Automotive fuse and normal cartridge fuse

Discussion in 'General Electronics Chat' started by CircuitsExplorer, Dec 22, 2008.

  1. CircuitsExplorer

    Thread Starter Member

    Oct 6, 2008
    23
    0
    Dear all,

    I was told by someone that automotive fuse works better than those kind of normal ceramic bodied or glass bodied fuse. Is that true?

    If I were to design a circuit that will make use of the fuses, with voltage at only 24V, can I use the automotive fuse instead of the normal glass or ceramic bodied fuse?

    The high side of the circuit current would be at about 10A, 5V after going through 24V to 5V DC-DC converter.

    Does it matter if I use automotive fuse instead?

    Thanks and best regards
    CircuitsExplorer
     
  2. bertus

    Administrator

    Apr 5, 2008
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  3. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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    No, the fuses rated for 32 volt operation do not work better than the ones rated for 250 volts. But they are guaranteed to blow clear at 12 volts whereas the 250 volt rated ones are pretty iffy at a low voltage.
     
  4. CircuitsExplorer

    Thread Starter Member

    Oct 6, 2008
    23
    0
    Dear all,

    Based on the answers I got, I don't really get it what it means by an automotive fuse rated at 32V at 12V blows clear?

    I hope the below 2 questions can be helped and answered:

    1) Does it mean an automotive fuse rated at 32V will not survive a 12V input voltage? How can that be possible?

    2) And I wish to know whether an automotive fuse is really better in terms of usage as compared to a glass bodied or ceramic bodied normal cylindrical fuse? If yes, why?

    Thanks and best regards
    CircuitsExplorer
     
  5. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
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    CircuitsExplorer, apologies for the spam filter incorrectly picking your post up again. I will jump this thread because of the delay in approval. Check your PMs. Thanks.

    Dave
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    An automotive fuse is best in low voltage usage, as the element will open properly for a fault, whereas a 250 volt rated fuse may not.

    They are not better than 250 volt fuses in any other way, and are usually not available in as many ratings.
     
  7. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    1A @ 250V fuse is not the same as 1A @ 32V fuse.
    P=EI, or Power(Watts) = Voltage * Current(Amperes)

    A 1A, 250V fuse will blow at somewhere over 250 Watts of power dissipation.
    A 1A, 32V fuse will blow at somewhere over 32 Watts of power dissipation.

    Does this make sense to you?
     
  8. leftyretro

    Active Member

    Nov 25, 2008
    394
    2
    1. It means a auto fuse is rated to operate with voltages up to 32 Volts, which includes 12 volt service. Therefore you shouldn't use auto type fuses in like say 120vac applications.

    2. No better, no worst, when operated within their respected specifications. However cylindrical fuses offer ultra-fast, normal and slow blow versions (in some but not all current ratings) for tailoring to one's application better. I think some may think that an auto type fuse might be more rugged against vibration and jots then a cylindrical fuse, but that's just an impression I get, not based on any real data.

    Lefty
     
    Last edited: Jan 8, 2009
  9. leftyretro

    Active Member

    Nov 25, 2008
    394
    2
    That confuses me a little :) Does not a fuse blow based on the heat generated by the current only. I thought the voltage ratings were more for flashover ratings, and such. I've used 250volt rated fuses on 5vdc circuits and have never seem them fail to blow when I screw something up ;)

    Lefty
     
  10. CircuitsExplorer

    Thread Starter Member

    Oct 6, 2008
    23
    0
    Dear all,

    Thanks for the information given.

    The P = IV (this formula I have come across it 18 years ago back in junior school! Of course I know this fundamental), I do know this formula and it is not what I was asking about. Anyway, thanks for that gentle reminder.

    Especially the explanation given on open properly whereas a 250V fuse may not as well as the one on the vibration consideration.

    Thank you very much for the 2 valuable information that I was asking for.

    Best regards
    CircuitsExplorer
     
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