Spirax Sarco SP8-10, Installation And Maintenance Instructions Manual

Page: 63 / 88

IM-P707-01 CTLS Issue 1
63
SP8-10 Smart positioner
5.1.23 Menu: Controller
(continued)
Menu/parameter Value range Description
TV Down 10 to 800 ms
Use this parameter to adjust the TV value for the down
positioning direction (towards 0 %).
The TV value is the derivative time of the controller.
The control speed and stability are affected by the TV
value in such a way that it counteracts the KP value
dynamically. The control speed decreases as the TV
value increases.
To compensate for existing dissymmetries in the
controlled system, the TV value should be configured
separately for both positioning directions (up/down).
Y-Offset Up 1 to 100.0 %
Use this parameter to adjust the Y offset for the up
positioning direction (towards 100 %).
The ‘offset for the set point signal’ linearizes the
behavior of the I/P module used and enables rapid
compensation even in the case of small control
deviations.
The value is limited at the lower end by a minimum
value (measuring range lower limit). The offset
significantly affects the control speed for control
deviations of less than 5 %.
To compensate for existing dissymmetries in the
controlled system, the offset should be configured
separately for both positioning directions (up/down).
For most actuators, satisfactory control behavior is
achieved with offset values between 40 and 80 %.
If, in the event of set point changes, the control
behavior demonstrates an overshoot of less than 2 %,
both offset values should be decreased.
Both offset values should be increased when the
actuator stops outside the dead band.