Teledyne 9060 - Zirconium oxide flue gas oxygen analyzer - Manual (Page 21)

9060-Zirconia Analyser
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If heated probes are being used, the transmitter will maintain the temperature of the
sensor(s) to over 700°C (1300°F). If the flue gas temperature is above 850°C (1560°F),
the probe heater will cut out completely and the process will provide probe heating. The
transmitter solves the Nernst equation and will provide accurate oxygen measurements up
to 1500°C (2730°F), although most probes are suitable only to 1400°C (2250°F). 1231
heated probes are limited to 900°C (1650°F).
2.4 ALARMS
Refer to OPERATOR FUNCTIONS Section 4 for details on alarm functions.
2.5 HEATER
CAUTION
The probe or sensor heater is supplied with mains voltage. This supply has electrical shock danger to
maintenance personnel. Always isolate the transmitter before working with the probe or sensor.
The EARTH wire (green) from the probe/sensor must always be connected to earth.
The heater is supplied from the mains power directly, and the temperature is controlled
initially at over 700°C (1300°F) after turn on.
2.6 APPLICATIONS WHERE SENSING POINT IS NOT AT ATMOSPHERIC
PRESSURE
To apply the 9060 Analyser to processes that have pressure at the point of
measurement significantly above or below atmospheric pressure, then compensation must
be applied. (Refer to Set-up Steps 37 and 38 in Section 5.5). If two probes are being
used, they must be close to the same pressure.
If the process pressure is not constant, it can be measured by a pressure transducer
and fed into the oxygen transmitter as a 4-20mA signal. The pressure compensation will
then change the oxygen reading according to the current process pressure.
2.7 SENSOR IMPEDANCE
The zirconia sensor impedance is a basic measurement of the reliability of the
oxygen reading. A probe or sensor with a high impedance reading will eventually produce
erroneous signals. The transmitter checks the zirconia sensor impedance every 24 hours
and if the impedance is above the maximum level for a specific temperature then the
impedance alarm (Sensor Fail) will be activated. Typical sensor impedance is 1 K
Ω to 8
K
Ω at 720°C (1320°F).
The impedance measurement can be updated manually whenever the sensor is over
700
°C (1290°F) by pressing the “AUTOCAL” button while in “RUN” mode. The “Z” will
appear in the top RH corner of the display for 3 seconds to confirm the measurement.
2.8 AUTO CALIBRATION - ELECTRONICS
The transmitter input section is self-calibrating. There are no adjustments. The
analog to digital converter input stages are checked against a precision reference source
and calibrated once every three seconds. Should the input electronics drift slightly then
the drift will be automatically compensated for within the microprocessor. If the calibration