Facility Grounding

Great control systems become useless very quickly when there is a nearby lightning strike or other major power surge and all manner of instruments, drives and PLC I/O die. This is often the result of poor facility grounding. Most electrical contractors are able to adequately ground commercial facilities where there a few HVAC units and normal lighting systems. But in facilities such as modern water treatment or wastewater treatment plants where there can be a ten or more variable speed drives, and dozens of instruments, valves and controllers, it is a different story.

Careful attention needs to be paid to all aspects of grounding from the site transformer, right through to the most remote instrument or valve. Nowadays there are some pretty basic rules that can be applied to get a reliable result, but I have yet to visit a plant that managed to implement all aspects of proper grounding. There is always a significant deficiency, be it the ground array itself or interconnection with lightning protection or a complete misunderstanding of isolated grounds.

If you are designing such a plant now, make the effort to get it right. One outage prevented will typically more than compensate for the time and money now. Over the life of a plant, a proper grounding installation will pay for itself many times over.