Capacitor Insulators

Discussion in 'The Projects Forum' started by Skeebopstop, Jul 4, 2009.

  1. Skeebopstop

    Thread Starter Active Member

    Jan 9, 2009
    358
    3
    Hi all,

    I've seen some high voltage designs use capacitor insulators to add in an effective stand off height to radial caps. I'm wondering how required this is?

    My example: I have high voltage caps and a high voltage copper pour under the radial caps. The clearance to the pins is adequate, however perhaps the base of the cap is susceptible.

    Really just boils down to an insulation question on the general materials on the bottom of electrolytics I guess. The datasheet didn't mention anything.

    Thanks
     
  2. studiot

    AAC Fanatic!

    Nov 9, 2007
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    513
    High voltage tests your insulation and uses any path it can find.

    Sometimes the path is not deliberately inherent in the design materials, but arises because of the environment.

    So operation in a temperature cycled humid atmosphere leads to condensation under components mounted flush with the board.

    Dirt etc can also get in and pose a problem.
     
  3. Skeebopstop

    Thread Starter Active Member

    Jan 9, 2009
    358
    3
    Interesting. I would have never though that the reason.

    Wouldn't this also mean that connectors etc.. should also suffer from this, even those rated to 400V+? For example on my board now, I have a screw terminal which is pretty flush.
     
  4. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
    513
    Yes, the protection process used to be called 'tropicalisation' and used to be achieved with spray varnish. These days terminals etc have shrouds. Think also of the flanges on high voltage test probes. They are there to prevent the HV leaking up along the surface of the probe.
     
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