Are PTC fuses called some other way?

I recently learnt about the existence of PTC fuses, and I'd like to use one for an USB power supply I'm building. I guess there are PTC fuses on the PC side, but you never know.

I went happily to buy some at my local electronic supply store, but unfortunately they said they don't have resettable fuses (weird, they've got almost anything.) Since I'm spanish I didn't ask for PTC fuses, but asked for resettable fuses and explained how they worked, in case they're called something else here at Spain. They didn't have the fuses or knew where I could find them.

I've read PTC fuses are essentially thermistors, is it possible that they know them as thermistor or some other name, instead of resettable fuse?

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I've heard them called polyswitches, polyfuses, multifuses and self-resetting fuses.

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Just a thought the PTC could mean Positive Temperature Coefficent, which would make sense with thermistors as you get 2 basic types PTC and NTC(Negative Temperature Coefficient).

This is what Wikipedia says are some trademark names for PTC Fuses:

These devices are sold by different companies under various trademarks, including PolySwitch (Tyco Electronics),[3] OptiReset (OptiFuse), Everfuse (Polytronics), Polyfuse (Littelfuse) and Multifuse (Bourns, Inc.).

Here is the link to the wikipedia article.

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Already readed Wikipedia's article before asking, of course, but thanks anyways. –  kaoD May 7 '11 at 22:10
@supercat What you described is standard way of thermistor operation. I fail to see how is that different from overloading any other type of resistor. Such reasoning led me to make the last part of my comment:Are you sure you used appropriate thermistors for your job? . If the thermistors keep blowing up, then thermistors which can dissipate larger amounts of heat should be used, so that they don't overload when they start dissipating large amounts of heat. –  AndrejaKo May 8 '11 at 8:02