Xylem WEDECO SMOevo PLUS Series Original Manual page 113

Under the given conditions a setpoint / actual value comparison is carried out after
completion of the Time Control Mode / Volume Control Mode interval with the result that the
Dose Trim output must be increased by +1.0% in this interval.
Correction of the Dose is carried out until the actual value approaches the setpoint (actual
value > 0.90 ppm / actual value < 1.10 ppm) or the minimum / maximum limit of the output is
reached. The limit deviation is signalled by a warning message:
Warnung dose trim out of range. Check settings.
Operating Mode Absolute
The setpoint/actual value comparison is based on an absolute level calculation depending on
the default setpoint. Example calculation based on the setpoint 1.0 ppm.
Example Calculations:
PV >> SP 1,0 ppm
= 2,00 ppm
PV > SP 0,50 ppm
= 1,50 ppm
PV < SP -0,50 ppm
= 0,50 ppm
PV << SP -1,0 ppm
= 0,00 ppm
Under the given conditions a setpoint / actual value comparison is carried out after
completion of the Time Control Mode / Volume Control Mode interval with the result that the
Dose Trim output needs not to be corrected since the actual value is in the dead zone of the
controller. The Trim function restarts the increase / decrease of the controller output if the
actual value is < 0.5 ppm or actual value > 1.5 ppm.
Correction of the Dose is carried out until the actual value approaches the setpoint (actual
value > 0.50 ppm / actual value < 1.50 ppm) or the minimum / maximum limit of the output is
reached. The limit deviation is signalled by a warning message:
Warnung dose trim out of range. Check settings.
Operating Mode Time Control
The setpoint / actual value comparison is not carried out continuously, only after the control
interval is completed. After the comparison the interval starts again. The control inverval is
entered in the screen Dose Trim (screen 03.01).
Operating Mode Volume Control
Depending on the reaction volume set, the control interval is calculated. How much time is
required between the setpoint / actual value comparison to completely exchange the reaction
volume depends on the process water flow. The process water flow is summed up every
minute. The corresponding sum is compared with the reaction volume. As soon as the
reaction volume is completely exchanged, the interval starts again. The calculated time until
Manual_SMOevoPLUS_eng_01.2019.doc
Manual Ozone Generating System SMOevo
Actual value 0,80 ppm
•
Actual value 0,80 ppm
•
Actual value 0,80 ppm
•
Actual value 0,80 ppm
•
Operation
-> Level -2,5%
•
-> Level -1,0%
•
-> Level +1,0%
•
-> Level +2,5%
•
page 113 of 179
PLUS