Evoqua WALLACE & TIERNAN SFC, Original Instruction Manual

Page: 101 / 288

SFC
Functions
4.
101
Completing
adaption without errors
When the loop times (dead time Tu and rise time Ts) have been
completed without error, calculation of the control parameters Xp
and Tn commences. This is indicated by the message "Adaption
OK". The calculated parameters are entered in the menus. When
adaption has been concluded, the measuring amplifier adjusts
with the newly calculated control parameters and continues in the
selected operating mode (e.g. automatic).
To monitor the determined loop times they are entered into the
"Tu" and "Ts" menus .
If errors occur in the control loop during adaption, incorrect loop
times and therefore incorrect control parameters can be
determined.
Caution!
The remaining control parameters Ymin, Ymax and Tp are not
influenced when adaption is performed. The control parameters
Xp and Tn are determined for Ymin = 0 % (no basic load) and
Ymax = 100 % (no dosing rate limitation). If there is a system-
specific requirement for a basic load Ymin or a dosing rate
limitation Ymax, it must be taken into account that the control loop
is restricted as a result. There is then the risk of excessive
chlorination (Ymin too high) or inadequate chlorination (Ymax
limits excessively).
Completing
adaption with error
If errors occur in the control loop during adaption (e.g. filter
backwashing, changes in the circulation or widely fluctuating
number of visitors to the pool) or if the reaction times of the control
loop are too long, adaption is interrupted.
Possible error conditions:
Initial value not reached (Display: "T = >8h")
When adaption has started and the dosing system has closed or
the dosing pump has switched off, the measuring amplifier waits
until the actual value has dropped below the initial value (0.2 x the
measurement range value). This delay is indicated by the
message "2: X = 20 %" and the maximum permissible time is 8
hours.
Loop dead time too high (Display: "Tu = > 1h")
The value determined by the time measurement between starting
up the dosing, switching on the dosing pumps and the rise of the
actual value may only take a maximum of 1 hour. This measured
time is displayed by "6: Tu!".