The Htg 2 Sequenced Valves Output Module controls two sequenced proportional steam valves for either preheat or reheat. The capacity ratio of the valves is a required input from the user. When controlling a temperature, the first (smaller) valve starts to modulate. When this valve is fully open the second valve starts to modulate. When the control temperature increases, the second valve (larger) closes first. When the second valve is fully closed, the first valve starts to close. The module can be configured for DA-T, RA-T, ZA-T, or PH-T control. The module has been designed with temperature control, low limit control, Low OA Temperature and Failsoft. 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.
You can view and modify the modules in this group’s logic.