Implementing modern electric motor control technology in the agriculture industry has become increasingly important to improve efficiency throughput, reduce downtime, reduce waste, and drive tangible cost reductions.

While the benefits of modern starting technologies, such as digital soft starters and variable-speed drives (VSDs) for irrigation systems, cannot be overstated, misconceptions about these technologies still exist.

For example, some people believe that VSDs are suitable only for high-power applications, but sales and distribution company Referro Systems MD Adrian van Wyk notes that even small-scale systems can benefit from using VSDs.

Similarly, there is a common misconception that VSDs are complex and difficult to use, but modern VSDs are designed to be user-friendly and intuitive.

By working with reputable manufacturers and experienced suppliers, manufacturers and users of agricultural equipment can improve efficiency, reduce costs and enhance their operations significantly.

By demystifying traditional starting methods and dispelling myths regarding VSDs, manufacturers in agriculture can “reap the rewards of these technologies and improve their operations for years to come,” adds Van Wyk.

While VSDs and soft starters may be seen by some users to be similar, they function completely differently to one another. Soft starters provide a smooth, stepless start as well as stop ramp, in the case of centrifugal pumps when in pump control mode, which reduces the mechanical stresses within the pumping system and water hammer as well as reducing peak starting currents.

They are often marketed as providing energy savings, but Van Wyk notes that they often offer potential savings only during the starting cycle, and even then, this saving may not be significant.

“If customers are being measured on a maximum demand, soft starters can help reduce that peak demand point, leading to some energy savings. However, during regular full speed running processes, the load does not see any energy savings,” he explains, lamenting that “many customers have been disappointed with the energy saving results because they were not accurately informed.”

VSDs, however, provide precise control over motor speed, torque and direction, which allows potential for optimal performance and energy efficiency during regular running processes, as well as during starting and stopping with an even lower peak current demand during start compared to soft starters.

They enable users to control the speed of the motor, which is essential for applications such as irrigation pumps, as the pressure and flow delivered to the crops can be easily controlled close to the demand point, which, in turn, leads to more efficient use of resources, energy and better crop yields, owing to optimised dosing and irrigation cycles using only the energy that is required to meet the demand.

Van Wyk comments that, while soft starters can be effective in reducing maximum demand and also offer many mechanical savings and protection, VSDs offer “the best of both worlds” in terms of energy and mechanical savings.

He notes, however, that, while older electric motors are quite robust, their insulation ratings are typically not rated to be controlled by VSDs. There are also many other factors to consider before implementing VSDs – be it in existing applications and/or new installations.

“VSDs can cause voltage stresses on the motor, potentially leading to, among other things, insulation failure in the motor windings over time if the necessary investigation is not done and the required mitigation is not applied. Suppliers and manufacturers need to provide accurate information to customers to ensure that they are aware of this and other potential issues that may arise.”

He, therefore, urges suppliers and manufacturers to provide accurate information and training for their salespeople to ensure that customers have a full understanding of the actual energy savings that are possible when using soft starters when weighed up against traditional electromechanical and VSD technologies.

“By providing accurate information, customers can make informed decisions and reap the rewards by improving their operations for years to come and secure their investment,” Van Wyk concludes.