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Thread: SKM let through curves modelling

  1. #1
    Join Date
    Apr 2017
    Location
    USA
    Posts
    19

    SKM let through curves modelling

    Hello,

    I was doing a short circuit study for a particular building.While i was running the SC calculations some results didnt look right to me.Like there was fuse installed on busduct and then you have like 15' cable and then to a panel.Now while i ran the SC calculations fault current on the line side of the fuse is 20kA but on loadside the fault current doesn't change much maybe like 18kA. This doesnt look right to me cause when you have a 200A fuse it restricts lot of SC current.But in SKM it doesnt do that.So i called them and to my surprise they said that they dont model the let through curves in their software for low voltage.

    Does anyone have experience working on SKM that can throw some light on this issue?

    Thanks in advance for answering my question.

  2. #2
    Join Date
    Mar 2013
    Location
    Rutland, VT, USA
    Posts
    234
    I don't have SKM but I am curious on why you would think that the 200A fuse would restrict a lot of fault current? You did not mention if it is a CLF, then it might restrict fault current if the fault current is in the current limit region of the fuse. If it is a standard type fuse it will not limit the amount of fault current.

    Also, if it is a CLF, SKM may have an option checkoff box for CLF.

  3. #3
    Join Date
    Apr 2017
    Location
    USA
    Posts
    19
    Quote Originally Posted by wbdvt View Post
    I don't have SKM but I am curious on why you would think that the 200A fuse would restrict a lot of fault current? You did not mention if it is a CLF, then it might restrict fault current if the fault current is in the current limit region of the fuse. If it is a standard type fuse it will not limit the amount of fault current.

    Also, if it is a CLF, SKM may have an option checkoff box for CLF.
    It is a current limiting fuse...If you look at any manufacturers let through curves, for a given amount of available SC current smaller fuses restrict lot of fault current...like almost half of the available SC current...

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