Manual Tuning | Marathon Computer AACC 2000 instruction

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

56

Nov. 1, 1997

Image 56

Marathon Computer AACC 2000 manual Manual Tuning

Contents

Copyright Marathon Monitors INC Marathon Monitors Inc Mechanical Installation Safety Electrostatic discharge precautionsCleaning Electromagnetic compatibility Safety Symbols WiringPower Isolation Personnel Over-temperature protection Overcurrent protectionVoltage rating Conductive pollution Routing of wires Installation requirements for EMCGrounding of the temperature sensor shield Environmental ratings Equipment ratings Electrical safety General Marathon Monitors Inc Installation Outline dimensions Model Outline dimensions Model 2000 controller To install the controller IntroductionController labels Unplugging and plugging-in the controller Rear terminal layouts Model Aacc 2000 rear terminal layout Marathon Monitors Inc Sensor input connections Module 1, 2 Two terminal modules Snubbers Dual output modules Four terminal modulesCOM Connections for Process Value 3 in module position Connections for Process Value 2 PV2 Communication module Wiring of 2-wire EIA-485 serial communications link EIA-485 wiring Marathon Monitors Inc Operation 26.0 Front Panel LAYOUTs Button or Name Explanation OP1OP2 SP2 Alarms Basic operation Operating modes Automatic mode Output power demandHome display Display units Manual Mode Setpoint Parameters and HOW to Access Them List header displays Marathon Monitors Inc To change the value of a parameter Parameter namesParameter displays OFF List1OFF PID PID.1 Fact STD Pass Hydrogen or CO constant Name Description Prob Probe list Process FactorMillivolt input Offset Name Description TunE DrADrA.t Adc Pid PID list SEtRES Hcb Setpoint list Input list InFo Information list Output listCmS Comms list Access List FF.OP Alarms Diagnostic alarms Display What it means What to do about it Shows 2b 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 list Promoting a parameter This sheet intentionally left blank Tuning Parameter Code Meaning or Function One-shot Tuning How to tune Adaptive tune Typical automatic tuning cycleCalculation of the cutback values Manual Tuning Setting the cutback values Proceed as follows Integral action and manual reset Automatic droop compensation Adc Name Description Values Mtr Motor list Min Max Default Motorized valve control Adjusting the minimum on-time ‘mp.t’ Inertia and backlash settings Marathon Monitors Inc Set the transfer point Enable in configuration levelGain scheduling Configuration Selecting configuration level Press to enter configuration Leaving Configuration Level Changing the passwords REU LIND1SA Enab SB.OP None RelyCMS DIG YES PMV InSt Instrument configuration Name Description Values MeaningH2O SP.FF CJC 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 output Cool 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 on Displayed value low 3A/b/C Module 3 configuration SEL C Module configuration Module configuration VAL.8 Point Custom LinearisationVAL.1 CAL Password configuration Exit Exit configurationDC Output Calibration User calibration User calibration User Calibration Enable Calibration Configuration ListUser Calibration Enable Exit configuration Calibration type Offset calibrationInput list header See table on the right for additional parameters Set Offset Two-point calibration Displayed Value Adjust low-point calibration Select Low-point Calibration Adjust High-point Calibration Select High-point Calibration Calibration points and Calibration offsets Name Parameter description Meaning Parameter 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