Emerson 54e pH/ORP instruction manual Interval Timer, Typical set points

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MODEL 54e pH/ORP

SECTION 6.0

 

THEORY OF OPERATION

A new glass electrode has an impedance of approxi- mately 200 megohms As it ages, this value typically increases over time because lithium ions (which carry current) in the glass are slowly depleted by the process. If an electrode cracks, the impedance drops sharply, usually to below 5 MΩ.

The following Diagnostic Checks are possible with the Model 54e pH/ORP:

Cracked Glass Diagnostic. One way to tell that you have a broken or cracked glass electrode is that the controller will read a constant value (usually between 5.0-7.0 pH) in any process or buffer. The other way is to note the impedance value. The controller can be configured to generate a fault when the glass imped- ance drops below a setpoint. When a crack occurs, the controller will indicate that the electrode is broken.

NOTE

A broken electrode may not be detected above 70°C (158°F).

Old Glass Diagnostic. This diagnostic is used for pro- gramming the high impedance limit. For example, if the set point is 1000 megohms, and the impedance rises above this value, the controller will go into a fault mode. The electrode is either worn out, severely coated, or not immersed in the process fluid..

Calibration Warning. Under this diagnostic you can select the percent increase in impedance before a cal- ibration warning fault appears. It is recommended to keep this feature disabled.

High Reference Impedance. The reference is also continuously checked. High values indicate a plugged liquid junction or a coated sensor. The setpoint can be adjusted depending on the sensor used. Always set this value above the value for a new clean sensor.

You may also get this fault if:

1.The sensor becomes excessively coated.

2.The sensor is not immersed in the process

Typical set points:

1.1000 Megohms for old glass diagnostics.

2.10 Megohms for cracked glass.

3.0 Megohms for calibration warning (disabled)

4.40 Kohms for high reference impedance.

NOTE

See Section 5.8 for instructions on chang- ing these setpoints.

6.3 INTERVAL TIMER

The interval timer may be used for periodic sensor cleaning or periodic process adjustment (see Section 5.7 for procedure).

The interval timer settings are:

1.

Timer

-

Enables/disables the interval timer.

2.

Interval

-

the time period between cycles.

3.Repeats - the number of relay activations per cycle.

4.

On time

-

the time period of one relay

 

 

 

activation.

5.

Off time

-

the time period between two or more

 

 

 

relay activations.

6.Recovery - the time period following the final relay activation.

The cycle begins at the Interval time when the Switch is turned on. When the Interval time has expired the analyzer activates hold mode and the relay is activated for the On time period. If the number of Repeats is greater than one, the relay is deactivated for the Off time period and reactivated for the On time period for the number of relay activations selected. When the final relay activation is complete the relay is deactivat- ed for the Recovery time period. Note that no Off time period follows this last relay activation. When the Recovery time period expires the Hold mode deacti- vates, and the cycle repeats, beginning with the Interval time.

Typically, the interval timer is configured with a long Interval, several Repeats of fairly short On times, fairly short Off times and a Recovery time which allows the process to stabilize. Setting Interval to zero results in continuous pulsing and setting Off time to zero will cause a single pulse equal to [On time x Repeats].

High reference impedance can be used to trigger timer activation. In this case, the interval time is used only to allow the analyzer time to determine whether the refer- ence impedance has exceeded the reference imped- ance setpoint. If the reference impedance setpoint is exceeded, the timer cycle will begin. This is an ideal way to start a cleaning cycle in a dirty application.

Note that the hold mode supersedes the Timer State. If the hold mode is on, the present interval time continues to expire and once expired the interval timer is sus- pended until the hold state is removed. For more infor- mation on Controller Mode Priority, see Table 6-1.

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Contents PH/ORP Hart Analyzer/Controller Model 54e pH/ORPEssential Instructions Electrical Shock HazardPage Model 54E PH/ORP Microprocessor Analyzer Description and SpecificationsSection Title List of Tables Appendix TitleTable No Title Table of Contents List of Figures About This DocumentGeneral Description Section Description and SpecificationsDescription of Controls Specifications Physical Specifications General PowerRelative Humidity 95%, non condensing Alarms Current OutputsAnalyzer Specifications @ 25C Recommended SensorsCode Options Ordering InformationPart NO. Description Section Installation Mechanical InstallationLocating the Controller Unpacking and InspectionPanel Mounting Section Wiring Power Input WiringAnalog Output Wiring Alarm Relay Output Wiring454EPH02 PH Sensor Compatibility PH Sensor WiringTions will Result in Controller MALFUNC- Tion 454EPH01 Cable Dressing Final Electrical Check Wiring to Model Section Calibration IntroductionAdjust temp 25.1 C Hold Mode OffTemperature Calibration Buffer 1 -- Wait Autocal bufferAutomatic TWO-POINT Calibration Use the arrow keys to select the correct buffer Auto buffer cal doneCalibration Notes Calibrate point Pt 04.00pH 25CPt calibration done Manual TWO-POINT CalibrationStandardize 7.01 pH SINGLE-POINT pH CalibrationTemperature Compensation Options Temp comp AutoOutput trim 59.16 mV/pHOutput trim Hold ModeTrim Outputs Section Software Configuration PH Settings ListRanges Factory Settings User Settings Diagnostics Section Outline of Menu Levels Alarm High 14.00pH Changing Alarm SetpointsSimulate tests Setpoint 07.00 pHSetpoint 7.00 pH 4mA 0.00 pH 20mA 2.00 pHSetpoint + 06.90 pH Changing Output Setpoints PID onlyOutput OutputMA 0.00 pH 20 mA 14.00 pH Output 1 12.00 mA MA +00.00 pHAlarm setpoints Output setpoints Test output Test alarmTesting Outputs and Alarms Simulated testsTest alarm 1 Open Test alarm 1 OpenDisplay right AL2 Measure pHDisplay contrast Timeout On Security CautionControl Mode DisplayChanging Output Parameters Output Control ParametersRange 4-20 mAl Fault 22.00 mARange 4-20 mA Fault 22.00mA Output 2 control Output 2 setupHold feature setup Hold Disable featureAlarm 3 control AlarmsInterval timer Alarm Low Setpoint 0.01 pH Delay 0 secHysteresis 0.01 pH Delay 0 sec Relay Default NoneRelay default None Setpoint +07.00 pHTime period 30 sec URV 2.00 pHAlarm Fault Feed limit DisableTimeout 3600 sec Alarm 4 SetupRecovery 600 sec Timer DisableOn time 120 sec Interval Timer Examples Diagnostics Off DiagnosticsZero offset 60 mV Diagnostics Auto Calibration SetupAutocal Standard Stabilize pH 0.01 pH Stabilize time 10 secAuto Calibration Setup Standard BuffersContinuous Sensor Diagnostics Section Theory of OperationTypical set points Interval TimerSee .8 for instructions on chang- ing these setpoints Alarm Relays Time Proportional Control TPC Mode CodeNormal Mode Analog OutputsController Mode Priority Controller Mode Priority ChartCondition Definitions Action DefinitionsPID Control Mode Combinations PID Control CodePID Control Measurement and Set Point Feedback ControlProportional Gain Plus Integral Reset Proportional Mode GainControl Loop Adjustment and Tuning Process Reaction Curve Method Process Reaction CurvePID Control Password Protection Section Special Procedures and FeaturesLevel 1 3 Password Privileges Configuring Security SecurityCustom Curve Lock allTemp coeff +.000 Solution Temperature CompensationSensor iso 07.00 pH Operate iso +07.00 pH Section Troubleshooting Troubleshooting is easy as 1, 2, 3…Diagnostic Messages Diagnostic Messages Description of problemQuick Troubleshooting Guide Symptom ActionDiagnostic Variables Theoretical pH vs. Millivolt Values at 25C 77F Troubleshooting Guidelines Temperature Compensation CircuitTroubleshooting Procedure Ohms Ambient TemperaturePreamp in a junction box Figure Preamplifier Troubleshooting ProcedureController preamp check Figure Junction Box Preamplifier Check Troubleshooting Guide No PowerCoated glass electrode Clean with soft cloth and clean water Password protected Replacement Parts Part Number DescriptionWarranty Repair NON-WARRANTY RepairSection Return of Material GeneralAppendix a ORP Configuration Quick Startup ORPTable A-1. ORP Settings List Item Choices ORP Settings User SettingsChoices ORP Settings User Settings Diagnostics SectionOutput setpoints Simulated testsStandardize 400 mV ORP CalibrationReturn of Materials Request Sensor or Circuit Board onlyWarranty Return of MaterialSpecifications subject to change without notice
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