The user locates the return fan control point on the schematic, assigns the status of the supply fan, and adds a 30-second delay. CARE's switching logic function can also handle some very complex applications that may include combinations of logical ANDs, logical ORs, or exclusive ORs. Also, there should be a differential on the discharge air temperature to keep the return fan from short cycling due to a change in temperature. The Switching Table Example diagram shows the logic table for this sequence. The CARE operator interface makes the sequence very easy to establish.
CARE can also provide a mathematical function that can be used along with the switching table.
Switching logic has a higher priority than control strategy. CARE switching logic and control strategy functionality work together to give the control engineer a very powerful tool. Back to Top Time function Control systems must also be able to function differently depending on the time of day. CARE provides an easy way to program the system so a scheduled operation can occur at different times of the day. The user can easily program the system to turn the ventilation system and lights off and on to meet these classroom schedules.