Doubt about using fuses. - Page 1
Forum section: electronics / projects

author: gabrielcassio
author_rank: Newbie
timestamp: August 29, 2017, 02:05:13 am
content: Hi to everyone.During my last electronic project, I got a big doubt. It's about using fuses. My PCB is powered by a 50V battery, but the fuses that I find specified the maximum current (20A, 25A max) and the voltage (32V). So this voltage rate is so important for the project? Can I use it normally (the fuse with 32V)? Or should I use a fuse whit higher voltage?I'm figuring out to use the fuses from automobiles.Thanks to everyone with any help.

author: Ian.M
author_rank: Super Contributor
timestamp: August 29, 2017, 02:22:52 am
content: If you exceed the fuses rated voltage , or use a fuse with only an AC rating on DC, it may not clear the arc when it blows, and the extreme heat of a sustained arc is likely to burn the wires connected to it, set the fuse holder on fire or even cause the fuse to violently explode.

author: hermit
author_rank: Frequent Contributor
timestamp: August 29, 2017, 02:25:25 am
content: They don't just make these numbers up.

author: dave_k
author_rank: Frequent Contributor
timestamp: August 29, 2017, 09:32:59 am
content: The JCASE fuse is rated to 58Vhttp://www.littelfuse.com/products/fuses/automotive-passenger-car/cartridge-fuses/895.aspxAvailable from DigiKey

author: tszaboo
author_rank: Super Contributor
timestamp: August 29, 2017, 10:21:18 am
content: High voltage, high current battery, packs will use expensive fuses. There is no safe workaround. Once I saw someone accidently drop a wrench of such battery contacts. We successfully pushed away the wrench with another one, as it started glowing red. I've also seen broken 10KA fuse. It is not fun, when you have to decide, whether to intervene, run for the fire extinguisher, or just run to avoid injury.Get a fuse with the proper rating.

author: Vtile
author_rank: Super Contributor
timestamp: August 29, 2017, 11:06:00 am
content: Plus fuses protect typically from collateral damage. Ie. prevent the meltdown, not to save the operator.

author: Chalky
author_rank: Regular Contributor
timestamp: August 29, 2017, 11:50:17 am
content: Quote from: hermit on August 29, 2017, 02:25:25 amC'mon, that doesn't really help! 'If you knew the answer you wouldn't ask the question' ?

author: Chalky
author_rank: Regular Contributor
timestamp: August 29, 2017, 11:54:27 am
content: Quote from: gabrielcassio on August 29, 2017, 02:05:13 amI think it depends where in the circuit they're used. It'll blow when the amperage is exceeded, but, once blown, the blown fuse won't arc unless the voltage is exceeded.

author: 4CX35000
author_rank: Regular Contributor
timestamp: August 29, 2017, 12:09:21 pm
content: Interesting guides on fuses.http://www.littelfuse.com/~/media/automotive/catalogs/littelfuse_fuseology.pdfhttp://www.littelfuse.com/~/media/electronics/product_catalogs/littelfuse_fuseology_selection_guide.pdf.pdf

author: hermit
author_rank: Frequent Contributor
timestamp: August 30, 2017, 12:20:41 am
content: Quote from: Chalky on August 29, 2017, 11:50:17 amI disagree. It was a concise and informative answer. Trust the ratings because "They don't just make these numbers up." Might not have been the one they wanted, but, it was the correct answer. Why bother telling people to look at data sheets if they don't want to accept the data given?