Advanced Motion Controls 12A8 - Motor Problems

FIGURE B.1 Peak Current Fold-Back
Continuous Current Limit
1
11
Peak Current Limit
t(s)
Drive Current
Output
Amps
0
Sustained maximum current demand, when switching between positive
and negative maximum current without allowing sufficient time for fold-
back, will result in drive damage. Drive RMS current should be below the
continuous current setting!
MNALAZIN-02 43
/ Fault Conditions and Symptoms
withinatimeframeoflessthan10seconds.Anover‐currentconditionwillnotcausethedrive
tobecomedisabled.
Motor Problems
Amotorrun‐awayconditioniswhenthemotorspinsrapidlywithnocontrolfromthe
commandinput.Themostlikelycauseofthiserrorcomesfromhavingthefeedbackelement
connectedforpositivefeedback.Thiscanbesolvedbychangingtheorderthatthefeedback
elementlinesareconnectedtothedrive,orforAZBHandAZBEdrives,changingSwitch4on
theDIPswitchbanktotheoppositesetting.Seethedrivedatasheetformoreinformationon
DIPswitchsettings.
Anothercommonmotorissueiswhenthemotorspinsfasterinonedirectionthanintheother.
Thisistypicallycausedbyimpropercommutation,usuallybecausethemotorpowerwiresare
connectedinthewrongorder.Tryallsixcombinationsofconnectingthemotorpowerwiresto
thedrivetofindthecorrectcommutationorder.Thepropercombinationofmotorwireswill
yieldsmoothmotionandidenticalspeedsinbothdirections.Impropercombinationswill
causejerkymotion,slowmovementinonedirection,and/oraudiblenoise.Asafinal
verificationthatthecommutationiscorrect,usetheVelocityMonitorOutputpintomeasure
motorspeedinbothdirections(see“VelocityMonitorOutput”onpage33formore
information).ThiscanalsobecausedbyinvalidHallCommutation.Checktoseeifthedriveis
setfor120‐or60‐degreephasing,andwhetherthissettingcorrespondstothetypeofmotor
beingused(typically120‐degreeforthreephasemotors,and60‐degreeforsinglephase
motors).See“HallSensors”onpage8formoreinformation.
Causes of Erratic Operation
• Impropergrounding(forexample,drivesignalgroundisnotconnectedtosourcesignal
ground).
• Noisycommandsignal.Checkforsystemgroundloops.
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