The Effects of DC Machine Adjustment on Loop Balance - Jun 08

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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The answerThe answer about 20 Volts perabout 20 Volts per

generator!!!generator!!!


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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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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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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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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 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


Commutation LimitsCommutation Limits

Loop 1Loop 1

Loop 2Loop 2

Unbalanced LoopUnbalanced Loop

CurrentCurrent


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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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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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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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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)



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BuckAmps

BuckAmps

Boost

Amps

Boost

Amps

00


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)



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BuckAmps

BuckAmps

Boost

Amps

Boost

Amps

00


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



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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


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


Volts

Volts



Vo

lts

Vo

lts

BeforeBefore

AfterAfter

Regulation increasesRegulation increases

GeneratorGenerator increased comm pole air gapincreased comm pole air gap


63/91

p g pp g p

or add nonmagnetic shimsor add nonmagnetic shims


Volts

Volts



Vo

lts

Vo

lts

BeforeBefore

AfterAfter

No EffectNo Effect


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


Volts

Volts



Vo

lts

Vo

lts

BeforeBefore

AfterAfter

No EffectNo Effect

Regulation deceasesRegulation deceases

GeneratorGenerator brush shift with rotationbrush shift with rotation


65/91

Ge e ato b us s t t otat o


Volts

Volts



Vo

lts

Vo

lts

BeforeBefore

AfterAfter

No EffectNo Effect


GeneratorGenerator brush shift against rotationbrush shift against rotation


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GeneratorGenerator brush shift against rotationbrush shift against rotation


Volts

Volts



Vo

lts

Vo

lts

BeforeBefore

AfterAfter

No EffectNo Effect


MotorMotor increased main pole air gapincreased main pole air gap


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MotorMotor increased main pole air gapincreased main pole air gap


Volts/RPM

Volts/RPM



RPM

RPM

BeforeBefore

AfterAfter


MotorMotor decreased main pole air gapdecreased main pole air gap


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MotorMotor decreased main pole air gapdecreased main pole air gap


Volts/RPM

Volts/RPM



RPM

RPM

BeforeBefore

AfterAfter


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


Volts/RPM

Volts/RPM



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


Volts/RPM

Volts/RPM



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


Volts/RPM

Volts/RPM



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


Volts/RPM

Volts/RPM



RPM

RPM

BeforeBefore

AfterAfter

Regulation decreasesRegulation decreasesNo EffectNo Effect

Voltage RegulationVoltage Regulation Shunt GeneratorShunt Generator


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Vo

lts

Vo

lts

Low Voltage RegulationLow Voltage Regulation



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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


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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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.



78/91


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.



79/91


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


80/91

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


81/91

Oversize HoleOversize Hole

UseUse Thin WallThin Wall

Conduit to CenterConduit to CenterStud on YokeStud on Yoke


82/91

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%


84/91

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%


85/91

Key 2 8750Key 2 8750

Drag UnbalanceDrag Unbalance As FoundAs Found1800 Amps1800 Amps 50%50%


86/91

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%


88/91

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


89/91

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


90/91

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

Documents

The Effects of DC Machine Adjustment on Loop Balance - Jun 08