Safety PLC

Safety PLC means Safety Programmable Logic Controller. Their functions are similar with traditional PLC. But the different is that it has additional built in features that set them apart. They are built with redundancy to prevent the failure in the system.

While standard and safety PLCs have similar appearances and functions, safety PLCs include additional redundancy and safety-specific capabilities, which are typically denoted by a bright color (yellow or red). The image was provided by Rockwell Automation.

Not all control systems are impossible to avoid malfunction and device failure, so it is very important in some large processes or systems. Security In the event of a failure, PLCs' predicted failure modes lessen the degree of system disturbance.

It is possible to reduce wiring complexity, time, labor expenses, and wire cabinet area by substituting safety PLCs for safety relays. A safety PLC also makes future system improvements simpler and less costly because, in most cases, just program edits need to be made. Traditional safety systems require wiring and physical infrastructure to be altered, which adds to the labor expenses for future changes.

So do we need this Safety PLC for every system? The answer is "No". The extra expense of a safety PLC might not be justified for basic safety tasks on tiny cells because it is more costly than a standard PLC. For instance, adding a safety PLC to a basic cell with just an E-stop and a single light curtain and no other safety infrastructure is probably going to be more expensive and complicated than adding a safety relay or safety contactor. A thorough evaluation of each application is necessary before choosing between a safety PLC and traditional safety.

Reference : Control, Ecoonline