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What to look for in a decentralised drive

01 August 2022

Marek Lukaszczyk explains the deliverable benefits of using a decentralised variable speed drive (VSD). 



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One of the main advantages that VSDs can potentially offer include 30% or more in savings when compared to the use of centralised systems. 

Decentralised VSDs are popular in applications where greater flexibility is required. They do not require a panel or enclosure, which allows them to be mounted close to the motor, eliminating the need for long cables. 

The latest decentralised drives on the market should offer embedded features and a high degree of ingress protection to facilitate installation directly on the motor or a nearby wall. The rugged nature of decentralised drives not only protects against penetration by dust or jets of water but provides complete protection for technicians and other plant personnel against contact with internal live parts. Further advantages include reduced installation costs and easy commissioning.

Networking capabilities
Today’s decentralised VSDs should also offer optional communications networking and I/O modules that are fast and easy to install, allowing adaptation of the standard drive to individual user applications.

The availability of various communications interfaces and the potential for flexible adaption makes decentralised VSDs suitable for use in a wide range of applications. Many of the latest VSDs enable plug-and-drive communication via real-time Ethernet networks. The use of plug-in interfaces for protocols, such as Profinet and EtherCAT, will permit their seamless integration into existing, high-performance communications networks.

Integrated PLC
Built-in PLCs allow the VSD, motor and application to work in an interactive way which enables the user to implement customised logic and applications. Having an integrated PLC not only reduces load on the higher-level controller, it also lowers the investment needed for control cabinet installation and wiring, thus cutting system costs for the user.

Decentralised VSDs can also help to simplify system maintenance, giving overall plant efficiency a boost. The specific features of the latest VSDs obviously vary between manufacturers, but some offer several useful functions.

Flying-start capability, for example, allows a motor to be started that was running freely, accelerating it from the speed at which it was running. Ride-through is another example, which keeps the VSD in operation during voltage dips. Typical applications for decentralised drives include pumps, mixers/ bottlers, conveyor belts, compressors, fans, and washers/dryers, to name but a few.

Decentralisation can, of course, occur on many different levels – from a motor starter or drive located at the motor – to an entire decentralised system, which may comprise, for example, a VSD, overload protection, motor disconnect switch, I/O and bus module. If preferred, all of this can be provided as part of a single package.

Deliverable benefits 
Investing in decentralised VSDs brings energy savings and operational benefits, which would entail more engineering time, more components and wiring, larger panels and PLCs, and slower installation and commissioning.

Opting for a decentralised format can help ensure greater efficiency. Moreover, users can freely configure decentralised VSDs for deployment in a multitude of different applications, guaranteeing flexibility. 

Another advantage is that the latest generation of decentralised drives can be integrated with most types of automation system. The VSD footprint will, typically, be significantly less than that required for a centralised system, a factor supported by heat-dissipating ability.

Marek Lukaszczyk is european and middle east marketing manager at WEG.


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