Badger Meter SRD/SRI Valve Positioners - Manual (Page 48)

Basically, the following is possible:
• a) To accept a remaining deviation
• b) To accept some response procedures (such as
remaining in over-response for a short time, and
remaining below setpoint and trailing)
When deciding a), Tn should become ineffective, table value
(15) Compensating P(kp) should be increased until the
setpoint jumps reach the setpoint within a short period of
time and without significant over-response (adapt to both
movement directions)
When deciding b) start as in a) above Thereafter Tn is
reswitched and decreased until the setpoint deviation has
been re-controlled within a short period of time and without
long after-response (adapt in both movement directions)
It is recommended to maintain the Tn’s for both directions
about the same
If a post oscillation occurs after a setpoint jump, Tn is selected
too small, possibly P(kp) was selected too large
The positioning time T63, also called valve damping, does
not have an effect during AUTOSTART in Menu 2, however,
setpoint jumps in Menu 8 reach the position controller in
a damped condition which then is not easily stimulated to
oscillation This behavior is also true for the setpoint input
This enables setting the controller to higher P(kp) values
without producing oscillations in the process On one side
this helps the position control to level disturbances due to
friction, changes in load or air supply pressure changes faster
On the other hand, it helps the superimposed valve control
circuit that neutral times in the valve control route do not
have such a big effect (stability in valve control circuit)
Changing valve dynamics during behavior B):
Increase Tn for both movement directions, possibly turn off
and proceed as described in behavior A) alternative b)
Page 48
Startup
August 2014 POS-UM-00009-EN-02