What is the purpose for the 'ovs_att' PIDFF parameter.

The 'ovs_att' is the overshoot attenuation parameter of PIDFF block.  It is a tuning coefficient that can have a value between 0 and 1.  It can be used to  reduce overshoot when the setpoint changes.  The value is a user defined input.

• A value equal to 1 provides the maximum attenuation.
• A value equal to 0 provides no attenuation.

This can be used on a slow acting loop (i.e., temperature control, level control, etc.).  It is common to set it to an intermediate value (for example around 0.3–0.7 depending on the dynamics) and fine‑tune it empirically to obtain an acceptable compromise between speed and overshoot.

Released for: Schneider Electric Canada