Advanced Motion Controls 12A8 - Motor Wires; Power Supply Wires; Feedback Wires

MNALAZIN-02 20
Integration in the Servo System / Wiring
ofbeingtoothickratherthantoothin.Thisrecommendationbecomesmorecriticalasthe
cablelengthincreases.
Motor Wires
Themotorpowerwiressupplypowerfromthedrivetothemotor.Useofatwisted,shielded
pairforthemotorpowercablesisrecommendedtoreducetheamountofnoisecouplingto
sensitivecomponents.
• Forabrushedmotororvoicecoil,twistthetwomotorwirestogetherasagroup.
• Forabrushlessmotor,twistallthreemotorwirestogetherasagroup.
GroundthemotorpowercableshieldatoneendonlytothemountingcardorPCBinterface
chassisground.Themotorpowerleadsshouldbebundledandshieldedintheirowncableand
keptseparatefromfeedbacksignalwires.
Power Supply Wires
ThePWMcurrentspikesgeneratedbythepoweroutput‐stagearesuppliedbytheinternal
powersupplycapacitors.Inordertokeepthecurrentrippleonthesecapacitorstoan
acceptablelevelitisnecessarytouseheavypowersupplyleadsandkeepthemasshortas
possible.Reducetheinductanceofthepowerleadsbytwistingthem.Groundthepowersupply
cableshieldatoneendonlytothemountingcardorPCBinterfacechassisground.
Whenmultipledrivesareinstalledinasingleapplication,precautionregardinggroundloops
mustbetaken.Whenevertherearetwoormorepossiblecurrentpathstoaground
connection,damagecanoccurornoisecanbeintroducedinthesystem.Thefollowingrules
applytoallmultipleaxisinstallations,regardlessofthenumberofpowersuppliesused:
1. Runseparatepowersupplyleadstoeachdrivedirectlyfromthepowersupplyfilter
capacitor.
2. Never"daisy‐chain"anypowerorDCcommonconnections.Usea"star"‐connection
instead.
Feedback Wires
Useofatwisted,shieldedpairforthefeedbackwiresisrecommended.Groundtheshieldatone
endonlytothemountingcardorPCBinterfacechassisground.Routecablesand/orwiresto
minimizetheirlengthandexposuretonoisesources.Themotorpowerwiresareamajor
sourceofnoise,andthemotorfeedbackwiresaresusceptibletoreceivingnoise.Thisiswhyit
isneveragoodideatoroutethemotorpowerwireswiththemotorfeedbackwires,evenif
theyareshielded.Althoughbothofthesecablesoriginateatthedriveandterminateatthe
DO NOT use wire shield to carry motor current or power!
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