[Tomisimo]

I found quite a few google results for interruptor térmico, but I think that would be translated as thermal switch or thermostat (termostato), which would probably be more involved than what you want (it would probably be a switch that you can reset, whereas this cutout only works once.)

EDIT: I found some more words for this, if it helps. It looks like thermal cutoff, thermal fuse, thermal regulator, temperature switch, temperature fuse, and thermal protector are synonymous with thermal cutout.