Marathon Computer AACC 2000 manual Tuning, Parameter Code Meaning or Function

Page 53

Marathon Monitors Inc.

TUNING

Before tuning, please read Chapter 2, Operation, to learn how to select and change a parameter.

This chapter has five topics:

∙WHAT IS TUNING?

∙AUTOMATIC TUNING

∙MANUAL TUNING

∙COMMISSIONING OF MOTORISED VALVE CONTROLLERS

∙GAIN SCHEDULING

WHAT IS TUNING?

In tuning, you match the characteristics of the controller to those of the process being controlled in order to obtain good control. Good control means:

∙Stable, ‘straight-line’ control of the process variable at setpoint without fluctuation

∙No overshoot, or undershoot, of the process variable setpoint

∙Quick response to deviations from the setpoint caused by external disturbances, thereby rapidly restoring the process variable to the setpoint value.

Tuning involves calculating and setting the value of the parameters listed in Table 4-1. These parameters appear in the ‘Pid’ list.

Parameter	Code	Meaning or Function

Proportional	Pb	The bandwidth, in display units, over which the output power is
band		proportioned between minimum and maximum.

Integral time	ti	Determines the time taken by the controller to remove steady-
		state error signals.

Derivative time	td	Determines how strongly the controller will react to the rate-of-
		change of the measured value.

High Cutback	Hcb	The number of display units, above setpoint, at which the
		controller will increase the output power, in order to prevent
		undershoot on cool down.

Low cutback	Lcb	The number of display units, below setpoint, at which the
		controller will cutback the output power, in order to prevent
		overshoot on heat up.

Relative cool	rEL	Only present if cooling has been configured and a module is
gain		fitted. Sets the cooling proportional band, which equals the Pb
		value divided by the rEL value.

AACC 2000 Carbon

53

Nov. 1, 1997

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Contents Copyright Marathon Monitors INC Marathon Monitors Inc Mechanical Installation Electrostatic discharge precautions SafetyCleaning Electromagnetic compatibilityWiring Safety SymbolsPower Isolation PersonnelOvercurrent protection Over-temperature protectionVoltage rating Conductive pollutionRouting of wires Installation requirements for EMCGrounding of the temperature sensor shield Equipment ratings Environmental ratingsGeneral Electrical safetyMarathon Monitors Inc Installation Outline dimensions Model 2000 controller Outline dimensions ModelIntroduction To install the controllerController labels Unplugging and plugging-in the controllerModel Aacc 2000 rear terminal layout Rear terminal layoutsMarathon Monitors Inc Module 1, 2 Sensor input connectionsSnubbers Two terminal modulesDual output modules Four terminal modulesCOM Connections for Process Value 2 PV2 Connections for Process Value 3 in module positionCommunication module EIA-485 wiring Wiring of 2-wire EIA-485 serial communications linkMarathon Monitors Inc Operation Front Panel LAYOUTs 26.0OP1 Button or Name ExplanationOP2 SP2Basic operation AlarmsOperating modes Output power demand Automatic modeHome display Display unitsSetpoint Manual ModeList header displays Parameters and HOW to Access ThemMarathon Monitors Inc To change the value of a parameter Parameter namesParameter displays OFF List1OFF PID.1 PIDSTD FactPass Hydrogen or CO constant Name Description Prob Probe list Process FactorMillivolt input Offset Name Description DrA TunEDrA.t AdcSEt Pid PID listRES HcbInput list Setpoint listInFo Information list Output listCmS Comms list FF.OP Access ListAlarms Display What it means What to do about it Shows Diagnostic alarms2b Diagnostic alarms Access Levels Access to Read-only Configuration Access list headerPassword entry Level selection Configuration passwordConfiguration level Edit level Setting operator access to a parameterReturning to Operator Level Hiding or revealing a complete listPromoting a parameter This sheet intentionally left blank Parameter Code Meaning or Function TuningHow to tune One-shot TuningAdaptive tune Typical automatic tuning cycleCalculation of the cutback values Manual Tuning Proceed as follows Setting the cutback valuesAutomatic droop compensation Adc Integral action and manual resetMotorized valve control Name Description Values Mtr Motor list Min Max DefaultInertia and backlash settings Adjusting the minimum on-time ‘mp.t’Marathon Monitors Inc Set the transfer point Enable in configuration levelGain scheduling Configuration Press to enter configuration Selecting configuration levelChanging the passwords Leaving Configuration LevelLIN REUD1SA Enab SB.OPNone RelyCMS YES DIGPMV Name Description Values Meaning InSt Instrument configurationH2O 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 Combining several digital events on to one output Comms 1 module configCool Module config1A b C1 Module 1 configuration For ‘id’ = ‘LoG.i’ i.e logic input use the LA Conf’ list on 2A/b/C Module 2 configurationDisplayed value low SEL 3A/b/C Module 3 configurationModule configuration C Module configurationVAL.8 Point Custom LinearisationVAL.1 CAL Exit Exit configuration Password configurationDC Output Calibration User calibrationUser calibration Calibration Configuration List User Calibration EnableUser Calibration Enable Exit configurationCalibration type Offset calibrationInput list header Set Offset See table on the right for additional parametersDisplayed Value Two-point calibrationSelect Low-point Calibration Adjust low-point calibrationSelect High-point Calibration Adjust High-point CalibrationName Parameter description Meaning Calibration points and Calibration offsetsParameter 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