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Mylar film charging problem ?

  1. Apr 23, 2010 #1
    I was studying the effect of high voltage on the properties of Mylar film.
    The voltage input can be both DC (around several hundred volts to 1000V) and AC (same level as DC).
    The Mylar film is very thin, 6um, I know the film is going to be charged, but I don't know
    1. how fast the film charges ? suppose you have 500VDC on a 6um thick film.
    2. and is there a long term charging process going on too, how can I measure this effects ??

    Anybody can help ? Thanks

  2. jcsd
  3. Apr 24, 2010 #2
    Did some tests on 0.003 inch thick Mylar years ago:

    Used DC and there were surface arcs on Mylar many minutes after DC voltage was set.
    Mylar didn't break down due to surface arcs.
    Breakdown voltage for 0.003 inch thick Mylar was 20,000 volt DC.

    Mylar breaks down at low AC voltage.
    6 um is 0.236 mil, 0.000236 inch. (If math is correct)
    0.152 mil Mylar will probably fail well below 200 volt, 60 hertz.

    Measuring charging current can be done by measuring the current. This will require some pretty elaborate equipment.

    Sounds like a fun project.
    Good Luck.
  4. Apr 26, 2010 #3

    The breakdown AC voltage may be dependent on frequency, I use quite high frequency ~60kHz, and it seems OK until 900Vpp.

    Once the film is charged, it has some internal E field, do you have some idea to measure this E field ?

    Appreciate your help
  5. Apr 27, 2010 #4
    Do not know how to measure internal E field.

    However results of internal E field manifests itself as dielectric absorption when Mylar capacitors are used.
    You could Google dielectric absorption and see if it answers any of your questions.

    Good Luck
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