3 ms·
I'm not going to watch the whole video but it doesn't seem like it supports the point you're trying to make. > How long does it take for your 400mA multimeter
by dns_snek 3y ago
I'm not going to watch the whole video but it doesn't seem like it supports the point you're trying to make.
> How long does it take for your 400mA multimeter fuse to blow at 600mA?
> The amazing unpredictability of fusing current ratings at low overloads.
It makes a point of saying that fuses are imprecise, i.e. that a fuse likely won't blow when 600mA of current passes through a 400mA fuse for a few seconds.
What Rossmann discovered was that fuses from Amazon took 4x the rated current for minutes. That's many orders of magnitude out of spec.
- B1FF_PSUVM 3y ago> 4x the rated current > That's many orders of magnitude An order of magnitude is 10 times, in my timeline.
- dns_snek 3y agoThe relationship between the amount of overload and how fast the fuse is supposed to blow is quadratic, not linear. As an example with somewhat made-up numbers, at 1x it might take hours to blow, at 2x it might take a minute or two, at 3x it shouldn't take more than a second and at 4x it should be nearly instant. If it's supposed to blow in 0.1 seconds when overloaded by 4x, then taking 10 minutes is many orders of magnitude in my book. While that fuse is taking its sweet time, wiring or other components are being heated out of spec (16x more heat at 4x the current), potentially posing a fire hazard or damaging the device it's supposed to be protecting.
- B1FF_PSUVM 3y agoSorry, I misread you, didn't catch you meant the time. Also good point about the possible power damage being quadratic on the current. Thanks for the polite clarification.