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Mission 56 · Pro PLC programming exercise

Three pumps, one well

Stage pumps on an analogue level, share the hours and survive failures.

Bring in one, two or three pumps as the level rises and take them out as it falls, start them at least 5 s apart, always start the healthy pump with the fewest running seconds and stop the one with the most, and fall back to the floats if the level fails.

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The 3D pumping station control this mission runs on Pro mission
Test replay

Staged up and down

Test 1 of 4
Set by the testChecked by the testStep 10 of 10 · 10.6 s
Level
Advanced
Time
About 70 min
Reward
+900 XP
Rig
3D pumping station control
Siemens editors
SCL, LAD
Rockwell editors
Structured Text, Ladder
Course stage
29. Machine lab 4: safety sequences and plant control
Automatic tests

What the tests check

  1. Pumps wanted follows the level with the start and stop levels given.
  2. Starts are at least 5 s apart.
  3. Starts choose the fewest running seconds; stops the most.
  4. A faulted pump stops at once and another takes its place.
  5. A failed sensor raises SensorAlarm and hands control to the floats.
  1. Try it Use the buttons below the model and watch the rig respond.
  2. Test solution Every check runs on your code in one press.
  3. Replay If one fails, step through it one scan at a time to see why.
Why it matters

Where you’d see this on site

Water companies run thousands of these stations unattended. Duty sharing, start spacing and sensor fallback are in every specification.

Start all three at once and the supply trips. Always start pump 1 and it wears out while pump 3 seizes. Trust a dead sensor and the station floods or runs its pumps dry.

Where you'd find thisNever flood, never run dry, never wear out one pump

Sewage and storm water stations run unattended for years. The controller stages pumps on the level, spaces their starts so the supply is not overloaded, shares the running hours, and falls back to simple floats if the level sensor fails.

  1. SewerInflow
  2. Wet wellUltrasonic + floatsYou are here
  3. Pumps1, 2 or 3
  4. Rising mainTo the works
On a real site: places, parts and safety
  • Sewage and surface water pumping stations
  • Mine and quarry dewatering
  • Building basements and road underpasses

Wet wells are confined spaces with hydrogen sulphide: nobody goes in without a permit, gas monitor and rescue plan.

A flooding station pollutes rivers and homes, and is reported to the regulator.

The sizes, timings and cutaways are teaching choices, not a drawing of any one real installation.

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