New standards promote effectiveness of integrated safety solutions
Safety has and always will be one of the most essential facets in any machine or plant design. Thanks to the introduction of new machinery safety standards – which now address contemporary advances in technology – safety has reverted from a necessary but often onerous afterthought into an essential, complimentary and even value-add element of the overall plant or machine.
The real value of integrated safety is the ability to change the way in which safety can be deployed. Not only can programmable controllers, such as our GuardLogix and Compact GuardLogix PACs, now form an intrinsic part of the safety infrastructure, but it is now also possible to utilise the automation network for the transmission of the safety data and signals.
"In general terms," explains Derek Jones, Business Development Manager at Rockwell Automation, "one of the most effective ways of making a machine safe is to make it ‘behave safely’. And an efficient way of doing this can be to utilise some of the same equipment that the machine is using for its production operations as part of its safety systems. You must follow the rules to provide that safety functions cannot be degraded by normal production functionality but if you build in safety-capable intelligence correctly you can use the same sensors (for example) as part of both roles."
This integration over a common network also delivers significant data-capture capabilities. With a single network, single controller and single HMI, operators are able to get a complete picture of the whole installation rather than relying on supplementary displays and intermediary data translation steps and hardware. This enhanced access to critical data will help operators adjust process variables, knowing that all sub systems are providing the necessary feedback. It will also allow them to undertake more effective proactive maintenance – another critical element of any safety system.
"With respect to addressing the new generation of safety related control standards " Jones explains. "The simple stuff is still there, but as you go up in scale you may seem to have more complexity to cater for but, in fact, if you design it carefully in the first place, using the same architecture, then it can actually be simpler to install and assess.
"An integrated-safety approach offers a huge variety of benefits in terms of cost, lower complexity, easier troubleshooting, enhanced interoperability and greater flexibility," Jones continues, "but it is also important to consider the design timescales and major stage gates relating to the machine or line. Safety should always be considered as you design your machine or plant, so the whole concept of integrating safety with the automation infrastructure as the design evolves makes complete sense."
The problem with many, bolt-on safety solutions is that they are applied too far down the design process. In most cases, safety systems are added after a machine, cell or line has been designed and their detrimental effect on production can be significant. Problems can arise with regards to throughput and efficient operator interaction and it is here that financial implications can arise. It is very easy to justify the impact of a safety system on safety grounds, but justifying the adverse financial implications, in relation to lower machine performance, becomes a little harder to accept.
By taking this more systematic or holistic approach, performance vs. safety issues can be defined and resolved much earlier in the machine design process – minimising the financial impact on the overall system. This resolution of any conflicts at such an early stage in a project also delivers multiple business benefits. As well as introducing the 'goodwill' that goes with any safety installation, users can also be confident that any impact on the volume-related profitability of a line or cell has also be considered and 'designed out' far earlier in the process. It is far easier and more cost-effective to resolve conflicts earlier in a process than when it is nearing completion.
Our concept of integrated safety is also eminently scalable, it is not restricted to large installations – in much the same way as it is not restricted to new builds. The scale of an operation does not define its ability to adopt an integrated safety infrastructure. Not every installation needs PACs or higher-level devices so, safety integration across a wider range of components means users are not restricted by the size of their application.
Rockwell Automation adopts its approach to integration by assessing the size, complexity and automation requirements of a machine, advising the correct level of safety integration and then offering an appropriate solution. Its comprehensive portfolio of safety solutions for any level of integration; from a safety-relay-based solution to a fully integrated PAC with motion, standard and safety control means it can offer its customers the right level of safety they need... not just the products it has.
We have also made significant strides in making safety assessments far easier thanks to virtually all of our hardware offering data e.g. for SISTEMA. This makes calculations simpler and, according to Jones, is steadily making helping turn SISTEMA into a communication language. He explains: "Engineers in different locations can swap SISTEMA files and they will both understand them thanks to their form, content and presentation. This is one of the reasons why SISTEMA is becoming a universal tool and language, supplanting company- and system-specific approaches."
Jones concludes elegantly: "To make a machine productive, you must control it properly. To make a machine safe, you must also control it properly. These are the one and the same goal... it therefore makes perfect sense that you should use the same infrastructure."
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