SeniorStar-Delta sequence~25 min

Star-Delta Motor Starter

The real-world finale: a star-delta starter. Start in STAR to limit inrush, run a 2 s transition timer, switch to DELTA, with the two contactors electrically interlocked so they can never be on together. Every element you've learned, in one machine.

New here? How to use it

Your goal

  • Start (with Stop, sealed) energises Main and Star together.
  • After 2 s, Star drops out and Delta takes over, in the same scan, cleanly.
  • Star and Delta must NEVER be on at the same time (interlock each with the other's NC contact).
  • Stop drops everything.
Stuck? Show hints (4)
  1. Rung 1 is your Start/Stop seal on Main: (NO Start OR NO Main) AND NC Stop → OTE Main.
  2. Rung 2: NO Main → TON Ts. The transition clock only runs while the motor circuit is live.
  3. Rung 3: NO Main AND NC Ts.DN AND NC Delta → OTE Star. Rung 4: NO Main AND NO Ts.DN AND NC Star → OTE Delta.
  4. Rung order does the clean handover: at the DN scan, rung 3 drops Star FIRST, so rung 4's NC Star is already satisfied Delta picks up the same scan.

The most-wired motor starter on Earth. Congratulations this is real controls work.

I/O for this exercise6 tags · show
Inputs
StartStart push button
StopStop push button
Outputs
MainMain contactor
StarStar contactor
DeltaDelta contactor
Timers
Ts · 2000msStar-to-delta transition
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