Electrical safety systems experienced a breakthrough in the mid-1990s with the advent of the IEC 61508 standard. Titled Functional Safety of Electrical/Electronic/Programmable Electric Safety rated Systems, it effectively allowed microprocessor-based controllers to be used within safety circuits, thereby ushering in the era of functional safety.
Prior to the release of IEC 61508, users were forced to resort to hardwired safety circuits. These were far more cumbersome and difficult to fault-find, but the heavy regulation demanded by the laws around safe workplaces meant there was little choice.
However, by utilising controllers that are programmable, users have far more flexibility when designing safety systems, which are also faster to build, simpler to change and easier to duplicate. The change towards programmable safety is much like the move away from hardwired circuits to PLCs that occurred several decades earlier.
IEC 61508 has since been adapted by numerous industry specific safety standards. These include ISO 26262 (Automotive), IEC 62279 (Rail), IEC 61511 (some process industries) IEC 61513 (Power plant) and IEC 62061 (Machinery). Significantly, all these industries have adopted programmable safety, as well as the networks they are often used with.
Many automation vendors now offer an abundance of product choices, including some with innovations. Despite variances in products, users can be assured that compliance to the relevant safety standards means that protection levels will be maintained.