before entering into calibration mode to start the Auto Tune. The tuning procedure will stroke the valve
back and forth several times and must not be run with the valve in service. The entire process takes
about 3 to 12 minutes. The resulting position controller parameters will be presented when the proce-
dure is finished and a graph of the positioner step response will be displayed. Figure 41 shows a typical
step response for a high friction valve after a successful Auto Tune.
The position controller is a type of non-linear PID controller with eight adjustable parameters.
The maximum range of the positioner parameters is as listed below. For typical values, see the parame-
ters description.
55
Figure 41. Diagnostic
Graph - Typical Step
Response
Note:
For a SVI positioner system using air booster or quick exhaust, the Auto Tune may fail
and manual adjustment of the positioner parameters therefore becomes necessary.
Parameter
Range
Proportional Gain
0 to 5000%
Integral Time
0 to 1000 seconds
Derivative
0 to 200 seconds
Padj
+ / - 3000 (depends on P)
Beta
- 8 to + 9
Position Compensation Coefficient
0 to 9
Dead Zone
0 to 1%
Damping Coefficient
0 to 9