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4.
The unit moves the air drives up to the point above the current set point, leaving the fuel drive
in the same position.
The display will show ‘Flow calc An + 1’
.
5.
When the new oxygen reading settles, the unit calculates and stores the new flow value. If
the oxygen reading exceeds 15.0% during this stage, the unit shuts the burner down with
F77.
6.
When the unit has completed the low fire point, the measured boiler transport delay (at low
fire) is stored in option parameter 30.7. Option parameter 30.5 (oxygen trim enable) is set to
zero.
7.
You must use “adjust ratio” mode to confirm each position from P3 (low fire) to Ph (high fire).
If the flow values appear reasonable (about 4 to 6% change at each position) once you have
finished, setting option 30.5 to 1 will enable O2 trim. There is a one-minute delay after exiting
commissioning mode before trim will enable. If the flow values are unreasonable, they may
be adjusted manually by placing the cursor to the “FLO” position and using the up/down
arrows set the desired flow value. Using EK44 verify the O2 levels at each position and adjust
to match if required. EK46 will help troubleshoot O2 trim issues.
BEFORE ENABLING TRIM, USE ADJUSTS RATIO MODE TO MANUALLY CHECK THE
CALCULATED FLOW VALUES, OXYGEN SETPOINTS AND TRANSPORT DELAY. THE LOW FIRE
PERCENTAGE FLOW VALUE SHOULD CONFORM APPROXIMATELY TO THE TURN-DOWN RATIO
OF THE BURNER.
SUMMARY
To perform automatic trim commissioning, follow the procedure below:
1.
If the probe is new, enter the offset and gain values in option parameters 30.1 and 30.2 which
are supplied with the probe. To re-calibrate the probe referto section 8.
2.
Enter adjust ratio mode (See section 5).
3.
Enable automatic trim commissioning by setting option parameter 30.9 to 1.
4.
Wait for procedure to finish.
5.
Check that the 0
2
, flow and transport delay values are sensible. Use EK44 for O2 value.
6.
Check calibration of the oxygen probe.
7.
Confirm setup using “adjust ratio” mode.
NOTE:
If the boiler shuts off for any reason during automatic commissioning, the sequence will continue
when the boiler re-starts.
Option parameter
30.9 value
Meaning
0
Not selected.
1
Perform automatic trim characterization.
The control will attempt to
characterize the burner profile by calculating flow values and selecting oxygen
set points to match the currently commissioned points.
Automatic trim commissioning will be performed under the following
conditions:
An oxygen probe is fitted and fully operational
The control is in adjust ratio mode.
A hydrocarbon ratio has been entered for the current fuel (see option
parameters 35.1 – 35.4).
Summary of Contents for NEXUS NX6100 series
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