Azbil DCP31 - Page 129

7-19
Chapter 7. PARAMETER SETUP

.-C
(motor control method selection)
0: MFBcontrol(conventional)+estimatedpositioncontrol
1: MFBcontrol(conventional)only
2: Estimatedpositioncontrolonly
•0: MFBcontrol(conventional)+estimatedpositioncontrol
•WhenMFB(MotorFeedBack)inputisnormal,themotorposition
iscontrolledbytheactuallymeasuredMFB.
•WhenMFBinputisinerror,themotorpositioniscontrolledbyan
estimatedMFBvalue.Thisstateisreferredtoas“estimatedposi-
tioncontrolstate.”
Forexample,whenthemotorrotatesatapositionwherethefeed-
backpotentiometerhasdeteriorated,MFBinputchangessuddenly.
Thissuddenchangeisdetectedasanerror,andthecorrectMFB
positionisestimated.Themotorpositionisalsocontrolledby
theestimatedMFBvaluewhentheMFBdisconnectedalarmhas
occurred.
•Intheestimatedpositioncontrolstate,anerrorwillinevitably
occurbetweentheactualmotorvalveopeningandestimatedMFB
value.
So,settheclosed-siderelaytoONatalltimeswhenoutput(MV)
≤0.0%,andtheopen-siderelaytoONatalltimeswhenMV≥
100.0%tosetthemotortoafully-openorfully-closedstateto
compensatethiserror.
However,notethatthiserrorisnotcompensatedwhenMVis
limitedtowithin0.1to99.9%bytheoutputlimitter,orwhenMV
is0.0%orlessor100%ormoreduetothecontrolstate.
•Thefollowingareprobablecauseswhenestimatedpositioncontrol
islikelytobecarriedout:
-Defectivemotorvalveopeningadjustment
-Deterioratedfeedbackpotentiometer,insufficientresolution
-DefectiveMFBwiring.
•1: MFBcontrol(conventional)only
•Whenthissettingisused,conventionalMFBcontroliscarried
out.WhentheMFBdisconnectedalarmoccurs,theMFBvalueis
regardedas150.0%,andtheclosed-siderelayisONatalltimes.
•2:Estimatedpositioncontrolonly
•Whenthissettingisused,controlisintheestimatedposition
controlstateatalltimes,andthemotorpositioniscontrolledby
theestimatedMFBvalueregardlessofthestateofMFBwiring.
•Whenthissettingisused,enterthecorrect
.-titem.