C
Good evening Sirs,
I have worked with SIEMENS S7-300 PLCs for a long time, including solutions design, programming and commissioning. Now I work as a consultant, and I was asked an opinion about a project with a SIEMENS S7-1500 PLC.
In my projects I've always used third-party galvanic isolation modules to the analog inputs and interface relays for the digital inputs and outputs. The PLC IO modules that I've used were isolated, no embedded output relays. The whole idea was to protect the PLC modules. An interface relay or a galvanic isolator are, of course, cheaper than a PLC module. The supplier of the solution tells me that the new PLCs don't need such protections.
I want to have your opinion on this issue, because I still think that the relays and the galvanic isolators should be used.
Does it make sense to expose the PLC modules to the electrical hazards typical of an industrial installation? Or do you think the galvanic isolators and interface relays should be used?
Please share your experiences with PLCs on this matter.
Best regards.
Carlos Melim
I have worked with SIEMENS S7-300 PLCs for a long time, including solutions design, programming and commissioning. Now I work as a consultant, and I was asked an opinion about a project with a SIEMENS S7-1500 PLC.
In my projects I've always used third-party galvanic isolation modules to the analog inputs and interface relays for the digital inputs and outputs. The PLC IO modules that I've used were isolated, no embedded output relays. The whole idea was to protect the PLC modules. An interface relay or a galvanic isolator are, of course, cheaper than a PLC module. The supplier of the solution tells me that the new PLCs don't need such protections.
I want to have your opinion on this issue, because I still think that the relays and the galvanic isolators should be used.
Does it make sense to expose the PLC modules to the electrical hazards typical of an industrial installation? Or do you think the galvanic isolators and interface relays should be used?
Please share your experiences with PLCs on this matter.
Best regards.
Carlos Melim