Can you lower the breakdown threshold voltage of solid insulators only once with high-voltage?

Discussion in 'General Electronics Chat' started by baoneil, Jun 24, 2016.

  1. baoneil

    Thread Starter New Member

    Jun 24, 2016
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    To be clear, I have been reading the textbook on this website, and in Chapter 2 Nonlinear Conduction it says,

    "Many solid insulating materials exhibit similar resistance properties: extremely high resistance to electron flow below some critical threshold voltage, then a much lower resistance at voltages beyond that threshold. Once a solid insulating material has been compromised by high-voltage breakdown, as it is called, it often does not return to its former insulating state, unlike most gases. It may insulate once again at low voltages, but its breakdown threshold voltage will have been decreased to some lower level, which may allow breakdown to occur more easily in the future. This is a common mode of failure in high-voltage wiring: insulation damage due to breakdown. Such failures may be detected through the use of special resistance meters employing high voltage (1000 volts or more)."
    Can this process be repeated to lower the voltage threshold even further? If so, is there a limit to how much you can compromise/damage a solid insulator?
     
  2. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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    That's a very broad question that depends on the insulator , the nature of the breakdown, types of conductors and the type of environment the insulator is in. Heat can be generated that melts or changes the insulation properties of the insulator, materials can be deposited on the surface of the insulator that reduces the breakdown voltage.

    Over time this can degrade or completely destroy the insulator.
     
  3. baoneil

    Thread Starter New Member

    Jun 24, 2016
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    Nice video. I didn't know voltage breakdown involved so many variables. I'm just starting to learn this material and wanted to know if there was one specific insulator material or more under certain conditions that could have its voltage threshold lowered more than once due to repeated exposure to high-voltages?

    The text that I quoted only mentions this happening once but neglects to say if repeated attempts could lead to lower voltage thresholds. I just want to know if that's possible so I can have a better overall idea.
     
  4. profbuxton

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    Feb 21, 2014
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    Generally , it is not recommended to subject insulation to repeated high voltage testing due to possible degradation. There are generally two types of testing done, insulation resistance with a DC "megger" usually at twice the operating voltage(500v for a 240v rms) or "hipot"(high potential) testing usually with an applied volts of 2000v RMS for one minute(for 240V rms equipment). Or there can be some variant of these voltages depending on equipment and customers requirements.
     
  5. baoneil

    Thread Starter New Member

    Jun 24, 2016
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    Not to beat around the bush.

    I haven't received a straight answer yet.
     
  6. Techno Tronix

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    Jan 10, 2015
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  7. baoneil

    Thread Starter New Member

    Jun 24, 2016
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    I've already read this section in chapter 2 and it doesn't say anything about repeated high-voltages to solid insulators. That's why I'm asking in the forum. You can't use this as a source of reference because what I asked is not in here. I think you may not understand what I'm asking.
     
  8. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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