Epson XDT manual Troubleshooting unexpected readings, Sat

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XDT User’s Manual

2.5 Troubleshooting unexpected readings

If erroneous readings are suspected on a newly acquired instrument, compare the serial number engraved on the sensor sintered filter, to the label on the instrument. The two should be the same; if they are not, the instrument may not be calibrated with the installed sensor. To troubleshoot other problems, identify the unexpected reading category in the following table, and consider the possible causes and appropriate diagnostic action and remedy.

Symptom

 

Possible Cause

Diagnostic/Remedy

 

 

 

 

 

 

 

 

 

 

 

Condensation will occur if the temperature of the sample system, at any point is below

Reading is not

Condensation in sample system.

(colder) the dewpoint temperature of the sample gas. Once having formed, the sample

changing

 

 

reaching the sensor will have a dewpoint equal to the temperature of the condensation,

 

 

 

regardless of the dewpoint of the source gas.

 

 

 

 

 

1.

Water vapor in the system.

It is usually more satisfactory to bleed a sample gas at atmospheric pressure through

Slow Response

2. Flow rate too low.

the sensor sampling chamber, and to use 1/8” (3mm) o.d. sample pipe.

 

3.

Sample pipe too large and/or too long.

 

 

4.

Unsuitable sample pipe.

 

 

5.

Leaks.

 

 

6.

Hygroscopic materials in sample system

See below re sample pipe material, also see section 2.3

 

 

 

Dry Reading

SpanCheck™, wrongly set, or faulty Sensor.

Verify SpanCheck™, or return sensor for full calibration to your represent ative.

 

 

 

 

Leak in system or use of unsuitable pipe.

Cure the leak, or replace unsuitable pipe with copper or stainless steel. Flexible con-

Wet Reading

 

 

nections should be made with PTFE pipe. NEVER use rubber or plastic pipe.

 

 

 

 

Comparison of readings with manual cooled-

This type of indicator reads about 10ºC dry at about -50ºC dewpoint due to tempera-

 

mirror instrument.

ture gradients within the device. The error increases at drier levels.

 

 

 

Display Shows

Prolonged exposure to wet gas.

Dry down the sensor, install sensor in either a known dry gas stream i.e. instrument

SAT

 

 

quality air or dry nitrogen, or place sensor in a dry can or bottle of desiccant and seal

 

 

the container from outside air (the shipping container is designed for this purpose)

 

 

 

 

 

 

also see section 3.4.4.3.1

 

 

 

 

 

1.

Instrument Failure

Disconnect cable from input terminals, if the instrument still reads SHR the problem

 

 

 

is with the instrument. However, if the instrument reads OPN then reconnect the cable

 

 

 

to the input terminals and check possible causes 2 or 3.

 

 

 

Display Shows

2.Short circuit on sensor cable or connections.

Disconnect cable from sensor and if meter still reads SHR, cure the short circuit in the

SHR

 

 

cable or connections or replace cable; otherwise check the sensor.

 

 

 

 

 

3.Short circuited sensor.

Disconnect cable from sensor and note that the meter reading returns to OPN. Use a

 

new sensor, or apply approximately 20V DC to the sensor MOMENTARILY with the

 

 

 

 

 

 

sensor in a known dry condition. Polarity is not important, but the contact MUST be

 

 

 

very brief or the sensor may be damaged. Consult with your representative for a cir-

 

 

 

cuit diagram.

 

 

 

 

 

 

 

Short the SIG and SHIELD contacts of the sensor input terminal, if the instrument

Display Shows

1.

Instrument failure.

reads SHR the problem is in the cable or sensor, otherwise return the instrument for

 

 

service.

 

 

 

OPN.

 

 

 

2.

Open circuit on cable.

Disconnect cable from sensor and short center pin of plug to the outer shell. If the dis-

 

 

play still shows OPN, repair cable.

 

 

 

 

 

 

 

 

3.

Open circuit on sensor.

Check sensor connection or replace sensor.

 

 

 

 

For non-sensor related problems (e.g. no reading on instrument) refer to section 3.6

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Contents Yyyyyyy y Sensor Serial No Instrument Serial No XDT User’s Manual Iii XDT User’s Manual Table of Contents Index Overview of the XDT XDT User’s Manual Sensor and Sampling Techniques Precautions using the sensor Sensor Installation & Sampling Techniques Sensor Technical SpecificationsNot Recommended In-situ InstallationExtractive Installation Mechanical Installation SAT Troubleshooting unexpected readingsElectromagnetic Compatibility Considerations Instrument Precautions using the XDTIsolation Instrument Technical SpecificationsXDT-NEMA IP65 Enclosure Installation InstallationInstrument Mechanical Installation XDT-PM DIN43700 Enclosure InstallationElectrical Connections Connecting PowerSensor Connection AC Mains Electrical Power ConnectionLow Voltage DC Powered Option Electrical Power Connection Wiring the Alarm ContactsInterfacing to the Analog Output Operating the Instrument Interfacing to the RS-232 optionStarting up Display Conventions 12 3 4 5 6 7 8Push Buttons Operating State Viewing Dewpoint ModeXDT User’s Manual Alarms Start Calibration HI **** ˚CSpanCheck Mode Single Point Self Calibration, manual or scheduled Instrument XDT User’s Manual SetUp State Viewing Serial Number ModeXDT User’s Manual Secured Password Protection Resetable Audio-Visual Alarm Option Nfpa compliant Troubleshooting the Instrument Display Explanation Required Action Maintenance XDT User’s Manual Glossary DB9 Glossary XDT User’s Manual Sign on message Calibration without key press Appendix a Flow Diagram of Operating State User InterfaceHere 16.24˚C˚F Appendix B Flow Diagram of Set-Up State User InterfaceSensor Mechanical AppendixAppendix D Optional Sensor Fittings Side View Appendix E XDT Circuit Board DimensionsAppendix E XDT-PM Enclosure Mounting Dimensions Appendix E XDT-NEMA Enclosure Mounting Dimensions Appendix F Sensor/SpanCheck Theory of Operation Appendix G Dewpoint Response time Analysis XDT User’s Manual Appendices Tested Instrument ˚C Appendix H Sample Gas Filter ConsiderationsSensor Appendix I XDT Grounding ConsiderationsAppendix J Analog Output vs. Dewpoint Instrument reading in ppmV Help command Receive Help Data Who Reset Login Data commandAppendix K RS-232C Interface Protocol K n m Error SensOpen or Error SensShort or Error SensSatLogin Command ? commandSerial Number Command Who CommandState User Interface Appendix L Procedure for Exchanging XDT SensorsAppendix M Uncertainty in LBS & ppmV calculations To obtain a RAN fill out this form and fax to 631 Xentaur Return Authorization Number Request FormPage Index Enclosure dimensions Pounds of H2O per million standard cubic Voltage, mains supply Iii Warranty