Meeting the needs of the modern machine builder
Smart drives have much to offer the machine builder. They can certainly
save money, even panel space, and they can be adapted to many different
types of application. However, the really intelligent drive achieves this
through modularity in both the hardware and the software, to meet the
immediate needs of the application, thus keeping the costs well under
control
When ac or dc drives were 'basic' and did as they were instructed, their
selection was relatively straightforward. However, today with increasing
demands for smart drives that can cut costs and increase the performance
of machines, the assumption that one drive does the same as any other is
no longer valid. Designers now need to consider a number of factors.
Cost: can the drive make other devices in the application (PLCs, for
example) redundant? Size: can cubicle size be reduced? Is there adequate
fieldbus and feedback device connectivity? Does the drive conform to the
safety requirements of the application? How easy is it to maintain or
restore following a power outage?
For many automation applications, the selection of an intelligent drive
can eliminate the need for an additional PLC, saving component and
installation costs, reducing programming time and saving cubicle space.
Certain drives have on-board PLC functionality as standard and powerful
application modules that can be added to extend these capabilities to the
control of pneumatics or hydraulics as well.
Designers need to be flexible in their approach to the installed factory
automation system, so allowing the drive to become a fieldbus 'gateway'
practically removes compatibility problems. But compatibility issues
don't end at fieldbus. It is also important to select drives that can
accept the wide variety of feedback signals from devices (such as
encoders) installed around the factory.
Conformance with legislation, and particularly the Machinery Directive,
has been shaping machine design for some time. Some modern drives feature
a secure disable feature (removing the need for an extra safety
contactor) that meets the requirements of the EN 954-1 safety standard,
whilst cutting costs at the same time. Separate power supplies to
maintain network connection in the event of a power-outage, and parameter
cloning features that can quickly restore a drive's settings, are other
useful features to look out for.
The move from centralised to distributed control, with the attendant
benefits of reduced wiring and installation costs and multiple built-in
redundancy, has spurred demand for intelligent drives. Machine designers
want more for less and they regard a drive with built-in intelligence, as
one of their best chances of achieving this. With clear understanding of
the machines and early involvement in their design, experienced drives
engineers can go part of the way to helping machine designers deliver the
productivity advances they seek.
Control Techniques is a world leader in the design, build and application
of ac, dc and servo drives and control systems. Formed in 1973, the
company has become a global 'no compromise' specialist in variable speed
drives, providing best practice in drive applications through an
international network of local Drive Centres. The company has built a
reputation for the design and integration of drives systems for
industries as varied as steel and paper, food and chemicals, assembly
machines and theatrical applications. Its benchmark product is the
Unidrive SP ac drive - designed to make applications engineers' lives
easier.
Control Techniques UK Drive Centre
Stafford Park 4, Telford, Shropshire TF3 3BA
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