Advanced Overload Relays Protect Health of Irrigation Pumps

The relationship between irrigation systems and sustainability can be overlooked when users are focused on achieving stronger crop yields and keeping their systems up and running. A recent guide from the Louisiana State University (LSU) Agricultural Center (AgCenter) opens with a brief exploration of the connections among irrigation maintenance and energy efficiency. It argues that when we transport large amounts of water quickly, we both consume and create energy. The AgCenter guide proposes that by adopting smarter irrigation practices, we can also conserve water, save money and reduce energy use. These efforts impact not only the health of the food supply and population, but also the planet. This article explores the use of intelligent motor and pump protection solutions for improved maintenance and efficiency.

Why Monitor Irrigation Pumps?

The Appropriate Technology Transfer for Rural Areas (ATTRA)—a U.S. National Sustainable Agriculture Assistance Program managed by the National Center for Appropriate Technology (NCAT) —points out “efficient irrigation begins with properly installed and maintained pumps, motors and engines.” The AgCenter seems to agree and asserts “designing for safety and reliability lowers cost by extending the operational life expectancy of the irrigation system.” Badly designed or poorly maintained irrigation equipment results in loss of control on many different levels. First and foremost, the water cannot be applied as desired. ATTRA cites issues such as patchy water and inadequate pressure leading to “incorrect soil moisture levels, crop stress, reduced yields, wasted water, runoff, soil erosion, and many other problems.” Inefficient or malfunctioning systems also reduce yield and can result in crop loss, affecting both food supply and profit. The use of intelligent monitoring and protection is ideal for irrigation applications. The overall goal is to capture critical data that can anticipate maintenance needs sooner in order to prevent costly damages. In pumping applications, these solutions provide superior protection for both pumps and motors—preventing costly damage from conditions such as pump dead-head, bad voltage and overload conditions.

Protection for What Matters Most

Preventive maintenance is important to maintaining safe operating conditions near irrigation pumps. Pump operators should become familiar with any slight variations in the operating conditions and parameters that affect each specific moving part in their irrigation system. Monitoring phase currents and voltages as well as power draw provides insight to and protection for the entire system. A number of conditions can shorten motor or pump life in irrigation applications. Excessive heat can be generated in the motor or the pump for a number of reasons. Line voltage issues coming from the utility such as voltage drops or phase imbalances are particularly common in remote irrigation applications. ATTRA confirms “voltage drops across loose connections will cause the motor to operate at less than its rated voltage, increasing internal motor temperature. Increased heat will break down motor winding insulation, resulting in electrical shorts and motor failures. A loose or broken connection can also unbalance the phases of three-phase power and damage the motor windings.” Issues can also arise at the pump itself. For example, running a pump dry or in a dead-headed condition can cause excessive heating, damaging expensive seals and reducing the life of the pump. Simply monitoring and protecting for motor current alone does not reliably detect these conditions. Advanced overload relay solutions protect the entire system—providing line (voltage), motor (current) and pump (power) protection. Customizable protections include under/overvoltage, low/high power, overload, phase imbalance, phase loss and phase reversal. Low power protection is especially important for pumps. This is because in starved or dead-head conditions, a portion of the load will drop. Unlike current, power is linear with loading across the load range, making low power an accurate and fast method for detecting these conditions and stopping the motor before excess damage occurs.

Balancing Protection with Uptime & Ease of Use

Irrigation pumps can be located in spread out, remote locations. Adding more comprehensive protections can extend equipment life, but getting back up and running quickly and safely remains critical. Configurable protection features, programmable timers and manual and auto-reset options help balance protection with uptime. Motor protection relays provide reset options customizable by fault type (load, motor and supply based). Embedded reset timers prevent manual or automatic reset so that a restart cannot be performed until after a critical amount of time passes—such as after a load fault while backspin is present. Voltage faults offer automatic reset options where the fault will reset as soon as the condition clears as the device can continue to monitor voltage health even while the system is stopped. Finally, protections can be configured uniquely to trip the motor or only provide an alarm. The final key is making it easy to take advantage of everything the product has to offer.