43
7 O
2
Trim
7.5.3 O
2
Limit Curve
You can set the monitoring bands’ parameters for 2 fuels, oil/gas, as a function of fuel. The
permitted deviation is calculated as a percentage of the setpoint. You can specify two separate
percentage values for base firing rate and full firing rate. The section between is interpolated
linearly.
Monitoring/shutdown times:
1
st
monitoring band: 120 seconds; active after “Control on”.
2
nd
monitoring band: 30 seconds; active after “Burner on”.
Factory setting
1
st
monitoring band, upward direction
– Base firing rate (parameters 923 / 925) 60%
– Full firing rate (parameters 924 / 926) 100%
1
st
monitoring band, downward direction
– Base firing rate (parameters 927 / 929) 40%
– Full firing rate (parameters 928 / 930) 50%
2
nd
monitoring band, downward direction (may be modified during commissioning)
– Base firing rate (parameters 931 / 933) 50%
– Full firing rate (parameters 932 / 934) 70%
7.5.4 Dynamic Probe Test
The ETAMATIC OEM monitors the measured O
2
value for changes during operation. If a fluc-
tuation no higher than 0.2 O
2
vol.% is detected over a period of 10 minutes, a state of excess
air is enforced by changing the fuel/air mixture. If there is still no change in the actual O
2
value
after 1 minute, the test is repeated with more excess air. If this does not lead to a change in
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