The machine safety lifecycle

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Written by Andy Maskell, Product Manager- Safety

A simple guide to Functional Safety for machines.

Ok, I do not want to make out that machine safety is simple…I would be out of a job! The reality is we have to take some essential steps in order to arrive at the correct safety solution and put it into action.

That is where we can help.

Phoenix Contact defines Functional Safety as a Safety life cycle. The safety lifecycle shows 8 phases dependent on whether safety related software is used or not.

Here are a few examples of what these stages involve:

Phase 0  – Risk Assessment

A risk assessment is required to identify specific hazards that anyone coming into contact with the machine will be exposed to.

Typical examples are:

  • Trapping
  • Crushing
  • Heat / Cold
  • Electrical

There are many types of risk assessment format available. You can download The HRN example here (Hazard Rating Number).

Also, always refer to the latest Risk assessment standards, currently BS EN ISO 12100:2010 This offers loads of information around hazard identification and how to use this information.

Phase 1  – Safety Planning

Now you can use the risk assessment to decide how you will protect against the hazards identified. Many hazards can be eliminated at this stage and designed out. The mechanical design can have an even larger impact than fitting electrical safety measures to compensate later on.

This is where you need to decide on the Category* B to 4? and Performance level (PL) a to e? We should also refer to BS EN ISO 13849-1 for general principles of design during this part of the process.

*Remember Category refers to architecture – Single/dual channel for example. Use our “Safety Application Guide” for category definitions and more (example here).

Performance level refers to the product capability. The typical lifetime of a mission or mission time is 20 years. This means all safety components used must last for this period based on intended use. You will need the B10d / Mttfd figures from the component manufacturer to be able to confirm this.

Phase 2 – Specification

Using the intended machine design you can now begin to decide on the hardware to best suit the requirements of your machine.

For smaller machines a single safety relay may do the job or if you have a larger system a configurable safety controller may be more suitable

Free software such as SISTEMA can be used to check the suitability of your chosen products. By using the Phoenix Contact SISTEMA library, safety calculations are made even easier. And example can be seen here (scroll down to “Software” and select “universal database”).

So that gives you an example of the first stages. Phoenix Contact can provide support throughout this whole process as well as providing hardware solutions to fit your safety applications.

So please contact me directly to discuss any or all of the Safety Lifecycle stages or any other questions around safety you may have.

Andrew Maskell(Product Manager – Safety)
Tel: 07584 235440
Email: amaskell@phoenixcontact.com

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