[postpawl]

I saw an example of this recently during the test of some large DC fuses for solar: https://youtu.be/6o9tbhgtws4?feature=shared

Some are slow burn fuses and don’t pop until you exceed the rated amperage for a long time and by a lot of amperage. Not really what I expected. Some of the fuses do work like you’d expect and pop when they exceed the amperage by a minor amount.

[blagie]

When I was a student, my lab professors had a saying: "Sometimes a fuse will blow to protect the circuit, and sometimes the circuit will blow to protect the fuse."

One problem is that fuses are thermal devices. They break due to overheating. They take a while to warm up and blow. If a fuse overheats at 2A at 100ms, it will get that same amount of energy at at 20A over 1ms, which is an eternity by the standards of transistors.

Most silicon devices can destroy themselves in milliseconds or microseconds.