Connect with us

In Rush Current Limiter

Discussion in 'General Electronics Discussion' started by mbyamukama, Apr 5, 2011.

Scroll to continue with content
  1. mbyamukama

    mbyamukama

    8
    0
    Apr 5, 2011
    Can I use an in-rush Current Limiter in a DC circuit? I have a 12V car battery and i dont want the current to the load to go beyond 7A. I have a 7A current limiter from Ametherm available. Is this possible?
    If not, what alternative doi I have?
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,490
    2,831
    Jan 21, 2010
    What is your load? Can your load draw more than 7A? Normally? or in fault conditions? A fuse is often the device used to limit fault current.

    Please describe more of what you're trying to do, and give some more information about this current limiter (a link to the specs for example)
     
  3. mbyamukama

    mbyamukama

    8
    0
    Apr 5, 2011
    The load should not draw more than 7A. I agree that I should use a fuse, and hence would like to know if there are special fuses for DC in this case. The spec should be a 7A trip voltage and it should operate at 12V. Please take note that it will be on a PCB so size is a very big issue. Thanks.
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,490
    2,831
    Jan 21, 2010
    7A is a current not a voltage -- do you mean 7A trip current?

    What do you want it to do? Limit the current, or act like a re-settable fuse?

    If you want to limit the current then you could well end up dissipating 84 Watts if the output is short circuited. This would require a pretty large heatsink.

    The other option is for it to cut the power if 7A is exceeded. This is easier and would not involve devices dissipating huge amounts of power.
     
  5. mbyamukama

    mbyamukama

    8
    0
    Apr 5, 2011
    Oh, sorry I mean current, not voltage. In short, steve, how do I protect my DC system, running a nominal current of 7A, from a short circuit?
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,490
    2,831
    Jan 21, 2010
    The traditional method is a fuse. Probably something between 10 and 15 amps.
     
  7. mbyamukama

    mbyamukama

    8
    0
    Apr 5, 2011
    Just any fuse? Will I not need a DC fuse...? Can you reccomend from RS or farnell or any of the major providers? Thanks!
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,490
    2,831
    Jan 21, 2010
    Except for some quite exotic uses (really huge currents), it doesn't matter a great deal if you're breaking AC or DC.

    The voltage rating is important, and you'll generally find that 12V is going to be OK for almost any fuse.

    There are many types, your choice depends on factors like the space you have available, whether you want the end user to be able to change it, the speed at which it has to blow, etc., etc.

    Reasonable options range from an in-line or board mounted 3AG fuse, to small surface mount fuses. In some cases, you could even use a very thin trace on your PCB (although that would not be my recommendation).
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-