56
6 Commissioning
NOTICE
The P-factor (proportionality factor, parameter 899) is specified by the parameter setting. The
new correction is obtained from two input quantities, deviation and P-factor. This would be
transmitted to the VMS as an output. The procedure is repeated after lag time's expiry. If the
internal firing rate has changed during this time, the O
2
controller exits this routine. It must then
be reactivated again as described above, via channel key 2 (4).
Deactivate test mode
Select channel key 2 (4) downwards
6.6.5.6 Lag time (Parameters 898 / 900)
Setting the control parameter:
t1 __ t4 = controlled system’s dead time
Specified by parameters 898 and 900.
The calculated value should be entered into parameter 898.
Factory setting: 15 seconds.
In parameter 900, the dead time can be adjusted according to the firing rate.
The dead time is reduced at full firing rate, due to the high gas velocities.
Factory settings: dead time is reduced by 3 seconds
To calculate dead time at full firing rate: proceed as described above.
Guideline for 2 or 3-draught boiler:
Parameter 898 12 seconds
Parameter 900 3 seconds
The P-factor should be adjusted so that a target/actual value deviation of 1...2 vol.% O
2
is cor-
rected within 4...6 steps without overshooting.
6.6.5.7 P-factor (Parameter 899)
Actuation pulse too short increase P-factor in parameter 899
Overshooting reduce P-factor in parameter 889
Repeat until the target value is corrected within approx. 4 ... 6 steps.
Check controller setting at intermediate and full firing rate.
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