The Variable Speed CW with Low Limit module controls the speed of the CW pumping while preventing it from falling below a minimum flow within a control application. The module accepts a mode, a process variable, a setpoint, and so on as inputs. Based upon the input mode and parameter settings, the module outputs a percent command and control status. This module is implemented as a standard Control Activity. This module also incorporates tracking the overridden value of the actual output object (AO, PAO). The module resets the PIDs to default tuning parameters if the Reset PID Tuning input is not Normal.
This module provides EWMA diagnostic values calculated by the PID. Controllers have the ability to collect data about their inputs, outputs, and internally calculated variables. Inside the controller, the EWMA minimizes memory requirements, reduces communication traffic, and provides an easy way to analyze collected data. See EWMA Diagnostics in the Commissioning a System section for more information.