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
, 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.
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
Gimme a break Chris! -
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.
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.
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.
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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