In the United States, irrigated agriculture produces about half of the total value of crop sales despite comprising only 17 percent of U.S. cropland. However, irrigated agriculture also represents the largest share of consumptive water use in the nation. Efficient agricultural irrigation helps to balance the incredible value of irrigated agriculture with the need to be conscious of water use.

- Irrigation Association

The Irrigation Association has recently released a new paper titled Principles of Efficient Agricultural Irrigation. The document discusses the key concepts that users and providers of irrigation need to consider to attain the most energy efficient use of water and energy.

With an estimated 80% of electric motor applications being fixed speed processes perhaps it isn’t surprising that variable speed drives are consistently being misapplied. Many motor driven systems are being designed with VSDs to add flexibility that isn’t needed, compromising efficiency while adding to capital and operating costs.

US-based JDA consulting engineers (now part of global consulting firm Exp Global.) offer an interesting discussion of this phenomenon in a blog on the Staticworx website. “As JDA's team commissions large, complex mechanical plants, we find more systems where the VSD is practically abandoned in place. Rather than providing the precise control of flow and pressure or reducing energy consumption and demand, the VSDs appear to be "stuck" at a single speed.”

What are the trade-offs in oversizing a motor for your next application?

Oversizing motors for any particular application is becoming more popular, as engineers seek to provide some ‘insurance’ for a new system. Insurance against possible system failure (and resulting damage to their reputation), and insurance for unanticipated future demands on the application.

An Automation World study on oversizing has asserted that over half of engineers choose to over specify motors. It seems like a ‘no-brainer’ – put in place a motor with plenty of margin of error for rated load, and use a variable speed drive (VSD) to throttle it to meet the system’s actual power needs. Peace of mind guaranteed.