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  1. Kayaker11

    Calculating Attenuation of GPR Transfer on OHL Grounds/Buried Grounds

    Ah, I think I see how I'm looking at this incorrectly. I was thinking of this as a single substation grid that gets a GPR and transfers that full potential onto a connected wire that is a "floating", carrying off full GPR out to the remote areas. But if I look at is a second remotely connected...
  2. Kayaker11

    Modelling an Open Delta (with LV Resistor) Earthing Transformer in ETAP

    I can't see a problem with modeling the grounding this way. When you run an LG fault as long as your 3IO contribution in the report is correct, everything should be equivalent. Other than putting an arrow on the the ground TCC to indicate fault level, you don't use this value for much in ETAP...
  3. Kayaker11

    Using Remote Earth as the Return Path for a HRG MV System

    Unfortunately not. If I move my MV transformer NGR grounding off the main substation grid and out to the mine "remote" grid, I would have all the other non-mine MV feeders that go to the process plant etc all having to go through remote earth to the remote new remote mine grid. The process...
  4. Kayaker11

    Using Remote Earth as the Return Path for a HRG MV System

    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...
  5. Kayaker11

    Calculating Attenuation of GPR Transfer on OHL Grounds/Buried Grounds

    I have read in reports and seen during testing, that substation GPR attenuates as it is transferred out to remote areas that are directly connected (via intentional grounds) to remote facilities. In the testing I witnessed, the substation had a ground fault imposed at a non-60Hz frequency...
  6. Kayaker11

    Erroneous SE-330 Resistor Faults

    Nope, that wasn't it. Not only were the voltage settings way higher than the ground (set so high they never would have picked up), the event record downloaded from the SE330 shows Ground Current = 0 and NGR Voltage = 0 for all the resistor faults.
  7. Kayaker11

    Erroneous SE-330 Resistor Faults

    Has anyone out there had erroneous resistor faults from their Startco (Littelfuse) SE-330 NGR monitors? I just had an outage where two SE-330's tripped on resistor fault (based on measuring a change of resistance greater than 2500 ohms). These units were properly commissioned and calibrated...
  8. Kayaker11

    Pad-mount versus "substation" class transformers

    Under what circumstances would I use a "substation" class transformer instead of a pad-mount transformer with all of the key electrical specifications (kVA, primary kV, secondary kV, oil filled, cable connections on primary and secondary) being equal. Pad-mount are cheaper yet every industrial...
  9. Kayaker11

    Meeting Touch Potential Limits on Long Cable Runs

    Thanks 7anoter4, The problem with mining apps is that they drag the substations around on skids. Nothing is permanent so there aren't any ground grids established. BTW, what's "homopolar"? I see you are using I"k for fault current. Something to do with IEC standards?
  10. Kayaker11

    Meeting Touch Potential Limits on Long Cable Runs

    Yes. When you have distances like I'm talking, even intentional ground return paths, like those in cable grounds, shields, armour etc, don't have nearly low enough impedance to bring the touch voltage down below 100V. The inductance alone would bring Z up over the limit, let alone the resistance.
  11. Kayaker11

    Meeting Touch Potential Limits on Long Cable Runs

    I have a medium-voltage cable run of almost 50,000 ft and because it is in an underground mine, the ground potential rise ("ground fault voltage") due to a ground fault at the remote end must be limited to 100V. The system is high-resistance grounded but with those kind of cable lengths, the...

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