How should the instrument grounding wire IE be handled?
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In a certain PLC project, the CPU is connected to n remote IO cabinets, which are located in n+1 rooms. Generally, a 16-gauge instrument ground wire is used. My usual approach is to connect insulated IE terminals at each cabinet and then run the wires to the next cabinet; as a result, this ground wire is interrupted n-1 times, which increases the grounding resistance. Moreover, as the contact surfaces oxidize, the resistance continues to rise. To avoid this situation, could a T-type clamp or a piercing clamp be envisaged to prevent the ground wire from being cut and preserve its surface integrity?
It can be done like in a DCS system: each cabinet is equipped with a grounding busbar, which is connected to the main busbar in each cabinet, and from there it is connected to the grounding system.
It’s possible to do this when things are concentrated relatively, but I’ve arranged them too dispersedly – one cabinet per workshop, with 9 cabinets in the entire factory area. The radial connection requires a lot of cables, which is why I raised this issue.
Does your system also require single-ended grounding like DCS?
Yes, there are many four-wire non-isolated AIs that require only single-point grounding.
Well, then you just need to invest some money to connect them with cables.