Post by thread:[EE] Odd fuse failures

We recently had two of three new machines fail at a customer site with fuses going out. Not too odd, but the mechanism of fuse failure is: the filament became detached at both ends of the fuse, so it was free to roll around inside the fuse (these are the cylindrical glass type). Both fuses had the same role in the machines; neither fuse is unique in the machine, but both machines lost the same fuse and no other. I guess the question is: Have any of you ever seen that kind of failure mode in a fuse caused by overcurrent? There were no obvious signs of a "blown" fuse- no soot inside the glass, or visible breaks in the wire, etc. Of course, the fuses were discarded before they came back to me. Mike H.

Sounds like it may have been defective fuses and a mechanical failure. Do you have any more fuses from the same batch? I'd also contact the fuse company and see if they have any idea about what the failure could be. -Adam On 10/13/06, Mike Hord <spam_OUTmike.hordTakeThisOuTgmail.com> wrote: {Quote hidden}> We recently had two of three new machines fail at a > customer site with fuses going out. Not too odd, but > the mechanism of fuse failure is: the filament became > detached at both ends of the fuse, so it was free to > roll around inside the fuse (these are the cylindrical > glass type). Both fuses had the same role in the > machines; neither fuse is unique in the machine, but > both machines lost the same fuse and no other. > > I guess the question is: Have any of you ever seen > that kind of failure mode in a fuse caused by > overcurrent? There were no obvious signs of a "blown" > fuse- no soot inside the glass, or visible breaks in > the wire, etc. > > Of course, the fuses were discarded before they > came back to me. > > Mike H. > -

On 10/13/06, M. Adam Davis <.....stienmanKILLspam@spam@gmail.com> wrote: > > Sounds like it may have been defective fuses and a mechanical failure. > Do you have any more fuses from the same batch? I'd also contact the > fuse company and see if they have any idea about what the failure > could be. What rating? could be vibration, or high inrush current.

These fuses came pre-installed in the common platform of our machine, which is assembled by a CM. I intend to contact them and see what I can find out along those lines- fuse manufacturer (it's not obviously on the fuse; at least, not that I can recognize), lot, etc. It's odd to me that of eight fuses of the same type, presumably grabbed from the same bucket of fuses during the assembly process, two failed, and those were the same fuse on two different machines. Mike H. > Sounds like it may have been defective fuses and a mechanical failure. > Do you have any more fuses from the same batch? I'd also contact the > fuse company and see if they have any idea about what the failure > could be. > > -Adam

M. Adam Davis wrote: {Quote hidden}> Sounds like it may have been defective fuses and a mechanical failure. > Do you have any more fuses from the same batch? I'd also contact the > fuse company and see if they have any idea about what the failure > could be. > > -Adam > > On 10/13/06, Mike Hord <mike.hordKILLspamgmail.com> wrote: > >> We recently had two of three new machines fail at a >> customer site with fuses going out. Not too odd, but >> the mechanism of fuse failure is: the filament became >> detached at both ends of the fuse, so it was free to >> roll around inside the fuse (these are the cylindrical >> glass type). Both fuses had the same role in the >> machines; neither fuse is unique in the machine, but >> both machines lost the same fuse and no other. >> >> I guess the question is: Have any of you ever seen >> that kind of failure mode in a fuse caused by >> overcurrent? There were no obvious signs of a "blown" >> fuse- no soot inside the glass, or visible breaks in >> the wire, etc. >> >> Of course, the fuses were discarded before they >> came back to me. >> >> Mike H. >> --

> > > It's odd to me that of eight fuses of the same type, presumably grabbed > from the same bucket of fuses during the assembly process, two failed, > and those were the same fuse on two different machines. That makes me think vibration even more. You get nodes that vibrate a lot, and others that vibrate very little. I've seen chips pop out of sockets, and even ceramic chips soldered in that blew their tops.

> That makes me think vibration even more. > You get nodes that vibrate a lot, and others that vibrate very little. > I've seen chips pop out of sockets, and even ceramic chips soldered in that > blew their tops. Very interesting thought. I suppose it's possible. This isn't a new machine, though- we've shipped dozens all over the planet and this is the first time this has happened. The general consensus seems to be that current related failure is not very likely, though. It's a 5A, 125V fuse. Not a slow-blow, so inrush COULD be a factor. The fuses are all mounted cheek-by-jowl on a DIN rail. Mike H. PS- Can anyone give me a satisfactory reason why a fuse has a voltage rating? It just doesn't make sense to me.

On 10/13/06, Mike Hord <.....mike.hordKILLspam.....gmail.com> wrote: > PS- Can anyone give me a satisfactory reason why a fuse has a voltage > rating? It just doesn't make sense to me. The only reason I can see is that fuses are designed to very precisely break at a single point in the fuse wire. A higher voltage fuse must have a longer breaking point so the voltage doesn't arc. As a fuse breaks a spark is drawn across the increasing gap, which also creats a lot of explosive pressure on the fuse casing. A higher voltage will have a hotter, longer lasting arc. There may be other reasons related to the materials, mechanical connection (fuse holder), etc. But I'm merely guessing. Sounds good enough for cocktail parties, though... :-P -Adam

Think its because its a wattage rating. How long were the machines running before they popped? Have they popped again since being replaced? ------------------------------------------------------------------------------------------------------------------------ PS- Can anyone give me a satisfactory reason why a fuse has a voltage rating? It just doesn't make sense to me. --------------------------------- How low will we go? Check out Yahoo! Messenger’s low PC-to-Phone call rates.

> How long were the machines running before they popped? > Have they popped again since being replaced? As far as we can tell, they weren't. We tested them, shipped them, they were setup at the customer site and never worked until the fuse was replaced. That is third hand, of course. The folks that did the initial setup are from a reseller. They told our apps techs what happened, who then discovered the fuse thing. The apps techs told their manager, who told me. Mike H.

Mike Hord wrote: >> How long were the machines running before they popped? >> Have they popped again since being replaced? >> > > As far as we can tell, they weren't. We tested them, shipped > them, they were setup at the customer site and never worked > until the fuse was replaced. > > That is third hand, of course. The folks that did the initial setup > are from a reseller. They told our apps techs what happened, > who then discovered the fuse thing. The apps techs told their > manager, who told me. > > Hmmm. Since you have used these in the past without problems, the install itself is suspect. You MIGHT not have a real problem, Mike. > Mike H. >

Wouldn't you LOVE to get your hands on those fuses and see if there really is something to this? It's too bad that people who recognized that the nature of the failure was extremely unusual (blown at both ends - thought it was unusual enough to mention it) didn't have enough casual curiosity to at least send the fuses back in case you were interested enough to look into it. Dave Mike Hord wrote: {Quote hidden}>> How long were the machines running before they popped? >> Have they popped again since being replaced? >> >> > >As far as we can tell, they weren't. We tested them, shipped >them, they were setup at the customer site and never worked >until the fuse was replaced. > >That is third hand, of course. The folks that did the initial setup >are from a reseller. They told our apps techs what happened, >who then discovered the fuse thing. The apps techs told their >manager, who told me. > >Mike H. > >

-----Original Message----- From: EraseMEpiclist-bouncesspam_OUTTakeThisOuTmit.edu [piclist-bouncesspam_OUTmit.edu] On Behalf Of Mike Hord Sent: Friday, October 13, 2006 2:15 PM To: Microcontroller discussion list - Public. Subject: Re: [EE] Odd fuse failures > That makes me think vibration even more. > You get nodes that vibrate a lot, and others that vibrate very little. > I've seen chips pop out of sockets, and even ceramic chips soldered in that > blew their tops. Very interesting thought. I suppose it's possible. This isn't a new machine, though- we've shipped dozens all over the planet and this is the first time this has happened. The general consensus seems to be that current related failure is not very likely, though. It's a 5A, 125V fuse. Not a slow-blow, so inrush COULD be a factor. The fuses are all mounted cheek-by-jowl on a DIN rail. Mike H. If you think about it the ENDS of the fuse are the greatest heat sink VERY unlikely to fuse there, rather in the middle where the thermal Effect is greatest. * | __O Thomas C. Sefranek @spam@WA1RHPKILLspamARRL.NET |_-\<,_ Amateur Radio Operator: WA1RHP (*)/ (*) Bicycle mobile on 145.41MHz PL74.4 ARRL Instructor, Technical Specialist, VE Contact. hamradio.cmcorp.com/inventory/Inventory.html http://www.harvardrepeater.org

I have a thought on this. I do not know the exact fuse type or shipping conditions. However there are two things that come to mind. 1) We used to have all sorts of unexplained failures at the other end, then we used "shock watch" sensors. Apparently, the problem was not vibration, but the habit of the receiving dock of letting the pallets drop 6 inches to the ground. The fuses ( granted, little tiny spring loaded things), all blew on impact 2) I also had the unnerving experience of watching a board during a thermal endurance test. During the bake, all the fuses failed, not because of the absolute temperature, but because of the fact that they were mounted to a heat sink. The heat sink actually got hot enough to fry the fuses in a hot environment. Again these were spring loaded, and I never was told whether the solder failed or there was a thermal expansion issue, or??? The end result was a fan added to dissipate heat better, as I was told at the time... .... Where are these things being shipped to? Under what conditions? Good luck though. Stuff like this where you aren't there and can't see the remains of the failed part can be nearly impossible to Puzzle out. Regards, Martin {Original Message removed}

Mike, On Fri, 13 Oct 2006 11:09:13 -0500, Mike Hord wrote: >... > > It's odd to me that of eight fuses of the same type, presumably grabbed > from the same bucket of fuses during the assembly process, two failed, > and those were the same fuse on two different machines. Could it be mechanical vibration setting up a resonant frequency that caused the fuses' wires to shake themselves to death? Cheers, Howard Winter St.Albans, England

Let's face it people. It could have been nearly anything that caused those fuses to die. It could have also been that the people installing the machine didn't even put the fuses in. We will never know as there are no fuses to test. {Quote hidden}> > Could it be mechanical vibration setting up a resonant frequency that > caused the fuses' wires to shake themselves to death? > > Cheers, > > > > -- -- Shawn Wilton (b9 Systems) http://b9Systems.com <- New web page

There WERE fuses there. The apps engineer pulled them and replaced them. He just didn't send them home for investigation. And he didn't check OTHER fuses in the system, although they must be working or the machine would've still be offline. I'm leaning towards this being an incredibly unlikely series of events, unlikely to be duplicated and probably not something we'll ever see again. I'm going to talk to our supplier, find out if they've heard any complaints about "broken" fuses elsewhere, and see if they recently changed fuse manufacturer/supplier. Otherwise I don't think there's much to be done- it's not a HUGE problem, since it's something we're aware of now and if something similar happens on delivery again, we will know right away to check those fuses. It's good to know that nobody here has heard of this or has an "easy" answer for it. Mike H. On 10/13/06, Shawn Wilton <KILLspamblack9KILLspamgmail.com> wrote: > Let's face it people. It could have been nearly anything that caused those > fuses to die. It could have also been that the people installing the > machine didn't even put the fuses in. We will never know as there are no > fuses to test. > > Could it be mechanical vibration setting up a resonant frequency that > > caused the fuses' wires to shake themselves to death?

Hi Mike, Recently at work we received a number of large industrial battery chargers with broken fuses in them. It turned out that the fuses (one each in perhaps 10 units) were broken by mechanical stress, probably in shipment. The fuses were not the glass cartrige type but rather forklift type fuses (flat fiberglass package with a mica window and two metal tabs). We were able to determine that the two mounting points for the fuse could move independently, thus placing mechanical stress on the fuse. Also, the bolts holding the fuse in were over-tightened. So, I have seen something similar to what you are describing but it was with a totally different type of fuse. Sean On 10/14/06, Mike Hord <RemoveMEmike.hordTakeThisOuTgmail.com> wrote: {Quote hidden}> There WERE fuses there. The apps engineer pulled them and replaced > them. He just didn't send them home for investigation. > > And he didn't check OTHER fuses in the system, although they must > be working or the machine would've still be offline. > > I'm leaning towards this being an incredibly unlikely series of events, > unlikely to be duplicated and probably not something we'll ever see > again. I'm going to talk to our supplier, find out if they've heard any > complaints about "broken" fuses elsewhere, and see if they recently > changed fuse manufacturer/supplier. Otherwise I don't think there's > much to be done- it's not a HUGE problem, since it's something > we're aware of now and if something similar happens on delivery > again, we will know right away to check those fuses. > > It's good to know that nobody here has heard of this or has an "easy" > answer for it. > > Mike H. >