Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [fuses]

Questions regarding physical fuses. A fuse is a safety device consisting of a strip of wire that melts and breaks an electric circuit if the current exceeds a safe level. PPTC, PTC, and Polyfuse questions should use the Polyfuse tag. Please keep in mind that repair questions are typically closed if not within the scope of the site and FAQ.

Questions regarding physical fuses. A fuse is a safety device consisting of a strip of wire that melts and breaks an electric circuit if the current exceeds a safe level.

Also known as a fusible link, it is a circuit element that is designed to fail when the fuse rating is met or exceeded. It works on the principal of heating a precisely thinned piece of metal as the current flows through it; too high a current will melt the metal, and the higher the current, the faster the fuse "blows".

Fuses typically are low-resistance until they blow and then they form a "open" (unconnected) circuit. They usually come in two varieties: slow blow and fast blow.

PPTC, PTC, and Polyfuse questions should use the tag.

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Slow Blow vs Fast Acting Fuse

Is there any way to tell the difference between a slow blow and a fast acting Fuse? I had one blow in my amp and I know its 125v 5a, but i'm not sure if it is a slow blow or fast acting fuse. Is there any way to discern the difference after one has…
Sean
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Why did my fuse not blow?

I purchased a few fuses to get familiar with their workings, and I was surprised to see that the 100mA fast-blowing fuses I bought happily conducted up to 215mA (6V power supply, 10\$\Omega\$ resistor), where the filament just started glowing. I…
Duoran
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How does a fuse blow at its current rating, regardless of voltage?

I know from reading elsewhere that it's safe to use a fuse with a higher voltage rating when replacing one, so long as the current rating and reaction speed is the same. For example, if a fuse is rated 125V 1A, then a 250V 1A can be used. Let's say…
JYelton
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Understanding fuse specs

Can somebody please help me in understanding the fuse specifications. Actually i went through many fuse parameters. I am getting cofused between the hold current and the cut-off current since there is a large gap between the two.
IamDp
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Can a fuse be placed after a load?

Considering that the regular treatment of a fuse is to place it on the positive side, "before" a load, is this just common practice, or is it backed by an actual reason? Can a fuse be placed on the negative side, "after" a load? Considering that 1,…
Passerby
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What is the schematic symbol for resettable fuses?

I have seen symbols for one shot fuses and circuit breakers, but not for resettable fuses which reset themselves when the fault goes away. What is the recommended schematic symbol to use?
peteey
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Resettable Fuse: Do they have a "Reset" limit?

Sorry for the confusing question, but for PTC's or Resettable Fuses such as something like this: http://www.sparkfun.com/products/8357 Is there a "limit" on how many......I guess "resets" it can handle? Im assuming it becomes more and more…
user3073
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Fuse position in relation to load and switch

Where should fuse be in relation to the power, switch and load? Any suggestions on a better approach or tips on the matter would also be helpful. POWER > [FUSE] > SWITCH > LOAD POWER > SWITCH > [FUSE] > LOAD
harayz
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Replacing SMD Fuses without access to schematics

I'm curious to know if there is a sane way to determine the specifications of a blown SMD fuse without resorting to manufactures schematics / repair manuals. In my particular case there are no obvious markings on either the board or the component…
nelsonda
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How do I know whether a fuse is a DC fuse or an AC fuse?

For example, I want to buy a 10A 50V DC fuse and a 10A 220V AC fuse online. Which website(s) should I go ? I tried on Mcmaster, but I could not get clear enough information of whether the fuse is an AC type or DC type
Superhero
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Breaking capacity for fuses at mains inlet

Is there any official guidance as to what the breaking capacity should be for a mains inlet fuse? Assuming the appliance is intended to be fed from a normal domestic socket. I understand that in an ideal world, the breaking capacity of a fuse should…
Peter Green
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combine two identical fuses in parallel

I'm thinking: If I have two fuses of same type and rating in parallel, the current would split approx 50/50. If one fuse have a lower resistance, then more current will flow in that, it will get hotter than the other. Then the resistance will rise,…
Lenne
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Using thermal fuses in parallel?

If one has some 216C 10A thermal fuses, could one wire two in parallel in order to fuse a 10A heated bed on a 3d printer? The bed is 110V and 1100W btw, so in normal operation it should draw 10A. Seeing as how this is right at the top of the current…
cds333
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Why are PPTC based fuses not used in power sockets?

I live in the UK. The fuses that I have always seen are the glass fuses which look like this: When they blow they need to be replaced. They are present in all AC plugs. They could also be present in the wall sockets. I recently came across…
quantum231
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Fuse at 250 volts versus fuse at 12 volts

I'm getting mixed answers. Will a 250 volts, 140 amperes fuse blow as fast as with 12 volts?
JustaMe
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