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Blown capacitor after close lightning strike

Discussion in 'Technical Discussion' started by Pascal, Aug 22, 2024.

  1. Pascal, Aug 22, 2024
    #1
    Pascal

    Pascal Senior Member

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    We had a close call with lightning on Monday and about 10/15 minutes later I hear a loud short while in the ER. Followed by another on a couple of minutes later coming from the aft corner where our Atlas shorepower system is located. I jumped on the main shutdown even though on board voltage looked ok.

    opened on of the boxes to find a blown capacitor out of the four

    atlas tech came today with four replacements and we re back in business off generator.

    whenever I m on board and a nasty thunderstorm approaches, I usually go to gen and disconnect the shore power plug both on my personal boat and the “office”. Didn’t see that one coming on Monday since i was in the ER working on the fire pump.

    tested most system and so far so good…. Lighting and thunder were pretty much simultaneous, one of my crew said it was a quarter mile off the bow on the spoil island.

    I hate summer! :)

    IMG_2433.jpeg IMG_2432.jpeg
  2. Cpt Sous-Leau, Aug 22, 2024
    #2
    Cpt Sous-Leau

    Cpt Sous-Leau Member

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    This can be avoided by using a decoupling transformer at the shore power of your boat. It's not cheap but will effectively isolate your onboard electrical system from the shore power connection. The transformer will saturate when a spike on the shore side happens, and none of that nasty lightning kilo-voltage will pass through.

    My Carver has one for each two shore legs.
  3. Pascal, Aug 22, 2024
    #3
    Pascal

    Pascal Senior Member

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    Well this a lot more complex than an isolation transformer…. It will take pretty much any shore power you can throw at it anywhere in the world and convert it to 120/240 60hz. We can connect to 1 or 2 single phase 100amp, three phase or even 480 which is what we re using at our home dock. We can connect to 50 hz and it will output 60hz…

    as to isolation transformers the only thing it does is isolate the neutral. If you get a voltage spike in you will get a spike out.
  4. Cpt Sous-Leau, Aug 22, 2024
    #4
    Cpt Sous-Leau

    Cpt Sous-Leau Member

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    Then if that's your situation, you already have an iso transformer(which will not spike kilovolts through), and the cap blew through water contact to the boat. Check your ground plane.


    And, you not only have an iso-transformer, but a complete AC-DC-AC converter to redrive 50 to 60Hz. Alternately, a motor-gen frequency converter(motor running 50, to gen turning 60Hz). That's pretty big commercial kind of electronic support for a pleasure vessel. And, those converters will absolutely not pass a KV lightning strike.
  5. rtrafford, Aug 24, 2024
    #5
    rtrafford

    rtrafford Senior Member

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    Correct. It's an AC to DC to AC conversion. It also boosts and isolates. The invasion likely came by sea...

    Those caps carry big loads. Replaced all of mine recently to resolve some instability issues.