PLC-03 · Free project

Star-delta fan starter

Start in star, change over to delta through a dead gap, and watch the starting current.

Free with a free account. Runs in your browser. About 60 minutes for a first attempt.

Open in the lab
The plant the controller runs, as drawn in the lab: Star-delta fan starter

What you will build

Work order KF-2603. Kestrel Foundry, Extract fan EF-2.

Kestrel Foundry (hvac) needs a controller program for Extract fan EF-2. Sequence the three contactors of a star-delta starter: star for a set time, a short dead gap with both open, then delta, with stop dropping everything.

We are fitting a star-delta starter to the kW motor of a ventilation fan to cut its starting current. Main_K is the main contactor, Star_K the star contactor and Delta_K the delta contactor. Start_PB is a momentary push button and Stop_PB is wired normally closed (1 is healthy, 0 is pressed). Pressing Start closes Main_K and Star_K together, and the motor keeps running after Start is released. After s in star, Star_K opens. Delta_K must then wait ms with both star and delta open, so the arc in the star contactor has cleared, before it closes. Main_K stays closed the whole time. Star_K and Delta_K must never be closed together. The motor then runs in delta until Stop is pressed, which opens all three contactors at once. Every start, including a restart after a stop part way through the star time, begins in star with the full star time.

What you will learn

  • Timer sequencing
  • Contactor interlocks
  • Motor starting methods
  • Reading a timing diagram
  • Read a short user requirement specification (URS) and turn it into ladder logic
  • Prove your program against a numbered factory acceptance test (FAT)

How it goes

  1. Read the work order and the URS.
  2. Build the ladder program against the tag table.
  3. Run the plant and watch it respond.
  4. Run the FAT and fix whatever fails.

Tools

  • Ladder editor in the browser

    Draw contacts, coils, timers and counters, then run the program.

  • A working simulated plant

    Watch the machine respond as your logic runs.

  • A tag table

    2 inputs and 3 outputs: Start_PB, Stop_PB, Main_K, Star_K, Delta_K.

  • URS and FAT documents

    The paperwork a real project starts from, with numbered tests.

Questions

Is it free?
Yes. The lab is free to use with a free account. There is nothing to buy to open this scenario.
Do I need to install anything?
No. It runs in your browser with the ladder editor and a simulated plant.
What will I do in PLC-03 Star-delta fan starter?
You build and test a program, then check your work against an acceptance test.
How long does it take?
A first attempt takes about 60 minutes.
Do I need experience?
No. Each work order says what to do step by step, and hints are there if you get stuck.
Open in the lab