Grounding

The grounding technique depends primarily on how the system is earthed, and configuration as well as the voltage. This varies between country, and local practices, but sees below for a general idea.

MV systems like 3.3, 6.6, 11, and 33kV are generally impedance earthed so the earth fault current is limited, which means that the grounding design is relatively straightforward unless it's a small rural substation fed via overhead lines.

HV systems like 66, 132,230, 380kV te ...

Everybody would definitely prefer 0.0 Ohm resistance as well. However, discussing earth resistance (a.k.a. combined resistance of earthing system to the general mass of earth) involves answering the question: what is the purpose of making this resistance as low as practically possible? Or, better yet, what conditions the earthing arrangement needs to satisfy?

Does 1.0 Ohm resistance makes sense, if a $0.5MM facility is installed on solid limestone and achieving 1.0 Ohm resistance ...

Consider that a stand-alone machine with a PLC: you are in control of what and what is not common grounded on most PLCs by the way you wire it. Often times there is a jumper you can removed so that you can force the common ground point to be that desired central point in your main panel. Now throw a PC into it; if your IT group mandates what PC is used (instead of being able to choose an industrial PC for this and other merits) you suddenly are not in control of the ground point! Most commerc ...

Many consider the "ground" of the building to be impeccable "earth ground". I have only found one building with a perfect earth ground. That plant used a 300 foot well with all metal piping, and a meticulously bonded water sprinkler system. They used this system to ground all their systems to. This was the only plant that I never had any noise problems with.

Back then, I was supporting a PLC control system with PC and instrumentation. Looking back, I think the system design was in ...

Without a ground connection there is potential (excuse the pun) of leakage or wiring fault (or rarely a component fault) biasing the circuit voltage; this is bad because DC control wiring is nominally SELV (safe extra low voltage) and many safety provisions and even component ratings depend on this. I once encountered a problem with unbonded ring wiring (UK) where one phase of 230 AC power was biased to 640 V above ground (exceeded the insulation rating of some equipment). BTW, SELV also has ...

A Neutral Grounding Transformer is NOT a three phase transformer, but a single phase transformer, with the primary (HV) rated voltage equal to the system phase-to-neutral voltage and the secondary (LV) rated voltage either 110V or 240V.

Why is it required? For economic reasons. Let us see how. Supposing you have an 11kV System, whose neutral you want to ground through a resistance. The desired ground fault current, let us say, is 10A. Now, if you want to connect a resistor directl ...

Sometimes adding more ground rods and pipes will not do achieve anything to bring the ground resistance down in high resistivity areas. Especially sometimes, adding more ground rods will not do anything to bring the resistance down (the resistance stays the same).

A good understanding of soil resistivity and related testing is extremely important. Some guidelines should be established for the soil testing. Similarly the testing and spacing to determine the soil resistivity with de ...