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8/3/2019 The Effects of DC Machine Adjustment on Loop Balance - Jun 08
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The Effect of DC MachineThe Effect of DC Machine
Adjustment onAdjustment on
Loop UnbalanceLoop Unbalance
WMEA, Edmonton, Alberta, CanadaWMEA, Edmonton, Alberta, Canada
June 11June 11--13, 200813, 2008
Rich HallRich Hall Morgan AM&TMorgan AM&T
Jim ShackelfordJim Shackelford Peabody EnergyPeabody Energy
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Technical ContributorTechnical Contributor
Jason ConradJason Conrad GE CanadaGE Canada
Peterborough, Ontario, CanadaPeterborough, Ontario, Canada
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Dragline Generator LoopsDragline Generator Loops
Loop 1Loop 1 Loop 2Loop 2
HG1HG1
HM1HM1
HG3HG3
HM3HM3
HG2HG2
HM2HM2
HG4HG4
HM4HM4
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Dragline Loops ContainDragline Loops Contain
Direct Current GeneratorsDirect Current Generators
Direct Current MotorsDirect Current Motors
Ammeter ShuntsAmmeter Shunts
CablesCables
ConnectionsConnections
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Dragline Generator LoopsDragline Generator Loops
Design BenefitsDesign Benefits
Multiple units in each loop average outsome of the variation in individual generatorsand motors, cabling, etc.
Multiple motors and generators averageout the effect of temperature variations
around the house
Multiple loops give some degree of control of
the machine if one loop is lost
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Loop BalanceLoop Balance
Ideally, the loops behave exactly theIdeally, the loops behave exactly thesame as each other under all conditionssame as each other under all conditions
Visually, they would look like aVisually, they would look like a
wellwell--choreographed synchronizedchoreographed synchronizedswim teamswim team
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Loop BalanceLoop Balancecont.cont.
This means each generator behavesThis means each generator behaveslike every other generatorlike every other generator
Each motor behaves like every otherEach motor behaves like every othermotormotor
Each loopEach loops cables and connectionss cables and connectionshave the same resistance as each otherhave the same resistance as each other
looploop
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These loops act electrically inThese loops act electrically in
parallelparallel
If the generators in one loop produceIf the generators in one loop producemore Voltage than the generators in othermore Voltage than the generators in other
loops, that loop will draw more currentloops, that loop will draw more current
If the motors in one loopIf the motors in one loop trytry to runto run
faster than the motors in other loops, theyfaster than the motors in other loops, theycannot because they are geared together,cannot because they are geared together,
but that loop will draw more currentbut that loop will draw more current
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These loops act electrically inThese loops act electrically in
parallelparallel
If the resistances of the cables andIf the resistances of the cables andconnections are lower in one loop thanconnections are lower in one loop than
the other loops, that loop will drawthe other loops, that loop will drawmore currentmore current
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So what??So what??
Unbalanced loop currents may causeUnbalanced loop currents may cause
excessive torque in some loops, causeexcessive torque in some loops, causeincreased mechanical wear and takeincreased mechanical wear and takelife out of couplings, gears, andlife out of couplings, gears, and
structural parts of the machinestructural parts of the machine
Unbalanced loop currents may result inUnbalanced loop currents may result intoo little torque in some loops andtoo little torque in some loops andreduce the productivity of the draglinereduce the productivity of the dragline
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Other ProblemsOther Problems
Unbalanced loop currents may result inUnbalanced loop currents may result in
increased brush and commutator wearincreased brush and commutator wear Unbalanced loop currents may result inUnbalanced loop currents may result in
flashoversflashovers Unbalanced loop currents may trip theUnbalanced loop currents may trip the
loop overcurrentloop overcurrent
Unbalanced loop currents may causeUnbalanced loop currents may cause
the generator field overcurrent to tripthe generator field overcurrent to trip
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Bigger Problems!!!Bigger Problems!!!
Unbalanced loop currents may result inUnbalanced loop currents may result in
overheating some generators or motorsoverheating some generators or motors
Badly unbalanced loop currents mayBadly unbalanced loop currents maycause the sync motors to pull out ofcause the sync motors to pull out of
synchronization, especially on weaksynchronization, especially on weak
power systemspower systems
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ResultsResults
This may cause damage to equipment,This may cause damage to equipment,
loss of productivity, increasedloss of productivity, increaseddowntime and increased repair costsdowntime and increased repair costs
Rule of thumb in the business lossRule of thumb in the business loss
insurance industry: the cost of theinsurance industry: the cost of the
repair is 10% of the business lossrepair is 10% of the business loss
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How much voltage does it take toHow much voltage does it take to
drive rated current?drive rated current?
The rating of a GE 1045 KW generatorThe rating of a GE 1045 KW generator
is 475 Volts and 2200 Amperes.is 475 Volts and 2200 Amperes.
It does not take 475 Volts to drive ratedIt does not take 475 Volts to drive rated
current in the loop, however.current in the loop, however.
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How much voltage does it take toHow much voltage does it take to
drive rated current?drive rated current?
The answerThe answer about 20 Volts perabout 20 Volts per
generator!!!generator!!!
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How much voltage does it take toHow much voltage does it take to
drive rated current?drive rated current?
When the machines are in aWhen the machines are in a motoringmotoring
quadrant, the generators are generatingquadrant, the generators are generating
an electro motive force (EMF), but thean electro motive force (EMF), but themotors aremotors are also generating angenerating an
electromotive force that opposes theelectromotive force that opposes the
generator EMF and it is called a countergenerator EMF and it is called a counter
EMF (CEMF).EMF (CEMF).
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How much voltage does it take toHow much voltage does it take to
drive rated current?drive rated current?
It is the sum of the generator VoltagesIt is the sum of the generator Voltages
minus the sum of the motor Voltages inminus the sum of the motor Voltages in
the loop that drives loop current.the loop that drives loop current.
This Voltage divided by the loopThis Voltage divided by the loopresistance gives the loop current.resistance gives the loop current.
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Dragline Generator LoopDragline Generator Loop
Loop 1Loop 1
HG1HG1
HM1HM1
HG3HG3
HM3HM3
++
++
++
++__
__
__
__LoopLoop
CurrentCurrent
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How much voltage does it take toHow much voltage does it take to
drive rated current?drive rated current?
The loop resistance is most easilyThe loop resistance is most easily
determined at stall when the motors aredetermined at stall when the motors are
not rotating or generating any CEMF.not rotating or generating any CEMF.
For a 1045 KW generator, about 40 VoltsFor a 1045 KW generator, about 40 Volts
per generator drives stall current (2X ratedper generator drives stall current (2X ratedcurrent or 4400 Amperes).current or 4400 Amperes).
Loop Resistance =Loop Resistance = (40V + 40V(40V + 40V 0V0V -- 0V)0V) == 0.0181 Ohm0.0181 Ohm4400 Amperes4400 Amperes
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How much voltage does it take toHow much voltage does it take to
drive rated current?drive rated current?
It does not take a large VoltageIt does not take a large Voltage
imbalance to drive a lot of current whenimbalance to drive a lot of current when
you divide it by 0.0181!!!you divide it by 0.0181!!!
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Standards for Loop Balance
5% of stall current at stall conditions5% of stall current at stall conditions
5% of stall current while running steady5% of stall current while running steady
(even at peak power)(even at peak power)
10% of stall current during transient10% of stall current during transient
load changesload changes
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How much voltage differenceHow much voltage difference
does it take to be at thedoes it take to be at therecommended limits?recommended limits?
5% of 4400 Amperes = 220 Amperes5% of 4400 Amperes = 220 Amperes
V = IR = 220 Amperes x 0.0181 OhmsV = IR = 220 Amperes x 0.0181 Ohms
V = 3.9 VoltsV = 3.9 Volts
So a 4 Volt difference between loops isSo a 4 Volt difference between loops is
all it takes to be at 5% of stall current!all it takes to be at 5% of stall current!
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Four Quadrant OperationFour Quadrant Operation
1122
33 44
+Volts
+Volts
--Volts
Volts
+ Amps+ Amps-- AmpsAmps
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First QuadrantFirst Quadrant
Armature
Volts
Armature
Volts
Armature AmpsArmature Amps
Commutation LimitsCommutation Limits
Loop 1Loop 1
Loop 2Loop 2
Unbalanced LoopUnbalanced Loop
CurrentCurrent
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Loop BalanceLoop Balance
Loop 1 is the control loop and is insideLoop 1 is the control loop and is inside
the commutation limits, so it is OK.the commutation limits, so it is OK.
Loop 2 is the slave loop and is insideLoop 2 is the slave loop and is insidethe commutation limits, so thethe commutation limits, so the
equipment is OK. It isequipment is OK. It is loafingloafing,,
however, so the dragline is working athowever, so the dragline is working at
less than capacity.less than capacity.
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First QuadrantFirst Quadrant
Armature
Volts
Armature
Volts
Armature AmpsArmature Amps
Commutation LimitsCommutation Limits
Loop 1Loop 1
Loop 2Loop 2
Unbalanced LoopUnbalanced Loop
CurrentCurrent
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Loop BalanceLoop Balance
Loop 1 is the control loop and is insideLoop 1 is the control loop and is inside
the commutation limits, so it is OK.the commutation limits, so it is OK.
Loop 2 is the slave loop and is outsideLoop 2 is the slave loop and is outsidethe commutation limits. This may leadthe commutation limits. This may lead
to commutation distress, flashovers,to commutation distress, flashovers,
excessive wear of couplings and gears,excessive wear of couplings and gears,
tripping of the machine, etc.tripping of the machine, etc.
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Assembling DC MachinesAssembling DC Machines
To work properly together and toTo work properly together and to
commutate well, machines must becommutate well, machines must bebuilt or rebuilt properly.built or rebuilt properly.
Following are GE factory tolerancesFollowing are GE factory tolerances
provided by GE Canada, Peterborough,provided by GE Canada, Peterborough,
Ontario.Ontario.
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GeneratorsGenerators
Pole centerline to pole centerline chordPole centerline to pole centerline chordmeasured at both ends of machinemeasured at both ends of machine
minimum to maximum values must notminimum to maximum values must not
differ by more than 0.125differ by more than 0.125 (3.2 mm)(3.2 mm)
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Pole Tip SpacingPole Tip Spacing
Difference Between A and B isDifference Between A and B is
1/81/8 (3.2 mm) Maximum(3.2 mm) Maximum
AA BB
FrameFrame
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GeneratorsGenerators
Brush Holder AssemblyBrush Holder Assemblyholders to be set 0.070holders to be set 0.070 to 0.080to 0.080 fromfrom
commutator surface (1.8 to 2.0 mm)commutator surface (1.8 to 2.0 mm)
axial skew must not exceed one micaaxial skew must not exceed one micathickness over the length of thethickness over the length of the
commutatorcommutator
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0.070 0.080
(1.8 2.0 mm)
Brush Box HeightBrush Box Height
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GeneratorsGenerators
Circumferential brush spacing (paperCircumferential brush spacing (paper
tape on commutator)tape on commutator)
arcs measured from one brush toe to thearcs measured from one brush toe to thenext must be within 3/64next must be within 3/64 (0.047(0.047 oror
1.2 mm)1.2 mm) (MAXIMUM)(MAXIMUM)
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Commutato
r
Commutato
r
A
F
E
D
C
B
A = ______
B = ______C = ______D = ______
E = ______F = ______
Max. SpacingDiff. = ______
Target is .030
On WestinghouseEquipment
Brush Spacing
Max. Spacing diff = .050 on GE equip.
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GeneratorsGenerators
Air GapsAir Gapsall air gaps to be within +/all air gaps to be within +/--0.0070.007 (0.18 mm)(0.18 mm)
commutating pole air gaps may becommutating pole air gaps may be
different than main pole air gapsdifferent than main pole air gaps
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Uneven And Tapered Air GapsUneven And Tapered Air Gaps
FrameFrame
PolePole
PolePole
FrameFrame
ArmatureArmature
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Air Gap Taper GaugeAir Gap Taper Gauge
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Air Gap MeasurementAir Gap Measurement
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MotorsMotors
Pole centerline to pole centerline chordPole centerline to pole centerline chordmeasured at both ends of machinemeasured at both ends of machine
minimum to maximum values must notminimum to maximum values must notdiffer by more than 0.125differ by more than 0.125 (3.2 mm)(3.2 mm)
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MotorsMotors
Brush Holder AssemblyBrush Holder Assemblyholders to be set 0.070holders to be set 0.070 to 0.080to 0.080 fromfrom
commutator surface (1.8 to 2.0 mm)commutator surface (1.8 to 2.0 mm)axial skew must not exceed one micaaxial skew must not exceed one mica
thickness over the length of thethickness over the length of the
commutatorcommutator
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MotorsMotors
Circumferential brush spacing (paperCircumferential brush spacing (papertape on commutator)tape on commutator)
arcs measured from one brush toe to thearcs measured from one brush toe to thenext must be within 3/64next must be within 3/64 (0.047(0.047 oror
1.2 mm)1.2 mm)
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MotorsMotors
Air GapsAir Gapsall air gaps to be within +/all air gaps to be within +/--0.0070.007 (0.18 mm)(0.18 mm)
commutating pole air gaps may becommutating pole air gaps may be
different than main pole air gapsdifferent than main pole air gaps
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N = Number of TurnsN = Number of Turns
g = Air Gapg = Air Gap
NN
gg
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N xN x iiNN
ee
ii
FluxFlux
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SATURATION CURVESATURATION CURVE
FluxFlux
ininAir GapAir Gap
N xN x
IIFF (Ampere Turns)
(Ampere Turns)
Iron Saturation RegionIron Saturation Region
AirGap
Reg
ion
AirGap
Reg
ion
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NN
ee
02
42
4
++--
Generated VoltsGenerated Volts
LL
VV
Volts = E. M. F. = B x LVolts = E. M. F. = B x L xxVV
wherewhere
B = Flux Density (B = Flux Density ( / area)/ area)L= Length of the conductorL= Length of the conductorVV = Velocity of the conductor= Velocity of the conductor
IIFF
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GeneratorGenerator
VV
B x L xB x L x VV
V (EMF)V (EMF)
BB
IIFieldField
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MotorMotor
VV =
B x L xB x L x VV
VV B x RPMB x RPMRPMRPM
VoltsVolts
VoltsVolts
BB IIFieldField
SpeedSpeed
TorqueTorque
FF B x IB x IAA xx LLTorque = Force x RadiusTorque = Force x Radius
TorqueTorque B x IB x IAA
BB
LL
rr
( Flux Density )( Flux Density )
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MotorMotor
VV B x L xB x L x VV
VV B x L x RPMB x L x RPM
V (CEMF)V (CEMF)
B x RPMB x RPM
IIFieldField x RPMx RPM
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GeneratorGenerator
Data SheetData Sheet
600600
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00
Armat
ureVolts
Armat
ureVolts
100100
200200
300300
400400
500500
600600
Field AmpsField Amps22 44 66 88 1010 1212 1414 1616 1818 2020
..
..
No Load SaturationNo Load SaturationCurveCurve
MCF866B, 836 KW, 475 Volt,MCF866B, 836 KW, 475 Volt,1760 Ampere, 1200 RPM1760 Ampere, 1200 RPM
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Load CurveLoad Curve 836 KW Gen.836 KW Gen.
Armature VoltsArmature Volts Arm. AmpsArm. Amps Field AmpsField Amps
600600 00 18.918.9575575 11201120 18.618.6
550550 22302230 18.618.6450450 25002500 13.513.5
350350 27702770 11.211.2250250 30303030 9.49.4
4040 36003600 6.26.2
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Adjusting DC MachinesAdjusting DC Machines -- FactoryFactory
Black Band MethodBlack Band Method
See the paperSee the paper NECPNECP Tuning DCTuning DC
Motors and GeneratorsMotors and Generators Jun 07Jun 07 onon
the WMEA web sitethe WMEA web site wmea.netwmea.net for otherfor other
methods of tuning DC machinesmethods of tuning DC machines
Buck Boost CurveBuck Boost Curve
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BuckAmps
BuckAmps
Boost
Amps
Boost
Amps
00
Load Amps (%)Load Amps (%)
uc oost Cu e
XX
XX
5050 100100 150150
XXNo Load BandNo Load Band
Center on BuckCenter on Buck
Side (Strong)Side (Strong) Corrective actionCorrective action
shiftshiftbrush rigging with rotationbrush rigging with rotation
(motor) or against rotation(motor) or against rotation
(generator)(generator)
Buck Boost CurveBuck Boost Curve
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BuckAmps
BuckAmps
Boost
Amps
Boost
Amps
00
Load Amps (%)Load Amps (%)
XX
XX
5050 100100 150150
XXNo Load BandNo Load BandCenter on BoostCenter on Boost
Side (Weak)Side (Weak)
Corrective actionCorrective action
shiftshiftbrush rigging againstbrush rigging against
rotation (motor) or withrotation (motor) or with
rotation (generator)rotation (generator)
Buck Boost CurveBuck Boost Curve
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BuckAmps
BuckAmps
Boost
Amps
Boost
Amps
00
Load Amps (%)Load Amps (%)
XX
XX
5050 100100 150150
xx
xx
xx
xx
xx
xx
Band CenterBand Center
Band Center on Boost SideBand Center on Boost Side(Weak)(Weak)
Corrective ActionCorrective Action RemoveRemove
nonmagnetic shims, add magneticnonmagnetic shims, add magnetic
shimsshims
No sparking in
black area,sparking outsideblack area
Buck Boost CurveBuck Boost Curve
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xxLoad Amps (%)Load Amps (%)
Corrective ActionCorrective Action RemoveRemove
magnetic shims, add non magneticmagnetic shims, add non magneticshimsshims
BuckA
mps
BuckA
mps
B
oostAm
ps
B
oostAm
ps
00
XX
XX
5050 100100 150150
xx
xx
xx
xx
xx
Band CenterBand Center
Band Center onBand Center on
Buck SideBuck Side (Strong)(Strong)
Sparking with no buck or boostSparking with no buck or boost
V l RPM R l i D fi dV l RPM R l i D fi d
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Voltage or RPM Regulation DefinedVoltage or RPM Regulation Defined
Armature AmpsArmature Amps
VoltsorRPM
VoltsorRPM
Increased Voltage or RPM RegulationIncreased Voltage or RPM Regulation
Decreased Voltage or RPM RegulationDecreased Voltage or RPM Regulation
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GeneratorGenerator increased main pole air gapincreased main pole air gap
Saturation CurveSaturation Curve
Volts
Volts
Field AmpsField Amps Armature AmpsArmature Amps
RegulationRegulation
Vo
lts
Vo
lts
BeforeBefore
AfterAfter
Regulation decreasesRegulation decreases
G tGenerator d d i l idecreased main pole air gap
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GeneratorGenerator decreased main pole air gapdecreased main pole air gap
Saturation CurveSaturation Curve
Volts
Volts
Field AmpsField Amps Armature AmpsArmature Amps
RegulationRegulation
Vo
lts
Vo
lts
BeforeBefore
AfterAfter
Regulation increasesRegulation increases
GeneratorGenerator increased comm pole air gapincreased comm pole air gap
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p g pp g p
or add nonmagnetic shimsor add nonmagnetic shims
Saturation CurveSaturation Curve
Volts
Volts
Field AmpsField Amps Armature AmpsArmature Amps
RegulationRegulation
Vo
lts
Vo
lts
BeforeBefore
AfterAfter
No EffectNo Effect
Regulation increasesRegulation increases
GeneratorGenerator decreased comm pole air gapdecreased comm pole air gap
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p g pp g p
or remove nonmagnetic shimsor remove nonmagnetic shims
Saturation CurveSaturation Curve
Volts
Volts
Field AmpsField Amps Armature AmpsArmature Amps
RegulationRegulation
Vo
lts
Vo
lts
BeforeBefore
AfterAfter
No EffectNo Effect
Regulation deceasesRegulation deceases
GeneratorGenerator brush shift with rotationbrush shift with rotation
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Ge e ato b us s t t otat o
Saturation CurveSaturation Curve
Volts
Volts
Field AmpsField Amps Armature AmpsArmature Amps
RegulationRegulation
Vo
lts
Vo
lts
BeforeBefore
AfterAfter
No EffectNo Effect
Regulation increasesRegulation increases
GeneratorGenerator brush shift against rotationbrush shift against rotation
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GeneratorGenerator brush shift against rotationbrush shift against rotation
Saturation CurveSaturation Curve
Volts
Volts
Field AmpsField Amps Armature AmpsArmature Amps
RegulationRegulation
Vo
lts
Vo
lts
BeforeBefore
AfterAfter
No EffectNo Effect
Regulation decreasesRegulation decreases
MotorMotor increased main pole air gapincreased main pole air gap
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MotorMotor increased main pole air gapincreased main pole air gap
Saturation CurveSaturation Curve
Volts/RPM
Volts/RPM
Field AmpsField Amps Armature AmpsArmature Amps
RegulationRegulation
RPM
RPM
BeforeBefore
AfterAfter
Regulation increasesRegulation increases
MotorMotor decreased main pole air gapdecreased main pole air gap
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MotorMotor decreased main pole air gapdecreased main pole air gap
Saturation CurveSaturation Curve
Volts/RPM
Volts/RPM
Field AmpsField Amps Armature AmpsArmature Amps
RegulationRegulation
RPM
RPM
BeforeBefore
AfterAfter
Regulation decreasesRegulation decreases
MotorMotor increased comm pole air gap orincreased comm pole air gap or
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p g pp g p
add nonmagnetic shimsadd nonmagnetic shims
Saturation CurveSaturation Curve
Volts/RPM
Volts/RPM
Field AmpsField Amps Armature AmpsArmature Amps
RegulationRegulation
RPM
RPM
BeforeBefore
AfterAfter
Regulation increasesRegulation increasesNo EffectNo Effect
MotorMotor decreased comm pole air gap ordecreased comm pole air gap or
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p g pp g p
remove nonmagnetic shimsremove nonmagnetic shims
Saturation CurveSaturation Curve
Volts/RPM
Volts/RPM
Field AmpsField Amps Armature AmpsArmature Amps
RegulationRegulation
RPM
RPM
BeforeBefore
AfterAfter
Regulation decreasesRegulation decreasesNo EffectNo Effect
MotorMotor Brush shift with rotationBrush shift with rotation
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MotorMotor Brush shift with rotationBrush shift with rotation
Saturation CurveSaturation Curve
Volts/RPM
Volts/RPM
Field AmpsField Amps Armature AmpsArmature Amps
RegulationRegulation
RPM
RPM
BeforeBefore
AfterAfter
Regulation increasesRegulation increasesNo EffectNo Effect
MotorMotor Brush shift against rotationBrush shift against rotation
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MotorMotor Brush shift against rotationBrush shift against rotation
Saturation CurveSaturation Curve
Volts/RPM
Volts/RPM
Field AmpsField Amps Armature AmpsArmature Amps
RegulationRegulation
RPM
RPM
BeforeBefore
AfterAfter
Regulation decreasesRegulation decreasesNo EffectNo Effect
Voltage RegulationVoltage Regulation Shunt GeneratorShunt Generator
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Voltage RegulationVoltage Regulation Shunt GeneratorShunt Generator
Armature AmpsArmature Amps
Vo
lts
Vo
lts
Low Voltage RegulationLow Voltage Regulation
Voltage RegulationVoltage Regulation Shunt GeneratorShunt Generator
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Voltage RegulationVoltage Regulation Shunt GeneratorShunt Generator
Armature AmpsArmature Amps
Vo
lts
Vo
lts
Low Voltage RegulationLow Voltage Regulation
Delta AmpsDelta Amps
DeltaDelta
VoltsVolts
Voltage RegulationVoltage Regulation DifferentialDifferential
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Compound GeneratorCompound Generator
Armature AmpsArmature Amps
Vo
lts
Vo
lts
Higher Voltage RegulationHigher Voltage Regulation
Delta AmpsDelta Amps
DeltaDelta
VoltsVolts
Differentially CompoundDifferentially Compound
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Differentially CompoundDifferentially Compound
GeneratorsGenerators Differentially compound generatorsDifferentially compound generators
limit loop current unbalances, aslimit loop current unbalances, asgenerators that are more heavily loadedgenerators that are more heavily loaded
(loop unbalance) will drop in voltage(loop unbalance) will drop in voltageand shed some load.and shed some load.
This helps, of course, but does notThis helps, of course, but does not
curecure loop unbalance.loop unbalance.
Machine Adjustments and LoopMachine Adjustments and Loop
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Machine Adjustments and LoopMachine Adjustments and Loop
Balance SummaryBalance Summary
DC machines must be built to acceptedDC machines must be built to accepted
tolerances of air gaps, brush spacing, brushtolerances of air gaps, brush spacing, brushbox heights, pole spacing,box heights, pole spacing, commcomm pole boltpole boltmaterial, etc. to be as much alike as possiblematerial, etc. to be as much alike as possible
for the machines to commutate well andfor the machines to commutate well andshare load.share load.
Connections within the machines must beConnections within the machines must betight to minimize variation in excitationtight to minimize variation in excitationcurrents and loop resistance.currents and loop resistance.
Machine Adjustments and LoopMachine Adjustments and Loop
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Machine Adjustments and LoopMachine Adjustments and Loop
Balance Summary cont.Balance Summary cont. When machines are disassembled andWhen machines are disassembled and
reassembled, it is important to keepreassembled, it is important to keeptrack of shims, especially commutatingtrack of shims, especially commutating
pole shims. Both the thickness andpole shims. Both the thickness andorder of shims are important! There isorder of shims are important! There is
not an easy way to correct interpolenot an easy way to correct interpole
shimming in the field, so care with theshimming in the field, so care with themachines when working on them inmachines when working on them in
shops is critical.shops is critical.
Machine Adjustments and LoopMachine Adjustments and Loop
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Machine Adjustments and LoopMachine Adjustments and Loop
Balance Summary cont.Balance Summary cont. There are many things that can contribute toThere are many things that can contribute to
commutation issues: rough commutators,commutation issues: rough commutators,symmetry of assembly, brush grades andsymmetry of assembly, brush grades and
construction, faulty machine componentsconstruction, faulty machine components
and electrical connections. Sometimesand electrical connections. Sometimespeople try topeople try to fixfix machines by tuning themmachines by tuning them
up with neutral adjustments. Rememberup with neutral adjustments. Remember
this affects machine output and loopthis affects machine output and loop
balance, and you cannotbalance, and you cannot adjust outadjust out thesethese
underlying causes of commutation distress.underlying causes of commutation distress.
Field Process to AddressField Process to Address
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Field Process to AddressField Process to Address
Loop UnbalancesLoop Unbalances Take Time versus: Drive Reference, Armature Volts
and Amps, and Motor Field Current
Make Stud to Stud Spacing Correct Set Neutral (on GE Generator 1/8 with Rotation)
Adjust Generator Air Gaps to Ensure that the Sum of
the Volts in Each Loop are Equal within 2.5 Volts perGenerator in the Loop ( 4 Generators in the Loop 10 Volts)
Trim Motor Fields As Necessary
Adjust Motor Neutral As Last Resort (Should be atNeutral Not with or Against Rotation)
If Possible Re-wire the Motion to Two Loops
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Oversize HoleOversize Hole
UseUse Thin WallThin Wall
Conduit to CenterConduit to CenterStud on YokeStud on Yoke
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Lot 8 2570WLot 8 2570W
Hoist UnbalanceHoist Unbalance As FoundAs Found
485 Amps485 Amps 12.2%12.2%
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Lot 8 2570WLot 8 2570W
Drag UnbalanceDrag Unbalance As FoundAs Found
988 Amps988 Amps 24.9%24.9%
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Lot 8 2570WLot 8 2570WHoist and Drag UnbalancesHoist and Drag Unbalances As LeftAs Left
After Adjustments and Making Both Motions into Two LoopsAfter Adjustments and Making Both Motions into Two Loops
Hoist Unbalance 53 AmpsHoist Unbalance 53 Amps 1.3% Drag Unbalance 95 Amps1.3% Drag Unbalance 95 Amps 2.4%2.4%
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Key 2 8750Key 2 8750
Drag UnbalanceDrag Unbalance As FoundAs Found1800 Amps1800 Amps 50%50%
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Key 2 8750Key 2 8750Drag UnbalanceDrag Unbalance As LeftAs Left
59 Amps59 Amps 1.6%1.6%
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Key 2 8750Key 2 8750
Hoist UnbalanceHoist Unbalance As FoundAs Found
616 Amps616 Amps --15.6%15.6%
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Key 2 8750Key 2 8750
Hoist Loop UnbalanceHoist Loop Unbalance As LeftAs Left
139 Amps139 Amps 3.5%3.5%
Related WMEA PapersRelated WMEA Papers
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Related WMEA Papersp
available onavailable on wmea.netwmea.net
National CarbonNational Carbon Successful BrushSuccessful BrushPerformancePerformance Jun 05Jun 05
NECPNECP Tuning DC Motors andTuning DC Motors and
GeneratorsGenerators Jun 07Jun 07
R f M t i lR f M t i l
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Reference MaterialsReference Materials
Loop Unbalance Guidelines GE
Benchmark, January 1997, Steve Baade
Loop Unbalance Guidelines GEBenchmark, April 1997, Steve Baade
GE DC Machine Adjustments andOperating Characteristics
R f W b SitReference Web Sites
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Reference Web SitesReference Web Sites
Morgan AM&TMorgan AM&T National ElectricalNational Electrical
CarbonCarbon www.morganAMT.comwww.morganAMT.com GE MotorsGE Motors -- www.GEMotors.comwww.GEMotors.com