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Dc high voltage test

  1. Dec 13, 2011 #1
    Hi every body
    I've some question that need to be answered
    WHy DC high voltage test devices always generate negative voltage rather than positive voltage
    I hope that i can get an answer

  2. jcsd
  3. Dec 13, 2011 #2


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    High voltage test supplies generate a voltage between two output terminals and one of these might be grounded, or it might not. If it is, it leaves the other terminal as the active one.

    I don't think there is any reason you would especially choose to ground the positive side of the supply. Power supplies for high voltage usually give you the option.

    High voltage insulation testers are usually battery powered and have both outputs floating, so you can connect them whichever way you like.

    Can you give an example of this type of test device?
  4. Dec 13, 2011 #3
    my device supplies negative (-V) to the tested item and a zero volt to the earth and this zero volt terminal is the earthing terminal of the test device
    it does not provide +v and -v
    I hope you understood what i mean
  5. Dec 13, 2011 #4


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    What is the function of your instrument?

    What is it used for?

    What voltage does it give?
  6. Dec 13, 2011 #5
    my device is used to test the insulation of the electrical equipments by applying high voltage DC to the device and merasuring the leakage current to the earth
    I observed that my device always injects negative votage instead of positive voltage with a zero volt on the other side of tested item (earthed)
    I did not find any acceptable reson for this ?
  7. Dec 13, 2011 #6


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    For insulation testing it doesn't make any difference which polarity is used, so I guess someone just made an arbitrary decision.

    Don't worry about it.
  8. Dec 14, 2011 #7
    Ok thanks for clarification
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