A simple question about MCB 's

Discussion in 'The Projects Forum' started by decelis, Aug 4, 2009.

  1. decelis

    Thread Starter New Member

    Aug 4, 2009
    2
    0
    consider a 240 V 16 A Miniatire Circuit Breaker :


    is that 240 only the maximum voltage ??
    that means - will it still be on if it were supplied by say 50 V? (withouth going over the 16 A obviously).
    a typical case would be - a variac (variable transformer) controling a motor, having the mcb in between. (assume that the motor is freewheeling.)

    thanks, steve


    (btw im a new member here still getting used to the scene.)
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    You can always check the specs on the breaker to be sure, but the 240 volt rating is a guarantee that the device can interrupt an overcurrent at that level of voltage. It should operate fine in a 50 volt situation. If you have any doubts, add a fuse.
     
  3. decelis

    Thread Starter New Member

    Aug 4, 2009
    2
    0
    Thanks m8, your answer was clear.
    (I asked this question coz i always get the rated voltage when i search in spec sheets,, never got any minimum voltage or so ...) but probably its fine - as u said. .
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    You run into minimum voltage ratings with automotive functions. That's why car fuses have 32 volt ratings. They will not guarantee clearing a higher voltage short, but will for the 12 volts in a car's electrical system. A 120 or 240 volt fuse may not interrupt a 12 volt fault.

    That is fuses and not breakers, though.
     
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