Marathon Computer AACC 2000 Integral action and manual reset, Automatic droop compensation Adc

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Marathon Monitors Inc.

Integral action and manual reset

In a full three-term controller (that is, a PID controller), the integral term ‘ti’ automatically removes steady state errors from the setpoint. If the controller is set up to work in two-term mode (that is, PD mode), the integral term will be set to ‘OFF’. Under these conditions the measured value may not settle precisely at setpoint. When the integral term is set to ‘OFF’ the parameter manual reset (code ‘rES’) appears in the ‘Pid LiSt’ in ‘FuLL’ level. This parameter represents the value of the power output that will be delivered when the error is zero. You must set this value manually in order to remove the steady state error.

Automatic droop compensation (Adc)

The steady state error from the setpoint, which occurs when the integral term is set to ‘OFF’ is sometimes referred to as ‘droop’. ‘Adc’ automatically calculates the manual reset value in order to remove this droop. To use this facility, you must first allow the process variable to stabilise. Then, in the autotune parameter list, you must set ‘Adc’ to

‘on’. The controller will then calculate a new value for manual reset, and switch ‘Adc’ to ‘OFF’.

‘Adc’ can be repeated as often as you require, but between each adjustment you must allow time for the process variable to stabilise.

AACC 2000 Carbon

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Nov. 1, 1997

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Contents Copyright Marathon Monitors INC Marathon Monitors Inc Mechanical Installation Cleaning SafetyElectrostatic discharge precautions Electromagnetic compatibilityPower Isolation Safety SymbolsWiring PersonnelVoltage rating Over-temperature protectionOvercurrent protection Conductive pollutionGrounding of the temperature sensor shield Installation requirements for EMCRouting of wires Environmental ratings Equipment ratingsElectrical safety GeneralMarathon Monitors Inc Installation Outline dimensions Model Outline dimensions Model 2000 controllerController labels To install the controllerIntroduction Unplugging and plugging-in the controllerRear terminal layouts Model Aacc 2000 rear terminal layoutMarathon Monitors Inc Sensor input connections Module 1, 2Two terminal modules SnubbersCOM Four terminal modulesDual output modules Connections for Process Value 3 in module position Connections for Process Value 2 PV2Communication module Wiring of 2-wire EIA-485 serial communications link EIA-485 wiringMarathon Monitors Inc Operation 26.0 Front Panel LAYOUTsOP2 Button or Name ExplanationOP1 SP2Alarms Basic operationOperating modes Home display Automatic modeOutput power demand Display unitsManual Mode SetpointParameters and HOW to Access Them List header displaysMarathon Monitors Inc Parameter displays Parameter namesTo change the value of a parameter 1OFF ListOFF PID PID.1Fact STDPass Millivolt input Offset Name Description Prob Probe list Process FactorHydrogen or CO constant Name Description DrA.t TunEDrA AdcRES Pid PID listSEt HcbSetpoint list Input listCmS Comms list Output listInFo Information list Access List FF.OPAlarms Diagnostic alarms Display What it means What to do about it Shows2b Diagnostic alarms Access Levels Password entry Access list headerAccess to Read-only Configuration Configuration level Configuration passwordLevel selection Returning to Operator Level Setting operator access to a parameterEdit level Hiding or revealing a complete listPromoting a parameter This sheet intentionally left blank Tuning Parameter Code Meaning or FunctionOne-shot Tuning How to tuneCalculation of the cutback values Typical automatic tuning cycleAdaptive tune Manual Tuning Setting the cutback values Proceed as followsIntegral action and manual reset Automatic droop compensation AdcName Description Values Mtr Motor list Min Max Default Motorized valve controlAdjusting the minimum on-time ‘mp.t’ Inertia and backlash settingsMarathon Monitors Inc Gain scheduling Enable in configuration levelSet the transfer point Configuration Selecting configuration level Press to enter configurationLeaving Configuration Level Changing the passwordsD1SA Enab REULIN SB.OPCMS RelyNone DIG YESPMV H2O InSt Instrument configurationName Description Values Meaning SP.FFInput configuration Process value configCJC VAL.L Setpoint configurationVAL.H Table a Alarm types Value Alarm configuration ValuesAlarm Modes Digital input 2 configuration Action on contact closure Digital input 1 configuration Action on contact closureIMP Vflt Alarm relay configurationPflt Comms 1 module config Combining several digital events on to one output1A b C1 Module 1 configuration Module configCool 2A/b/C Module 2 configuration For ‘id’ = ‘LoG.i’ i.e logic input use the LA Conf’ list onDisplayed value low 3A/b/C Module 3 configuration SELC Module configuration Module configurationVAL.1 Point Custom LinearisationVAL.8 CAL DC Output Calibration Password configurationExit Exit configuration User calibrationUser calibration User Calibration Enable User Calibration EnableCalibration Configuration List Exit configurationInput list header Offset calibrationCalibration type See table on the right for additional parameters Set OffsetTwo-point calibration Displayed ValueAdjust low-point calibration Select Low-point CalibrationAdjust High-point Calibration Select High-point CalibrationCalibration points and Calibration offsets Name Parameter description MeaningParameter Table Default HY1 Ssel FLT3 Marathon Monitors Inc AL1 Module 2A High Value VAL.1 101 Index Two-point calibration User calibration Aacc 2000 Carbon