Suggestions:
Reference:
1. IEEE Std 142-1991 "IEEE Recommended Practice for Grounding of Industrial and Commercial Power Systems," (Green Book)
1. There are various AC grounds, e.g.:
1a. Equipment ground that may contain a lot of noise (noisy ground). This ground is usual ground in power distribution systems, e.g. receptacles (120VAC, 15A, one phase)
1b. Computer or Instrument Ground, which is often called "quiet" since it contains a minimum or no noise. It is run over separated ground conductors from the noisy ground.
1c. Special or dedicated grounds, e.g. for substations, substation mats, etc.
2. Also, there are various DC grounds, e.g.
2a. DC ground tied to chassis that may contain noise, i.e. noisy ground
2b. DC ground that is quiet, i.e. with the minimum noise or no noise. It may be local leading to a local dc power supply and behind shielding.
2c. DC ground bus system of computers, Reference 1
2d. DC ground for mobile equipment, Reference 1