Electronics > Beginners
Actual Fuse Current Rating
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codingwithethanol:
I bought some 1 amp fuses off of Ebay, and I hooked one up to see how accurate the rating was. To my surprise, it didn't blow anywhere near 1 amp. As a matter of fact, I used my PSU to step up the current 100mA at a time, and found that it blew at 1.8 amps! I did this with another and confirmed that it wasn't a fluke. Do you think they sent me 2 amp fuses by accident, or is there something i'm missing here? This could have been a drastic issue, had I actually depended on it to blow at its specified value in a circuit.
Cubdriver:
Fuses blow as a function of heat, and are designed to pass their rated current for some time without failure.  As the current passing increases, the time required for the fuse to open will decrease.  The time for opening will also depend upon the fuse characteristics; there are time lag or slow blow types that intentionally take longer to cope with things like starting surges, and others designed to be extra sensitive and open more quickly.

This may help shed some light:
https://www.allaboutcircuits.com/technical-articles/understanding-the-details-of-fuse-operation-and-implementation/

-Pat

codingwithethanol:
@Cubdriver thank you for the info
wraper:
Rated current is maximum current at which fuse must hold indefinitely. And current you should expect it to blow at within a few seconds generally is around 1.5-2x of rated current.
Nerull:
A 2 amp fuse blowing at 1.8A would be defective.
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