Fireye NEXUS NX6100 series, Manual

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Option 30.7 - Boiler transport delay (5 – 60 seconds) LV 3
Boiler transport delay is the time taken for 'gas' to travel from the burner to the oxygen probe. This delay
varies with burner fire rate.
In order for the oxygen trim control loop to be stable, this parameter must be set accurately to the
transport delay of the boiler
when at low fire . This option may be set between 5 and 60 seconds
inclusive.

To measure the transport delay, ignite the burner and enter adjust ratio mode. Select the low fire set
point and allow time for the flue oxygen reading to settle. Once the oxygen reading is steady, make a
step change to the fuel/air ratio and start a timer. As soon as the measured oxygen reading
begins
to change, stop the timer. Set the option parameter to the recorded timer value in seconds.

Automatic trim commissioning (option 30.9) will attempt to set this automatically. However the value
must be checked by the engineer.
Option 30.8 - Reset oxygen trim profile (0/1) LV3
During full automatic operation, the O2 trim system will learn and store the percentage of trim applied to
various firing rates. This provides a “feed forward” aspect to O2 trim. If any changes to target O2 values
are made after the system has been in operation, the trim profile must be reset so as to not apply
previous trim feed forward. A new trim profile will be learned as the burner modulates. Only the trim
profile is affected. The Oxygen set points and flow values are not changed.
This option parameter allows the learned trim profile to be reset. If the option is set to 1 any learned
profile currently held in memory will be reset and the trim drives will return to their commissioned positions
for the corresponding modulation position. Once the profile has been reset this option parameter will
automatically be reset to 0.
Option 30.9 – Automatic trim commissioning (0 / 1) LV3
The unit is able to automate the manual calculation procedures (option parameter 34.5), automatically
calculating and entering flow values, oxygen trim set points, and boiler transport delay. The automatic
commissioning procedure will only work if the following conditions are met:

Option parameter 30.9 (automatic trim commissioning) is set to 1

An oxygen probe is fitted and fully operational

The unit is in adjust ratio with the burner firing a single fuel only

A hydrocarbon ratio has been entered for the current fuel (see option parameters 35.1 — 35.4).
The auto commissioning procedure will usually take between 10 and 30 minutes (depending on number
of set points), and is performed by the unit as follows:
1. Beginning with high fire, the unit moves the drives to each point in the firing range. The
display will show O2 .
2. When the measured oxygen reading settles, the unit stores the measured oxygen reading as
the new oxygen set point.
3. The drives are moved to the next position directly below high fire (Ph-1) and wait for the
oxygen to stabilize.
O 2