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Re: [multimachine] bad tig practice

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  • Darwin Wandler
    Your response is contradictory. If the GFI prevents currents on the supply side from shocking or damaging equipment by detecting small fault current and open-
    Message 1 of 3 , Sep 9, 2007
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      Your response is contradictory. If the GFI prevents currents on the supply side
      from shocking or damaging equipment by detecting small fault current and open-
      ing the circuit how then does damage occur to other equipment on the supply side
      by bonding the ground to earth? Floating outputs or isolated outputs have no
      problem bonding one side of the output to the ground it is done all the time in
      power supplies as long as both outputs are never connected at the same time.
      The key is did the manufacturer inadvertently link the electronics to supply
      ground in some way that creates a short circuit path!
      And, the GFI is to immediately disconnect any device with fault from the source
      not intended to just prevent shocking someone. GFI's act regardless of operator
      present. All outdoor sockets are required GFI and I have had them fault when no
      one was around and they detected a ground current to the system I had plugged
      in. Ground loop GFI's trigger on both neutral fault and no earth ground present.
      Power and neutral could be intact but if earth ground is missing reset can not occur.
      Darwin

      Roger wrote:

      Hey Folks initially this thread was about workers not properly grounding the work. Their practice of laying or hanging the ground on the work led to damage to some of the equipment. The ground fault is intended to protect the operator from a hazardous shock, but being on the working end of the system the GFI will not shut down with an improper earth on the work. It is possible that by bonding the work to the ground of the primary electrical system the GFI may function but damage could result in other equipment using the power, not only on that circuit but even as far as other people on the same side of the power transformer. With the “ground “ of the welder incorrectly doing its job the added resistance that builds up at the connection point increases power usage, leads to poor welds because the current varies and if it slides on finished stainless surfaces causes rework. It would be most practical to allow the equipment to work as it is supposed to and find a way to convince the operator to operate it in that fashion by properly attaching the ground!

    • Roger
      I do not intend to get into an argument further on this. I did say The ground fault is intended to protect the operator from a hazardous shock, but being on
      Message 2 of 3 , Sep 9, 2007
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        I do not intend to get into an argument further on this. I did say” The ground fault is intended to protect the operator from a hazardous shock, but being on the working end of the system the GFI will not shut down with an improper earth on the work.” It is isolated from the power side because the transformer of the welder acts as an isolation transformer between the incoming current and the work current side of the transformer. You said “Floating outputs or isolated outputs have no problem bonding one side of the output to the ground it is done all the time inpower supplies as long as both outputs are never connected at the same time.” The outputs are neither isolated nor floating if they are connected to the primary side because the earth has been provided a path to the ground of the primary electrical system. My response was toward the suggestion that the work earth be further bonded or supplied a path directly to the primary ground I do not know for sure if this will cause the GFI to work. In the case described the GFI is a comparator for the power side of the transformer. . My purpose in posting was not to attack anyone but I see no advantage to a GFI if its sole intent is to prevent someone from improperly earthing their work. Refer to the ORIGINAL POST (bad earth tig or something like that) please.  I do know that running the earth side of the welder directly to the ground of the primary side and NOT properly hooking up the earth of the welder can possibly cause damage to other equipment on the system. I do have a few case in points but this is not the point of this thread. I do not believe I have been contradictory, Very possibly not an effective communicator by not expressing my thought completely. My apologies if this has caused confusion. Does it make sense that the work should be properly attached to the EARTH to expect the best performance of the welder? This has been the point of my posts.

         

        Roger

         


        From: multimachine@yahoogroups.com [mailto: multimachine@yahoogroups.com ] On Behalf Of Darwin Wandler
        Sent: Sunday, September 09, 2007 2:01 AM
        To: multimachine@yahoogroups.com
        Subject: Re: [multimachine] bad tig practice

         

        Your response is contradictory. If the GFI prevents currents on the supply side
        from shocking or damaging equipment by detecting small fault current and open-
        ing the circuit how then does damage occur to other equipment on the supply side
        by bonding the ground to earth? Floating outputs or isolated outputs have no
        problem bonding one side of the output to the ground it is done all the time in
        power supplies as long as both outputs are never connected at the same time.
        The key is did the manufacturer inadvertently link the electronics to supply
        ground in some way that creates a short circuit path!
        And, the GFI is to immediately disconnect any device with fault from the source
        not intended to just prevent shocking someone. GFI's act regardless of operator
        present. All outdoor sockets are required GFI and I have had them fault when no
        one was around and they detected a ground current to the system I had plugged
        in. Ground loop GFI's trigger on both neutral fault and no earth ground present.
        Power and neutral could be intact but if earth ground is missing reset can not occur.
        Darwin

        Roger wrote:

        Hey Folks initially this thread was about workers not properly grounding the work. Their practice of laying or hanging the ground on the work led to damage to some of the equipment. The ground fault is intended to protect the operator from a hazardous shock, but being on the working end of the system the GFI will not shut down with an improper earth on the work. It is possible that by bonding the work to the ground of the primary electrical system the GFI may function but damage could result in other equipment using the power, not only on that circuit but even as far as other people on the same side of the power transformer. With the “ground “ of the welder incorrectly doing its job the added resistance that builds up at the connection point increases power usage, leads to poor welds because the current varies and if it slides on finished stainless surfaces causes rework. It would be most practical to allow the equipment to work as it is supposed to and find a way to convince the operator to operate it in that fashion by properly attaching the ground!

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