Submergible pump meggring

Discussion in 'General Electronics Chat' started by Teromig, Oct 12, 2007.

  1. Teromig

    Thread Starter New Member

    Oct 12, 2007
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    :confused:I was told that you can not megger a submergible pump. I work at a nuclear plant and the electricians just want us to remove the pump out of the water to megger. It looks to me that it would be better to megger in the pumps own environment, you could see condition of cable and motor, that is what they are going to do anyhow.

    Please documentation one way or the other. Can just tell me where to find it and that would work.

    Thanks an operator that wants to know,

    teromig
     
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
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    I once helped install a replacement submersible 6KV pump motor. The original was damaged when waterproofing at the connection failed and an explosion resulted.

    How much voltage does your megger produce? And what is the conductivity of your water?
     
  3. Teromig

    Thread Starter New Member

    Oct 12, 2007
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    The water is very conductive (2400 ppm boron) and is only a 480 volt motor I would expect not to use a megger rated at maybe 1000 volts, I'm not sure what voltage of megger they will use. The megger would not produce enought currrent for a explosion would it?

    And if it is meggered out of the water with a cable fault then placed in the water could you not miss the fault due to the insulation of open air?

    Motor draws about 6 amps at normal load.
     
  4. cumesoftware

    Senior Member

    Apr 27, 2007
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    For 1000V, the open air is not a real problem (if you keep a minimum distance of 2cm between electrodes, just to get sure). I would not use any electrical part inside water, even distilled water. I remind you that distilled water is still preety conductive, because of the free H3O+ and OH- that dissociate naturally. Water has a pH 7 at 25ºC, so the concentration of H3O+ is 0.1uM/dm3 and it is equal to the concentration of OH-. In your water, I would expect boron to cause a ionic unbalance that would generate much more OH- ions (since boron is a metal, and its oxide dissociates H2O, converting to boron hydroxide and more OH- ions).
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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    Testing the insulation aside, there may be regulations that completely govern the way that the pumps get checked out. If the regs say "do it like this", then, common sense notwithstanding, that is the way it gets done.
     
  6. Teromig

    Thread Starter New Member

    Oct 12, 2007
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    Yes, but where would I find the regulations? That is really what I'm looking for I guess. I want done what is right.

    Thanks.

    Terry
     
  7. kender

    Senior Member

    Jan 17, 2007
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    Follks,

    Pardom my ignorance, but what's "meggring"? I tried googling this word, but only one resume came up, and "meggring" was mentioned there without any explanation.

    Chers,
    Nick
     
  8. nanovate

    Distinguished Member

    May 7, 2007
    665
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  9. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
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    Let me get this straight... you work in a nuclear plant as an operator with this submersible pump, and you can't find the paperwork on how preventative maintenance is done? Please tell me I mis-perceive!!
     
  10. Teromig

    Thread Starter New Member

    Oct 12, 2007
    4
    0
    Thank you for the help,

    I had info come in on Mike Holt's Forum that answered my questions.

    Terry
     
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