DCS grounding is a very complex problem, involving many nodes and links from the field to DCS cabinet, such as grounding point, grounding mode, grounding resistance, etc. However, there are several aspects in routine inspection of DCS
1. DCS cabinet shall adopt single point grounding method to check whether there are places that may lead to multi-point grounding, such as the contact between cabinet and channel steel, whether the grounding point is a single down lead (wire diameter is greater than 16mm2, length is less than 30m) to the ground pile or ground grid, and whether the connection (or welding) points of components are in good condition (corrosion).
2. Check whether the DCS grounding point is shared with the electrical ground or lightning rod down lead grounding, and whether the distance meets the requirements. Generally, the distance between the DCS grounding point and the electrical ground is more than 15m, and the distance between the DCS grounding point and the lightning rod grounding point is more than 15m.
3. Measure whether the grounding resistance of DCS system is less than 4 ohm. The size of grounding resistance and
Many factors are related, such as good contact, soil moisture, conductivity, etc. the instruments available for measuring grounding resistance are megger, clamp meter, etc.