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How to reduce the operation cost of water distribution system?

How to reduce the operation cost of water distribution system?

How to reduce the operation cost of water distribution system?

How to reduce the operation cost of water distribution system?pumps

For years, engineers have been pursuing their goals in water distribution systems in terms of ensuring pressure or flow control and reducing operation cost.

Firstly, the old systems Swirl flaps, three-way valves are examples of methods have been used to regulate the pressure or flow in booster pumps applications and moving the pump operating point along their characteristic. In this old system no chance to minimize the energy consumption.

On the other hand, old system operation applied high pressure on the mechanical part which cause more mechanical faults that reflect on the operation cost.


And after a while, the engineers found a way to achieve their goals of pressure or flow control and reducing operation costs by controlling the pump speed.

This method will be mainly depending on the Variable Frequency Drive (VFD)

VFD will be used to provide your water distribution network with the required pressure and flow as per the actual demand that done by controlling the pump speed.


What is the Multi Motor Follower MMF (Master Slave VFD Function)?



The main purpose of this method is to maintain a constant pressure in the water distribution network. MMF system can be used when the water distribution system is feed by more than one equal sized pump. Each pump will be controlled by individual VFD unit.


All units will communicate together to coordinate the system operation.

Some VFDs are equipped by Master –Slave option with ability to connect (up to 8) unit in one system through RS-485 communication. One feedback signal from the pressure transmitter will be sufficient to control whole system.

Once the system receives the start signal, one of the drives will be the leader (master) and the other drives will operate as slaves (followers).

PID function will be active to calculate the error between the set value (PID reference) and the feedback value.


Based on the difference between the set value and the actual value of pressure in water distribution network, MMF system will give instruction to all units to adjus t the pumps speed that maintain system pressure by using PID Function.

MMF system also offer option to calculate the operation time for each pump. Depending on this Master VFD will energize the suitable pump using Equal Aging function that will increase the lifetime of pump.

In the following example, we will give an explanation about MMF System:

Let us say there is a commercial building equipped with MMF system to manage water distribution network, when the network demand increased, the pressure will decrease in the network. Due to this Master VFD will increase the pump feed by increasing the speed of main working pump.

After a real operating speed reaches to certain speed, adjustable delay time passes, and the pressure does not reach to the set value.


Then the Master VFD will energize another VFD and decrease the speed of the main pump after that Master VFD will monitor the speed of the energized VFDs to meet the pump speed that achieve target pressure and keep it constant.

When the system demand become less, the pressure will increase in the water network. Master VFD will reduce the water feed by reducing the speed of operated VFDs units, then stop it if its speed became less than specific speed unit.  Same sequence will be applied to next unit till the system pressure match with the pressure set point.

In conclusion the main benefits of using MMF System:

  • Energy Saving by pump speed control (20% / 50%) depending on Affinity laws low.  
  • Multi-Pump Multi-Drive duplicates energy saving.
  • Reduce maintenance by equalizing run time for all pumps.
  • In old and weak pipe system where huge pressure surges can lead to leakage, the high performance of MMF system can be a real benefit.
  • In constant pressure water systems, the pumps can be operated in the most energy efficient way by using Master slave VFD operation.
  • In systems with large variances in flow, the fast-reacting MMF system will safely and fast maintain a constant pressure.
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