Electricity + Control March 2019

DRIVES, MOTORS + SWITCHGEAR

The priority could simply be small size relative to performance. This often goes hand in hand with the need for good thermal performance so that re- liability is not compromised by high packing and power density of the drive electronics and their cabinets leading to thermal stress. All users’ priorities interact and change with time, with factors such as lifetime cost less easy to quantify and factor-in. Although energy saving might be the issue today, a user might plan to im- plement IIoT with a view to further process cost savings. The user might then realise that size-effi- cient drives and motors give better floor usage and more throughput and economies of scale, again helping with cost and energy savings. Ideally the final choice of a drive should cover all the require- ments, either built-in or by simple expansion of ca- pability through modular construction. Drives with a built-in PLC can be considered, saving costs and improving performance, typically running application programs many times faster than external PLCs or motion controllers. Also, with the right drive architecture, scalability in pow- er output could be achieved with families of drives that share common interfaces and programming/ communication protocols for easy upgrade. Drive selection also involves consideration of what tomorrow’s requirements might be; visionary users that anticipate IIoT with its data sharing pos- sibilities might appreciate comprehensive control and monitoring features that allow predictive main- tenance and autonomous process optimisation, again saving costs and energy while improving the end user’s experience. Use of ‘open’ languag- es and protocols would give a range of benefits including optimised performance, increased sys- tem development speed, choice of components, future-proofing and security of knowing that engi- neers can always be recruited with knowledge of the open technologies. The drive should meet current and anticipated statutory requirements for performance and safety

Industry 4 or the Industrial Internet of Things (IIoT).

To get the best value from equipment, users now need to have the technical know- how to configure the drive and integrate it into a wider IT network.

As part of this, drives can be connected to a net- work, typically by Ethernet, so control and monitor- ing can be dynamic allowing for ‘on-the-fly’ adjust- ments and continuous monitoring of parameters that might indicate process variations. Energy can be saved and loads levelled for financial benefit. An issue with automation though is the physi- cal space taken up. A monetary value of potential productivity can be attributed to each square me- tre of a factory floor so equipment size is impor- tant. Also, to get the best value from equipment, users now need to have the technical know-how to configure the drive and integrate it into a wider IT network. The installer is a ‘drives’ engineer with skills in programming and knowledge of the mul- titude of external safety and EMC specifications that the drive has to meet for proper installation and operation. In this case, support from the drive manufacturer is key. Equally important is an under- standing of network security issues to ensure the drive’s programming cannot be unintentionally al- tered or its analysis data intercepted. Selecting a drive A good starting point for drive selection is one that can be configured for different motor types and sizes. Different users may have different priorities though. Energy efficiency of the process is often high on the list because of the power consumed and controlled by large motors. It has been stat- ed that electric motors account for about 45% of global energy consumption [1] so for many users, drives that can optimise process energy efficiency may be the first choice. For others, flexibility might be key and scalable drives that can be expanded in capability with optional modules would be at- tractive. Achieving the benefits of IIoT could also be important in which case connectivity needs to be considered with flexibility in support of different networking standards.

Electricity + Control

MARCH 2019

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