This video shows how to calibrate a Woodward SPC. For this example, the SPC is configured at a PI with Lead-Lag control. Calibration for P, PI and PI with Lag is identical. Proportional with Trim is very similar.
The actuator for this example is a 4-20 mA actuator. Ideally, the mechanical linkage/interface should be adjusted so that the null current is 12 mA, not 14.xx mA as shown here.
As seen in the Calibration screens, this control had already been calibrated (minimum/maximum positions already read ~0%/~100%). If this was a first time calibration, much more wild % numbers may be seen the first time through.
The actuator is biased/moved by biasing the null current. The ONLY purpose of this is to get the valve/rack to move. The actual number used to do this has no other affect whatsoever. REMEMBER: The only purpose of this calibration process is to tell/show the SPC what the feedback device (LVDT, etc.) looks like/reads at the 0% valve/rack stroke position and at the 100% valve/rack stroke position. Everything in between is assumed linear.
As always, make sure the feedback device is configured correctly before attempting calibration!