Some fuses will have differing rates that they open at depending on the change of the current.
Well what are you including?
All 4 amp fuses are not the same. Some will open as the rated current is exceeded, others will set there for 30 seconds at the rated current. Some will arc over at higher voltages, other help damp an arc. It might be fun for you to use that new search engine called Google, to try to find more information about fuses. Let us now what you find out that surprises you. Mikek
A fuse heats up, eventually melts, and in doing so, opens the conduction pa th. So in that sense, a fuse is a fuse.
That said, at high enough voltage, an open fuse might still conduct if an a rc can be sustained across the gap. (Thus, there are different voltages ra tings for fuses.)
Then there is the possibility that the fuse might explode. So, more variet ies for that.
Some fuses need to blow quickly, other slowly. So, more varieties for that . The list or requirements goes on and on....
If you are new to fuses (and it sounds like you might be), probably the #1 thing to know is to use the right voltage fuse. Automotive fuses, (like th e ATO, ATC and glass ACG fuses that you mentioned) are usually rated to 32 volts DC. So, don't use them in higher voltage circuits. If you over-volt age the fuse, you can't be certain of interrupting the current as an arc co uld technically form across the fuse, rendering it useless.
Another thing to know: Fuses protect wiring, not equipment. (While they m ay save your equipment, they're really there to keep the wire from overheat ing, potentially causing a fire.) Don't count on a fuse to protect anythi ng else. And obviously, a fuse should be placed near the source of the cur rent (to protect as much wiring as possible). If a short occurs before the fuse, the fuse doesn't do anything (it's not even in the circuit).
I'm sure there's tons of great research about fuses on the web. Find something that's entry level and understandable, and then go from ther e.
BTW: If you are truly desperate for a replacement ACG fuse, did you know y ou can solder-suck out the ends and replace the internal wire yourself? Of course, at that point, you won't really know the fuse rating anymore. But it beats chewing gum wrappers wrapped around the fuse. (Barely.)
** Not really true, the fuses and breakers in your home are rated to protect cabling - but the much smaller fuses in the supply inlet of electronics are there to prevent or limit damage and fire.
If these fuses are ever severely overloaded by say a short, resulting in an end to end arc, the AC supply fuse takes on the job.
BTW
32VDC fuses have lower than usual resistance so they have less effect on low voltage circuits.
IME they are usually OK to use in *AC* circuits to much higher voltages, even 240VAC because AC current is so much easier to break with a short gap.
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