Gaining competitive advantage from integrated safety
04 October 2011
In his last article in this series, Paul Davies looks at how you can turn necessary safety technology into a competitive advantage
This series of articles has looked at the rapidly changing world of industrial automation safety, and we have covered issues of great importance to understanding the requirements of contemporary safety systems for machine builders and end users.
We have looked at compliance; what is necessary and how best to seek to prove and maintain compliance with the standards that are relevant to your enterprise. We have also looked in some detail at ENISO 13849-1, machine safety classification, Performance and Safety Integration Levels and the free SISTEMA tool which exists to help users understand what equipment will reach the required safety level for the job in hand.
Throughout the series we’ve referred to why the ‘field of play’ is changing and how a strong safety culture in your business can benefit the bottom line and make you more competitive and sustainable. This article is intended to offer a little more detail about how this is possible by making a business case for contemporary safety solutions, and integrated safety in particular.
Today’s market provides many challenges to both machine builders and end users and it is these challenges that help define the nature of the best available safety strategies. Machine builders are looking to drive more throughput out of their machines on the one hand, while addressing myriad global market requirements on the other. They are also looking to increase the value and differentiation of their machines to establish a strong market position and, of course, need to do all of these things in such a way as to make sure safety standards are met.
End users have slightly different challenges, which are no less pressing. Most are seeking ways to improve the overall equipment effectiveness (OEE) of their machines and reduce the mean time to repair (MTTR) or product line changeover times. Add to this the safety dimension of making a safe and productive workplace and ensuring safety standards are met, and it is clear that the challenges of today’s market are considerable and developing rapidly.
A contemporary approach to safety automation is one that approaches the application on its own merits. It is not necessarily a highly integrated system; there are levels of integration that are appropriate for different applications, and choosing the right safety supplier will mean that the correct approach is often scalable, according to the changing requirements of the application or business.
At the low end of the integration continuum are simple safety relay measures for relatively straightforward processes, which, for many smaller applications provide the correct level of safety with a comparatively small capital outlay. At the next level of integration is the rapidly expanding market of modular configurable relays (MCRs). MCRs sit between the relays and safety integrated PLCs (more on these shortly), and feature many of the benefits of safety PLCs but at less expense.
Importantly, the rise in adoption of MCRs and, indeed, the speed with which they are being taken up, is more evidence of increasing safety integration across industry. Using a rotary switch instead of software, they offer control of separate zones and specialist control features such as safe speed, two hand control, muting and communications gateway modules.
Managing control and safety through a single network was not possible until Common Industrial Protocol (CIP) provided a set of common services for configuration, control and sharing across all CIP networks, namely, DeviceNet, ControlNet and Ethernet/IP which could simultaneously enable transport of data across multiple plant-floor physical networks.
With the introduction of CIP Safety, the control and safety systems could sit on the same network and share information between control and safety processes. This ‘live link’ allows engineers to use zone control methods whereby certain elements or processes within the system can be brought to a stop or a safe state while the rest of the machine continues to operate normally (or as desired).
With the enriched data available from an integrated system, which is allowing the sharing of information between the safety and control systems, safety ‘events’ can be managed more effectively by engineers. Using the machine or system HMI engineers can see all of the machine events that have caused the safety system to react and respond quickly to bring the machine into full operation faster, thus reducing downtime.
For larger and more complex applications a fully integrated safety PLC is often the most advantageous approach. This is because to maximise the uptime of equipment, improve productivity and keep costs to a minimum, it is best to integrate the safety functions of a control system with the non-safety functions in a single controller.
As well as meaning that you no longer run a second (safety) controller, the integrated safety system can use a single software program to operate both the machine functions and its safety. By not having to write and manage two or more programs on separate controllers the application programming, maintenance and training costs can be vastly reduced.
Fewer components also directly results in reduced space requirements, saving money on control cabinets and floor space as well as wiring and panel complexity. For larger plants or business operations that work across multiple sites where line replication is commonplace, not only are the above savings multiplied by repetition, the original application can be ‘ported’ from one to another, reducing implementation costs and eliminating expensive redevelopment.
The business advantage of operating with the degree of integrated safety appropriate to your plant application does not end today, however. The unprecedented rate of technological development, which is allowing progressive businesses to evolve into tighter, more efficient, more productive and sustainable enterprises, will only quicken with changing global legislation designed to harmonise the various regional health and safety laws.
On the near horizon, high integrity add-on instructions (AOIs) are being taken up as a new software tool which contributes towards accurate and efficient safety system design. AOIs use a digital signature to help designers protect information from being altered, either intentionally or by accident. By informing engineers of any modifications to the ‘signature’, greater consistency can be achieved - of significant importance to highly regulated industries or those where intellectual property needs to be closely guarded in order to maintain market position.
Further future developments are likely to result in more flexible application of safety technology to a greater variety of industrial activities, and for more integration and richer data feedback from every element of the machine, plant or process. Safety will soon no longer be a discipline separate from the control platform implementation; it is set to become a seamless, concurrent aspect of the entire design process. And successful businesses will be the ones that can integrate changing market and regulatory demands in the most efficient way.
For many this will mean working closely with plant engineers and/or a safety partner to implement the best level of integrated safety to meet current compliance standards. With the integration of safety into standard control technology the safety of machines and personnel is being brought into direct line with the commercial objectives of plant operators, offering new opportunities to improve output while helping protect sustainability, reputation and profitability.
Paul Davies is field business leader – safety, sensing & connectivity, Rockwell Automation. The other published articles by this author can be accessed via the digital issue archive (March and May 2011 editions)
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