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Build Guide · Motor Control

Two-Wire Control

One maintained switch energizes a coil, which pulls in a contactor to run a motor. The simplest motor control.

Difficulty: BeginnerBuilds on: the complete circuitLesson: read the theory →

What you’re building

L1L2/NSWM
A maintained switch energizes coil M (its contactor, not shown, runs the motor).

Parts to add

  • 1Power Source
  • 1Single-Pole Switch
  • 1Coil
  • 1Contactor (3-pole)
  • 1Motor

Steps

  1. Add the parts

    Click Power Source, Single-Pole Switch, Coil, Contactor (3-pole), and Motor from the palette. Spread them out.

  2. Label the coil and contactor

    Click the Coil and type the letter M. Click the Contactor and type M too. They now share a name — energizing coil M pulls in contactor M.

  3. Wire the control circuit

    To wire, click the first terminal (it highlights), then click the second — a wire connects them. Click empty space to deselect. The maintained switch feeds the coil. A1 and A2 are the coil’s two terminals.

    Power Source L1 → Switch (left)
    Switch (right) → Coil A1
    Coil A2 → Power Source N
  4. Wire the power circuit

    Now run motor-level power through the contactor’s main pole to the motor and back.

    Power Source L1 → Contactor T1 input
    Contactor T1 output → Motor (left)
    Motor (right) → Power Source N
  5. Energize and flip the switch

    Click Energize. Close the switch — coil M energizes, contactor M pulls in, and the motor runs. Open the switch and it stops. Notice there’s no Start/Stop: the switch holds its own state. That’s two-wire control.

✓ Test it

  • Open the switch: motor stops. Close it: motor runs.
  • Notice there is no Start/Stop — the switch holds its own state. This is two-wire control.
Tip: Imagine the switch is a float or pressure switch. That is exactly how an unattended pump or compressor runs — and why it restarts on its own after a power blip.

Open the Sandbox and build it

Follow the steps above with the trainer open in another tab.

Open the Sandbox →PLC Sandbox