Direct Control of Motor Contactors via PLCs and Distributive Control Systems

As we automate the process systems more and more, we are looking for direct control of the motor starters with PLCs and Distributive Control Systems (DCS). A commonly asked question is whether or not the interposing relay situated between the two systems is really needed. I have gone through and looked at the more common systems and put together this technical brief to highlight some of the concerns involving the interposing relay.
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