Reduce energy consumption on irrigation systems

By Fanie Steyn, ABB South Africa

 

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Published in: 

Energy Efficiency Made Simple Vol III: Energy and enviroFiciency

November 2012  Chapter 4: page 56

Enquiries: email Fanie.Steyn@za.abb.com

 

With irrigation systems the pump may be overdesigned in terms of water flow rate to ensure that the pump is able to supply sufficient water to crops and throttled mechanically afterwards to control the flow while the electric motor is running at full speed - thereby wasting surplus energy through friction (amongst others). When designing for the pressure head, a safety factor is also built into the design to ensure that the pump supplies sufficient pressure at the emitter furthest away from the pump or at the highest point of delivery and afterwards using a pressure control valve to regulate the pressures. In most cases, electric motors are running at full speed, regardless of the actual output needed. Many motors are oversized to cope with a maximum demand that rarely or never occurs.

 

Take note

  • The electrical energy savings potential in irrigation systems is enormous.
  • The concept of a VSD is to reduce the output of an application, such as a pump, by controlling the speed of the motor to ensure that it does not run faster than necessary.
  • When electing to use VSDs in the agricultural sector, one must be careful to select the correct type of VSD for environmental requirements.