Marathon Computer AACC 2000 manual Setting the cutback values, Proceed as follows

Page 57

Marathon Monitors Inc.

Setting the cutback values

The above procedure sets up the parameters for optimum steady state control. If unacceptable levels of overshoot or undershoot occur during start-up, or for large step changes in process variable, then manually set the cutback parameters ‘Lcb’ and ‘Hcb’.

Proceed as follows:

1.Set the low and high cutback values to three proportional bandwidths (that is to say, Lcb = Hcb = 3 x Pb).

2.Note the level of overshoot, or undershoot, that occurs for large atmosphere changes (see the diagrams below).

In example (a) increase ‘Lcb’ by the overshoot value. In example (b) reduce ‘Lcb’ by the undershoot value.

Example (a)

Atmosphere

OvershootSetpoint

Example (b)

Atmosphere

Setpoint

Undershoot

Time

Where the atmosphere approaches setpoint from above, you can set ‘Hcb’ in a similar manner.

AACC 2000 Carbon

57

Nov. 1, 1997

Image 57

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 pollutionInstallation requirements for EMC Grounding of the temperature sensor shieldRouting of wires 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 modulesFour terminal modules COMDual output modules 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 Parameter names Parameter displaysTo change the value of a parameter List 1OFFOFF PID.1 PIDSTD FactPass Name Description Prob Probe list Process Factor Millivolt input OffsetHydrogen or CO constant Name Description DrA TunEDrA.t AdcSEt Pid PID listRES HcbInput list Setpoint listOutput list CmS Comms listInFo Information list FF.OP Access ListAlarms Display What it means What to do about it Shows Diagnostic alarms2b Diagnostic alarms Access Levels Access list header Password entryAccess to Read-only Configuration Configuration password Configuration levelLevel selection 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 TuningTypical automatic tuning cycle Calculation of the cutback valuesAdaptive tune 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 Enable in configuration level Gain schedulingSet the transfer point Configuration Press to enter configuration Selecting configuration levelChanging the passwords Leaving Configuration LevelLIN REUD1SA Enab SB.OPRely CMSNone YES DIGPMV Name Description Values Meaning InSt Instrument configurationH2O SP.FFProcess value config Input configurationCJC Setpoint configuration VAL.LVAL.H Alarm configuration Values Table a Alarm types ValueAlarm Modes Digital input 1 configuration Action on contact closure Digital input 2 configuration Action on contact closureIMP Alarm relay configuration VfltPflt Combining several digital events on to one output Comms 1 module configModule config 1A b C1 Module 1 configurationCool 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 configurationPoint Custom Linearisation VAL.1VAL.8 CAL Exit Exit configuration Password configurationDC Output Calibration User calibrationUser calibration Calibration Configuration List User Calibration EnableUser Calibration Enable Exit configurationOffset calibration Input list headerCalibration type 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