It is hard to avoid safety in today’s world. It is always best to design safety into the system, rather than add it in later. While the basic safety circuit has changed dramatically over the year (what used to require a simple e-stop wired to a standard relay, now requires multiple safety strings into a safety monitoring relay), the best development has been the acceptance of the safety rated plc. As safety circuits have become more and more complex, designing and troubleshooting safety has become exponentially harder. The safety plc has made the whole process much more manageable. Now safety can be configured in complex combinations, while reporting the cause of a shutdown can be much more reliable.
WBA has implemented dozens of plc-based safety systems, utilizing several different models of safety PLCs. These have included: Allen-Bradley Safety CompactLogix, Allen-Bradley 440 programmable safety relay, Pilz, Safety PLCs,and Phoenix Contact safety PLCs.
