User Guide - Eurotherm Ltda

nanodac RECORDER/CONTROLLER: USER GUIDE4.7.4 Advanced Loop Master PID menuAdvanced Loop.Master PIDControl ActionPB UnitsDerivative TypePBTiTdCBHCBLMRLBTError limitReverseEngineeringPV20.0360.0 sec60.0 secAutoAuto0.0 %100 sec999999.0 secControl ActionPB UnitsDeriv TypePBTiTdCBHCBLMRLBTFigure 4.7.4 Advanced Loop master PID menuSelect ‘Reverse’ or ‘Direct’.‘Reverse’ means that the output is ‘on’ when the process value (PV) is below the targetsetpoint (SP). This is normal for heating control.‘Direct’ means that the output is on when PV is above SP. This is normal for cooling control.Select ‘Engineering’ or ‘Percent’.‘Engineering’ displays values in (for example) temperature units (e.g. °C or °F).‘Percent’ displays values as a percentage of loop span (Range High - Range Low).‘Error’ means that changes to PV or SP cause changes to the derivative output. Derivativeon error should be used with a programmer since it tends to reduce ramp overshoot.‘Error’ provides rapid response to small setpoint changes which makes it idealfor temperature control systems.‘PV’ means that changes in PV alone cause changes to the derivative output. Typicallyused for process systems using valve control, as it reduces wear on the valve mechanics.Proportional band. The proportional term in the units (Engineering units or %) set in‘PBUnits’ above. See Appendix B section B2.2.2 for more details.Integral time constant. Valid entries are1 to 9999.9 seconds, or ‘Off’. If set Off, then integralaction is disabled. Removes steady state control offsets by moving the output upor down at a rate proportional to the error signal.Derivative time constant. Valid entries are 1 to 9999.9 seconds, or ‘Off’. If set Off, thenderivative action is disabled. Determines how strongly the controller reacts to the rateof-changein the PV. Used to control overshoot and undershoot and to restore the PVrapidly if there is a sudden change in demand.Cutback high. Valid entries ‘Auto’ (3×PB) or 0.1 to 9999.9. The number of display unitsabove setpoint at which the controller output is forced to 0% or -100% (OP min), in orderto modify undershoot on cool down. See section B2.3.2 for more details.Cutback low. Valid entries ‘Auto’ (3×PB) or 0.1 to 9999.9. The number of display unitsbelow setpoint at which the controller output is forced to 100% (OP max), in order tomodify overshoot on heat up. See section B2.3.2 for more details.Manual reset. Valid entries -100% to +100%. Introduces a fixed additional power levelto the output in order to eliminate steady state error from proportional only control.Applied instead of the integral component when Ti is set to ‘Off’.Loop break time. valid entries are 1 to 99999 seconds, or ‘Off’. See section B2.3.6 formore detailsHA030554Issue 7 Nov 12Page 113