Onan UF Series Instruction Manual

INSTRUCTION MANUAL
AND PARTS CATALOG
FOR
O
nan
GENERATORS
UF
SERIES
ALTERNATINGCURRENT-!PHASE-4WIRE
andI At
ALTERNATINGCURRENT-3PHASE-4WIREJ^F
REVOLVINGARMATURE
INHERENTLYREGULATED
ONAN140073RD
AVENUE N.E.• MINNEAPOLIS,MINNESOTA55432
A DIVISION OFSTUDBBAKER CORPORATION
-f^plrN.Y.INTERNATIONALOFFICE:EmpireStateBldg.
943-1
5AD70 Printed inU.S.A.

GENERAL INFORMATION
This instructionbookcontainsinformationfortheproperinstallation,
operation,andmaintenanceofyourequipment.We suggest thatthis
bookbekepthandysothatitcanbereferredtowhennecessary.
This equipmentistheresultofprovenengineeringdesign,hig;hest
quality materials,andexpert workmanship. Thoroughinspectionand
testingassuresyouthatthisequipment will performasexpected.
If youwishtocontactyourdealerorthefactoryregardingthisequip-
ment,besuretosupplythecomplete MODEL and SPEC. NO.,andthe
full serial numberoftheequipmentasshownonthenameplate. This
informationisnecessarytoidentifytheequipmentamongthemany
basic andspecialoptional types manufactured.
MANUFACTURER'S WARRANTY
TheManufacturerwarrants, tothe originaluser,thateachproduct of
its.manufacture'isfreefromdefects in material and factoryworkmanship
ifproperlyinstalled,serviced and operatedundernormalconditions
according tothe Manufacturer'sinstructions.
Manufacturer'sobligationunderthiswarranty is limited to correcting
withoutcharge atits factory any part or partsthereofwhichshall be
returned toits factory oroneofits AuthorizedServiceStations,trans-
portationchargesprepaid,within one yearafterbeing put intoservice
by the originaluser, and -whichuponexaminationshalldisclose tothe
Manufacturer'ssatisfaction to havebeenoriginallydefective.Correction •
ofsuchdefects by repair to,or supplying of replacements for defective
parts, shallconstitutefulfillment.of all obligations to originaluser.
Thiswarrantyshall not apply toanyofthe Manufacturer'sproducts
whichmust be replacedbecause of normalwear,whichhavebeensubject
tomisuse,negligence or accident or whichshallhavebeenrepaired or
alteredoutside ofthe Manufacturer'sfactoryunlessauthorized bythe
Manufacturer.
Manufacturershall hotbe liable for loss,damage or expensedirectly or
indirectlyfrom theuseofits product or from any othercause.
Theabovewarrantysupersedes andisin lieu of-all otherwarranties,
expressed or implied, andofall otherliabilities or obligations on part of
Manufacturer. No person,agent or dealer is authorized to give any
warranties on behalf ofthe Manufacturer norto assume forthe Manu-
facturer any otherliability in connectionwith anyofits productsunless
made in writing and signed byan officer ofthe Manufacturer.
DATED August 1,1963
IMPORTANT
RETURN WARRANTY CARD ATTACHED TOUNIT

5 TABLE OF CONTENTS
SUBJECT PAGE NO.
Description
Table ofRatings1
Generator2
Switchboards2
Installation
Location4
GeneratorCooling5
MountingtheGenerator5
Wiring Connections5
EnginePower; 5
EnginePulleySpeed6
PulleySelection6
1800RPMPulleySelectionTable7
1500 RPM PulleySelectionTable8
ReversingtheScroll. , 9
Operation
Starting10
Operating10
Maintenance
General Servicing,BrushandSpringRemoval11
Brush Contact, n
Brush RigNeutralPosition12
Major GeneratorRepair13
Disassembly13
Armature Grounded13
Testing.theArmatureforanOpen Circuit . 13
TestingtheArmatureforShortCircuits14
Field WindingsOpen Circuit 14
ServiceDiagnosis
PoorCommutationorArcingattheGeneratorBrushes.. 15
OverheatingofGenerator15
Generator Noisy 16
GeneratorRunsbut does notProduceCurrent16
Low VoltageOutputofGenerator: 16
Parts Catalog
InstructionsforOrderingRepairParts18
Parts Illustration19
Parts List 20
Wiring Diagrams22

DESCRIPTION
GENERATORTABLE OF RATINGS
GENERATOR GEN„ tPARTS
MODEL NO. CY. PH. WIRE VOLTS
WIRING
DIA. NO.
KEY
NO.
120/240
2e«UF-3*/J(^t 60 1 4
120/240
620B52 1
120/240
^UF-53^/^ 50 1 4
120/240
620B52 2
^UF-sl/l^llf
60 1 4
120/240
620 B 52 2
rD S
^UF-SSl^/l^P
50 1 4
120/240 620B52
3
^iuF-sl/itei^.
60 1 4
120/240
620B52
3
%UF-4M/l-ISt#
60 3
4 120/240
620B54 4
Note t - UsethePartsKeyNo.inthiscolumnforyourmodelwhen
selectingpartsfromthelistherein. Order only those parts
withnoPartsKeyNo.referenceor those partswhichrefer
tothePartsKeyNo.foryourmodel.
SWITCHBOARDTABLE OF RATINGS
SWITCHBOARD
MODELNO. * CYCLE PHASE
WIRE
VOLTS
CONTROL
WIRING
DIA. NO.
4SA-3/1A 50or60 1 4
120/240
615B84
5SA-3/1A 50 1 4 120/240
615B84
7SA-3/1A
60 1
4
120/240
615B84
* - ForallSwitchboardRepairPartsrefertothewiringdiagramfur-
nishedwiththecontrol.
NOTE: 120,240or 120/240 voltreferenceshereinapplyalsoto115,
230or 115/230 voltratings respectively.

DESCRIPTION
GENERATOR. - This generatorisinherentlyregulatedand will main-
tain theoutput voltage withinlimitsof 10% between no
loadand full load,whendrivenatitsnameplatespeedandatnormal
ambienttemperature.The voltage will besomewhathigherwhenthe
generatoriscold,and will vary withthedrivenspeed.Frequency will
vary 1 cycleforeach30rpmofvariationfromratedspeedaccording
tothecurvesbelow., % * -
CURVES OF VARIATION OF FREQUENCYWITHSPEED
*
c
y si
§ 50
5 49
LL,
E46
5 0 C'l CLI :GE ATO ST
62
o.
g»
u
g
60
I
59
K-
I* 58
6 3 CY CLE
CZl
JERJ LTOI
11
?
-
1440 1470
1500
SPEED IN RPM
1530 1560 1740 1770
Fig. 1. 1800
SPEED IN RPM
1830 1860
The powerfactorratingforallsinglephasemodelsis100%.Thepower
factorratingof3 phasemodelsis80%.The voltage regulation will not
begreaterthan10%at full loadandratedpowerfactor.
The generatormay*bedrivenineithera clockwise,prcounterclockwise
direction, asinstallationrequirementsdemand. - The blowerscroll
mustbereversedwheneverthegeneratorrotationischanged.See par-
agraph on REVERSINGTHESCROLL. Thegeneratorisshippedfrom
thefactorywiththescrollassembledforcounterclockwiserotation.
The directionofrotationofthegeneratorisdeterminedwhilelooking
attheendofthegenerator opposite tothedriveend.Thegeneratoris
drip proofindesign,butreasonableprecautionsshouldbetakenagainst
excessiveexposuretomoisture.
The instructionmanualcoversboth1 phase4 wire,and3 phase4 wire
ONAN Ball BearingSeparateGenerators.
A manualfieldrheostatcanbeusedwiththegeneratorifitisnecessary
tooperateaboveratedspeed.Itcanbeobtained,atadded cost after
thegeneratorisreceived.See "PARTS LIST" forcorrectpartnumber.
It canalsobeusedtoreducethe voltage atlightloads.Therheostat
can notbeusedtoincreasethe voltage abovewhatitwouldbewithout
it. Seewiringdiagramforproperconnections.
SWITCHBOARDS. - Switchboardsareoptionalequipmentwhichcanbe
purchased ataddedcost. Listed inthe TABLE OF
RATINGS aretheSwitchboardModelNo.'s.Theycontaina voltmeter,
ammeter,circuitbreaker,generatorandloadterminals.Theswitch-
board isgenerallyusedtocheckgeneratorandloadoperationaccurately
and topreventthegeneratorfrombeingoverloaded.Theoperatorcan

DESCRIPTION
checkthefollowing things byusinga switchboard:
(1)Generator voltage
(2) Load current
(3)Voltageregulationwithvaryingload
The circuitbreakerautomatically disconnects theloadfromthe gen-
eratorwhentheload exceeds thegeneratorkilowattratingbyapproxi-
mately25%.Whenthecircuitbreakertrips,itmustberesetmanually.
The causeoftheoverloadshouldbedetermined before resettingthe
breaker. Theloadcurrentvalueatwhichthecircuitbreakertripsis
affected somewhat bytheambienttemperature.Donotmountthe
switchboardina locationwhere excessive temperaturescan develop or
onsurfaceswhichvibrate.Excessivevibrationmayalterthetrip
current valueofthecircuitbreaker.
Whenorderingrepairpartsforswitchboards,obtain Part No's,and
descriptionofpartfromthewiringdiagramwhichissuppliedwiththe
switchboard.

INSTALLATION
LOCATION. - Selecta site forthegeneratorwiththefollowing points
in mind.
1.Ventilation.- Thegenerator will warmupandcreate some heat
whenoperatingunderloadconditions.Itisofvital
importancethatthisheatbedissipatedbyproperventilation.Ifthe
generatorisinstalledina smallroomorcompartment,providean
openingforentryoffresh,coolair.Providea separateopeningfor
exhaustingtheairheatedbythegenerator.Locatetheexhaustopening
above theinletopening,for best aircirculation.Heatedairisdis-
charged fromthedriveshaftendofthegenerator.
2. Convenienceto Driving Power.- Locatethegeneratoraftercon-
sidering thefollowingpoints:
A. Driving unitlocation.
B. Desireddirectionofshaftrotation.
C. Pulleyalignment,ifused.
D. Shaftalignmentofgeneratoranddrivingunitifa flexible
couplingisused.
A. Driving unitlocation.- Regardlessofthe type ofdrivingunitit
MUST beboltedsecurelytoa heavy
mountingbasetomaintainpulleyandshaftalignment.
B. Desireddirectionofshaftrotation.- Thedirectionofrotation
will bedeterminedbythe
direction ofrotationofthedrivingunit.Thegeneratordirectionof
rotationisreversibleandworksequallywellineitherdirection.
Howeverthegeneratorleadwiresandblowerscrollmustbeproperly
installed forwhateverdirectionofrotationisnecessary.Seewiring
diagram forproperleadconnections.Seeparagraphdn REVERSING
THESCROLL forproperscrollinstallation.
C. Pulleyalignmentifused.- Theshaftsofthegeneratorand
driving unitmustbeparalleland
the sides ofthepulleysmustbelinedup. Correct belttensionmust
bepermanentlymaintained.Afterthepulleysareinproperalign-
ment,bothgeneratoranddrivingunitmustbebolteddowntoa heavy
rigid mountingbase.
D. Shaftalignment.- Ifa flexiblecouplingisused,theshaftalign-
mentofthegeneratoranddrivingunitmust
beaccuratelymadeandpermanentlymaintained.Incorrectshaft
alignment will cause excessive wearonbothgeneratoranddriving
unit andunnecessary loss ofpowerfromthedrivingunit.

INSTALLATION
3. DustyorDampConditions.- Avoidexcessivedustyordampcon-
ditionsasmuchaspossible. Rust and
dirt are enemies ofanypieceofmachinery.Thegeneratorisdrip
proof indesign,butunnecessaryexposuretomoistureshouldbeavoided.
The generatorshouldbemountedundercoverorinsidea buildingto
protectitagainsttheweather.
4.ServicingConvenience.- Topermiteasyaccessforservicingthe
bearingsandbrushes,allowatleast24
inchesofspacearoundthegenerator.
5. Wiring Convenience.- Locatethegeneratorasnearaspossibleto
theelectricalequipmentitistoserve.
GENERATORCOOLING. - Thegeneratorblowersystem uses a revers-
ible scroll. Whentheblowerscrollisin-
stalledproperly,a strongflowofair comes outofthegeneratoratthe
generatordriveshaftend. Lack ofairflowindicatesimproperinstal-
lationoftheblower scroll. - Seeparagraphon "REVERSING THE
SCROLL".
MOUNTING THEGENERATOR. - Themountingsurfacemustbeflatso
thatthegeneratormountingbase will
notbesprung^whentightenedintoplace.Itshouldbepossibleto turn
thegeneratorshaftbyhandafterthegeneratorisbolteddown.
WIRINGCONNECTIONS. - Thegeneratorexternalleadsarenotcon-
nected,andtheirmannerofconnection will
dependuponwhethera rheostatistobeused,andthe DIRECTION OF
ROTATION. Refertothewiringdiagram.A rheostatoftheproper
sizeshouldbeinstalledifthespeedvariation will betoogreat,orifit
isnecessarytoreducethe voltage atlightloads.Theadditionofa
rheostat will notraisethe voltage abovethatwhichcouldbeobtained
withouttherheostat.A circuitbreaker between generatorandloadis
recommended.
Follow specificationsoflocalandnationalelectrical codes forinstall-
ingwiringandgroundingthegenerator.Besuretousewirelarge
enoughtoavoidexcessivedropin voltage between thegeneratorandthe
load, dependinguponthedistanceandtheamountoftheload.
The propersizeandtypeofdrivingunitforthegeneratorisimportant
forsatisfactoryoperationofthegenerator.Whena gasolineordiesel
engine isusedthefollowingfactorsshouldbeconsidered:
1.EnginePower.- The engine musthavea minimumof2 horsepower
foreach1000wattsofgeneratoroutput.Forex-
ample,ifa 5000 wattgeneratoristobeoperated,the engine must
deliver atleast10horsepoweratthedriveshaft.Ifthe engine hasa
considerablereserveofpowerthespeedregulationand voltage regula-
tion will bemuchbetter.
/

6 INSTALLATION
2. EnginePulley Speed. - Theenginemay have a variable speed gov-
ernor which regulatesengine speed atabout
8-1/2to12%.Ifso,governoroperationis best atthemaximumrated
speed oftheengine.Whenthegeneratorisoperatingator near its
capacity,thetendencyoftheengineisto increase speed whentheload
is suddenlyremoved.Theenginegovernor does notreactfastenough
atlow speed topreventmomentaryaccelerationand high voltage.This
maypossibly cause serious damage toanyelectricalequipment left
connected.Governoractionismuchbetterwhentheengineisoperat-
ing atitsrated speed, andtheenginecannot increase its speed too
much whentheloadisremoved.Iftheenginehasa constant speed gov-
ernor,the speed regulationis5%or less andtheaboveeffectsarenot
present.
Low generator speed causes lowvoltageandfrequency.If,forex^
ample,an1800rpmgeneratorisslowedto1500rpm,thefrequencyof
thecurrentproduced will be50cyclesinsteadof60cycles.Thecom-
bination oflowvoltageandfrequency will almostcertainlyresultin
burnedoutwindingsofanymotorsconnectedtothegenerator.
3.PulleySelection.- Therated speed oftheengineorelectricmotor
will determinethesizeofpulleytouseonthe
generatori,.Todeterminethecorrectgeneratorpulleysizetouse,pro-
ceedas follows, orrefertothe PULLEY SELECTION. TABLE.
A. Multiply the DIAMETER ofthe driving unit pulleybyitsSPEED
in rpm(revolutionsperminute).
B. Divide theaboveresultbythenameplate speed ofthegenerator
(1800rpm).
Example: A driving pulley15inchesindiameter operates at1200
rpm.. Multiply 15x 1200gettinga resultof18,000.
Divide the18,000by1800rpm(generatorpulley speed
desired)andthe final resultis10, which expresses the
Sizeofthepulley(ininches)required.Ifthis same
driving unit hasan8 inch pulleyoperatingat1200rpm
thegenerator pulley would thenbe5.33"orapproximately
5-3/8"(8x 1200, divided by1800= 5.33).

INSTALLATION
USETHIS TABLE ONLYFORGENERATORS STAMPED 1800 RPM ON
THE GENERATORNAMEPLATE.
The pulleysizesrecommendedinthistableareapproximatesizesonly,
in 1/2"steps.Thesizesshowndonotincludeanyallowanceforbelt
slippage.Beltslippageforflat belts may sometimes reducethegener-
ator drivenspeed,underload,asmuchas4 percent.
To selecta generatorpulleysizefromthetable,measurethe DIA-
METER (notthedistancearound)ofthedrivingpulley.Selecttheline
at theleftsideofthetableforthedrivingpulleysize.Followthisline
across tothespeedcolumnthatisnearesttotherecommendedspeedof
thedrivingpulley.Thesizeinthesquareatthispointistheapprox-
imatesizeofthegeneratorpulleywhich will berequired.Iftherecom^
mendedsizepulleycannotbeobtained,selectonesizesmallerpulley.
This will helpto offset beltslippage. Adjust throttleorgovernoras
necessary toobtainproperspeed.
Example:
If a 12inchdrivepulleyoperatesat1100rpm,followthe12inchline
across tothe1100rpmcolumn.Thegeneratorpulleysizeatthepoint
ofintersectionis7 inch. This exampleisoutlinedinheavylinesinthe
table.
DRIVING PULLEY SPEED IN REVOLUTIONSPERMINUTE
DRIVING
PULLEY
SIZE
600 700
GI
800900
:NERATO
ioooj^noQji20o|
R PULLEYSIZE 1
130o|
*EQU]
1400 j
RED
15001
^1800I
1600
R.P.N
1700
I. GEI
1800 1
JERA1
1900
[•OR)
2000
6 2 2
2i 3 3 k
44
5 5 54 6 6 64
6| 2
2i
24
3
34
/ 4
k H 5 5
54 6 64 64
7
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2i 3
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k '/
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5
54 54 6 ^4
7
74 74
7* 2|
3 3 34
k
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15 16 ^64 174

8 INSTALLATION
1500 RPMGENERATORPULLEYSELECTIONTABLE
USETHISTABLEONLYFORGENERATORS STAMPED 1500 RPMON
THE GENERATORNAMEPLATE.
The pulleysizesrecommendedinthistableareapproximatesizesonly,
in 1/2"Steps.Thesizesshowndonotincludeanyallowanceforbelt
slippage.Beltslippageforflat belts may sometimes reducethegen-
erator drivenspeed,underload,asmuchas5percent.
To selecta generatorpulleysizefromthetable,measurethe DIAMETER
(notthedistancearound)ofthe"drivingpulley.Selectthelineatthe
leftsideofthetableforthe driving pulleysize.Followthislineacross
tothespeedcolumnthatisnearesttotherecommendedspeedofthe
driving pulley.Thesizeinthesquareatthispointistheapproximate
sizeofthegeneratorpulleywhich will be required. Iftherecommended
sizepulleycannotbeobtained,selectonesizesmallerpulley. This
will helpto offset beltslippage. Adjust throttleorgovernorasneces-
sary toobtainproperspeed.
Example: Ifa 12 inch drivepulleyoperatesat1100rpm,followthe12
inch lineacrosstothe1100rpmcolumn.Thegenerator
pulley sizeatthepointofintersectionis9 inch. This exampleisout-
lined inheavylinesinthetable.
DRIVING PULLEY SPEED IN REVOLUTIONS PER MINUTE
DRIVING
PULLEY
SIZE
600 700]800
GENEP
1
900
ATC
1000|1100
)RPULLEY
i
1200
SIZE]
1300
*EQU]
1400[1500
RED (15OOR
i
1600
PM G
1700
ENER
1800)1900
ATOR)
i
2000
6
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4
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17 18 19 20 214 23 24

INSTALLATION
REVERSINGTHESCROLL.- The generator is shipped from thefactory
with theblowerscrollmountedforcoun-
terclockwiserotation.Thedirectionofrotationis determined while
looking attheend opposite thedriveend.Ifa clockwisedirectionof
rotationis desired, theblowerscrollposition must be reversed. The
arrowwhichisprintedonthescroll must bepointinginthedirection
of therotationofthe generator shaft.
ROTATION-CAS VIEWED FROM OPPOSITE TO DRIVE END J. .
CLOCKWISE COUNTERCLOCKWISE
"iii)felfiifjlrii
SCROLL TAB INDICATES Mii-nl,
DIRECTION OF' ssS&OS
ROTATION
FIG. 2 - BLOWERSCROLL
To reverse thescroll, remove onlythescroll with screen attached,
turn itendforendandreinstallitso that thescroll will beatthe
opposite endoftheairoutlethole,asillustrated.
POLARIZING THEGENERATOR FIELD,, - The field ispolarizedatthe
factory.Ifrotationdirection
is reversed (scroll reversed and leads properly connected) andvoltage
does notautomaticallybuild-upthe first time,"flashthe field" tore-
polarizethe generator.
Connect anacvoltmeter across the generator output,runthe generator
in the desired direction,toucha battery positive(-+•) cable to generator
field leadFl,andthe battery negative (—) cable to generator field lead
F2.Ifthevoltmeter does notindicatevoltagebuild-up,a larger battery
orhigherdc source mayberequiredto kill theexistingresidualmag-
netism.

10OPERATION
STARTING. - Besurethatthe generator is connected forthedirection
ofrotation being used.Startupthe generator andcheck
the voltage whilerunningatnoloadandrated speed (1,500-rpmfor50-
cycle generators and1,800-rpmfor 60-cycle generators).Thegenera-
tor voltage shouldbeas follows:
Generator NameplateApproximateLinetoLine
VoltageRatingNoLoadVoltageatRated Speed
120/240252
120/208 220
If the generator voltageatnoloadisnotasspecified above, adjustthe
generator speed until no-loadvoltageis reached beforeproceeding.
Checkthe generator coolingaircirculation.Whentheblowerscroll
isinstalledproperly,a strongcurrentofair comes outofthedrive
shaftendofthe generator. See paragraph onREVERSINGTHESCROLL
for properinstallationoftheblowerscroll.
OPERATING. - Connectthevariouselectrical loads afterthe generator
voltageisadjustedtothepropervalueatnoload.It
maybe necessary to advance orretardthe engine throttlecontrolfor
engine driveunitstocontroltheoutputvoltage.Thismay also be
necessary whenlarge changes intheelectricalloadare made.
Keeptheelectricalloadonthe generator within its nameplate rating.
Overloadingthe generator will cause thevoltagetobelow, will shorten
the life and void warranty..
Considerloadandinstallation characteristics todeterminetheproper
starting procedure which will assure voltagebuild-up each time. Fail-
ureof generator to build upvoltagemayoccurwhenthestartingload
istooheavy.(Thisisnotlostresidualmagnetismifthevoltagebuilds
up(1)whenonlypartialloadis connected, or(2)whenloadis connected
after generator reaches speed.)
A. Whenelectricmotor loads are connected, connect oneata time,
begin with largest motor,allow each to reach running speed, then
connect thenextmotor.Electricmotorsrequiremuchmorecur-
rentforstartingthanwhenrunningatnormal speed.
B. Whena rheostat (to limit voltageathigher speed orat light load)is
used, disconnecttheload(turnswitchorcircuit breaker OFF)or
turn rheostat to decrease resistance, until generator reaches speed
to assure build up.
C.Turnoffthelightstoattainpartialloadornoload until generator
reaches speed. Incandescent light bulbs(lamps)drawasmuchas
eighttimestheirrating until filaments heat up.

MAINTENANCE
11
GENERAL SERVICING. - Thegeneratorisdesignedtogive long and
satisfactoryservicewhenproperlycaredfor.
Regularservicingasoutlined here will be well worth the effort required.
The ball bearingsarethedouble-sealedpre-lubricatedtypeanddonot
requirefuture lubrication.
Tolift brushes away from contact, first removethebrushspring(con-
stant pressure type) from itsholder,thenremovethebrush from its
guide, asillustrated.Donot pull thebrushoutasmaybedonewhen
spiral typespringsareused.Donot unwind thespring past theendof
its supportplate.A springsodistortedor kinked mustbereplaced
with a newone .
INSTALL BRUSHES WITH BEVELLED
TOP SLANTING DOWN TOWARD
SPRING HOLDER
TO REMOVE BRUSH
SPRING PRESS
SPRING HOLDER
DOWN ANDOUTAS
SHOWN IN BROKEN
LINES. T-rrrT A513
- Commutator-
TO REMOVE
SPRING LIFT
UP ONTAB
A51 4
NOTE-SPEC A
~ MODELS
ONLY
- Slip Ring -
FIG. 3 - BRUSHES AND SPRINGS(Constant Pressure Type)
BRUSH CONTACT. - Maintain goodelectrical full brushcontactatall
times.
Each200hoursofoperation,oroncea month,cleanthecommutator
and slip rings with a dry, lint free cloth. Donotattempttomaintaina
bright, newlymachined appearance. A dark,glossy appearance is
normal. Heavydepositsor slight roughnessmayberemediedbycare-
ful sanding with #00 sandpaper. Hold the sandpaper flat againstthe
commutator, or slip ring, while thegeneratorisoperating.Usea flat
wooden stick, with light pressure, to hold the sandpaper. Neveruse
emeryorcarborundum cloth orpapei*.Wipeor blow outaccumulations
of brushdust, which may cause a short circuit.
It isnot necessary toremovethebrushrigorend bell when installing
new brushes orcleaningthecommutator.Thebrushes,commutator
and slip ringsareeasilyreachedbyremovingtheend bell cover.
Brusheseventuallyweartooshorttoperformtheir function. Brush
wear will bemorerapidunderdustyoperatingconditions.Replace
brushes with new ones only when worn to5/8 inch inlength.Thebrush
springsprovideequal pressure asthe brushes wearshorterinuse.

12 MAINTENANCE
Eachspringispermanentlyattachedtoa metalplate which snaps into
place,asillustrated.Toreplacea commutatorbrush, first removethe
spring bypushingthespringplate inward andaway from thebrushguide.
To replacea collector ring brush, first removethespringby pulling
straight outwardonthespringplate.When installing a new
brushinitsguide,be sure thatthe"low"orshortersideofthebeveled
top ofthebrushistowardthespring-platesideoftheguide.Be sure
each brushisfreeinitsguide.Keepthebrushrigandend bell cleaned
of carbondust,etc.
Thesurfaceofthecommutatormaybecome worn down level with the
mica insulationbetweenthebars.Ifthecommutatoris worn smooth,
themicabetweenthe bars maybecutdownto1/32"belowthesurface
without removingtherotor.Removetheend bell only, carefully tagging
or otherwisemarkingall leads disconnected.
Remove each springandbrush from itsguide. Pull theend bell off
carefully. Anundercutting tool maybefashioned from a hacksawblade
grinding thebladeteethtoa thicknessequaltothemicabetweenthe bars
of thecommutator.Use care nottoscratchthesurfaceofanybar
while undercuttingthemica.Removeanyburrsformedalongthe edges
of thebars.
If, duetounfavorableoperatingconditions,thecommutatoror slip
rings become worn outofround,grooved,or pitted it will be necessary
to removethearmatureand turn thecommutatorsmoothina lathe.
After turning downthecommutator,undercutthemicabetween bars as
previously described.
BRUSH RIG "NEUTRAL" POSITION. - Eachtime brushes andsprings
areserviced,seethatthebrush
rig witnessmarkisaligned,asillustrated.
BRUSH \ \ /-REFERENCE
RIG—m / MARK
-MOUNTING
^SCREW
//
FOR PROPER NEUTRAL POSITION
ALIGN YELLOW PAINT OR CHISEL
REFERENCE MARK ON BRUSH RIG
TO TOUCH EDGE OFEND BELL NEAR
BRUSH RIG MOUNTING SCREW.
FIG. 4 - BRUSH RIG POSITION
Thepositionofthebrushrigassemblyinthegeneratorend bell isvery
important. Thecorrectsettingofthebrushrigwasdeterminedatthe

900-153 (2-12-71)
SUPPLEMENTARY INSTRUCTIONS
FORONANTWO-BEARINGGENERATORS
Beginning with theSpec, letters shown below, two-bearinggenerator model designation
will change. The reason for this changeis to identify single-bearinggeneratorsfrom
two-bearinggenerators.
The two-bearinggenerators will change to letter "S" after the voltage code. The sin-
gle-bearing generators will havethe letters "C" or "N" after the_voltage code.
EXAMPLE
2.SUD-IS/ID WAS 2.5UD-IN/1C
GENERATORMODEL
EFFECTIVE SPEC. . INSTRUCTION MANUAL
1.5UF-232S B
943-3
2.0UF-232S/32 B 943-4
2.0UF-125S B 943-9
2.0UG-1S/135 B 943-10
2.SUD-IS D 937-5
2.5UF-1S
E 943-1
3.0UF-232S B
943-3
3.SUD-IS
D 937-5
4.OUF-IS^
E 943-1
S.0UF-210S B
943-3
5.0UF-210S B
943-9
7.0UF-1S-^ E
943-1
10.0UF-150S
B 943-5
12.0UF-3S E
943-8
12.0UF-4S E
943-8
15.0UB-150S B
914-33
15.0UF-3S/104
E
943-7
25.0UT-3S/106
B 971-1
25.0UT-5DS/106 B 971-1

MATNTF.NANTF __13
factoryandisidentifiedbya paintedorchisel mark ontheouter edge of
thebrushrigandmustalignwiththe edge oftheendbellwherethe
brush rigismounted.
As longastheoriginalbrushrigandarmaturearecontinuedinservice,
these alignmentmarksmustbeobserved.
MAJORGENERATORREPAIR. - Consulta competentmechanicorelec-
trician, familiarwitha.c.generators,
tolocateanyfaultywindingsandtoperformanynecessarymajorre-
pair. Several tests foropenorgroundedcircuitscanbemadewithout
disassemblingthegenerator.Beforemakingtests,andbeforedisas-
semblingthegenerator,liftthebrushesawayfromcontact.Aftercom-
pletingthemaintenance,returnthebrushestotheiroperatingposition.
DISASSEMBLY. - Ifitshouldbecomenecessarytodisassemblethegen-
erator, liftallbrushesfromcontact.Tagallleads
which aredisconnected,toinsurecorrectreplacementwhenthegenera-
torisreassembled.
When reassemblingbesurethebearing stop clipisinplaceonthebear-
ing opposite thedriveend.Avoidpossibledamagetopartsthrough
carelessdisassemblyandreassembly.Mostotherassemblyprocedures
are self-evident.
ARMATUREGROUNDED, - Seethatallbrushesareliftedoutoftheir
holders.Usea continuitytype test lamp
set.Placeone test prodonthecommutator,andtheotherprodona
bare cleanpartofthegeneratorframeorarmatureshaft.Theprods
mustmake good electricalcontact.The test setlampshouldnotlight.
If it does lightup,thearmatureisgrounded.Testtheslipringsinthe
samemanner.Ifthearmature tests grounded,replacewitha newone.
TESTING THEARMATUREFOR AN OPENCIRCUIT. - The AC winding
ofanalternat-
ingcurrentgeneratormaybetestedforanopencircuitbyuseofthe
test lampset.^Placeone test prodononeslip ring, andtheother test
prod ona second ring. The test lampshouldlight.Ifit does notlight,
an opencircuitispresent.Iftherearethreeorfourrings, test between
eachtwointhesamemanner. Install a newarmatureifanopencircuit
ispresent.
To test thedirectcurrentwindingofanarmatureforanopen circuit,
theuseofanarmaturegrowlerisnecessary.Mostelectricalrepair
shopshavesuchequipment.It will benecessarytoremovethe arma-
ture fortesting.Proceedasfollows.
a. Placethearmatureinthegrowlerwhichisconnectedtoalternating
current. Ruba smoothsteelblade(back edge ofa hacksawblade)

14 MAINTENANCE
acrossthe segments ofthecommutator.
b.At some pointaroundthecom-
mutatora sparkshouldoccurasthe
bladecontactsthetwoadjacent segments.
If a sparkoccurs,thecircuitiscomplete
(notopen) between those two segments.
Then it will benecessarytorotatethe
armature justenoughto test thenexttwo
segments.
Continue therotatingandtestinguntilthe
commutator segments havebeen tested FIG. 5 - OPEN CIRCUITTEST
completelyaround.A good sparkshould
occur between alladjacent segments when those segments andwindings
attachedtothemareinthecorrectpositioninthegrowlermagnetic
field. Ifnosparkoccurs,thewinding between those two segments is
opencircuited.(Thereisa possibilitythata shortcircuitofa winding)
mightpreventthesparking,butthenthearmaturewouldalsobemag-
netizedasdescribedinthefollowingparagraph.)
TESTING THEARMATUREFORSHORT CIRCUITS. - Placethe arma-
tureinthegrowler
(seefigure)whichisconnectedtoalternatingcurrent.Holda steelblade
(oroldhack-sawblade)1/4inchfromthearmaturelaminations.Ifthe
steelbladeisattractedtoanymagnetizedarmaturelaminations,either
thearmaturewindingsorcommutatorisshortcircuited.Donot test
formagnetismatjustonepointofthe
armature laminations,but test allof
thearmaturelaminationsfromone
sideovertotheotherside(alongthe
dotted lineonfigure).Aftertesting
thearmatureinoneposition,revolve
thearmatureabout1/8revolutionand
test formagnetismagain.Continue
therevolvingandtestinguntilthe arma-
turehasbeen tested completelyaround.
APMATUPE
GPOWLEJ?
TO AC
SOU/?C£-
6- SHORT CIRCUIT
TEST
FIELD WINDINGS, OPEN CIRCUIT. - A
test
lampsetcanbeusedto test fieldwindings
foranopencircuit.Placeone test prodonFIG.
oneoftheterminalendsofthefieldwindings,
and theother test prodontheotherterminal
endofthewinding.The test lampshouldlight.Ifit does not,anopen
circuit isindicated. Check carefullytoseethattheopencircuitisnot
atthaterminalleadsora loose terminal.Anopencircuitduetoa
broken leador loose terminaliseasilyrepaired.Anopencircuitwith-
in a coilrequiresreplacementofthesetofcoils.

SERVICE DIAGNOSIS
15
Following isa listoftroublesthatmaybeexperiencedintheoperation
ofthegenerator.Alsolistedarethepossiblecausesandusual rem-
edies for getting thegeneratorbackintoproperefficientoperation.
POSSIBLECAUSEREMEDY
POORCOMMUTATIONORARCING AT THEGENERATORBRUSHES
Brushes outofneutralposition.
Brushes notseatingproperly.
Generator heavilyoverloaded.
Brushes bindinginholder.
Brush tensioninsufficient.
Brushes worntooshort.
Brush tensionunequal.
Wrong type brush.
Loose commutator bars.
High mica.
Commutator outofround.
Commutator surfacedirtyor
oily.
Turn brushringuntiltheidentify-
ingmarksarealigned:
Sand thebrushtothepropercontour.
If the AC orDCamperageismore
than statedonthegeneratorname-
plate,removepartoftheload.
Clean eachbrushandholder.
Replace brushsprings.
Replace brushes.
Replace weakbrushsprings.
Replace withcorrecttypeandmake
ofbrushandspring.
Replace withnewarmature.
Undercut themica.
True thecommutatorinatlathe.
Clean thecommutator.
Windings andpartscovered
with dirt andoil.
Overloaded.
Short circuitorgrounded
circuit inthefieldwindingor
armature winding.
OVERHEATINGOFGENERATOR
Clean generator.
Check loadoroutputofgenerator.
Replace defectiveparts.

16 SERVICE DIAGNOSIS '
POSSIBLECAUSEREMEDY,
OVERHEATINGOFGENERATOR (Cont.)
Excessive arcingatthebrushes.See"PoorCommutation"above.
Unequal airgap between poleshoe Shimup poleshoe untilair gaps are
and armature.equal.'
Generator blowerscrollinstalledReverseblowerscrollposition,
in wrongposition.
GENERATORNOISY
Generator loose onbase.Tightenmountingbolts.
Worn or defective bearing., Replacewornparts.Checkalign-
ment.
Field pole*rubbingarmature.Tightenfield poles toframe.
GENERATOR RUNS BUTDOESNOTPRODUCECURRENT
Brushes notcontactingcom-Freebrushesinholders.Assemble
mutator.brushesandspringscorrectly.
Open, shortorgroundedcir-Testwindingsandrepairorreplace
cuitingenerator. defective parts.
Generator, lineleadsbrokenTightenconnectionsandreplace
or loose. brokenleads.
Generator armaturerotating1. Correct directionofrotation.
in thewrongdirection.2.Or,connectwires,polarize
fieldandreinstallscrollto
agreewithdirectionofrotation.
LOWVOLTAGEOUTPUT OF GENERATOR
Speedlowbecauseof loose, Adjustbelttension,
slippingbelts., • . .
Generator brushesnotin Turn brushringuntiltheidentifying
neutral position.marksarealignedcorrectly
External shortcircuitonline.Testgeneratorwith.linewiresdis-
connected.