DAC 2021_12

45 www.drivesncontrols.com November/December 2021 CONTROLGEAR n Do you need to use soft-starters? I magine you are waiting at a traffic light. When it turns green, it’s usually a good idea to not stamp your foot on the accelerator to reach full speed, because this may cause mechanical wear and would be rather inefficient – as well as being dangerous. The same is true for electronic equipment, where a slow start helps reduce energy consumption and excessive wear. This is why using soft-starters with electric motors can boost energy efficiency and improve a machine’s performance. Soft-starters limit the initial inrush of current and provide a gradual ramp-up to full speed, or stop gradually where a sudden halt may damage connected equipment. They help to reduce mechanical stresses on the motor and shaft, as well as electrodynamic stresses on the attached power cables and electrical distribution network. Electric motors are responsible for two-thirds of the UK’s industrial electricity consumption. The energy cost to run a motor over ten years is at least 30 times its original price. Because accelerating up to speed needs a lot of power, motors can consume vast amounts of energy when they start up. To control the energy consumption during this period, you should consider using soft-starters. Without a soft-starter, a motor starts immediately, consuming the maximum amount of energy, and continues to do so for the whole of its operation. With a soft-starter, the voltage rises gradually to the maximum, accelerating the motor and coupled load smoothly, and using less energy. Soft-starters generally use three pairs of silicon- controlled rectifiers (SCRs), one for each phase of power. They are applied gradually for the portion of each voltage phase, controlling the voltage to the motor, and temporarily reducing the terminal voltage. Current reduces proportionally to the reduction in voltage. As torque is proportional to the square of the voltage, even a small reduction in voltage can lead to a large reduction in torque. For instance, a 50% reduction in voltage results in a 50% reduction in current and a 75% reduction in torque. As well as reducing energy consumption, soft- starters also help to protect the motor and its connected equipment from damage by reducing the mechanical shock associated with start-up. The reduced mechanical wear on motors and components such as belts, pulleys, gears, chains, couplings and bearings, can extend a system’s lifetime significantly, cutting downtime and the need for maintenance. Moreover, soft-starters can cost 10% as much as high-power drives. Therefore, for applications where speed and torque only need to be controlled during motor start-up, a soft-starter can be an economical choice. Another benefit is that soft-starters usually need less space than VSDs. By adopting soft-starters, you can boost energy efficiency while also improving motor performance. For maximum benefits, a soft-starter should be applied to a motor before it is operated for the first time. n Europe’s eight billion electric motors consume almost half of the continent’s electricity, making technologies that reduce power consumption – such as soft-starters and VSDs – essential. Neil Ballinger, EMEA head at automation parts supplier EU Automation, explains the benefits of soft-starters. Meet your new colleague Discover the flexible robotics solution Prepare for the future and boost production with OMRON TM cobots. Take a leap towards a manufacturing environment where humans and machines work side by side in harmony. Collaborative robots are ideal for a VUPNBUJOH QBMMFUJTJOH MPBEJOH BOE VOMPBEJOH‰G reeing their human colleagues from repetitive and potentially dangerous tasks. Would you like to knowmore? +44 (0)1908 258258 oeeuk_sales@omron.com industrial.omron.co.uk/cobots Contact us to see how you can deploy cobots quickly in stand-alone applications, or integrated into a total automation concept from OMRON. Contact us for Proof of Concept testing! Soft-starters can save energy as well as helping to protect electric motors and connected equipment