10/11/2026
⚡ Contactor Control Wiring: START, STOP & Self-Holding Circuit Explained! 🔧
Do you know how a contactor remains energized even after releasing the START push button? 🤔
The answer is Self-Holding (Seal-in) Circuit!
In this practical electrical guide, you'll learn:
🔹 STOP Push Button (NC): Interrupts the control circuit to switch OFF the contactor.
🔹 START Push Button (NO): Energizes the contactor coil when pressed.
🔹 Contactor Coil (A1–A2): Creates the magnetic force required to operate the contactor.
🔹 Auxiliary Contact (13–14 NO): Provides the self-holding path to keep the coil energized after releasing START.
🔹 Main Contacts: Connect or disconnect the power supply to the motor or other load.
💡 How does it work?
1️⃣ Press START → Contactor coil energizes.
2️⃣ Auxiliary NO contact closes → The circuit holds itself ON.
3️⃣ Release START → Contactor remains energized.
4️⃣ Press STOP → The control circuit opens and the contactor switches OFF.
📌 Important: Always verify the actual terminal markings and manufacturer’s wiring diagram before making connections. In a typical circuit, terminals 13–14 are NO, while 21–22 are NC—the terminal designations shown in the diagram should be checked carefully.
👇 Quiz for Electrical Engineers: What is the purpose of the auxiliary contact in a self-holding circuit?
Share your answer in the comments!
