Results 1 to 4 of 4

Thread: PTC fuses

  1. #1
    Join Date
    Oct 2017
    Location
    Grand Junction, CO
    Posts
    1,593
    Thanks Thanks Given 
    61
    Thanks Thanks Received 
    6
    Thanked in
    6 Posts

    Default PTC fuses

    Are there any ATX power supplies that use PTC (self-resetting) fuses?

    I have a DMM that has a self-resetting fuse, which is very nice, and my washing machine has a self resetting fuse so that when the pump had some shorted windings I was able to figure it out without going through a box of fuses (the pump was working which is what made it so hard to diagnose).

    I also have a breakout box that turns an ATX power into a lab supply but also uses self-resetting fuses so if I accidentally short the outputs all is fine a few seconds later.


    Then again, an ATX power supply shuts itself down on overload without blowing the main fuse, so today's fatigue sees me making a fool of myself yet again ;-)
    Last edited by ashiekh; 1 Week Ago at 09:34 AM.

  2. #2
    Join Date
    Oct 2006
    Location
    jonnyGURU forums, of course!
    Posts
    15,516
    Thanks Thanks Given 
    502
    Thanks Thanks Received 
    46
    Thanked in
    36 Posts

    Default

    Expensive and not really practical for a PSU.

    DMM, yes. PSU? No.

    So.. Fuse blows in a PSU. How often does that happen? Maybe <.01% of units. So you double the cost of the fuse to make things easier for .01% of users?

    And that's assuming you're making life easier for anyone.

    Number of times I've replaced a fuse only to have the fuse blow again because the problem is inside the PSU, not because the fuse was protecting the PSU itself? I'd say 80%. I think their use in PSUs is more along the lines of keeping bad problems from getting worse (fire?) more than anything.

    And finally, fuses in PSUs tend to be fast acting. I've had them blow quite dramatically with shards of glass going everywhere. Pretty sure all of the self-resetting fuses out there are pretty slow.

  3. #3
    Join Date
    Oct 2017
    Location
    Grand Junction, CO
    Posts
    1,593
    Thanks Thanks Given 
    61
    Thanks Thanks Received 
    6
    Thanked in
    6 Posts

    Default

    You are right; I was exhausted that day, and just not thinking straight.

  4. The Following User Says Thank You to ashiekh For This Useful Post:

    Jon Gerow (7 Hours Ago)

  5. #4
    Join Date
    Jul 2009
    Location
    Germany
    Posts
    3,416
    Thanks Thanks Given 
    6
    Thanks Thanks Received 
    12
    Thanked in
    10 Posts

    Default

    Quote Originally Posted by Jon Gerow View Post
    So.. Fuse blows in a PSU. How often does that happen?
    Regularly
    if the PFC section is shorted

    Quote Originally Posted by Jon Gerow View Post
    Number of times I've replaced a fuse only to have the fuse blow again because the problem is inside the PSU, not because the fuse was protecting the PSU itself? I'd say 80%. I think their use in PSUs is more along the lines of keeping bad problems from getting worse (fire?) more than anything.
    Its an additional protection mechanism that trips at lower currents than the breaker in your box. + Cable Lenth and other stuff.
    Yeah, it makes a bit sense. Though to be honest, mostly for lower wattage units.

    And for the Brits: That unit is double fused. One in the Plug, one in the device. And obviously another one in the breaker box...

    But yeah, its mostly to keep the traces from burning inside the PSU...

    With a 2200W PSU; I'd say the fuse makes little sense and is only there for situation where you don't have a breaker...
    Quote Originally Posted by Jon Gerow View Post
    And finally, fuses in PSUs tend to be fast acting. I've had them blow quite dramatically with shards of glass going everywhere. Pretty sure all of the self-resetting fuses out there are pretty slow.
    Well, at least you know when the fuse blew, theoretically
    But sometimes they have a condom around them...

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •