This block implements a filter that is used to approximate the actuators of valves, dampers and fans.
The implementation is based on
Modelica.Blocks.Continuous.CriticalDamping.
It differs from that model in that the internal state of the filter s
is transformed using x = u_nominal*s.
It turns out that this transformation leads to smaller system of nonlinear equations if u_nominal ≠ 0, see
IBPSA, #1498
for a discussion.