Machine and Process Management

Variable Speed Drives: An IIoT Tool That Benefits Both OEMs and Manufacturers

Manufacturers, in their efforts to remain globally competitive, face many challenges including fluctuating demand, mass customization, high productivity/output expectations, and consistency of high quality. And the machine builders (OEMs) that support them face their own set of challenges. In today’s competitive environment, a key differentiating factor has become the ability of machines to continuously adapt to changes required by end users.

Variable speed drives

For OEMs, success hinges on their ability to build better performing machines in terms of production speed and output quality. Flexible architectures are necessary in order to comply with varying end user specifications and connectivity in terms of integration into different architectures is critical, as well as accommodating suitable infrastructure for the Industrial Internet of Things (IIoT). Last but not least, machines must not compromise the machine operator’s safety.

Addressing these challenges has become simpler thanks to recent enhancements on the variable speed drives (VSD). A VSD is an automation component that controls and regulates the speed and rotational force, or torque output, of an electric motor. These drives are altering the way mechanical movement-oriented processes such as packaging, material handling, material working and hoisting are managed. Control of mechanical movements relies heavily on drive technologies with the ability to start and stop motors rapidly, with sufficient fluxing and motor current, and with the ability (accuracy) to repeat tasks during a given process. Precise control of mechanical movements in these application areas results in the following benefits:

  • Efficiency – According to US. Energy Information Administration, industry accounts for more than 40% of world electricity consumption. Within the industrial sector, electrical motors consume more than half of all electricity consumption. Today, synchronous motors are much more widely used in industrial applications than are induction motors due to better energy efficiency and higher dynamism. VSDs can control IE2, IE3, IE4 induction motors, reluctance motors and synchronous motors.  And VSDs are much more efficient than direct online start methods. Depending on the application, up to 30% energy savings (depending on torque profile of the load) can be achieved with VSDs. In direct online start scenarios, the motor runs at the nominal frequency with no possibility of controlling the motor speed. In addition, direct start/stop methods place high mechanical stress on the equipment, which significantly reduces equipment lifetime.  On the other hand, VSD-based applications provide thermal motor protection, deliver required torque at each start, and reduce the mechanical stress of the system, while lowering energy consumption. This results in higher efficiency.
  • Safety – In applications like material working or woodworking, emergency stop functions–bringing a machine to a safe operating state within the shortest time possible–helps to avoid accidents and increases productivity. Material handling and conveying applications can also be secured depending on the design needs.  For instance, safety sensing devices like light curtains or door locks can be used to limit machine speed (or to stop the machine if necessary).  Drives are equipped with safe torque-off (STO) dual safety input. They comply with machine safety standards such as EN ISO 13849-1 and EN62061, meet machinery directives, and can address specialized safety needs. They also contribute to optimizing the machine design. These drives offer perceptive and simple-to-integrate functional safety.
  • Dynamism and repeatability – On conveying applications, products often need to be grouped on a conveyer belt in a certain pattern (for example products laid out on the belt in a 4 by 4 or 8 by 8 configuration). Machines along the belt first group the products and then pass them along. This happens incredibly fast, yet not all sub-processes involved are moving along at the same speed. Precise and rapid acceleration and deceleration are required. A VSD provides a high output torque of up to 220%Tn, runs cyclic application tasks as fast as 1ms, and is capable of capturing rapid input signals or control commands of an application so that the required dynamism and process repeatability can be ensured.
  • Predictive maintenance – Some VSDs come equipped with a web server that is capable of monitoring the continuity of an application with time-stamped motor or drive relevant data. In addition, the motor or drive data can be shared with a master; programmable logic controller (PLC), in the event of an application fault. The VSD provides motor and drive information such as motor current, motor thermal state, motor torque, drive thermal state, and DC bus voltage at the exact time of a fault (over a 50ms duration and within 5ms intervals). This allows for in-depth root cause analysis. Re-occurrence of the fault can be prevented by triggering alarms and warnings or even stopping the application if a vulnerable application data exceed a defined threshold.  This allows issues to be addressed before any unanticipated downtime occurs.
  • Connectivity and cybersecurity – VSDs are connected devices and this connectivity can be used to log application data with time-stamp without physically having sensors. As more industrial machines and control systems connect to the internet, cybersecurity becomes a growing concern. It’s important that VSDs are Achilles® Level 2 certified.  Such a certification results from an independent verification that the device in question meets industry-recognized security benchmarks. As a result, these machines offer protection against cyber threats.

New VSDs also provide machine builders with the flexibility they need to accommodate demanding end user requirements. This includes the ability to control interfaces such as communication fieldbuses, pulse trains, and digital or analog I/O. The drives are capable of controlling motors in both open loop or closed loop scenarios.  In addition, VSDs that support web services bring IIoT connectivity at the device level but also provides the machine builders’ the possibility to analyze and improve their applications or perform diagnostics locally or remotely. This enables them to implement fixes while testing and avoid the occurrence of unexpected downtime in the future.

To learn more about VSDs for high performance machines, click here.

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