Multiple Pumps Control using PLC

Write the PLC program to control multiple pumps using programmable logic controllers. We have two input pumps used to fill a tank. Make sure pumps operate in an equal amount of time over their lifetime.

Multiple Pumps Control using PLC

Multiple Pumps Control using PLC

Program Logic:

Develop ladder logic program according to the logic given below,

  1. The start/stop push button is provided for control of the two input pump motors P1 and P2.
  2. The Start/Stop pushbutton station is operated to control pump P1.
  3. When the tank is full drain pump motor P3 is started automatically and runs until the low-level sensor is actuated.
  4. After 3 fillings of the tank by pump P1 control automatically shifts to pump P2.
  5. The operation of the start/stop pushbutton now controls pump P2.
  6. After 3 fillings of the tank by pump P2, the sequence is repeated.

PLC Program:

PLC based Multi-Pump Logic
Pump Control with a PLC

Program Description:

Rung 0000:

Start/Stop PB latched with memory B3:0/0.

Rung 0001:

B3:0/0 enabled to turn on B3:0/1 which is to turn ON PUMP P1 (O:0/0) when low-level sensor(I:0/3) turn ON and High-level sensor (I:0/2) is in off condition.B3:0/1 is latched with low-level sensor because pump p1 should not go off once water started rising.

Rung 0002:

Memory contacts used to turn on PUMP P1 (O: 0/0) with counter (C5:0).

Since we are going to shift pump operation from P1 to P2, two counters are used to shift between Pl and P2.

Counter C5:1 is used to turn on PUMP P2(O:0/2).

Rung 0003 & 0004:

B3:0/0 enabled to turn on B3:0/2 which is to turn on PUMP P3(O:0/1) when high-level sensor(I:0/2) turn ON and low-level sensor (I:0/3) is in off condition.B3:0/2 is latched with high-level sensor because pump p3 should not go off once water started reducing.

Rung 0005:

When Pump 3 (O: 0/1) is running, the low-level sensor turns on will make Pump p3 off and pump P1(O:0/0) ON.

Rung 0006:

Both Counter reset is done once the second counter (C5:1) done bit turns ON.


We can use this example to understand the programming logic in AB PLC.

Author: Hema Sundaresan

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