Marathon Computer AACC 2000 manual Manual Tuning

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Marathon Monitors Inc.

MANUAL TUNING

If for any reason automatic tuning gives unsatisfactory results, you can tune the controller manually. There are a number of standard methods for manual tuning. The one described here is the Ziegler-Nichols method.

With the process at its normal running process variable:

1.Set the Integral Time ‘ti’ and the Derivative Time ‘td’ to OFF.

2.Set High Cutback and Low Cutback, ‘Hcb’ and ‘Lcb’, to ‘Auto’.

3.Ignore the fact that the process variable may not settle precisely at the setpoint.

4.If the process variable is stable, reduce the proportional band ‘Pb’ so that the process variable just starts to oscillate. If the process variable is already oscillating, increase the proportional band until it just stops oscillating. Allow enough time between each adjustment for the loop to stabilise. Make a note of the proportional band value ‘B’ and the period of oscillation ‘T’.

5.Set the Pb, ti, td parameter values according to the calculations given in Table 4-2.

Type of control	Proportional	Integral time	Derivative time
	band ‘Pb’	‘ti’	‘td’
Proportional only	2xB	OFF	OFF

P + I control	2.2xB	0.8xT	OFF

P + I + D control	1.7xB	0.5xT	0.12xT

	Table 4-2 Tuning values

AACC 2000 Carbon

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Nov. 1, 1997

Image 56

Contents Copyright Marathon Monitors INC Marathon Monitors Inc Mechanical Installation Safety Electrostatic discharge precautionsCleaning Electromagnetic compatibilitySafety Symbols WiringPower Isolation PersonnelOver-temperature protection Overcurrent protectionVoltage rating Conductive pollutionRouting of wires Installation requirements for EMCGrounding of the temperature sensor shield Environmental ratings Equipment ratingsElectrical safety GeneralMarathon Monitors Inc Installation Outline dimensions Model Outline dimensions Model 2000 controllerTo install the controller IntroductionController labels Unplugging and plugging-in the controllerRear terminal layouts Model Aacc 2000 rear terminal layoutMarathon Monitors Inc Sensor input connections Module 1, 2Two terminal modules SnubbersDual output modules Four terminal modulesCOM 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 LAYOUTsButton or Name Explanation OP1OP2 SP2Alarms Basic operationOperating modes Automatic mode Output power demandHome display Display unitsManual Mode SetpointParameters and HOW to Access Them List header displaysMarathon Monitors Inc To change the value of a parameter Parameter namesParameter displays OFF List1OFF PID PID.1Fact STDPass Hydrogen or CO constant Name Description Prob Probe list Process FactorMillivolt input Offset Name Description TunE DrADrA.t AdcPid PID list SEtRES HcbSetpoint list Input listInFo Information list Output listCmS Comms list Access List FF.OPAlarms Diagnostic alarms Display What it means What to do about it Shows2b Diagnostic alarms Access Levels Access to Read-only Configuration Access list headerPassword entry Level selection Configuration passwordConfiguration level Setting operator access to a parameter Edit levelReturning to Operator Level Hiding or revealing a complete listPromoting a parameter This sheet intentionally left blank Tuning Parameter Code Meaning or FunctionOne-shot Tuning How to tuneAdaptive tune Typical automatic tuning cycleCalculation of the cutback values 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 Set the transfer point Enable in configuration levelGain scheduling Configuration Selecting configuration level Press to enter configurationLeaving Configuration Level Changing the passwordsREU LIND1SA Enab SB.OPNone RelyCMS DIG YESPMV InSt Instrument configuration Name Description Values MeaningH2O SP.FFCJC Process value configInput configuration VAL.H Setpoint configurationVAL.L Alarm Modes Alarm configuration ValuesTable a Alarm types Value IMP Digital input 1 configuration Action on contact closureDigital input 2 configuration Action on contact closure Pflt Alarm relay configurationVflt Comms 1 module config Combining several digital events on to one outputCool Module config1A b C1 Module 1 configuration 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.8 Point Custom LinearisationVAL.1 CAL Password configuration Exit Exit configurationDC Output Calibration User calibrationUser calibration User Calibration Enable Calibration Configuration ListUser Calibration Enable Exit configurationCalibration type Offset calibrationInput list header 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