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Thread: Underground Mine Grounding

  1. #21
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    Just hardrock gold, no ignition hazard, but it is in Canada so M421 applies. I’m not sure how to accomplish that level of separation without crazy amount of insulated wire running all over the place. There are many surface infrastructure buildings all around the two shafts (each has an independent feeder going down).

    Might need to message you the layout for some tips!

  2. #22
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    Quote Originally Posted by Bigjabe View Post
    Just hardrock gold, no ignition hazard, but it is in Canada so M421 applies. I’m not sure how to accomplish that level of separation without crazy amount of insulated wire running all over the place. There are many surface infrastructure buildings all around the two shafts (each has an independent feeder going down).

    Might need to message you the layout for some tips!
    do the feeders to the buildings have a ground from a source isolated from the mine power?
    if that is tied to the station bed you should be good (on a wye sec)

  3. #23
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    Quote Originally Posted by Ingenieur View Post
    do the feeders to the buildings have a ground from a source isolated from the mine power?
    if that is tied to the station bed you should be good (on a wye sec)
    The underground surface infrastructure is isolated from the main plant - so no GPR issues from utility tie sub. However, current design is all underground surface infrastructure is tied to same ground bed as Underground feeder NGRs and also surface equipment. Lightning is the only problem... with all the pipes going underground and steel structures at the underground surface area I’m not sure how we can isolate?

    Note this isn’t built yet so still time to fix.

    Edit: to make it clearer... the underground portal area is isolated from the main plant. Current design is the underground portal area (including feeders to underground) is fed from isolation substations (with substation ground tied to main plant ground) with NGRs tied to portal area ground to prevent utility ground fault GPR from transferring to the underground mine.

    Maybe we can tie overhead line shield wire and phase LAs on the overhead line feeding the portal area back to main plant ground..? That still won’t help if portal surface equipment is hit by lightning.:
    Last edited by Bigjabe; 01-21-18 at 12:38 AM.

  4. #24
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    do you have a single line?

    is surface power and mine power on the same xfmr?

    are you saying the hoist structures (and other surface structures like fans, etc) are tied to the ngr?
    or bypass it straight to the ground bed?

    for your application you may be compliant
    as far as the pipes and other steel entering the mine is it all bonded to a ground bed?
    again may not be an issue

    we use plastic pipe or rubber flex joints to isolate
    since there is no explosion hazard you do not require the same level of isolation

  5. #25
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    Quote Originally Posted by Ingenieur View Post
    do you have a single line?

    is surface power and mine power on the same xfmr?

    are you saying the hoist structures (and other surface structures like fans, etc) are tied to the ngr?
    or bypass it straight to the ground bed?

    for your application you may be compliant
    as far as the pipes and other steel entering the mine is it all bonded to a ground bed?
    again may not be an issue

    we use plastic pipe or rubber flex joints to isolate
    since there is no explosion hazard you do not require the same level of isolation
    I agree it may be compliant, M421 only discusses GPR due to faults. Nevertheless, it's still a concern. I made a sketch of the layout to hopefully understand - the file is too big to post here though, can you PM me your email?

  6. #26
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    Quote Originally Posted by Bigjabe View Post
    I agree it may be compliant, M421 only discusses GPR due to faults. Nevertheless, it's still a concern. I made a sketch of the layout to hopefully understand - the file is too big to post here though, can you PM me your email?
    Unless the file contains info that you wish to remain undisclosed, I am willing to PM my email address and attempt to upload for you.
    "Electricity is really just organized lightning." George Carlin


    Derek

  7. #27
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    Quote Originally Posted by jumper View Post
    Unless the file contains info that you wish to remain undisclosed, I am willing to PM my email address and attempt to upload for you.
    That'd be great - no confidential info, would be good for the public discussion to have it available for everyone.

  8. #28
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    Quote Originally Posted by Bigjabe View Post
    That'd be great - no confidential info, would be good for the public discussion to have it available for everyone.

    PM sent.
    "Electricity is really just organized lightning." George Carlin


    Derek

  9. #29
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    Gimme a sec. Asking another member for help. He is more computer savvy than I.

    Edit: I HATE APPLE AND IPADS!!!!!

    This would so easy on a PC.
    Last edited by jumper; 01-21-18 at 01:24 PM.
    "Electricity is really just organized lightning." George Carlin


    Derek

  10. #30
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    eta: the free software I used for this only does one pic/hour, so if someone wants to resize and rotate it for clarity, it would be much appreciated.

    jumper asked me to post a file here, here we go:

    pdf file is too big, converted it to jpeg. also rotated it 90*:

    which also wont download. let me d/l it elsewhere... brb



    Name:  20180121_DT_000013.jpg
Views: 120
Size:  123.3 KB
    Last edited by JFletcher; 01-21-18 at 04:20 PM.
    Electricians do it until it Hertz!

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