需求
“Create a centrifugal pump HOA ladder with hand and auto selection, auto start-stop seal-in, overload protection, and a pump contactor output.”
接著試試Add a low-level stop interlock.Add a pump run indicator lamp.
這張圖裡有什麼
看懂背後的決策。
01
Use separate internal coils for Hand and Auto commands so both modes safely drive one physical output without duplicate physical coils.
02
Place the pump overload contact in series with both mode commands so an overload drops the output and clears the Auto seal-in.
03
Add a parallel seal-in branch around the Auto Start pushbutton so the pump remains running after a momentary start.
Reusable for any single-motor HOA starter where hand operation bypasses PLC auto sequencing and auto mode requires start/stop or permissive logic.