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high voltage on flat ribbon cables?

Discussion in 'Electronic Design' started by Lou Dietz, Nov 8, 2012.

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  1. Lou Dietz

    Lou Dietz Guest

    Hi all,

    I am working on a product design that requires distributing about 100 high voltage signals between two circuit boards. The max voltage is about 300 to 400 volts, and current flow is just microamps. We have been using 50-pinflat ribbon cables with 0.050" pitch for breadboarding, but are looking for a product-compatible solution. Two ribbon cable manufacturers (3M and TE) spec this type of cable for 300V in USA, but <50V in EU. Even larger-pitch cable and connectors that are spec'ed for 600V in US are still <50V in EU.

    We intend to get UL and CE mark approvals, so we need a product solution that will satisfy the testing agencies. Does anyone have experience with this issue?

    Thanks,
    Lou
     
  2. Robert Baer

    Robert Baer Guest

    Easy, but not cheap: use Teflon(TM) flat cable.
     
  3. legg

    legg Guest

    The EU doesn't 'rate' cabling, but examines the minimum insulation
    thickness, sutability of insulator and termination creepage and
    clearance.

    http://tinyurl.com/avg8k7h

    It could be that the connectors are the issue. If you don't use IDC
    (Insulation Displacement Connectors), then the 60918 (IDC) standards
    will not apply.

    IEC 60183 - Guide to selection of high voltage cables.
    IEC 60227 - PVC insulated cables (up to 450/750V)
    IEC 60245 - Rubber/Silicone insulated cables (up to 450/750V)
    IEC 60287 - Cable current rating
    IEC 60304 - Cable Colour Code
    IEC 60332 - Cable flamability
    IEC 60502 - HV cables an accessories (>1KV)
    IEC 60705 - Polyolefin insulated cables.
    IEC 60754 - cable combustion products.
    IEC 60811 - test methods for cable insulation and sheathing material
    IEC 60918 - PVC insulated ribbon cable for insulation displacement
    connection. (bingo this issue)
    IEC 60986 - RF and coaxial cables

    etc etc..........

    If you have reversed polarity or AC signals, the '400V' may be read
    with different AC, RMS or pk-peak values for rating purposes.

    If the cabling is enclosed

    RL
     
  4. Uwe Hercksen

    Uwe Hercksen Guest

    Hello,

    after a short look in datasheets I found IDC connectors with 2,54 mm
    pitch (0.1 inch) rated for 1000 V eff.

    Bye
     
  5. Lou Dietz

    Lou Dietz Guest


    Thanks, Robert. I see that Gore offers Teflon flat cable, but the voltage rating for the 0.050" pitch cable is still 300 Volts. However, it does notindicate a lower rating for EU, so maybe that is an improvement? or maybe they are just silent on the EU rating. I can't be sure, so I will contact them. Thanks for the tip. -Lou
     
  6. Lou Dietz

    Lou Dietz Guest

    Thanks for the link and info. I'm still not sure how to find the answer though. Do you know anyone who knows how to navigate these specs? Perhaps the safety testing companies? -Lou
     
  7. Robert Baer

    Robert Baer Guest

    Talk to CJ Wire and Cable; these guys actually make cable to order
    and so know the stuff.
    I have in hand EE24(19) 1000V 200C - RED (and - BLACK) which
    indicates to me that your requirement should not be out of line.
     
  8. legg

    legg Guest

    The actual insulation thickness requirement for the application
    (functional voltage and safety isolation) will be listed in the
    relevent IEC safety standard that you're addressing: functional
    insulation between adjacent conductors, or safety insulation between
    conductors and the external environment.

    The standard for the cable type itself merely describes dimensions and
    materials relevent to their manufacturing and inspection, for the
    listed uses. Any similar standard, produced by an accredited source
    would be considered suitable, if it accurately describes the materials
    being used, in an IEC document package for CE.

    Safe insulation barriers may be constructed, independent of the cable
    itself, by adding layers of reognized and appropriate material to meet
    the requirements of the safety standard.

    High voltage energy-limited circuits may also be considered 'safe' if
    there's no stored energy delivered during single-fault contact, or
    residual current in excess of stated limits, depending on the specific
    standard.

    So the safety standard is the place to look first, before determining
    cabling requirements.

    RL
     
  9. Robert Baer

    Robert Baer Guest

    Talk to Bill Thune of CJ Wire and Cable; he is an expert on custom
    and semi-custom stuff.
     
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