As a systems integrator we are seeing a significant shift in our customers’ understanding of machine safety and the need to provide safe systems. We get a lot of questions about safety. We see more customers adding functional safety into their control’s specifications.
In the past many customers would perceive functional safety and risk assessments as just added costs to a project (expensive!). There was a time when this was probably accurate. Risk assessments can be time consuming. The safety design process can be iterative and slow. Safety hardware can add cost. Validation and verification processes take time and may delay qualification.
These can all be true, but we are seeing a change being driven by a need to provide safe systems, but it’s also due to the availability of functional safety hardware and the tools for designing and integrating these systems. There are a lot of options and functions to address whatever is needed.
The first step is understanding the system you have and the safety requirements with that type of a system. Some systems have specific requirements (for example, robots) while other systems fall under more general requirements. Knowing which standards to reference can be a challenge but is getting easier as general knowledge with safety increases. Working with a safety systems integrator or a safety certified functional engineer can help provide direction on requirements and respective safety standards.
Once the requirements are understood then a risk assessment approach can be defined to ensure all hazards are identified, assessed, and appropriately mitigated. Including this risk assessment early in the design process allows for these hazards to be mitigated most effectively (or eliminated) with minimal impact to the overall design.
With the latest technologies, designing safety control has become much easier, and these technologies are very well integrated with standard controls. Safety I/O is distributed and integrated directly along with non-safety I/O. Most controls configurators allow the designer to easily select both safety and non-safety I/O as needed.
The risk assessment should define the safety functions required for the system. Many of these functions are now a fundamental part of a control system software development package. Logic solvers that support safety (i.e., relays, PLCs, robots) include predefined functions that can easily be configured to meethe requirements. This reduces software development time, ensures a consistent program (reducing errors), and makes validation and verification easier.
The objective to any safety control system is to protect the operators from the harms of the system. The benefit with today’s controls is that they all do this very well, but because they can be integrated at such a systemic level, it creates a design that is very well engineered and easier to operate and maintain.
About the Author: Jim Ford
Jim Ford is engineering director at Concept Systems, a certified member of the Control System Integrators Association (CSIA). For more, visit the company profile on the Industrial Automation Exchange.
