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Mission 20 · Pro duty and standby pump exercise

Bring in the standby

Choose one pump for the job.

There are two pumps. The duty pump does the work and the standby pump is the spare. While Start is held and Permit is ON, run DutyPump if Fault is OFF. If Fault is ON, run StandbyPump instead.

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The 3D pump skid this mission runs on Pro mission
Test replay

Duty pump runs when Fault is OFF

Test 1 of 4
Set by the testChecked by the testStep 1 of 1 · 20 ms
Level
Applied
Time
About 12 min
Reward
+200 XP
Rig
3D pump skid
Siemens editors
FBD
Rockwell editors
FBD
Course stage
9. Choose the working pump
Automatic tests

What the tests check

  1. With Start held and Permit ON, exactly one pump runs.
  2. Fault ON moves the run from DutyPump to StandbyPump.
  3. Without Start or Permit, both pumps are OFF.
  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

Two pumps supply water to a block of flats. If the main pump fails, the spare should take over.

Without the spare, residents lose water. Neither pump should run dry when the shared supply tank is empty.

Where you'd find thisWater for the top floors

In a block of flats, a basement tank holds water from the mains. Two pumps push it up to the taps above. One runs while the other waits as a spare. A low-water switch stops the pumps before the tank runs dry.

  1. Street mainsWater enters the building
  2. Storage tankHolds a supply for the pumps
  3. Water pumpsPush water to the floors aboveYou are here
  4. Taps upstairsResidents use the water they need
On a real site: places, parts and safety
  • Block of flats — pushing water up to the top floors
  • Brewery — sending hot water to a brewing tank
  • Water-treatment works — moving water between filter tanks
  • Office building — pumping water round the heating pipes

A low-water switch can take away permission to run. The pump must stop before it runs dry and damages its seal.

The PLC can say ON even when a pump has failed. Check the measured flow as well as the command.

The Stop input in these exercises is not an emergency stop. Real machines also need guards, emergency stops and a safe way to cut the power.

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

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