A7.7
3.10.5 Failure to Auto-Calibrate
The analyser will not calibrate if any of the following are in error:
1. Sample gas oxygen reading is within 1.5% O
2
of the zero gas content.
2. Sample gas oxygen reading is within 1.5% O
2
of the span gas oxygen content.
3. Zero or span gas oxygen contents out of limits.
4. DV lag exceeds programmed limits (time between switching a different gas and the
analyser output responding).
5. Response time exceeds programmed limits.
6. Stabilisation period exceeds programmed limits.
7. The sample gas oxygen level has changed by more than 1.5% O2 since the start of auto-
calibration. This may occur on multi-stream systems if a stream has switched during the
auto-calibration sequence.
Parameter code 46 (Auto-calibration alarm) can be dedicated to an alarm relay to provide
contact closures for the prevention of stream switching during auto-calibration (Refer to
section 4.9.1).
The default values of the various time lags itemised in 1, 2, and 3 are detailed in the parameter
code listing in Appendix 3. These codes 49 and 57 are user adjustable to suit individual
installations. The analyser stores the time lags from the previous auto-calibration in parameter
codes 25 to 30. These time lags will aid the resetting of default values for codes 49 to 57.
3.10.6 Auto Calibration Alarms
alarms available in auto-calibration are : Analogue output frozen 45
Analyser in auto-calibration 46
Zero gas flow failure 63
Span gas flow failure 64
Sample gas flow failure 65
Gas out of limits 66
All of these alarms can be allocated to relays. See Section 3.9.1 for allocation procedure.
3.10.6.1 Analogue Output Frozen - 45
See Section 3.10.3 for description. This alarm is cleared automatically at the conclusion of auto-
calibration.
3.10.6.2 Analyser in Auto-Calibration - 46
Goes active as soon as auto-calibration starts and is cleared automatically at the conclusion of the
sequence. May be used as an indication that the analyser is not measuring the sample gas.
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