Does anyone have any history with or heard of any anecdotes of someone using remote earth intentionally as the return path on a high resistance grounded system?
I have a MV distribution system that feeds mobile mining equipment that is tied to a utility substation ground grid and is subject to excessive GPR transfer. I have the ability to build a very low resistance remote ground system out near the mining facilities using abandoned deep well casings. Here's the rub. The MV distribution system feeds a myriad of other loads that I cannot isolate from the substation ground system so I can't fall back on building a safety ground bed. It would be a fairly straight-forward matter to get the mining system grounds back to the safety ground bed but other feeders on this MV system also feed the mill, crushing, infrastructure etc that are inseparable from the substation ground. That rules out tying the secondary of the MV transformer to the remote ground grid through the NGR.
If I separate the mining ground system from the substation ground grid but leave the NGR on the substation grid, the only path for ground current back to the MV winding NGR is via remote earth. If my two grids, substation and mine, are isolated low-resistance-to-remote-earth and the ground protection will still operate through remote earth is this a legit solution?
One of my main holdbacks is that IEEE 142, in the section on safety ground systems/ portable mining equipment supplies, states that for proper operation "earth cannot be used as a grounding conductor". I wonder if this isn't because safety ground bed is typically built with a much a higher resistance to remote earth than the main substation.
I have a MV distribution system that feeds mobile mining equipment that is tied to a utility substation ground grid and is subject to excessive GPR transfer. I have the ability to build a very low resistance remote ground system out near the mining facilities using abandoned deep well casings. Here's the rub. The MV distribution system feeds a myriad of other loads that I cannot isolate from the substation ground system so I can't fall back on building a safety ground bed. It would be a fairly straight-forward matter to get the mining system grounds back to the safety ground bed but other feeders on this MV system also feed the mill, crushing, infrastructure etc that are inseparable from the substation ground. That rules out tying the secondary of the MV transformer to the remote ground grid through the NGR.
If I separate the mining ground system from the substation ground grid but leave the NGR on the substation grid, the only path for ground current back to the MV winding NGR is via remote earth. If my two grids, substation and mine, are isolated low-resistance-to-remote-earth and the ground protection will still operate through remote earth is this a legit solution?
One of my main holdbacks is that IEEE 142, in the section on safety ground systems/ portable mining equipment supplies, states that for proper operation "earth cannot be used as a grounding conductor". I wonder if this isn't because safety ground bed is typically built with a much a higher resistance to remote earth than the main substation.
