anatech said:Inrush current waveform?
Otherwise I'm clueless, well to tell the truth I am just plain clueless.![]()
-Chris![]()
This is a record of short-circuit test current of the fuse /y axis multiplier not shown/. I have been designing instruments for measurements in high-power testing plants and high voltage labs for some 25 years.
I am not the fuse designer, so I cannot advice.
The test shown was an AC test, these tests performed also on small type glass fuses according to valid standards. Cut-off current depends on di/dt, for fast slopes (high slew rates
, someone might guess why I sincerely laugh
), the higher di/dt the higher cut-off current, as it is a question of melting integral. Withstand (recovery) voltage is a question of distance and filling material.
The test shown was an AC test, these tests performed also on small type glass fuses according to valid standards. Cut-off current depends on di/dt, for fast slopes (high slew rates
PMA said:Poobah,
quite well, you can see melting current (current shape firstly follows 50Hz shape from short-circuit generator of some 10 - 100kA current, according to test type), fuse wire melts after some 100us and then you can see arc current.
I am sorry I mixed cut-off current and melting current. First you see cut-off current and then melting current.
Hi Pavel,
Thanks, now that makes sense to me. I didn't realise you had enough energy an create an arc as well.
Most people don't understand that a blowing fuse is very much a time lag thing.
Poobah,
If I am correct, the length of the element gives it it's withstand voltage during and after an interruption. My very simplified understanding.
-Chris
Edit: Pavel, I see you answered my question as I was posting.
Thanks, now that makes sense to me. I didn't realise you had enough energy an create an arc as well.
Most people don't understand that a blowing fuse is very much a time lag thing.
Poobah,
If I am correct, the length of the element gives it it's withstand voltage during and after an interruption. My very simplified understanding.
-Chris
Edit: Pavel, I see you answered my question as I was posting.
poobah said:PMA,
Do you know any tricks for extending the interrupting voltage rating of a fuse... this is for a DC application? Right now, I have 60 Volt ratings (SMT fuses) but I may need to increase to 160 Volts. I wish avoid large tubular fuses.
![]()
Try searching the littlefuse site,
I found these , I don't know if it helps you: http://www.littlefuse.com/data/en/Data_Sheets/446_447.pdf
I use other types of littlefuses at work, some SMT you can get sockets for.
\Jens
anatech said:Hi Pavel,
Thanks, now that makes sense to me. I didn't realise you had enough energy an create an arc as well.
-Chris
Hi Chris,
it is not me who has enough power to create arc, but High Power testing plant here in Prague, they have short-circuit generators up to some 63kArms/50Hz/0,1s, and I have been designing a lot of measuring instruments for their short-circuit tests.
Gimme a break Chris! - ![Big grin :D :D](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Thanks Jens,
Those are better at 125 VDC... but I still may need 160. All depends... I am preparing for protracted battle with U.L.
We may be forced to ditch the onboard fuses anyway in favor of in-lines... which I hate because the packages are either cheesey or pricey. One system may require 70 to 140 fuses... so cost is an issue.
![xeye :xeye: :xeye:](https://files.diyaudio.com/forums/images/smilies/xeye.gif)
Thanks Jens,
Those are better at 125 VDC... but I still may need 160. All depends... I am preparing for protracted battle with U.L.
We may be forced to ditch the onboard fuses anyway in favor of in-lines... which I hate because the packages are either cheesey or pricey. One system may require 70 to 140 fuses... so cost is an issue.
![xeye :xeye: :xeye:](https://files.diyaudio.com/forums/images/smilies/xeye.gif)
Hiya poobah!
I thought those fuses would be good for 160VDC. I know interrupting DC is harder that AC. Didn't know that the interrupting voltage rating would be that much lower than the AC rating.
I guess you can't use those fuse board things for the 3AG size either.
-Chris
I thought those fuses would be good for 160VDC. I know interrupting DC is harder that AC. Didn't know that the interrupting voltage rating would be that much lower than the AC rating.
I guess you can't use those fuse board things for the 3AG size either.
-Chris
Right now I have 2 fuse sizes... 2 at 15 Amps & 5 at 0.125 Amps. These are SMT and mounted directly.
The typical interupting voltage is 54 Volts +/-. Under very rare circumstances, an open circuit battery, the interupting voltage could be as high as 160 Volts... I am hoping that U.L. won't realize the very rare circumstance. Or, that I can find a legit solution.
We may well be forced to relocate fusing as close to the batteries as possible... in which case, the SMTs are out of the question anyway. I have yet to find to inline holder that is: about 1$ or less, suitable for high-speed (automatic) termination, NO pigtails with butt splices/crimps, and doesn't look like ****.
EDIT: Inrush... no real numbers... but very small... 2.2 uF @ 13.5 to 54 Volts /with 154K in series. & 100 uF @ 54 Volts /with 100 Ohm in series.
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
The typical interupting voltage is 54 Volts +/-. Under very rare circumstances, an open circuit battery, the interupting voltage could be as high as 160 Volts... I am hoping that U.L. won't realize the very rare circumstance. Or, that I can find a legit solution.
We may well be forced to relocate fusing as close to the batteries as possible... in which case, the SMTs are out of the question anyway. I have yet to find to inline holder that is: about 1$ or less, suitable for high-speed (automatic) termination, NO pigtails with butt splices/crimps, and doesn't look like ****.
EDIT: Inrush... no real numbers... but very small... 2.2 uF @ 13.5 to 54 Volts /with 154K in series. & 100 uF @ 54 Volts /with 100 Ohm in series.
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