Evoqua WALLACE & TIERNAN SFC, Оригинальное руководство пользователя

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SFC
Functions
4.
77
Behavior in operation
Operation after a flow rate change:
The single feedback closed-loop control remains switched off (Ypi
stop function) during the disturbance variables (flow rate change,
positioner running time, dead time from line lengths). This
maintains a stable control, which means the control operates with
the dosing factor from the dosing factor table applicable for the
new flow rate.
The time the single feedback closed-loop control is switched off is
determined by the fuzzy module and is therefore variable („PI“
display in seconds). The parameter "PI shutdown“ can be used to
define the effect of the disturbance variables or the degree of the
flow rate change caused by the YPI stop function.
A larger change in the setpoint deletes all learning meters, in order
to reinitialize the dosing rate curve when the setpoint is reached.
However, the learned dosing factors remain initially unchanged.
Inactivated flow rate values are automatically preassigned a
dosing factor.
The single feedback closed-loop control is always active.
Control deviations that occur are quickly offset by the PI single
feedback closed-loop control during continuous flow.
A positive jump in the flow rate causes a brief drop below the
setpoint due to the running time of the positioner and the dosing
delay. Therefore, the PI controller freezes for a brief period ("PI"
display in seconds).
A negative jump in the flow rate causes the setpoint to be briefly
exceeded due to the running time of the positioner and the dosing
delay. Therefore, the PI controller freezes for a brief period ("PI"
display in seconds).
The PI controller is not deactivated when the flow rate is
continuously rising or falling, so long as the dosing capacity can
quickly adjust to these changes. This is true of fast positioner
running times and loops without dosing delay.