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Automation Today

• Overview:
  SAFETY SPECIAL - All you need to know to re-certify your machines to the NEW European Machinery Directive

Latest News

• Rockwell Automation Addresses the Challenge of Staying competitive at the World Drug Manufacturing Summit
• Rockwell Automation® Leads the Debate on Manufacturing Convergence at the European Manufacturing Strategies Summit
• Safety Categories are being replaced… What do I do next?

Customer applications

• Ice Cream Specialist Focuses on Reliable Operations
• Thanks to Integrated Architecture Thomas Butler Engineering Ltd Halves Time to Market

Technology watch

• Functional Safety
• Holistic Safety – It’s all Connected
• Safety – when Integrated means Integrated
• Machine Safety Starts with Design

Functional Safety – Achieving the Right Balance with Automation

With safety so high on the agenda of many companies, the introduction of new and evolving standards – like EN ISO 13849-1:2008 ‘Safety of Machinery – Safety-related parts of control systems’ – is always going to be a prime consideration.

In the case of AGR Automation, a specialist designer and manufacturer of advanced automation solutions for the worldwide market, safety was right at the forefront of its machine designs and there was a real drive to achieve conformity to standards, while at the same time achieving manufacturing flexibility at the right stage of the
design process.

As a leading supplier of safety solutions in both the machine and process sectors and a major contributor to the development of contemporary safety standards, Rockwell Automation has a vested interest in how its safety equipment is deployed by its customers. In this particular instance, the UK’s Health & Safety Executive also took an interest as an observer, for many of the same reasons. With its role to oversee installations such as this, it was important that it gained the same understanding of the issues faced by companies adopting these new standards.

For equipment suppliers, machine builders, end-users and national governing bodies, not only is there the need to know how new safety systems can be successfully integrated, but there is also a need to understand how modern safety standards can affect the optimal functionality of automation applications.

Unfortunately, the adoption of safety standards and systems is seen by many as an issue that can disrupt the functionality of a machine and add significant cost. In so many cases safety is added on to a machine after the machine design is virtually finalised, which can then affect carefully crafted automation routines or solutions. By introducing functional safety principles per EN ISO 13849-1 from the outset, AGR Automation has demonstrated that when safety is designed in from the very beginning of a design process – as an integral part of the automation system – many of the hurdles other companies face can be dealt with in a much more positive and cost- effective manner.

According to Craig Dickson, operations manager at AGR Automation: “If you use the right ingredients in the right way, you will make a good cake.” What he is alluding to here is the synergy between the ingredients, in this case machine safety and the machine’s function, and how they can work together to create the right result – known as functional safety. Functional safety is a term introduced in IEC 61508 (Functional Safety of Electrical, Electronic and Programmable Electronic safety-related systems). Functional safety covers a broad range of devices that are used to create safety systems. Devices such as interlocks, light curtains, safety relays, safety PLCs, safety contactors and safety drives are interconnected to form a safety system, which performs a specific safety related function.

By considering the functional safety requirements of the machines from the beginning of the design process, AGR was able to create the right balance between safety integrity and functionality and the throughput its machines are required to achieve. The performance level of the safety systems required were achieved by utilising principles set out in EN ISO 13849-1. Dickson adds: “We market our machines all over the world, so we have to make sure that all of our safety systems are acceptable and in compliance with local safety standards.” In the case of AGR, functional safety is designed into the machine from the outset to maximise the flexibility, productivity and safe operation of the machine. The automation components and method of operation may be different in each machine, but in all cases, the automation control system has functional safety built in.

Thanks to the scaleability and integration of the Rockwell Automation solution, no matter how many modules AGR makes, safety is designed into the whole machine as part of the total machine package. Dickson adds: “If it is right at module level, it will be right at machine level.” After discussions with Rockwell Automation’s personnel, a risk assessment was conducted utilising Performance Level (PL) calculation from EN ISO 13849-1. The decision to use PL as opposed to SIL (Safety Integrity Level as outlined in IEC 62061), was due to the fact that AGR was familiar with Categories outlined in EN 954-1 and the methodology of PL allows for an easier transition from one to the other. After the risk assessment, engineers from AGR and Rockwell Automation worked together to develop the final automation solution. This close interaction resulted in many benefits for AGR, primarily speed of change-over implementation and installation. The fact that safety specialists from Rockwell Automation were on hand made the entire process smoother and it was much easier to manage, especially with regards to the integration and interaction between the safety and functional aspect of the solution.

AGR uses Allen-Bradley® GuardLogix® Programmable Automation Controllers (PAC) – which allows safety and standard automation control to be managed within one controller. The automation solutions are also based on EtherNet/IP which allows safety and standard data to be communicated over one network (CIP Safety over EtherNet/IP) for all of its automation and safety control requirements. These are used to communicate with a SCADA system for sensor monitoring and high-speed SERCOS interfaces for the motion control requirements. The use of Rockwell Automation Allen-Bradley Guardmaster® safety interlock switches to provide guard locking in combination with Safe-off functionality of the drives, allows safer operator interaction to be achieved during machine operation.
Dickson elaborates: “The new safety standards require MTTFd (Mean Time To dangerous Failure) figures for the safety equipment. Because functional safety data is available for Rockwell Automation safety products, AGR could determine the machine performance level (PL) it required quicker, allowing it to design and integrate the systems effectively.

“The most important thing from our perspective is that we can deliver productive machines that are safer. We are not just doing it for the certificate, we are doing it so we can protect and safeguard our customer’s employees.” Dickson concludes. “The great thing is that, if we can match the needs of the safety standards in the EU, then we pretty much meet requirements in other regions due to the EU standards being some of the toughest. With Rockwell Automation equipment driving the automation and safety within our machines, we can also offer the worldwide service capabilities that Rockwell Automation can offer because of its significant global presence.”

For more information, please e-mail us at: info_at@ra.rockwell.com with ref: Functional Safety