~ Understanding the advantages of using a decentralised variable speed drive ~
Decentralised variable speed drives (VSDs) can potentially offer 30 per cent or more in savings compared to centralised systems. This is one of the many advantages presented when opting for a decentralised drive. Here, Marek Lukaszczyk, European and Middle East marketing manager at motor and drives specialist WEG, explains the deliverable benefits when using a decentralised VSD.
Decentralised VSDs are popular in applications where greater flexibility is required. Such drives do not require a panel or enclosure, allowing them to be mounted close to the motor and eliminating the need for long cables.
The latest decentralised drives offer embedded features and a high degree of IP66/NEMA 4X 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.
Today’s decentralised VSDs 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.
Indeed, the availability of various communications interfaces and the potential for flexible adaption makes decentralised VSDs suitable for many uses. 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 permits the seamless integration of VSDs into existing, high-performance communications networks.
Built-in PLCs allowing the VSD, motor and application to work in an interactive way permit 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.
Furthermore, decentralised VSDs 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 is a good example, as it 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 when using decentralised VSDs
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.
By opting for a decentralised format, can ensure greater efficiency. Moreover, users can freely configure decentralised VSDs for deployment in a multitude of different applications, guaranteeing flexibility.
Another advantage is that it is compatible, meaning the latest decentralised drives can be integrated with most types of automation system. Furthermore, the VSD footprint is significantly less than that required for a centralised system, a factor supported by heat-dissipating ability.
With decades of experience in developing electronic products, WEG offers high performance and efficiency solutions in drives for industrial electric motors. More information on the latest decentralised drives can be found on the WEG Automation microsite.