How digital natives and frequency inverters drive energy efficiency

Craig Nelson, product manager, Sinamics S, Siemens Industry: The typical decentralized drive is mounted on or at the motor, rather than in a control cabinet. This saves money in one respect by eliminating the control cabinet and cooling but puts higher demands on the drive protection against the elements, including higher temperatures and vibration, which can reduce the lifespan. Additionally, with on-motor designs, the motor heat dissipation is reduced, and derating is a factor. For wiring and circuit protection, decentralized drives may need special attention, especially depending on the local codes and regulations. On smaller decentralized drives where the motor and drive are encapsulated together, field maintenance may not be feasible.

What are some applications where decentralized drives might benefit an industrial system being designed and built?

Craig Nelson, product manager, Sinamics S, Siemens Industry: In many applications such as conveyors, which would require long motor cable runs from the control cabinet, the decentralized approach has several advantages. Also, in servo applications, which tend to be smaller power ratings, a decentralized approach can offer advantages over centrally mounting the drives in a control cabinet, but the vast majority of users still prefer the centralized design.

Servo motors have traditionally been preferred for high-precision, high-response applications. How might an inverter affect someone's evaluation of switching out servos for induction motors?

Craig Nelson, product manager, Sinamics S, Siemens Industry: Permanent magnet synchronous servo motors are not only high performance; they are very efficient, albeit at a higher initial cost than induction motors. Many drives are capable of running either type of motor, but, if an encoder is required for closed-loop control, this needs to be taken into consideration. In continuous applications or long cycle times, the payback of a more efficient motor can be attractive, but in these cases synchronous reluctance motors should also be considered if the inverter is compatible.

How have frequency inverters evolved over recent generations in terms of control features, communication protocols and energy efficiency?

Craig Nelson, product manager, Sinamics S, Siemens Industry: New-generation frequency inverters are characterized by ease of use. This includes setup, diagnostics and integration into controllers. Simple user interfaces and built-in web pages, along with remote access, have limited on-site commissioning. Features such as auto tunning and startup wizards have also helped remove complexity.

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Clean power drives, featuring active infeed, increase energy efficiency, while reducing the harmonics, but built-in firmware functions such as automatic flux adaption, Eco mode and hibernation are becoming standard features. Trends in power recovery and lower loss-switching devices are also now readily available in the industry.

What sorts of emerging technologies, such as edge computing, AI-assisted diagnostics or advanced simulation are being integrated into drives and inverters?

Craig Nelson, product manager, Sinamics S, Siemens Industry: The expansion of drive-based safety integrated functions are enablers for a sea change in plant-floor functional safety. Functions such as safe stops, safe speeds and safe position are used in today’s production environments with robotics and mobile units becoming the norm. Another emerging technology that is becoming the new norm thanks to incoming regulations is security integrated in drives. These security-integrated functions for secure communication, managed user access, encryption and secure by default are an integral part of the plant’s defense-in-depth concept to protect the integrity of operations.

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