Fuses in series?

Discussion in 'General Electronics Chat' started by TheComet, Dec 3, 2013.

  1. TheComet

    Thread Starter Member

    Mar 11, 2013
    88
    12
    What is the purpose of having two fuses in series, and how does this affect the breaking current?

    This is the plug I bought: http://www.digikey.com/product-search/en?x=0&y=0&lang=en&site=us&KeyWords=817-1489-ND

    The holder has space for two fuses, and they are connected in series, as described in the datasheet (image attached).

    I want the fuse to melt at 3A. Can I simply insert 2x 3A fuses (240V) and know that it will act the same as one fuse (240V)?
     
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  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    Dual fusing (or one on the hot and one on the neutral) is an European requirement for power entry modules.
    and yes you simply put a 3A fuse into each.
     
  3. TheComet

    Thread Starter Member

    Mar 11, 2013
    88
    12
    Is this because the voltage is double in Europe?

    Can I use two European 240V rated fuses in series then? Or is this designed for two 110V rated fuses to be used with 240V mains?
     
  4. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    Fairly sure in some parts of Europe there is no distinction between live/neutral and their plugs are asymmetrical so they require fusing on both legs "just in case"..

    The voltage rating of each individual fuse must be greater than the power entry voltage..
     
  5. Electric Al

    Member

    Nov 6, 2013
    58
    8


    You could use as many fuses in series as you want. REDUNDANT!
    It makes no difference , if any fuse blows then the circuit will be open !

    good-work.jpg
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,526
    2,369
    I am not sure of the standard in Switzerland, but I assume you are using 240v like the most of Europe?
    You should only use one fuse if your 240v supply has a one side as an earth grounded neutral.
    If neither side is grounded, then it is OK.
    If the former, you should put a solid non-fusible link in the neutral side for safety.
    In N.A. the only time you would use two fuses if the socket was used on 240v or on a 120v isolated supply.
    This is the reason they offer two types, single and double fused.
    Max.
     
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