YOKOGAWA UT55A - Page 127

7-20
IM 05P01C31-01EN
SwitchingattheInputSwitchingPVHighLimit(ParameterPV.2C=1)
Thismethodautomaticallyswitchestwoinputsatswitchingpoint(inputswitchingPVhigh
limit)
Itshouldbe
selectedincasewhereasuddenchangeinPVisallowed.
Controloutputwillchangesmoothly(i.e.,withoutanybumps)whenPVswitches.
Hysteresis(0.5%ofPVrangespan)isprovidedaroundtheswitchingpoint.
PVrisingprocess
PV.HL
Input 2
(High-temperature side)
PV
Input 1
(Low-temperature side)
Time
Hysteresis
PV = Input 1 PV = Input 2
PVfallingprocess
PV.HL
Input 2
(High-temperature side)
PV
Input 1
(Low-temperature side)
Time
Hysteresis
PV = Input 1 PV = Input 2
Wheninput1<PV.HL–0.5%ofPVinputrangespan,PV=Input1.
WhenPV.HL≤Input1,PV=Input2.
7.7SettingPVSwitchingMethodsofLoopControlwithPVSwitching