Burkert Type 8750 - Manual (Page 23)

I NSTALLATION
8750 - 21
Explanations on the starting value
The setpoint step is realized between a starting
value and the process-setpoint SP to be specified
(SP-Tune). The height of the setpoint step must be
determined in relation to the process
(setpoint step = SP-Tune minus starting value).
The starting value used is the measured real
momentary value of the controlled variable PV.
This starting value depends directly on the
momentary valve position and can in the automatic
mode be displayed with
in m³/h. If it differs very
little from the planned setpoint SP, it should be
changed manually. For this purpose, the program is switched with key into the manual
mode (LED off). With key or , the valve position can now be suitably changed.
With key , return to the automatic mode; show starting value for checking with . If the
result is unsatisfactory, modify the starting value.
Possible display of process values in the automatic mode
Apart from the starting value (= process value), by pressing the arrow keys
or in the
automatic mode (yellow LED flashes), the value shown in the following table may be dis-
played from the menu item SP ≡ XXX.X
Value Remark Value Remark
SP process setpoint still to be entered TEMP Interior temperature in the TopControl
in °C or °F
PV starting value or process value of the
controlled variable in m³/h or m/s M.TEMP Medium temperature in °C or °F;
Option with temperature transmitter
POS actual position of valve actuator in % P1 pressure before valve in bar
(∆P = P1 - P2)
CMD setpoint position of valve actuator in % P2 pressure after valve in bar
Entering the setpoint step and initiating PROCESSTUNE
Before initiation of the function PROCESSTUNE, the starting value must already be properly
set for the process. The program is in the automatic mode (yellow LED flashes),
menu item SP ≡ XXX.X.
On setting a setpoint step suitable for the process, PROCESSTUNE is initiated.
For this purpose, entry of a process setpoint SP (SP-Tune) is required:
Hold one of the arrow keys or depressed for at least 3 s.
After release of the key, the first digit X of the process setpoint SP ≡ XXX.X flashes.
Enter at the flashing digit X with key
or the value for this digit (in m³/h or m/s,
depending on the configuration).
Confirm the value set at this digit with key .
The program moves automatically to the next digit.
Enter in the same manner the value for this digit.
After confirmation of the value for the fourth digit with
, the now completely entered
process setpoint SP (SP-Tune) is transferred to memory as the final value for the setpoint
step and the function PROCESSTUNE starts automatically.
While the function PROCESSTUNE runs, the display P.TUNE is shown ( symbolizes
here a rotating bar).
After completion of PROCESSTUNE, the program assumes the optimized controller
parameters and returns by itself to the automatic mode (yellow LED flashes).
The process controller now works with the newly determined controller parameters.