Better Water Coverage, Better Yield: Drives for Agriculture & Irrigation

05/31/2023 | White Paper

Plant the Seeds for a Successful Growing Season with Constant Pressure and Consistent Water Delivery

From vegetable fields in California to dairy farms in Wisconsin and commercial fruit growers in Washington—agriculture feeds us all. Yet, what is feeding the fields and livestock to keep them strong and healthy? With weather patterns more unpredictable than ever and climate concerns leading to more uncertainty, consistent annual precipitation seems more unreliable than ever. Enter irrigation systems. Once seen as a backup to Mother Nature, these systems have become critical infrastructure for farmers, assuring “100% precipitation” even during dry periods.

What goes into engineering a water system for irrigation that’s beneficial to the agriculture industry? What components are needed and what considerations factor into getting the most out of the systems water supply? This white paper takes a closer look at agriculture and irrigations systems: what to consider and why variable frequency drives (VFDs) are an essential part of any water system.


Pumping Systems for Agriculture & Irrigation

A complete irrigation water supply system consists of pumps, motors and controls. The number of pumps and motors depends on the water source you are tapping into and the size of the property. Accessing water is one thing; optimizing and controlling its delivery is something else entirely. Too much water, and you can flood fields. Too little and the effort is wasted. In both
cases, money is also wasted with excess water usage or spoiled crops.

This is where a VFD system comes in. VFDs put technology to work for owners, allowing them to control water with constant pressure and precision. They are available in an array of submersible and above ground applications with varying horsepower options. When selecting a VFD, you should consider the features that offer the biggest benefits to the agriculture industry: constant pressure, soft-start protection, input and output adjustments, reporting capabilities and more.



Constant Pressure: A Must for Any Size Farm

To understand the benefit of a VFD system, consider what likely happens without one. Many conventional irrigation systems utilize a pumping system running at a single
speed to distribute water across a field. The result is often inconsistent surface-level watering, coverage gaps, increased watering time, runoff—and wasted water. That’s where constant pressure systems—which are designed to maintain a set pressure across the entire system—offer better performance. Whether driving a center pivot, multiple sprinklers, a drip system or misters, the system is designed to perform efficiently across the board. Constant pressure systems deliver the right amount of water across a property without gaps to keep plants growing strong. Constant pressure allows operators to dial in the ideal pressure required to operate their nozzles and emitters to what’s best for their application and crops. This is how a VFD—such as Franklin Electric’s SubDrive Connect Plus™—provides a simple, powerful constant pressure solution that optimizes water supply from pumping systems up to 30 horsepower (hp).

Wasting water isn’t the only concern for irrigation systems: you also want to save money on energy costs and minimize pump system mechanical wear. In contrast with your demanding needs during the peak irrigation season, wouldn’t it be good to slow the system down during months when irrigation demand is more limited? The installation of a constant pressure system allows irrigation professionals to set the pressure to one setpoint at varying flow rates; just what you need to match your pump’s performance for irrigation demand that changes with the season, vegetation type or drought conditions. Most VFD systems use a pressure sensor to measure water pressure. The sensor sends a signal to the VFD which automatically regulates the speed of the pump to meet the demand for water: all while keeping pressure constant throughout the system.
Dry seasons can also lead to low water levels in your well. VFDs can account for this, and are customizable for underload sensitivity and off time. This helps to protect your pump from dry run while it also reduces the risk of the well running dry entirely.

Constant Pressure: Better for Your Motor & Pipes

When considering the merits of a VFD, consider the wear and tear your overall operation puts on your system. Starting pumps at the beginning of the growing season as well as starting them for daily use is often when the most stress is put on a pumping system. In fact, the average number of starts per day over a period of months or years influences the life of a submersible pumping system. Too much stress can lead to water hammer, hard starts and, eventually, premature pump failure.

Yet, with a VFD, this stress is alleviated.


When it comes to daily start-up, VFDs improve system life with a soft- start feature. This controls the electrical current and therefore the voltage applied to a motor to reduce stress at start-up. This “easing-in” to running at full speed minimizes pressure on elbows, underground pipe joints and pivot nozzles. It also helps reduce the heat input to the motor—a big help in
prolonging motor life.

An additional benefit that is common with VFDs is the ability to provide phase conversion, which is a feature that allows the VFD to accept single-phase voltage inputa nd provide a three-phase voltage output. This allows users to take advantage of the benefits of a three-phase motor, such as improved efficiency, increase operational torque, and reduced cable sizei n applications where only single-phase power is available from the utility.

An additional benefit that is common with VFDs is the ability to provide phase conversion, which is a feature that allows the VFD to accept single-phase voltage input and provide a three-phase voltage output. This allows users to take advantage of the benefits of a three-phase motor, such as improved efficiency, increased operational torque, and reduced cable size in applications where only single-phase power is available from the utility.

At the beginning of the growing season, VFDs help to reduce water hammer with a pipe fill mode. Water hammer occurs when empty pipes in an irrigation system are rushed full of water. Pressure can’t be controlled, and this causes a flood of water to overwhelm the pipes and check valves, creating mini shock waves across the system. It’s like slamming a hammer on your pipes, and this force can damage piping, fittings, emitters and valves. If severe enough, it can
also damage the thrust bearing in a submersible motor.

With a VFD’s pipe fill mode, operators can automatically reduce the flow and velocity of water to eliminate water hammer.

In addition to regulating water pressure during start-up, VFDs can protect against over pressure or underload, stabilizing the entire system. Whether your water levels are high or low, a VFD paired with a properly sized pump will offer consistent operation in various conditions. Engineered to deliver benefits across an entire irrigation system, and a must for agricultural settings, SubDrive Connect Plus offers these and additional advanced features including broken pipe protection and multidrive/multi pump capabilities.



Simple to Set Up & Customizable to Individual Needs

VFDs can also come with advanced features like dual demand or dual setpoints. This is important in irrigation systems that vary in distance, elevation, zone size or differing in water coverage. For example, if a farm is near a mountainous area and experiences elevation changes across their
property, this may affect water distribution. Dual setpoints can manually be established to assure consistent water across the fields, from valleys to hills. If a system uses different irrigation emitters—drip tape in one area and overhead sprinklers in another—dual setpoints can optimize coverage for various types of distribution.

Farmers or their irrigation operators also have more customizable control over their system with a VFD. VFD run commands can be tied into sprinkler timers or other irrigation controls, so that the pump and motor will only run when the system is ready to irrigate. Users can also take advantage of built-in relays and other input and outputs on the VFD to communicate with propulsion motors and start-stop commands. These advanced communication options also provide the potential to be utilized with remote monitoring of multiple systems to enable status tracking and added control. All of this information is stored and readily available for run reports or allow service professionals to access needed details about the system.

Whether you choose to go plug-and-play or require advanced customization, with SubDrive Connect Plus, setup is fast and easy, using simple LCD graphic display and single-level menu—no complicated programming is required for startup. The drive can also be configured and monitored using integrated Bluetooth and the FE Connect SubDrive Connect Plus mobile app.

Finding the Right VFD for Your Needs

Understanding the benefits available with VFDs can help agriculture professionals prioritize what’s most important for their system. Constant pressure is essential, as is reporting capabilities, soft-start protection and cost-effectiveness. It’s also important to understand the long-term performance capabilities of the VFD—how has it performed in the field and how much power does it provide? The biggest benefits come from selecting the best system from the start.

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Franklin Electric is a global leader in the production and marketing of systems and components for the movement of water and energy. Recognized as a technical leader in its products and services, Franklin Electric serves customers around the world in residential, commercial, agricultural, industrial, municipal, and fueling applications. Franklin Electric is proud to be named in Newsweek’s lists of America’s Most Responsible Companies and Most Trustworthy Companies for 2024 and America’s Climate Leaders 2023 by USA Today.