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Consider this SW-104T thermal fuse. It has a current rating of 10A.

Does this mean that in addition to its thermal fuse capabilities (blowing at a certain temperature profile), it also behaves as a 10A fuse, and will blow safely when current exceeds 10A (within the parameters of its delay time, maximum voltage, etc)? Or does it just mean that it is specified to operate properly at 10A and below, and if you exceed that it is now out of spec and anything may happen?

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Does this mean that in addition to its thermal fuse capabilities (blowing at a certain temperature profile), it also behaves as a 10A fuse,

No.

Both current and voltage rating are the "safe operating conditions" for the part and your application should stay below these limits. Above this limits, the behavior is "undefined". Chances are, that the fuse will just pop at some point, but that's not guaranteed and you shouldn't design that way. If you need over-current protection, put in an extra current-triggered fuse.

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The data sheet is in German and says this: -

wo Strom und Temperatur aufeinandertreffen und geregelt werden müssen

Using google translate it tells me this: -

enter image description here

So I would say it acts like a 10 amp fuse and a thermal fuse BUT there will be some interaction and the data sheet (being in German) does not help me drill-down further. If in fact the data sheet does not help resolve this you should contact the supplier.

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  • \$\begingroup\$ Thanks, I also took a look at the data sheet and ran into the same barrier. However, my question could be interpreted as a more general one about thermal fuses as well: from a wide variety of providers they seem to have similar temperature and amperage ratings, so what is the general behavior of such fuses? \$\endgroup\$ – BeeOnRope Dec 20 '18 at 19:15
  • \$\begingroup\$ General behavior is that there is no general behavior - it's down to what each data sheet says and studying the graphs in each data sheet. Your device's DS is really poor and unless there was a fuller DS I wouldn't use it in my designs. \$\endgroup\$ – Andy aka Dec 20 '18 at 19:23
  • \$\begingroup\$ Interesting, I never knew thermal fuses varied so much! I'm not using this in a design but trying to evaluate what fuses can be substituted in a design that uses this one. \$\endgroup\$ – BeeOnRope Dec 20 '18 at 20:42

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