful mechanical energyby running electrical current through

a coil resulting in the tor!ue neededto turn a shaft. Almost every majorpiece of e!uipment in a commercialbuilding*boilers chillers air

handlers pumps and cooling towersto name a few*relies on electricmotors.


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Electrical Motors


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Electrical Motors


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Electrical Motors

As they run motors can become lesse+cient because of wear brea,down oflubricants and misalignment. Good

motor-maintenance practice helps avoidor postpone these problems. A lac, ofmaintenance can reduce a motorsenergy e+ciency and increase

unplanned downtime. cheduledmaintenance is the best way to ,eep themotors operating e+ciently and reliably.


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Common Motor Applications

Pumps0ans

Conveyors

)1truders

AgitatorsCrushers

&illsGrinders

)levators


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Parts of Electrical Motor

3. Centrifugal witch

4. 'earing

5. "erminal 'o16. Power upply

7. Cooling 0an

8. 9rive Pulley:. $otor

;. tator


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Parts of Electrical Motor


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CENTRIFGA! "#ITC$

A type of switch thatoperates using the

centrifugal force createdfrom the rotating shaft. "hecentrifugal switch activates

and de-activates dependingon the speed of the motor.


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%EARING

A device that supportsguides and reduces the

friction of motion between(1ed and moving machineparts.


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TERMINA! %O&

=n a piece of electric e!uipment>such as a motor? a bo1 withinwhich the leads from the pieceof e!uipment are connected tothe leads supplying thee!uipment with power@ usuallyprovided with a removablecover plate for access.


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PO#ER "PP!'

A power supply is a devicethat supplies electric

power to an electrical load.


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COO!ING FAN

Is a self cooling electric motor. 0ancooled motors feature an a1ialfan attached to the rotor of the

motor >usually on the oppositeend as the output shaft? thatspins with the motor providing

increased airow to the motorBsinternal and e1ternal parts whichaids in cooling.


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ROTOR

In an electric motor the movingpart is the rotor which turns theshaft to deliver the mechanical

power. "he rotor usually hasconductors laid into it which carrycurrents that interact with the

magnetic (eld of the stator togenerate the forces that turn theshaft.


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"TATOR

"he stationary part isthe stator usually has

either windings orpermanent magnets.


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Electric MotorsCare and Maintenance

ohy and when invest resourcesto maintain )lectric &otors D

o

hat strategies can beimplementedD

ohat have other motor users

done to maintain t(eir motorso#hat support resources andtools are available D


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Motor Enemies

Eeat

"ime

Power upply IssuesEumidity

Improper #ubricationFnusual &echanical #oads


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!eadin) causes of MotorFailures

'earings 73

tator inding 38

)1ternal 38Fn,nown 3H

$otor 'ar 7haft/Coupling 4


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Common Causes For Motor

Failures


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Operation and Maintenance ofMotors * Generators


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"AFET' FIR"T

Eigh voltage and rotating partscan cause serious or fatal injury.afe installation operation and

maintenance must be performedby !uali(ed personnel.0amiliariation with and

adherence to J)&A &G4 theJational )lectrical Code >J)C?and local codes is re!uired.


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"AFET' FIR"T

It is important to observe safetyprecautions to protect personnelfrom possible injury. Personnel

should be instructed to%

3.'e familiar with the e!uipmentand read all instructions

thoroughly before installing orwor,ing on e!uipment.


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"AFET' FIR"T

4. Avoid contact with energiedcircuits or rotating parts.

5. 9isconnect all power sourcesbefore initiating any maintenanceor repair.

6.Act with care in accordance with

prescribed procedures in handlingand lifting this e!uipment.


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"AFET' FIR"T

7. 'e sure unit is electricallygrounded in accordance withcode re!uirements.

8.'e sure e!uipment is properlyenclosed or protected to preventaccess by children or otherunauthoried personnel in orderto prevent possible accidents.


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"AFET' FIR"T

:. 'e sure shaft ,ey is fullycaptive before unit is

energied.;. Avoid contact withcapacitors until safedischarge procedures havebeen completed.


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"AFET' FIR"T

K. Provide proper guarding forpersonnel against rotatingparts and applicationsinvolving high inertia loadswhich can cause over speed.

3H. Avoid e1tended e1posureto e!uipment with high noiselevels.


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"afet+ Issues

'efore servicing motors and motor-operated e!uipment disconnect thepower supply to the motor and

accessories. An electrical loc,out/tagout procedure is recommendedwhere every piece of e!uipmentserviced is logged and electricaldisconnects are physically disabled.


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%est Practicesfor E,cient Operation

"he following bestpractices will reduce the

cost of operation andmaintenance%


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Turn O- nneeded Motors

Identify motors that rununnecessarily and turn them owhen appropriate. )1amples

include e1haust fans runningwhen ventilation needs are metand escalators operating after

closing. Lou may need toreprogram the building controlsystems to accomplish this.


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Reduce t(e seof t(e Motor "+stem

Increasing the e+ciencyof mechanical systems can

reduce the amount of timethat associated motorsneed to run.


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Increasing the e+ciency ofmechanical systems can reducethe amount of time that

associated motors need to run. 0or e1ample improving theperformance of a cooling tower

can reduce the run time that thefans need to reject the sameamount of heat.


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)liminating e1cessive startsand stops is also worthwhile.

tarting and stopping amotor stresses its parts anddegrades its performance.

0re!uent stops and startsincrease the need formaintenance.


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%est Practices for Maintenance

Properly selected andinstalled motors can operate

for many years with minimalmaintenance. Jonethelessregular care will e1tend

their life and ma1imie theirenergy e+ciency.


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%est Practices for Maintenance

In addition to periodicup,eep good

record,eeping and smartreplacement planning are,ey elements of a good

motor- maintenanceprogram.


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Re)ular p.eep

Clean motor surfaces andventilation openings

periodically. Eeavyaccumulations of dust andlint will result in

overheating andpremature motor failure.


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Properl+ lubricate movin) parts

ome motors have sealedbearings that re!uire noservicing. 0or others regular

lubrication will avoidunnecessary wear. 'e sure toapply appropriate types and

!uantities of lubricant. Applyingtoo little or too much can harmmotor components.


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/eep motor couplin)s properl+ali)ned

Correct shaft alignmentensures smooth e+cienttransmission of power fromthe motor to the load.Incorrect alignment puts

strain on bearings and shaftsshortening their lives andreducing system e+ciency


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hafts should be parallel anddirectly in line with each other.haft alignment should be

chec,ed and adjusted regularly.&any couplings have hardrubber inserts that can degrade

so rubber dust on the e!uipmentbase may indicate problems.


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Properly align and tensionbelts and pulleys when

they are installed andinspect them regularly toensure that alignment and

tension stay withintolerances.


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Abnormal wear patterns on beltsmay indicate problems. #oosebelts may s!ueal and will slip on

the pulley generating heat.Correctly tensioned pulleys runcool. )1cessive tension strains

bearings and shafts andshortens their lives.


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Maintain bearin)s b+ .eepin)t(em clean0 lubricated0 andloaded 1it(in tolerances2

Proper belt tension or

shaft alignment minimiesstrain on the bearings and

helps them achieve theire1pected life.


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Maintain bearin)s b+ .eepin)t(em clean0 lubricated0 andloaded 1it(in tolerances2

"hese can be prone to shaft

currents which can causeserious damage to thebearings. 0ortunately there are

several technologies that canmitigate shaft-currentproblems.


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%earin) Failures in Motors


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C(ec. for proper suppl+


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C(ec. for proper suppl+volta)es

Fnbalanced power*that isthree-phase motors where thesupply voltage to the phases

varies by more than 3*canlead to overheating and reducedmotor life. o too can situations

where the supply voltage is muchhigher or lower than the motorsrated voltage.


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Avoid paintin) motor (ousin)s

Paint acts as insulationincreasing operatingtemperatures andshortening motor life. =necoat of paint has little eect

but years of paint buildupcan have a signi(cant eect.


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Periodicall+ inspectcommutators visuall+

Potential problems withcommutators >which are

only re!uired for 9Cmotors with brushes? willbe seen as discolorations

at spots or burn mar,s.


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Periodicall+ inspectcommutators visuall+

Color patterns can benormal as long as they

appear around the entirecommutator. If you noticeproblems remove and

repair the commutator orreplace ,ey components.


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Good Record.eepin)

&aintain an up-to-datemotor inventory.

"he inventory shouldinclude all substantialmotors but can begin with

the largest and those withthe longest run times.


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Good Record.eepin)

"his inventory lets facilitymanagers ma,e informedchoices about replacementeither before or after a motorfails. 0ield-testing motorsbefore they fail can helpensure that replacements areproperly sied.


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/eep maintenance lo)s


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"hese logs should contain vitalinformation such as the ma,emodel serial number type and

speci(cations of each motor@the locations and speci(cationsfor belts pulleys etc.@ and a

historical record of maintenanceactivities.


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"his helps the maintenance staremember when tests inspectionsor servicing are due. It also allows

the sta to !uic,ly identify spareparts or replacements whenneeded. In addition comparingrecent test results to past valuescan provide early indications ofreduced motor performance.

Maintenance "c(edule for


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Maintenance "c(edule forMotors9escription Comments

&aintenance 0re!uencyMotor use/sequencing Turn o or sequence unnecessary motors.

WeeklyOverall visual inspection Verify equipment is operating and safety systems are in place. Weekly

Ceck !earings "nspect for #ear$ and ad%ust$ repairand drive !elts or replace as necessary.

Weekly

Motor alignment &ook for ru!!er or steel savings under couplings$ or listen for odd noises$

as tese may indicate a pro!lem'.

Weekly

Motor condition Ceck condition !y analy(ing temperatureor vi!ration$ and compare to !aseline values.on #eekly inspections'

)uarterly *or as neede

Cleaning +emove dust and dirt to facilitate cooling.)uarterlyCeck lu!rication ,nsure !earings are lu!ricated as recommended !y manufacturer.

-nnually*or !ased on run our

Ceck mountings ecure any loose mountings. -nnuallyCeck terminal tigtness Tigten any loose connections.

-nnuallyCeck for !alanced Trou!lesoot un!alanced motor circuit and-nnually

treepase po#er 01 pro!lems if te voltage im!alance e1ceeds 23.Ceck for over or Trou!lesoot motor circuit and 01 pro!lemsunder voltage conditions if te supply voltage diers signi0cantly from rated voltages.

-nnually

#or.in)


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#or.in)

Procedurs

i d i


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3irt and Corrosion

i d C i


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3irt and Corrosion

ipe brush vacuum or blowaccumulated dirt from the frameand air passages of the motor.

9irty motors run hot when thic,dirt insulates the frame andclogged passages reduce cooling

air ow. Eeat reduces insulationlife and eventually causes motorfailure.

3i d C i


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3irt and Corrosion

0eel for air beingdischarged from the cooling

air ports. If the ow is wea,or unsteady internal airpassages are probably

clogged. $emove the motorfrom service and clean.

3i t d C i


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3irt and Corrosion

Chec, for signs of corrosion.erious corrosion may indicateinternal deterioration and/or a

need for e1ternal repainting.chedule the removal of themotor from service for

complete inspection andpossible rebuilding.

3i t d C i


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3irt and Corrosion

In wet or corrosiveenvironments open the

conduit bo1 and chec, fordeteriorating insulation orcorroded terminals. $epair

as needed.

! b i ti


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!ubrication

! b i ti


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!ubrication

#ubricate the bearingsonly when scheduled or if

they are noisy or runninghot. 9o J=" over-lubricate. )1cessive

grease and oil creates dirtand can damage bearings.

! b i ti


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!ubrication

! b i ti


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!ubrication

0actor

ylubedball

bearing

! b i ti


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!ubrication

0actor

y #ubein

housin

g

! b i ti


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!ubrication

"ypical lube after time

! b i ti


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!ubrication

Contaminated #ube

$ t N i d 4ib ti


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$eat0 Noise and 4ibration

0eel the motor frame andbearings for e1cessive heat orvibration. #isten for abnormalnoise. All indicate a possiblesystem failure. Promptlyidentify and eliminate thesource of the heat noise orvibration.

$eat


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$eat

)1cessive heat is both acause of motor failure and

a sign of other motorproblems.

=verheating results from

a variety of dierentmotor problems.

$eat


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$eat

- "hey can be grouped asfollows%

3- $=JG &="=$% It may be too

small or have the wrong startingtor!ue characteristics for theload. "his may be the result of

poor initial selection or changesin the load re!uirements.

$eat


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$eat

4- P==$ C==#IJG% Accumulateddirt or poor motor location mayprevent the free ow of cooling air

around the motor. In other casesthe motor may draw heated airfrom another source. Internal dirt

or damage can prevent proper airow through all sections of themotor.

$eat


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$eat

- 9irt on the frame mayprevent transfer of internal

heat to the cooler ambientair.

$eat


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$eat

5- =M)$#=A9)9 9$IM)J&ACEIJ)% )1cess loads or

jams in the driven machineforce the motor to supplyhigher tor!ue draw more

current and overheat.

Motor Operatin) Conditions


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#ight 9uty% &otors operateinfre!uently >3 hour/day orless? as in portable oor

sanders valves door openers.tandard 9uty% &otors operatein normal applications >3 or 4

wor, shifts?.



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)1amples include airconditioning units conveyorsrefrigeration apparatus

laundry machinerywoodwor,ing and te1tilemachines water pumpsmachine tools garagecompressors.



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Eeavy 9uty% &otorssubjected to above normaloperation and vibration

>running 46 hours/day 587days/year?. uch operationsas in steel mill service coaland mining machinery motor-generator sets fans pumps.



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evere 9uty% )1tremelyharsh dirty motor

applications. everevibration and highambient conditions often

e1ist.

$eat


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$eat

6- )NC)IM) 0$IC"I=J%&isalignment poor bearingsand other problems in the

driven machine powertransmission system or motorincrease the tor!ue re!uiredto drive the loads raisingmotor operating temperature.

$eat


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$eat

7- )#)C"$ICA# =M)$#=A9%An electrical failure of a

winding or connection inthe motor can cause otherindings or the entire

motor to overheat.

Noise and 4ibration


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Noise and 4ibration

Joise indicates motorproblems but ordinarily

does not cause damage.Joise however is usuallyaccompanied by vibration.

Noise and 4ibration


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Noise and 4ibration

Mibration can causedamage in several ways.

It tends to sha,e windingsloose and mechanicallydamages insulation by

crac,ing a,ing orabrading the material.

#indin) Insulation


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#indin) Insulation

hen records indicate a tendencytoward periodic winding failures inthe application chec, the condition

of the insulation with an insulationresistance test. uch testing isespecially important for motors

operated in wet or corrosiveatmospheres or in high ambienttemperatures.

Cleanin) and 3r+in) #indin)s


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&otors which have beenooded or which have lowmegger readings because of

contamination by moisture oilor conductive dust should bethoroughly cleaned and dried.

"he methods depend uponavailable e!uipment.



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A hot water hose and detergents arecommonly used to remove dirt oildust or salt concentrations from

rotors stators and connectionbo1es. After cleaning the windingsmust be dried commonly in a

forced-draft oven. "ime to obtainacceptable megger readings variesfrom a couple hours to a few days.

oo s an 5u pmen n ec r c o orMaintenance


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%asic tools


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%asic tools

4ibration measurement tools


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Electrical disc(ar)e detector


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Electrical disc(ar)e detector

T(ermal scanner


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T(ermal scanner

T(ermal ima)e


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T(ermal ima)e

!ubricants


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!ubricants

Ta.e care of +our bearin)sd t( 7ll t . f 8


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and t(e+7ll ta.e care of +ou8


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Documents

Maintenance for Generators and Motors_Training course.pptx