I am going to install a Siemens PLC on a project. It has relay outputs and I am in 2 minds whether I should slave the outputs through relays before driving contactors like ABB's A-lines or just directly connect. I've heard if the output from the PLC is going to a "high load" device like a motor operated valve or a motor starter I should always use a interposing relay no matter what kind of output I have on the PLC. Little things like pilot lights and outputs for permissive to other devices (voltage sense inputs) it would be OK wiring direct. Is that accurate?
Your thoughts would be appreciated.
