September 2020

33 www.drivesncontrols.com September 2020 Secondly, by preventing a full factory shutdown, the higher energy needed to restart all machines can be avoided. Soft starters For machines and motors that do not run continuously, you can install soft starters. These devices temporarily reduce the load and torque in the powertrain, and the electric current surge of the motor during start-up. This is similar to what happens at traffic lights. While you could slam your foot on the accelerator when the light turns green, you know this is an inefficient and mechanically stressful way to drive – as well as being dangerous. Similarly, for machinery, a slower start uses less energy and results in less mechanical stress on the motor and shaft. Over the lifespan of the motor, a soft starter reduces energy consumption. Some soft starters also provide automatic energy optimisation. Ideal for compressor applications, the soft starter judges the load requirements and makes adjustments to minimise energy use. Variable-speed drives (VSD) VSDs adjust the speed of a motor, based on the application. Without them, the system would simply brake when less force is required, generating heat. Combine a VSD with a super-premium (IE4) efficiency motor and the energy costs will speak for themselves. In cooling tower applications, for example, using IE4 super premium motors with a properly sized VSD, can deliver energy cost reductions of up to 80% and average water savings of 22%. While the current regulations state that IE2 motors must be used with a VSD, this has been difficult to enforce. This explains why the regulations are becoming stricter. From 1 July, 2021, three-phase motors will need to meet IE3 standards, regardless of whether they are being used with VSDs or not. The 2021 changes are also holding VSDs to higher standards. Drives will be expected to meet the IE2 standard – although an IE2 drive does not represent the equivalent efficiency of an IE2 motor because they are separate rating systems. Hidden functions Installing a VSD is one thing; using it to its full potential is another. Many VSDs are packed with useful functions that plant managers don’t know exist. Pump applications are a good example. Fluid handling can be turbulent – from leaks to low fluid levels, there’s a lot that can go wrong. Built-in controls, such as the Pump Genius in WEG VSDs, enable more effective use of motors based on production demands and fluid availability. Some VSDs can detect broken pipes automatically, identifying fluid leakage zones and adjusting the motor performance accordingly. In addition, dry pump detection can deactivate a motor automatically if fluid runs out, and issue a dry pump alert. In both cases, the motor reduces its energy consumption because less energy is required to handle available resources. When using multiple motors in a pump application, jockey pump control can optimise the use of different sized motors. Demand may require that just one small motor be used, or a combination of a small and large motor. Dedicated pump controls can offer increased flexibility to use the best sized motor for a given flow rate. VSDs can even clean motor impellers automatically, ensuring that de-ragging is carried out consistently. This keeps the motor in optimal condition, which has positive effects on its efficiency. If you’re not happy to pay 30 times a motor’s price in energy bills over the course of a decade, it’s time to make some of these changes. They won’t happen overnight, but a strategic plan that targets your most inefficient pain points will result in significant energy efficiency benefits. n Intelligent Ap IoT Ready Smart Products plications for Actuators Cross-Roller Ri l 44 i f bh @thk U.K. Office • GmbH THK Ball Screw T g n s (0) 1384 471550 .thk.c www e . + • n o. x .eu om -