DRIVES, CONTROLS & MOTORS FEATURE


VSDs: THE BENEFITS FOR METALS AND MINING INDUSTRIES


In the metals and mining industries, efficiency, reduced costs and


sustainability are crucial concerns. Jose Giacomoni, senior commercial product manager at Nidec, explains how VSDs can help


A


variable speed drive (VSD), also known as a variable frequency drive (VFD), is a power electronic device that controls the speed and torque of an electric motor by varying the frequency and voltage of


its power supply. This allows the motor to be operated at optimal speeds, reducing energy consumption and wear and tear on equipment. In mining and metal processing facilities, for example, by adjusting the speed of the conveyor systems used to transport materials, VSDs help prevent material spillage, belt wear and excessive energy use. Mining operations also require extensive use of pumps for dewatering,


slurry transport, and cooling systems. VSDs enable dynamic speed control, adjusting pump performance to match demand, reducing both energy consumption and equipment wear. Similarly, ventilation fans in underground mines benefit from VSDs by optimising air circulation via speed regulation, thus reducing power. Crushing and grinding operations are among the most energy-intensive


processes in mining and metal refining. By employing VSDs, operators can adjust the torque of crushers and grinding mills to accommodate varying ore hardness and feed rates, greatly improving efficiency and reducing unnecessary power consumption. VSDs can also provide enhanced control for hoisting systems, ensuring smooth lifting operations. This is especially important in deep mining applications where hoists transport heavy loads over long distances. Controlled acceleration and deceleration improve safety and prevent sudden movements that could damage equipment. Regenerative drive systems, also known as active front end (AFE), are well used in this type of application, taking advantage of excess energy during braking, returning it back to the mains or reusing it in other parts of the integrated system. During smelting and refining, assets such as mixers, blowers


and casting equipment can benefit from VSDs. These applications require precise speed control to maintain product quality, reduce energy costs, and ensure optimal process conditions. Each operation has its own requirements and while the hardware within a range of VSDs will be similar, it is the software that provides the detailed control and functionality. Having selected a solution depending on the motor type, AC, DC or


servo, the next step is to ensure the required features and controls are built-in. Modern drives, such as those from Nidec, are tailored to applications to ensure they deliver the required inputs, outputs, communications, motor protection, and integration with connected hardware to achieve optimum performance.


KEY BENEFITS The ancillary field hardware installation cost comparison between a conventional fixed speed application (direct- on-line (DOL), star delta, reactor starter, etc.) to that of a VSD is beneficial due to the intelligent motor fluxing optimisation during the initial start cycle. This reduces the excessive peak inrush currents, resulting in smaller power cables at a reduced cost. In addition to this, the maximum peak electrical power demand during the start cycle is dramatically lower, thus the electrical billing base rate is at a lower tariff. By optimising motor speeds based on demand, VSDs can reduce energy


consumption by 20% to 50%. Providing precise control over motor speeds on equipment that operates under fluctuating loads such as conveyors, crushers, pumps and fans, VSDs offer improved process control and consistency. Of further benefit, the reduction in energy consumption is directly proportional to the drop in associated carbon emissions.


JUNE 2025 DESIGN SOLUTIONS 53 In mining and metals processing, VSDs allow for smoother


adjustments to process requirements. This helps prevent bottlenecks, enhances throughput and minimises operational disruptions, resulting in lower operating expenditure (OPEX) and a reduced carbon footprint, making operations more sustainable. One example is the cooling system, which is crucial to maintaining


a comfortable working environment in underground mining sites. Energy audits highlight the feasibility of installing VSD technology on the pumps and fans. In fact, motors running at lower currents not only consume less energy,


they also generate less heat, which reduces the demand on the cooling systems. VSDs also contribute to a quieter working environment; and they reduce the strain on mechanical components, extending their service life. Variable speed drives offer fully adjustable speed, ideal for pumps,


conveyors and fans, and can control starting, stopping and acceleration. The speed control that a VSD offers can be used to reduce the pressure surges caused in pumping systems, optimising performance and extending service life. They also have dynamic torque control and provide smooth motion for applications such as elevators and cranes. However, the overarching benefits come from the continuous control of peak energy demand and reducing power when it is not required, minimising energy costs. The ability to maintain speed while torque requirements vary is important for many applications including conveyors, mixers, grinders and crushers.


VSDs - FOR SUSTAINABILITY AND EFFICIENCY As the metals and mining industries continue to prioritise sustainability and operational efficiency, the adoption of VSDs will likely increase. The key to achieving these benefits is not just about installing the VSD, it is the way in which the VSD delivers the control, how it is configured, and how the hardware interacts with the software. It is therefore important to engage with a leading drive manufacturer, such as Nidec, to apply their industrial expertise to optimise the application.


Nidec Drives www.ControlTechniques.com


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