Ladder Diagram
Click START/STOP buttons to control the circuit. Watch the current flow and seal-in contact behavior.
Control Panel
STOPPED
Motor: Stopped
Interactive AC induction motor start/stop control circuit
Click START/STOP buttons to control the circuit. Watch the current flow and seal-in contact behavior.
Rung 1 (Control): STOP button (NC) in series with START button (NO) control the motor contactor coil (M). When START is pressed and STOP is released, the coil energizes.
Rung 2 (Seal-in): M contact parallel to START button. Once the coil energizes, the M contact closes and "seals-in," maintaining coil energization even after START is released.
Overload Protection: OL relay monitors motor current. If current exceeds the threshold (40A), the OL contact opens and de-energizes the coil, stopping the motor.
Motor: When contactor closes, power flows to the motor. The motor creates mechanical rotation proportional to applied load.
Start the motor, monitor current at 10A. What happens when you press STOP?
Increase current beyond 40A. Observe OL relay tripping the circuit automatically.
Press START. The seal-in contact maintains operation. Manually increase current to trip OL.